diff --git a/eng/Versions.props b/eng/Versions.props
index 3d628323e1bad..22dc4926a7d55 100644
--- a/eng/Versions.props
+++ b/eng/Versions.props
@@ -94,8 +94,8 @@
     <MicrosoftDiagnosticsRuntimeVersion>0.8.31-beta</MicrosoftDiagnosticsRuntimeVersion>
     <MicrosoftDiagnosticsTracingTraceEventVersion>1.0.35</MicrosoftDiagnosticsTracingTraceEventVersion>
     <MicrosoftDiaSymReaderVersion>1.4.0</MicrosoftDiaSymReaderVersion>
-    <MicrosoftDiaSymReaderConverterVersion>1.1.0-beta2-22273-03</MicrosoftDiaSymReaderConverterVersion>
-    <MicrosoftDiaSymReaderConverterXmlVersion>1.1.0-beta2-22273-03</MicrosoftDiaSymReaderConverterXmlVersion>
+    <MicrosoftDiaSymReaderConverterVersion>1.1.0-beta2-21528-01</MicrosoftDiaSymReaderConverterVersion>
+    <MicrosoftDiaSymReaderConverterXmlVersion>1.1.0-beta2-21528-01</MicrosoftDiaSymReaderConverterXmlVersion>
     <MicrosoftDiaSymReaderNativeVersion>17.0.0-beta1.21524.1</MicrosoftDiaSymReaderNativeVersion>
     <MicrosoftDiaSymReaderPortablePdbVersion>1.7.0-beta-21528-01</MicrosoftDiaSymReaderPortablePdbVersion>
     <MicrosoftExtensionsLoggingVersion>5.0.0</MicrosoftExtensionsLoggingVersion>
diff --git a/src/Compilers/CSharp/Portable/Compiler/MethodCompiler.cs b/src/Compilers/CSharp/Portable/Compiler/MethodCompiler.cs
index 7eca7f0d035e8..9ae7b2f0ac368 100644
--- a/src/Compilers/CSharp/Portable/Compiler/MethodCompiler.cs
+++ b/src/Compilers/CSharp/Portable/Compiler/MethodCompiler.cs
@@ -264,7 +264,6 @@ private static MethodSymbol GetEntryPoint(CSharpCompilation compilation, PEModul
                 VariableSlotAllocator lazyVariableSlotAllocator = null;
                 var lambdaDebugInfoBuilder = ArrayBuilder<LambdaDebugInfo>.GetInstance();
                 var closureDebugInfoBuilder = ArrayBuilder<ClosureDebugInfo>.GetInstance();
-                var stateMachineStateDebugInfoBuilder = ArrayBuilder<StateMachineStateDebugInfo>.GetInstance();
                 StateMachineTypeSymbol stateMachineTypeOpt = null;
                 const int methodOrdinal = -1;
 
@@ -281,7 +280,6 @@ private static MethodSymbol GetEntryPoint(CSharpCompilation compilation, PEModul
                     ref lazyVariableSlotAllocator,
                     lambdaDebugInfoBuilder,
                     closureDebugInfoBuilder,
-                    stateMachineStateDebugInfoBuilder,
                     out stateMachineTypeOpt);
 
                 Debug.Assert((object)lazyVariableSlotAllocator == null);
@@ -289,11 +287,9 @@ private static MethodSymbol GetEntryPoint(CSharpCompilation compilation, PEModul
                 Debug.Assert(dynamicAnalysisSpans.IsEmpty);
                 Debug.Assert(lambdaDebugInfoBuilder.IsEmpty());
                 Debug.Assert(closureDebugInfoBuilder.IsEmpty());
-                Debug.Assert(stateMachineStateDebugInfoBuilder.IsEmpty());
 
                 lambdaDebugInfoBuilder.Free();
                 closureDebugInfoBuilder.Free();
-                stateMachineStateDebugInfoBuilder.Free();
 
                 if (emitMethodBodies)
                 {
@@ -304,7 +300,6 @@ private static MethodSymbol GetEntryPoint(CSharpCompilation compilation, PEModul
                         loweredBody,
                         ImmutableArray<LambdaDebugInfo>.Empty,
                         ImmutableArray<ClosureDebugInfo>.Empty,
-                        ImmutableArray<StateMachineStateDebugInfo>.Empty,
                         stateMachineTypeOpt: null,
                         variableSlotAllocatorOpt: null,
                         diagnostics: diagnostics,
@@ -704,7 +699,6 @@ private void CompileSynthesizedMethods(TypeCompilationState compilationState)
                 return;
             }
 
-            var stateMachineStateDebugInfoBuilder = ArrayBuilder<StateMachineStateDebugInfo>.GetInstance();
             var oldImportChain = compilationState.CurrentImportChain;
             try
             {
@@ -734,13 +728,13 @@ private void CompileSynthesizedMethods(TypeCompilationState compilationState)
                     {
                         // Local functions can be iterators as well as be async (lambdas can only be async), so we need to lower both iterators and async
                         IteratorStateMachine iteratorStateMachine;
-                        BoundStatement loweredBody = IteratorRewriter.Rewrite(methodWithBody.Body, method, methodOrdinal, stateMachineStateDebugInfoBuilder, variableSlotAllocatorOpt, compilationState, diagnosticsThisMethod, out iteratorStateMachine);
+                        BoundStatement loweredBody = IteratorRewriter.Rewrite(methodWithBody.Body, method, methodOrdinal, variableSlotAllocatorOpt, compilationState, diagnosticsThisMethod, out iteratorStateMachine);
                         StateMachineTypeSymbol stateMachine = iteratorStateMachine;
 
                         if (!loweredBody.HasErrors)
                         {
                             AsyncStateMachine asyncStateMachine;
-                            loweredBody = AsyncRewriter.Rewrite(loweredBody, method, methodOrdinal, stateMachineStateDebugInfoBuilder, variableSlotAllocatorOpt, compilationState, diagnosticsThisMethod, out asyncStateMachine);
+                            loweredBody = AsyncRewriter.Rewrite(loweredBody, method, methodOrdinal, variableSlotAllocatorOpt, compilationState, diagnosticsThisMethod, out asyncStateMachine);
 
                             Debug.Assert((object)iteratorStateMachine == null || (object)asyncStateMachine == null);
                             stateMachine = stateMachine ?? asyncStateMachine;
@@ -758,7 +752,6 @@ private void CompileSynthesizedMethods(TypeCompilationState compilationState)
                                 loweredBody,
                                 ImmutableArray<LambdaDebugInfo>.Empty,
                                 ImmutableArray<ClosureDebugInfo>.Empty,
-                                stateMachineStateDebugInfoBuilder.ToImmutable(),
                                 stateMachine,
                                 variableSlotAllocatorOpt,
                                 diagnosticsThisMethod,
@@ -792,14 +785,11 @@ private void CompileSynthesizedMethods(TypeCompilationState compilationState)
                     {
                         Debug.Assert(emittedBody is null);
                     }
-
-                    stateMachineStateDebugInfoBuilder.Clear();
                 }
             }
             finally
             {
                 compilationState.CurrentImportChain = oldImportChain;
-                stateMachineStateDebugInfoBuilder.Free();
             }
         }
 
@@ -879,7 +869,6 @@ private void CompileFieldLikeEventAccessor(SourceEventSymbol eventSymbol, bool i
                         boundBody,
                         ImmutableArray<LambdaDebugInfo>.Empty,
                         ImmutableArray<ClosureDebugInfo>.Empty,
-                        ImmutableArray<StateMachineStateDebugInfo>.Empty,
                         stateMachineTypeOpt: null,
                         variableSlotAllocatorOpt: null,
                         diagnostics: diagnosticsThisMethod,
@@ -1182,7 +1171,6 @@ forSemanticModel.Syntax is { } semanticModelSyntax &&
                 StateMachineTypeSymbol stateMachineTypeOpt = null;
                 var lambdaDebugInfoBuilder = ArrayBuilder<LambdaDebugInfo>.GetInstance();
                 var closureDebugInfoBuilder = ArrayBuilder<ClosureDebugInfo>.GetInstance();
-                var stateMachineStateDebugInfoBuilder = ArrayBuilder<StateMachineStateDebugInfo>.GetInstance();
                 BoundStatement loweredBodyOpt = null;
 
                 try
@@ -1202,7 +1190,6 @@ forSemanticModel.Syntax is { } semanticModelSyntax &&
                             ref lazyVariableSlotAllocator,
                             lambdaDebugInfoBuilder,
                             closureDebugInfoBuilder,
-                            stateMachineStateDebugInfoBuilder,
                             out stateMachineTypeOpt);
 
                         Debug.Assert(loweredBodyOpt != null);
@@ -1255,7 +1242,6 @@ forSemanticModel.Syntax is { } semanticModelSyntax &&
                                     ref lazyVariableSlotAllocator,
                                     lambdaDebugInfoBuilder,
                                     closureDebugInfoBuilder,
-                                    stateMachineStateDebugInfoBuilder,
                                     out initializerStateMachineTypeOpt);
 
                                 processedInitializers.LoweredInitializers = lowered;
@@ -1316,7 +1302,6 @@ forSemanticModel.Syntax is { } semanticModelSyntax &&
                                 boundBody,
                                 lambdaDebugInfoBuilder.ToImmutable(),
                                 closureDebugInfoBuilder.ToImmutable(),
-                                stateMachineStateDebugInfoBuilder.ToImmutable(),
                                 stateMachineTypeOpt,
                                 lazyVariableSlotAllocator,
                                 diagsForCurrentMethod,
@@ -1337,7 +1322,6 @@ forSemanticModel.Syntax is { } semanticModelSyntax &&
                 {
                     lambdaDebugInfoBuilder.Free();
                     closureDebugInfoBuilder.Free();
-                    stateMachineStateDebugInfoBuilder.Free();
                 }
             }
             finally
@@ -1361,7 +1345,6 @@ internal static BoundStatement LowerBodyOrInitializer(
             ref VariableSlotAllocator lazyVariableSlotAllocator,
             ArrayBuilder<LambdaDebugInfo> lambdaDebugInfoBuilder,
             ArrayBuilder<ClosureDebugInfo> closureDebugInfoBuilder,
-            ArrayBuilder<StateMachineStateDebugInfo> stateMachineStateDebugInfoBuilder,
             out StateMachineTypeSymbol stateMachineTypeOpt)
         {
             Debug.Assert(compilationState.ModuleBuilderOpt != null);
@@ -1416,7 +1399,10 @@ internal static BoundStatement LowerBodyOrInitializer(
                     return loweredBody;
                 }
 
-                lazyVariableSlotAllocator ??= compilationState.ModuleBuilderOpt.TryCreateVariableSlotAllocator(method, method, diagnostics.DiagnosticBag);
+                if (lazyVariableSlotAllocator == null)
+                {
+                    lazyVariableSlotAllocator = compilationState.ModuleBuilderOpt.TryCreateVariableSlotAllocator(method, method, diagnostics.DiagnosticBag);
+                }
 
                 BoundStatement bodyWithoutLambdas = loweredBody;
                 if (sawLambdas || sawLocalFunctions)
@@ -1441,7 +1427,7 @@ internal static BoundStatement LowerBodyOrInitializer(
                     return bodyWithoutLambdas;
                 }
 
-                BoundStatement bodyWithoutIterators = IteratorRewriter.Rewrite(bodyWithoutLambdas, method, methodOrdinal, stateMachineStateDebugInfoBuilder, lazyVariableSlotAllocator, compilationState, diagnostics,
+                BoundStatement bodyWithoutIterators = IteratorRewriter.Rewrite(bodyWithoutLambdas, method, methodOrdinal, lazyVariableSlotAllocator, compilationState, diagnostics,
                     out IteratorStateMachine iteratorStateMachine);
 
                 if (bodyWithoutIterators.HasErrors)
@@ -1449,7 +1435,7 @@ internal static BoundStatement LowerBodyOrInitializer(
                     return bodyWithoutIterators;
                 }
 
-                BoundStatement bodyWithoutAsync = AsyncRewriter.Rewrite(bodyWithoutIterators, method, methodOrdinal, stateMachineStateDebugInfoBuilder, lazyVariableSlotAllocator, compilationState, diagnostics,
+                BoundStatement bodyWithoutAsync = AsyncRewriter.Rewrite(bodyWithoutIterators, method, methodOrdinal, lazyVariableSlotAllocator, compilationState, diagnostics,
                     out AsyncStateMachine asyncStateMachine);
 
                 Debug.Assert((object)iteratorStateMachine == null || (object)asyncStateMachine == null);
@@ -1474,7 +1460,6 @@ private static MethodBody GenerateMethodBody(
             BoundStatement block,
             ImmutableArray<LambdaDebugInfo> lambdaDebugInfo,
             ImmutableArray<ClosureDebugInfo> closureDebugInfo,
-            ImmutableArray<StateMachineStateDebugInfo> stateMachineStateDebugInfos,
             StateMachineTypeSymbol stateMachineTypeOpt,
             VariableSlotAllocator variableSlotAllocatorOpt,
             BindingDiagnosticBag diagnostics,
@@ -1624,7 +1609,6 @@ private static MethodBody GenerateMethodBody(
                     stateMachineHoistedLocalScopes,
                     stateMachineHoistedLocalSlots,
                     stateMachineAwaiterSlots,
-                    StateMachineStatesDebugInfo.Create(variableSlotAllocatorOpt, stateMachineStateDebugInfos),
                     moveNextBodyDebugInfoOpt,
                     dynamicAnalysisDataOpt);
             }
diff --git a/src/Compilers/CSharp/Portable/Emitter/EditAndContinue/CSharpDefinitionMap.cs b/src/Compilers/CSharp/Portable/Emitter/EditAndContinue/CSharpDefinitionMap.cs
index 024eafe5e7b33..893d1b9130241 100644
--- a/src/Compilers/CSharp/Portable/Emitter/EditAndContinue/CSharpDefinitionMap.cs
+++ b/src/Compilers/CSharp/Portable/Emitter/EditAndContinue/CSharpDefinitionMap.cs
@@ -192,8 +192,17 @@ protected override ImmutableArray<EncLocalInfo> GetLocalSlotMapFromMetadata(Stan
             return result;
         }
 
-        protected override ITypeSymbolInternal? TryGetStateMachineType(MethodDefinitionHandle methodHandle)
-            => _metadataDecoder.Module.HasStateMachineAttribute(methodHandle, out var typeName) ? _metadataDecoder.GetTypeSymbolForSerializedType(typeName) : null;
+        protected override ITypeSymbolInternal? TryGetStateMachineType(EntityHandle methodHandle)
+        {
+            string typeName;
+            if (_metadataDecoder.Module.HasStringValuedAttribute(methodHandle, AttributeDescription.AsyncStateMachineAttribute, out typeName) ||
+                _metadataDecoder.Module.HasStringValuedAttribute(methodHandle, AttributeDescription.IteratorStateMachineAttribute, out typeName))
+            {
+                return _metadataDecoder.GetTypeSymbolForSerializedType(typeName);
+            }
+
+            return null;
+        }
 
         /// <summary>
         /// Match local declarations to names to generate a map from
diff --git a/src/Compilers/CSharp/Portable/Lowering/AsyncRewriter/AsyncExceptionHandlerRewriter.cs b/src/Compilers/CSharp/Portable/Lowering/AsyncRewriter/AsyncExceptionHandlerRewriter.cs
index d8c903fd0d847..e070c6be33c39 100644
--- a/src/Compilers/CSharp/Portable/Lowering/AsyncRewriter/AsyncExceptionHandlerRewriter.cs
+++ b/src/Compilers/CSharp/Portable/Lowering/AsyncRewriter/AsyncExceptionHandlerRewriter.cs
@@ -135,7 +135,13 @@ public override BoundNode VisitTryStatement(BoundTryStatement node)
             var tryStatementSyntax = node.Syntax;
             // If you add a syntax kind to the assertion below, please also ensure
             // that the scenario has been tested with Edit-and-Continue.
-            Debug.Assert(SyntaxBindingUtilities.BindsToTryStatement(tryStatementSyntax));
+            Debug.Assert(
+                tryStatementSyntax.IsKind(SyntaxKind.TryStatement) ||
+                tryStatementSyntax.IsKind(SyntaxKind.UsingStatement) ||
+                tryStatementSyntax.IsKind(SyntaxKind.ForEachStatement) ||
+                tryStatementSyntax.IsKind(SyntaxKind.ForEachVariableStatement) ||
+                tryStatementSyntax.IsKind(SyntaxKind.LocalDeclarationStatement) ||
+                tryStatementSyntax.IsKind(SyntaxKind.LockStatement));
 
             BoundStatement finalizedRegion;
             BoundBlock rewrittenFinally;
@@ -705,7 +711,7 @@ public override BoundNode VisitLocalFunctionStatement(BoundLocalFunctionStatemen
 
         private AwaitFinallyFrame PushFrame(BoundTryStatement statement)
         {
-            var newFrame = new AwaitFinallyFrame(_currentAwaitFinallyFrame, _analysis.Labels(statement), statement.Syntax);
+            var newFrame = new AwaitFinallyFrame(_currentAwaitFinallyFrame, _analysis.Labels(statement), (StatementSyntax)statement.Syntax);
             _currentAwaitFinallyFrame = newFrame;
             return newFrame;
         }
@@ -884,7 +890,7 @@ private sealed class AwaitFinallyFrame
             public readonly HashSet<LabelSymbol> LabelsOpt;
 
             // the try or using-await statement the frame is associated with
-            private readonly SyntaxNode _syntaxOpt;
+            private readonly StatementSyntax _statementSyntaxOpt;
 
             // proxy labels for branches leaving the frame. 
             // we build this on demand once we encounter leaving branches.
@@ -903,16 +909,20 @@ public AwaitFinallyFrame()
                 // root frame
             }
 
-            public AwaitFinallyFrame(AwaitFinallyFrame parent, HashSet<LabelSymbol> labelsOpt, SyntaxNode syntax)
+            public AwaitFinallyFrame(AwaitFinallyFrame parent, HashSet<LabelSymbol> labelsOpt, StatementSyntax statementSyntax)
             {
                 Debug.Assert(parent != null);
-                Debug.Assert(syntax != null);
+                Debug.Assert(statementSyntax != null);
 
-                Debug.Assert(SyntaxBindingUtilities.BindsToTryStatement(syntax));
+                Debug.Assert(statementSyntax.Kind() == SyntaxKind.TryStatement ||
+                    (statementSyntax.Kind() == SyntaxKind.UsingStatement && ((UsingStatementSyntax)statementSyntax).AwaitKeyword != default) ||
+                    (statementSyntax.Kind() == SyntaxKind.ForEachStatement && ((CommonForEachStatementSyntax)statementSyntax).AwaitKeyword != default) ||
+                    (statementSyntax.Kind() == SyntaxKind.ForEachVariableStatement && ((CommonForEachStatementSyntax)statementSyntax).AwaitKeyword != default) ||
+                    (statementSyntax.Kind() == SyntaxKind.LocalDeclarationStatement && ((LocalDeclarationStatementSyntax)statementSyntax).AwaitKeyword != default));
 
                 this.ParentOpt = parent;
                 this.LabelsOpt = labelsOpt;
-                _syntaxOpt = syntax;
+                _statementSyntaxOpt = statementSyntax;
             }
 
             public bool IsRoot()
@@ -973,8 +983,8 @@ public LabelSymbol ProxyReturnIfNeeded(
                     returnValue = this.returnValue;
                     if (returnValue == null)
                     {
-                        Debug.Assert(_syntaxOpt != null);
-                        this.returnValue = returnValue = new SynthesizedLocal(containingMethod, TypeWithAnnotations.Create(valueOpt.Type), SynthesizedLocalKind.AsyncMethodReturnValue, _syntaxOpt);
+                        Debug.Assert(_statementSyntaxOpt != null);
+                        this.returnValue = returnValue = new SynthesizedLocal(containingMethod, TypeWithAnnotations.Create(valueOpt.Type), SynthesizedLocalKind.AsyncMethodReturnValue, _statementSyntaxOpt);
                     }
                 }
 
diff --git a/src/Compilers/CSharp/Portable/Lowering/AsyncRewriter/AsyncIteratorMethodToStateMachineRewriter.cs b/src/Compilers/CSharp/Portable/Lowering/AsyncRewriter/AsyncIteratorMethodToStateMachineRewriter.cs
index 6a5506952a903..704f12678935d 100644
--- a/src/Compilers/CSharp/Portable/Lowering/AsyncRewriter/AsyncIteratorMethodToStateMachineRewriter.cs
+++ b/src/Compilers/CSharp/Portable/Lowering/AsyncRewriter/AsyncIteratorMethodToStateMachineRewriter.cs
@@ -41,9 +41,9 @@ internal sealed class AsyncIteratorMethodToStateMachineRewriter : AsyncMethodToS
         private readonly LabelSymbol _exprReturnLabelTrue;
 
         /// <summary>
-        /// States for `yield return` are decreasing from <see cref="StateMachineStates.InitialAsyncIteratorState"/>.
+        /// States for `yield return` are decreasing from -3.
         /// </summary>
-        private readonly ResumableStateMachineStateAllocator _iteratorStateAllocator;
+        private int _nextYieldReturnState = StateMachineStates.InitialAsyncIteratorStateMachine;  // -3
 
         internal AsyncIteratorMethodToStateMachineRewriter(MethodSymbol method,
             int methodOrdinal,
@@ -55,40 +55,20 @@ internal AsyncIteratorMethodToStateMachineRewriter(MethodSymbol method,
             IReadOnlySet<Symbol> hoistedVariables,
             IReadOnlyDictionary<Symbol, CapturedSymbolReplacement> nonReusableLocalProxies,
             SynthesizedLocalOrdinalsDispenser synthesizedLocalOrdinals,
-            ArrayBuilder<StateMachineStateDebugInfo> stateMachineStateDebugInfoBuilder,
             VariableSlotAllocator slotAllocatorOpt,
             int nextFreeHoistedLocalSlot,
             BindingDiagnosticBag diagnostics)
             : base(method, methodOrdinal, asyncMethodBuilderMemberCollection, F,
                   state, builder, hoistedVariables, nonReusableLocalProxies, synthesizedLocalOrdinals,
-                  stateMachineStateDebugInfoBuilder, slotAllocatorOpt, nextFreeHoistedLocalSlot, diagnostics)
+                  slotAllocatorOpt, nextFreeHoistedLocalSlot, diagnostics)
         {
             Debug.Assert(asyncIteratorInfo != null);
 
             _asyncIteratorInfo = asyncIteratorInfo;
             _currentDisposalLabel = _exprReturnLabel;
             _exprReturnLabelTrue = F.GenerateLabel("yieldReturn");
-
-            _iteratorStateAllocator = new ResumableStateMachineStateAllocator(
-                slotAllocatorOpt,
-                firstState: StateMachineStates.FirstResumableAsyncIteratorState,
-                increasing: false);
         }
 
-#nullable enable
-        protected override BoundStatement? GenerateMissingStateDispatch()
-        {
-            var asyncDispatch = base.GenerateMissingStateDispatch();
-
-            var iteratorDispatch = _iteratorStateAllocator.GenerateThrowMissingStateDispatch(F, F.Local(cachedState), CodeAnalysisResources.EncCannotResumeSuspendedIteratorMethod);
-            if (iteratorDispatch == null)
-            {
-                return asyncDispatch;
-            }
-
-            return (asyncDispatch != null) ? F.Block(asyncDispatch, iteratorDispatch) : iteratorDispatch;
-        }
-#nullable disable
         protected override BoundStatement GenerateSetResultCall()
         {
             // ... _exprReturnLabel: ...
@@ -217,7 +197,7 @@ protected override BoundBinaryOperator ShouldEnterFinallyBlock()
             // We don't care about state = -2 (method already completed)
 
             // So we only want to enter the finally when the state is -1
-            return F.IntEqual(F.Local(cachedState), F.Literal(StateMachineStates.NotStartedOrRunningState));
+            return F.IntEqual(F.Local(cachedState), F.Literal(StateMachineStates.NotStartedStateMachine));
         }
 
         #region Visitors
@@ -236,7 +216,9 @@ protected override BoundStatement VisitBody(BoundStatement body)
             //  this.state = cachedState = -1;
             //  ... rewritten body
 
-            AddState(StateMachineStates.InitialAsyncIteratorState, out GeneratedLabelSymbol resumeLabel);
+            var initialState = _nextYieldReturnState--;
+            Debug.Assert(initialState == -3);
+            AddState(initialState, out GeneratedLabelSymbol resumeLabel);
 
             var rewrittenBody = (BoundStatement)Visit(body);
 
@@ -244,7 +226,7 @@ protected override BoundStatement VisitBody(BoundStatement body)
             return F.Block(
                 F.Label(resumeLabel), // initialStateResumeLabel:
                 GenerateJumpToCurrentDisposalLabel(), // if (disposeMode) goto _exprReturnLabel;
-                GenerateSetBothStates(StateMachineStates.NotStartedOrRunningState), // this.state = cachedState = -1;
+                GenerateSetBothStates(StateMachineStates.NotStartedStateMachine), // this.state = cachedState = -1;
                 rewrittenBody);
         }
 
@@ -263,7 +245,8 @@ public override BoundNode VisitYieldReturnStatement(BoundYieldReturnStatement no
             //  _promiseOfValueOrEnd.SetResult(true);
             //  return;
 
-            AddResumableState(_iteratorStateAllocator, node.Syntax, out var stateNumber, out GeneratedLabelSymbol resumeLabel);
+            var stateNumber = _nextYieldReturnState--;
+            AddState(stateNumber, out GeneratedLabelSymbol resumeLabel);
 
             var rewrittenExpression = (BoundExpression)Visit(node.Expression);
             var blockBuilder = ArrayBuilder<BoundStatement>.GetInstance();
@@ -288,7 +271,7 @@ public override BoundNode VisitYieldReturnStatement(BoundYieldReturnStatement no
 
             blockBuilder.Add(
                 // this.state = cachedState = NotStartedStateMachine
-                GenerateSetBothStates(StateMachineStates.NotStartedOrRunningState));
+                GenerateSetBothStates(StateMachineStates.NotStartedStateMachine));
 
             Debug.Assert(_currentDisposalLabel is object); // no yield return allowed inside a finally
             blockBuilder.Add(
diff --git a/src/Compilers/CSharp/Portable/Lowering/AsyncRewriter/AsyncMethodToStateMachineRewriter.cs b/src/Compilers/CSharp/Portable/Lowering/AsyncRewriter/AsyncMethodToStateMachineRewriter.cs
index 65634991addeb..54d51eeb76004 100644
--- a/src/Compilers/CSharp/Portable/Lowering/AsyncRewriter/AsyncMethodToStateMachineRewriter.cs
+++ b/src/Compilers/CSharp/Portable/Lowering/AsyncRewriter/AsyncMethodToStateMachineRewriter.cs
@@ -74,11 +74,10 @@ internal AsyncMethodToStateMachineRewriter(
             IReadOnlySet<Symbol> hoistedVariables,
             IReadOnlyDictionary<Symbol, CapturedSymbolReplacement> nonReusableLocalProxies,
             SynthesizedLocalOrdinalsDispenser synthesizedLocalOrdinals,
-            ArrayBuilder<StateMachineStateDebugInfo> stateMachineStateDebugInfoBuilder,
             VariableSlotAllocator slotAllocatorOpt,
             int nextFreeHoistedLocalSlot,
             BindingDiagnosticBag diagnostics)
-            : base(F, method, state, hoistedVariables, nonReusableLocalProxies, synthesizedLocalOrdinals, stateMachineStateDebugInfoBuilder, slotAllocatorOpt, nextFreeHoistedLocalSlot, diagnostics)
+            : base(F, method, state, hoistedVariables, nonReusableLocalProxies, synthesizedLocalOrdinals, slotAllocatorOpt, nextFreeHoistedLocalSlot, diagnostics)
         {
             _method = method;
             _asyncMethodBuilderMemberCollection = asyncMethodBuilderMemberCollection;
@@ -121,12 +120,6 @@ private FieldSymbol GetAwaiterField(TypeSymbol awaiterType)
             return result;
         }
 
-        protected sealed override string EncMissingStateMessage
-            => CodeAnalysisResources.EncCannotResumeSuspendedAsyncMethod;
-
-        protected sealed override int FirstIncreasingResumableState
-            => StateMachineStates.FirstResumableAsyncState;
-
         /// <summary>
         /// Generate the body for <c>MoveNext()</c>.
         /// </summary>
@@ -150,7 +143,7 @@ internal void GenerateMoveNext(BoundStatement body, MethodSymbol moveNextMethod)
                     F.Block(ImmutableArray<LocalSymbol>.Empty,
                         // switch (state) ...
                         F.HiddenSequencePoint(),
-                        Dispatch(isOutermost: true),
+                        Dispatch(),
                         // [body]
                         rewrittenBody
                     ),
@@ -161,7 +154,7 @@ internal void GenerateMoveNext(BoundStatement body, MethodSymbol moveNextMethod)
             bodyBuilder.Add(F.Label(_exprReturnLabel));
 
             // this.state = finishedState
-            var stateDone = F.Assignment(F.Field(F.This(), stateField), F.Literal(StateMachineStates.FinishedState));
+            var stateDone = F.Assignment(F.Field(F.This(), stateField), F.Literal(StateMachineStates.FinishedStateMachine));
             var block = body.Syntax as BlockSyntax;
             if (block == null)
             {
@@ -235,7 +228,7 @@ protected BoundCatchBlock GenerateExceptionHandling(LocalSymbol exceptionLocal,
 
             // _state = finishedState;
             BoundStatement assignFinishedState =
-                F.ExpressionStatement(F.AssignmentExpression(F.Field(F.This(), stateField), F.Literal(StateMachineStates.FinishedState)));
+                F.ExpressionStatement(F.AssignmentExpression(F.Field(F.This(), stateField), F.Literal(StateMachineStates.FinishedStateMachine)));
 
             // builder.SetException(ex);  OR  if (this.combinedTokens != null) this.combinedTokens.Dispose(); _promiseOfValueOrEnd.SetException(ex);
             BoundStatement callSetException = GenerateSetExceptionCall(exceptionLocal);
@@ -443,7 +436,7 @@ private BoundExpression GenerateGetIsCompleted(LocalSymbol awaiterTemp, MethodSy
 
         private BoundBlock GenerateAwaitForIncompleteTask(LocalSymbol awaiterTemp)
         {
-            AddResumableState(awaiterTemp.GetDeclaratorSyntax(), out int stateNumber, out GeneratedLabelSymbol resumeLabel);
+            AddState(out int stateNumber, out GeneratedLabelSymbol resumeLabel);
 
             TypeSymbol awaiterFieldType = awaiterTemp.Type.IsVerifierReference()
                 ? F.SpecialType(SpecialType.System_Object)
@@ -497,7 +490,7 @@ private BoundBlock GenerateAwaitForIncompleteTask(LocalSymbol awaiterTemp)
 
             blockBuilder.Add(
                     // this.state = cachedState = NotStartedStateMachine
-                    GenerateSetBothStates(StateMachineStates.NotStartedOrRunningState));
+                    GenerateSetBothStates(StateMachineStates.NotStartedStateMachine));
 
             return F.Block(blockBuilder.ToImmutableAndFree());
         }
diff --git a/src/Compilers/CSharp/Portable/Lowering/AsyncRewriter/AsyncRewriter.AsyncIteratorRewriter.cs b/src/Compilers/CSharp/Portable/Lowering/AsyncRewriter/AsyncRewriter.AsyncIteratorRewriter.cs
index d65f85549dbca..e445aec99d928 100644
--- a/src/Compilers/CSharp/Portable/Lowering/AsyncRewriter/AsyncRewriter.AsyncIteratorRewriter.cs
+++ b/src/Compilers/CSharp/Portable/Lowering/AsyncRewriter/AsyncRewriter.AsyncIteratorRewriter.cs
@@ -36,11 +36,10 @@ internal AsyncIteratorRewriter(
                 MethodSymbol method,
                 int methodOrdinal,
                 AsyncStateMachine stateMachineType,
-                ArrayBuilder<StateMachineStateDebugInfo> stateMachineStateDebugInfoBuilder,
                 VariableSlotAllocator slotAllocatorOpt,
                 TypeCompilationState compilationState,
                 BindingDiagnosticBag diagnostics)
-                : base(body, method, methodOrdinal, stateMachineType, stateMachineStateDebugInfoBuilder, slotAllocatorOpt, compilationState, diagnostics)
+                : base(body, method, methodOrdinal, stateMachineType, slotAllocatorOpt, compilationState, diagnostics)
             {
                 Debug.Assert(!TypeSymbol.Equals(method.IteratorElementTypeWithAnnotations.Type, null, TypeCompareKind.ConsiderEverything2));
 
@@ -195,7 +194,7 @@ private BoundExpressionStatement GenerateCreateAndAssignBuilder()
             protected override void InitializeStateMachine(ArrayBuilder<BoundStatement> bodyBuilder, NamedTypeSymbol frameType, LocalSymbol stateMachineLocal)
             {
                 // var stateMachineLocal = new {StateMachineType}({initialState})
-                int initialState = _isEnumerable ? StateMachineStates.FinishedState : StateMachineStates.InitialAsyncIteratorState;
+                int initialState = _isEnumerable ? StateMachineStates.FinishedStateMachine : StateMachineStates.InitialAsyncIteratorStateMachine;
                 bodyBuilder.Add(
                     F.Assignment(
                         F.Local(stateMachineLocal),
@@ -323,7 +322,7 @@ private void GenerateIAsyncEnumeratorImplementation_MoveNextAsync()
 
                 BoundStatement ifFinished = F.If(
                     // if (state == StateMachineStates.FinishedStateMachine)
-                    F.IntEqual(F.InstanceField(stateField), F.Literal(StateMachineStates.FinishedState)),
+                    F.IntEqual(F.InstanceField(stateField), F.Literal(StateMachineStates.FinishedStateMachine)),
                     // return default;
                     thenClause: F.Return(F.Default(moveNextAsyncReturnType)));
 
@@ -433,13 +432,13 @@ private void GenerateIAsyncDisposable_DisposeAsync()
 
                 BoundStatement ifInvalidState = F.If(
                     // if (state >= StateMachineStates.NotStartedStateMachine /* -1 */)
-                    F.IntGreaterThanOrEqual(F.InstanceField(stateField), F.Literal(StateMachineStates.NotStartedOrRunningState)),
+                    F.IntGreaterThanOrEqual(F.InstanceField(stateField), F.Literal(StateMachineStates.NotStartedStateMachine)),
                     // throw new NotSupportedException();
                     thenClause: F.Throw(F.New(F.WellKnownType(WellKnownType.System_NotSupportedException))));
 
                 BoundStatement ifFinished = F.If(
                     // if (state == StateMachineStates.FinishedStateMachine)
-                    F.IntEqual(F.InstanceField(stateField), F.Literal(StateMachineStates.FinishedState)),
+                    F.IntEqual(F.InstanceField(stateField), F.Literal(StateMachineStates.FinishedStateMachine)),
                     // return default;
                     thenClause: F.Return(F.Default(returnType)));
 
@@ -651,7 +650,7 @@ private void GenerateIAsyncEnumerableImplementation_GetAsyncEnumerator()
                     .AsMember(IAsyncEnumerableOfElementType);
 
                 BoundExpression managedThreadId = null;
-                GenerateIteratorGetEnumerator(IAsyncEnumerableOfElementType_GetEnumerator, ref managedThreadId, initialState: StateMachineStates.InitialAsyncIteratorState);
+                GenerateIteratorGetEnumerator(IAsyncEnumerableOfElementType_GetEnumerator, ref managedThreadId, initialState: StateMachineStates.InitialAsyncIteratorStateMachine);
             }
 
             protected override void GenerateResetInstance(ArrayBuilder<BoundStatement> builder, int initialState)
@@ -698,7 +697,6 @@ protected override void GenerateMoveNext(SynthesizedImplementationMethod moveNex
                     hoistedVariables: hoistedVariables,
                     nonReusableLocalProxies: nonReusableLocalProxies,
                     synthesizedLocalOrdinals: synthesizedLocalOrdinals,
-                    stateMachineStateDebugInfoBuilder,
                     slotAllocatorOpt: slotAllocatorOpt,
                     nextFreeHoistedLocalSlot: nextFreeHoistedLocalSlot,
                     diagnostics: diagnostics);
diff --git a/src/Compilers/CSharp/Portable/Lowering/AsyncRewriter/AsyncRewriter.cs b/src/Compilers/CSharp/Portable/Lowering/AsyncRewriter/AsyncRewriter.cs
index 6616076c64846..d26488e5948d7 100644
--- a/src/Compilers/CSharp/Portable/Lowering/AsyncRewriter/AsyncRewriter.cs
+++ b/src/Compilers/CSharp/Portable/Lowering/AsyncRewriter/AsyncRewriter.cs
@@ -25,11 +25,10 @@ private AsyncRewriter(
             MethodSymbol method,
             int methodOrdinal,
             AsyncStateMachine stateMachineType,
-            ArrayBuilder<StateMachineStateDebugInfo> stateMachineStateDebugInfoBuilder,
             VariableSlotAllocator slotAllocatorOpt,
             TypeCompilationState compilationState,
             BindingDiagnosticBag diagnostics)
-            : base(body, method, stateMachineType, stateMachineStateDebugInfoBuilder, slotAllocatorOpt, compilationState, diagnostics)
+            : base(body, method, stateMachineType, slotAllocatorOpt, compilationState, diagnostics)
         {
             _constructedSuccessfully = AsyncMethodBuilderMemberCollection.TryCreate(F, method, this.stateMachineType.TypeMap, out _asyncMethodBuilderMemberCollection);
             _methodOrdinal = methodOrdinal;
@@ -42,7 +41,6 @@ internal static BoundStatement Rewrite(
             BoundStatement bodyWithAwaitLifted,
             MethodSymbol method,
             int methodOrdinal,
-            ArrayBuilder<StateMachineStateDebugInfo> stateMachineStateDebugInfoBuilder,
             VariableSlotAllocator slotAllocatorOpt,
             TypeCompilationState compilationState,
             BindingDiagnosticBag diagnostics,
@@ -75,8 +73,8 @@ internal static BoundStatement Rewrite(
             compilationState.ModuleBuilderOpt.CompilationState.SetStateMachineType(method, stateMachineType);
 
             AsyncRewriter rewriter = isAsyncEnumerableOrEnumerator
-                ? new AsyncIteratorRewriter(bodyWithAwaitLifted, method, methodOrdinal, stateMachineType, stateMachineStateDebugInfoBuilder, slotAllocatorOpt, compilationState, diagnostics)
-                : new AsyncRewriter(bodyWithAwaitLifted, method, methodOrdinal, stateMachineType, stateMachineStateDebugInfoBuilder, slotAllocatorOpt, compilationState, diagnostics);
+                ? new AsyncIteratorRewriter(bodyWithAwaitLifted, method, methodOrdinal, stateMachineType, slotAllocatorOpt, compilationState, diagnostics)
+                : new AsyncRewriter(bodyWithAwaitLifted, method, methodOrdinal, stateMachineType, slotAllocatorOpt, compilationState, diagnostics);
 
             if (!rewriter.VerifyPresenceOfRequiredAPIs())
             {
@@ -230,7 +228,7 @@ protected override BoundStatement GenerateStateMachineCreation(LocalSymbol state
             bodyBuilder.Add(
                 F.Assignment(
                     F.Field(F.Local(stateMachineVariable), stateField.AsMember(frameType)),
-                    F.Literal(StateMachineStates.NotStartedOrRunningState)));
+                    F.Literal(StateMachineStates.NotStartedStateMachine)));
 
             // local.$builder.Start(ref local) -- binding to the method AsyncTaskMethodBuilder<typeArgs>.Start()
             var startMethod = methodScopeAsyncMethodBuilderMemberCollection.Start.Construct(frameType);
@@ -267,7 +265,6 @@ protected virtual void GenerateMoveNext(SynthesizedImplementationMethod moveNext
                 hoistedVariables: hoistedVariables,
                 nonReusableLocalProxies: nonReusableLocalProxies,
                 synthesizedLocalOrdinals: synthesizedLocalOrdinals,
-                stateMachineStateDebugInfoBuilder,
                 slotAllocatorOpt: slotAllocatorOpt,
                 nextFreeHoistedLocalSlot: nextFreeHoistedLocalSlot,
                 diagnostics: diagnostics);
diff --git a/src/Compilers/CSharp/Portable/Lowering/IteratorRewriter/IteratorMethodToStateMachineRewriter.IteratorFinallyFrame.cs b/src/Compilers/CSharp/Portable/Lowering/IteratorRewriter/IteratorMethodToStateMachineRewriter.IteratorFinallyFrame.cs
index 24656238528aa..d1acb500db5af 100644
--- a/src/Compilers/CSharp/Portable/Lowering/IteratorRewriter/IteratorMethodToStateMachineRewriter.IteratorFinallyFrame.cs
+++ b/src/Compilers/CSharp/Portable/Lowering/IteratorRewriter/IteratorMethodToStateMachineRewriter.IteratorFinallyFrame.cs
@@ -57,7 +57,7 @@ public IteratorFinallyFrame(
 
             public IteratorFinallyFrame()
             {
-                this.finalizeState = StateMachineStates.NotStartedOrRunningState;
+                this.finalizeState = StateMachineStates.NotStartedStateMachine;
             }
 
             public bool IsRoot()
diff --git a/src/Compilers/CSharp/Portable/Lowering/IteratorRewriter/IteratorMethodToStateMachineRewriter.cs b/src/Compilers/CSharp/Portable/Lowering/IteratorRewriter/IteratorMethodToStateMachineRewriter.cs
index 2b647596d65c3..8de0bbf1aba92 100644
--- a/src/Compilers/CSharp/Portable/Lowering/IteratorRewriter/IteratorMethodToStateMachineRewriter.cs
+++ b/src/Compilers/CSharp/Portable/Lowering/IteratorRewriter/IteratorMethodToStateMachineRewriter.cs
@@ -53,7 +53,7 @@ internal sealed partial class IteratorMethodToStateMachineRewriter : MethodToSta
         /// The purpose of distinct finally states is to have enough information about 
         /// which finally handlers must run when we need to finalize iterator after a fault. 
         /// </summary>
-        private int _nextFinalizeState;
+        private int _nextFinalizeState = StateMachineStates.FinishedStateMachine - 1;  // -3
 
         internal IteratorMethodToStateMachineRewriter(
             SyntheticBoundNodeFactory F,
@@ -63,23 +63,14 @@ internal IteratorMethodToStateMachineRewriter(
             IReadOnlySet<Symbol> hoistedVariables,
             IReadOnlyDictionary<Symbol, CapturedSymbolReplacement> nonReusableLocalProxies,
             SynthesizedLocalOrdinalsDispenser synthesizedLocalOrdinals,
-            ArrayBuilder<StateMachineStateDebugInfo> stateMachineStateDebugInfoBuilder,
             VariableSlotAllocator slotAllocatorOpt,
             int nextFreeHoistedLocalSlot,
             BindingDiagnosticBag diagnostics)
-            : base(F, originalMethod, state, hoistedVariables, nonReusableLocalProxies, synthesizedLocalOrdinals, stateMachineStateDebugInfoBuilder, slotAllocatorOpt, nextFreeHoistedLocalSlot, diagnostics)
+            : base(F, originalMethod, state, hoistedVariables, nonReusableLocalProxies, synthesizedLocalOrdinals, slotAllocatorOpt, nextFreeHoistedLocalSlot, diagnostics)
         {
             _current = current;
-
-            _nextFinalizeState = slotAllocatorOpt?.GetFirstUnusedStateMachineState(increasing: false) ?? StateMachineStates.FirstIteratorFinalizeState;
         }
 
-        protected override string EncMissingStateMessage
-            => CodeAnalysisResources.EncCannotResumeSuspendedIteratorMethod;
-
-        protected override int FirstIncreasingResumableState
-            => StateMachineStates.FirstResumableIteratorState;
-
         internal void GenerateMoveNextAndDispose(BoundStatement body, SynthesizedImplementationMethod moveNextMethod, SynthesizedImplementationMethod disposeMethod)
         {
             // scan body for yielding try blocks
@@ -95,7 +86,9 @@ internal void GenerateMoveNextAndDispose(BoundStatement body, SynthesizedImpleme
             ///////////////////////////////////
 
             F.CurrentFunction = moveNextMethod;
-            AddState(StateMachineStates.InitialIteratorState, out GeneratedLabelSymbol initialLabel);
+            int initialState;
+            GeneratedLabelSymbol initialLabel;
+            AddState(out initialState, out initialLabel);
             var newBody = (BoundStatement)Visit(body);
 
             // switch(cachedState) {
@@ -115,10 +108,10 @@ internal void GenerateMoveNextAndDispose(BoundStatement body, SynthesizedImpleme
                     F.HiddenSequencePoint(),
                     F.Assignment(F.Local(cachedState), F.Field(F.This(), stateField)),
                     CacheThisIfNeeded(),
-                    Dispatch(isOutermost: true),
+                    Dispatch(),
                     GenerateReturn(finished: true),
                     F.Label(initialLabel),
-                    F.Assignment(F.Field(F.This(), stateField), F.Literal(StateMachineStates.NotStartedOrRunningState)),
+                    F.Assignment(F.Field(F.This(), stateField), F.Literal(StateMachineStates.NotStartedStateMachine)),
                     newBody);
 
             //
@@ -328,7 +321,9 @@ public override BoundNode VisitYieldReturnStatement(BoundYieldReturnStatement no
             //     <next_state_label>: ;
             //     <hidden sequence point>
             //     this.state = finalizeState;
-            AddResumableState(node.Syntax, out int stateNumber, out GeneratedLabelSymbol resumeLabel);
+            int stateNumber;
+            GeneratedLabelSymbol resumeLabel;
+            AddState(out stateNumber, out resumeLabel);
             _currentFinallyFrame.AddState(stateNumber);
 
             var rewrittenExpression = (BoundExpression)Visit(node.Expression);
@@ -458,18 +453,11 @@ public override BoundNode VisitTryStatement(BoundTryStatement node)
 
         private IteratorFinallyFrame PushFrame(BoundTryStatement statement)
         {
-            var syntax = statement.Syntax;
-
-            if (slotAllocatorOpt?.TryGetPreviousStateMachineState(syntax, out var finalizeState) != true)
-            {
-                finalizeState = _nextFinalizeState--;
-            }
-
-            AddStateDebugInfo(syntax, finalizeState);
+            var state = _nextFinalizeState--;
 
-            var finallyMethod = MakeSynthesizedFinally(finalizeState);
-            var newFrame = new IteratorFinallyFrame(_currentFinallyFrame, finalizeState, finallyMethod, _yieldsInTryAnalysis.Labels(statement));
-            newFrame.AddState(finalizeState);
+            var finallyMethod = MakeSynthesizedFinally(state);
+            var newFrame = new IteratorFinallyFrame(_currentFinallyFrame, state, finallyMethod, _yieldsInTryAnalysis.Labels(statement));
+            newFrame.AddState(state);
 
             _currentFinallyFrame = newFrame;
             return newFrame;
@@ -486,10 +474,10 @@ private bool ContainsYields(BoundTryStatement statement)
             return _yieldsInTryAnalysis.ContainsYields(statement);
         }
 
-        private IteratorFinallyMethodSymbol MakeSynthesizedFinally(int finalizeState)
+        private IteratorFinallyMethodSymbol MakeSynthesizedFinally(int state)
         {
             var stateMachineType = (IteratorStateMachine)F.CurrentType;
-            var finallyMethod = new IteratorFinallyMethodSymbol(stateMachineType, GeneratedNames.MakeIteratorFinallyMethodName(finalizeState));
+            var finallyMethod = new IteratorFinallyMethodSymbol(stateMachineType, GeneratedNames.MakeIteratorFinallyMethodName(state));
 
             F.ModuleBuilderOpt.AddSynthesizedDefinition(stateMachineType, finallyMethod.GetCciAdapter());
             return finallyMethod;
diff --git a/src/Compilers/CSharp/Portable/Lowering/IteratorRewriter/IteratorRewriter.cs b/src/Compilers/CSharp/Portable/Lowering/IteratorRewriter/IteratorRewriter.cs
index a1429a11033e7..4c3ab2c33e4b2 100644
--- a/src/Compilers/CSharp/Portable/Lowering/IteratorRewriter/IteratorRewriter.cs
+++ b/src/Compilers/CSharp/Portable/Lowering/IteratorRewriter/IteratorRewriter.cs
@@ -30,11 +30,10 @@ private IteratorRewriter(
             MethodSymbol method,
             bool isEnumerable,
             IteratorStateMachine stateMachineType,
-            ArrayBuilder<StateMachineStateDebugInfo> stateMachineStateDebugInfoBuilder,
             VariableSlotAllocator slotAllocatorOpt,
             TypeCompilationState compilationState,
             BindingDiagnosticBag diagnostics)
-            : base(body, method, stateMachineType, stateMachineStateDebugInfoBuilder, slotAllocatorOpt, compilationState, diagnostics)
+            : base(body, method, stateMachineType, slotAllocatorOpt, compilationState, diagnostics)
         {
             // the element type may contain method type parameters, which are now alpha-renamed into type parameters of the generated class
             _elementType = stateMachineType.ElementType;
@@ -49,7 +48,6 @@ internal static BoundStatement Rewrite(
             BoundStatement body,
             MethodSymbol method,
             int methodOrdinal,
-            ArrayBuilder<StateMachineStateDebugInfo> stateMachineStateDebugInfoBuilder,
             VariableSlotAllocator slotAllocatorOpt,
             TypeCompilationState compilationState,
             BindingDiagnosticBag diagnostics,
@@ -82,7 +80,7 @@ internal static BoundStatement Rewrite(
 
             stateMachineType = new IteratorStateMachine(slotAllocatorOpt, compilationState, method, methodOrdinal, isEnumerable, elementType);
             compilationState.ModuleBuilderOpt.CompilationState.SetStateMachineType(method, stateMachineType);
-            var rewriter = new IteratorRewriter(body, method, isEnumerable, stateMachineType, stateMachineStateDebugInfoBuilder, slotAllocatorOpt, compilationState, diagnostics);
+            var rewriter = new IteratorRewriter(body, method, isEnumerable, stateMachineType, slotAllocatorOpt, compilationState, diagnostics);
             if (!rewriter.VerifyPresenceOfRequiredAPIs())
             {
                 return body;
@@ -250,7 +248,7 @@ private void GenerateEnumerableImplementation(ref BoundExpression managedThreadI
             var IEnumerableOfElementType_GetEnumerator = F.SpecialMethod(SpecialMember.System_Collections_Generic_IEnumerable_T__GetEnumerator).AsMember(IEnumerableOfElementType);
 
             // generate GetEnumerator()
-            var getEnumeratorGeneric = GenerateIteratorGetEnumerator(IEnumerableOfElementType_GetEnumerator, ref managedThreadId, StateMachineStates.InitialIteratorState);
+            var getEnumeratorGeneric = GenerateIteratorGetEnumerator(IEnumerableOfElementType_GetEnumerator, ref managedThreadId, StateMachineStates.FirstUnusedState);
 
             // Generate IEnumerable.GetEnumerator
             var getEnumerator = OpenMethodImplementation(IEnumerable_GetEnumerator);
@@ -287,7 +285,7 @@ protected override void InitializeStateMachine(ArrayBuilder<BoundStatement> body
         {
             // var stateMachineLocal = new IteratorImplementationClass(N)
             // where N is either 0 (if we're producing an enumerator) or -2 (if we're producing an enumerable)
-            int initialState = _isEnumerable ? StateMachineStates.FinishedState : StateMachineStates.InitialIteratorState;
+            int initialState = _isEnumerable ? StateMachineStates.FinishedStateMachine : StateMachineStates.FirstUnusedState;
             bodyBuilder.Add(
                 F.Assignment(
                     F.Local(stateMachineLocal),
@@ -320,7 +318,6 @@ private void GenerateMoveNextAndDispose(
                 hoistedVariables,
                 nonReusableLocalProxies,
                 synthesizedLocalOrdinals,
-                stateMachineStateDebugInfoBuilder,
                 slotAllocatorOpt,
                 nextFreeHoistedLocalSlot,
                 diagnostics);
diff --git a/src/Compilers/CSharp/Portable/Lowering/LocalRewriter/LocalRewriter_UsingStatement.cs b/src/Compilers/CSharp/Portable/Lowering/LocalRewriter/LocalRewriter_UsingStatement.cs
index 41ecea365c121..4a7083be57f42 100644
--- a/src/Compilers/CSharp/Portable/Lowering/LocalRewriter/LocalRewriter_UsingStatement.cs
+++ b/src/Compilers/CSharp/Portable/Lowering/LocalRewriter/LocalRewriter_UsingStatement.cs
@@ -186,7 +186,7 @@ private BoundBlock MakeExpressionUsingStatement(BoundUsingStatement node, BoundB
                 expressionStatement = _instrumenter.InstrumentUsingTargetCapture(node, expressionStatement);
             }
 
-            BoundStatement tryFinally = RewriteUsingStatementTryFinally(usingSyntax, usingSyntax, tryBlock, boundTemp, usingSyntax.AwaitKeyword, node.AwaitOpt, node.PatternDisposeInfoOpt);
+            BoundStatement tryFinally = RewriteUsingStatementTryFinally(usingSyntax, tryBlock, boundTemp, usingSyntax.AwaitKeyword, node.AwaitOpt, node.PatternDisposeInfoOpt);
 
             // { ResourceType temp = expr; try { ... } finally { ... } }
             return new BoundBlock(
@@ -229,7 +229,7 @@ private BoundBlock RewriteDeclarationUsingStatement(
             if (boundLocal.ConstantValue == ConstantValue.Null)
             {
                 //localSymbol will be declared by an enclosing block
-                return BoundBlock.SynthesizedNoLocals(declarationSyntax, rewrittenDeclaration, tryBlock);
+                return BoundBlock.SynthesizedNoLocals(usingSyntax, rewrittenDeclaration, tryBlock);
             }
 
             if (localType.IsDynamic())
@@ -250,10 +250,10 @@ private BoundBlock RewriteDeclarationUsingStatement(
                 BoundAssignmentOperator tempAssignment;
                 BoundLocal boundTemp = _factory.StoreToTemp(tempInit, out tempAssignment, kind: SynthesizedLocalKind.Using);
 
-                BoundStatement tryFinally = RewriteUsingStatementTryFinally(usingSyntax, declarationSyntax, tryBlock, boundTemp, awaitKeywordOpt, awaitOpt, patternDisposeInfo);
+                BoundStatement tryFinally = RewriteUsingStatementTryFinally(usingSyntax, tryBlock, boundTemp, awaitKeywordOpt, awaitOpt, patternDisposeInfo);
 
                 return new BoundBlock(
-                    syntax: declarationSyntax,
+                    syntax: usingSyntax,
                     locals: ImmutableArray.Create<LocalSymbol>(boundTemp.LocalSymbol), //localSymbol will be declared by an enclosing block
                     statements: ImmutableArray.Create<BoundStatement>(
                         rewrittenDeclaration,
@@ -262,15 +262,14 @@ private BoundBlock RewriteDeclarationUsingStatement(
             }
             else
             {
-                BoundStatement tryFinally = RewriteUsingStatementTryFinally(usingSyntax, declarationSyntax, tryBlock, boundLocal, awaitKeywordOpt, awaitOpt, patternDisposeInfo);
+                BoundStatement tryFinally = RewriteUsingStatementTryFinally(usingSyntax, tryBlock, boundLocal, awaitKeywordOpt, awaitOpt, patternDisposeInfo);
 
                 // localSymbol will be declared by an enclosing block
-                return BoundBlock.SynthesizedNoLocals(declarationSyntax, rewrittenDeclaration, tryFinally);
+                return BoundBlock.SynthesizedNoLocals(usingSyntax, rewrittenDeclaration, tryFinally);
             }
         }
 
         private BoundStatement RewriteUsingStatementTryFinally(
-            SyntaxNode typeSyntax,
             SyntaxNode syntax,
             BoundBlock tryBlock,
             BoundLocal local,
@@ -353,7 +352,7 @@ private BoundStatement RewriteUsingStatementTryFinally(
 
             if (isNullableValueType)
             {
-                MethodSymbol getValueOrDefault = UnsafeGetNullableMethod(typeSyntax, local.Type, SpecialMember.System_Nullable_T_GetValueOrDefault);
+                MethodSymbol getValueOrDefault = UnsafeGetNullableMethod(syntax, local.Type, SpecialMember.System_Nullable_T_GetValueOrDefault);
                 // local.GetValueOrDefault()
                 disposedExpression = BoundCall.Synthesized(syntax, local, getValueOrDefault);
             }
@@ -363,7 +362,7 @@ private BoundStatement RewriteUsingStatementTryFinally(
                 disposedExpression = local;
             }
 
-            BoundExpression disposeCall = GenerateDisposeCall(typeSyntax, syntax, disposedExpression, patternDisposeInfo, awaitOpt, awaitKeywordOpt);
+            BoundExpression disposeCall = GenerateDisposeCall(syntax, disposedExpression, patternDisposeInfo, awaitOpt, awaitKeywordOpt);
 
             // local.Dispose(); or await variant
             BoundStatement disposeStatement = new BoundExpressionStatement(syntax, disposeCall);
@@ -420,7 +419,6 @@ private BoundStatement RewriteUsingStatementTryFinally(
         }
 
         private BoundExpression GenerateDisposeCall(
-            SyntaxNode typeSyntax,
             SyntaxNode syntax,
             BoundExpression disposedExpression,
             MethodArgumentInfo? disposeInfo,
@@ -436,7 +434,7 @@ private BoundExpression GenerateDisposeCall(
                 if (awaitOpt is null)
                 {
                     // IDisposable.Dispose()
-                    Binder.TryGetSpecialTypeMember(_compilation, SpecialMember.System_IDisposable__Dispose, typeSyntax, _diagnostics, out disposeMethod);
+                    Binder.TryGetSpecialTypeMember(_compilation, SpecialMember.System_IDisposable__Dispose, syntax, _diagnostics, out disposeMethod);
                 }
                 else
                 {
diff --git a/src/Compilers/CSharp/Portable/Lowering/StateMachineRewriter/MethodToStateMachineRewriter.cs b/src/Compilers/CSharp/Portable/Lowering/StateMachineRewriter/MethodToStateMachineRewriter.cs
index f9920cb65fbc8..b0fb061e344da 100644
--- a/src/Compilers/CSharp/Portable/Lowering/StateMachineRewriter/MethodToStateMachineRewriter.cs
+++ b/src/Compilers/CSharp/Portable/Lowering/StateMachineRewriter/MethodToStateMachineRewriter.cs
@@ -22,6 +22,11 @@ internal abstract class MethodToStateMachineRewriter : MethodToClassRewriter
     {
         internal readonly MethodSymbol OriginalMethod;
 
+        /// <summary>
+        /// Generate return statements from the state machine method body.
+        /// </summary>
+        protected abstract BoundStatement GenerateReturn(bool finished);
+
         protected readonly SyntheticBoundNodeFactory F;
 
         /// <summary>
@@ -51,10 +56,7 @@ internal abstract class MethodToStateMachineRewriter : MethodToClassRewriter
         /// </summary>
         protected readonly LocalSymbol cachedThis;
 
-        /// <summary>
-        /// Allocates resumable states, i.e. states that resume execution of the state machine after await expression or yield return.
-        /// </summary>
-        private readonly ResumableStateMachineStateAllocator _resumableStateAllocator;
+        private int _nextState;
 
         /// <summary>
         /// For each distinct label, the set of states that need to be dispatched to that label.
@@ -88,11 +90,6 @@ internal abstract class MethodToStateMachineRewriter : MethodToClassRewriter
         private readonly SynthesizedLocalOrdinalsDispenser _synthesizedLocalOrdinals;
         private int _nextFreeHoistedLocalSlot;
 
-        /// <summary>
-        /// EnC support: the rewriter stores debug info for each await/yield in this builder.
-        /// </summary>
-        private readonly ArrayBuilder<StateMachineStateDebugInfo> _stateDebugInfoBuilder;
-
         // new:
         public MethodToStateMachineRewriter(
             SyntheticBoundNodeFactory F,
@@ -101,7 +98,6 @@ public MethodToStateMachineRewriter(
             IReadOnlySet<Symbol> hoistedVariables,
             IReadOnlyDictionary<Symbol, CapturedSymbolReplacement> nonReusableLocalProxies,
             SynthesizedLocalOrdinalsDispenser synthesizedLocalOrdinals,
-            ArrayBuilder<StateMachineStateDebugInfo> stateMachineStateDebugInfoBuilder,
             VariableSlotAllocator slotAllocatorOpt,
             int nextFreeHoistedLocalSlot,
             BindingDiagnosticBag diagnostics)
@@ -139,27 +135,8 @@ public MethodToStateMachineRewriter(
                 BoundExpression thisProxyReplacement = thisProxy.Replacement(F.Syntax, frameType => F.This());
                 this.cachedThis = F.SynthesizedLocal(thisProxyReplacement.Type, syntax: F.Syntax, kind: SynthesizedLocalKind.FrameCache);
             }
-
-            _stateDebugInfoBuilder = stateMachineStateDebugInfoBuilder;
-
-            // Use the first state number that is not used by any previous version of the state machine
-            // for the first added state that doesn't match any states of the previous state machine.
-            // Note the initial states of the previous and the current state machine are always the same.
-            // Note the previous state machine might not have any non-initial states.
-            _resumableStateAllocator = new ResumableStateMachineStateAllocator(
-                slotAllocatorOpt,
-                firstState: FirstIncreasingResumableState,
-                increasing: true);
         }
 
-        protected abstract int FirstIncreasingResumableState { get; }
-        protected abstract string EncMissingStateMessage { get; }
-
-        /// <summary>
-        /// Generate return statements from the state machine method body.
-        /// </summary>
-        protected abstract BoundStatement GenerateReturn(bool finished);
-
         protected override bool NeedsProxy(Symbol localOrParameter)
         {
             Debug.Assert(localOrParameter.Kind == SymbolKind.Local || localOrParameter.Kind == SymbolKind.Parameter);
@@ -198,66 +175,33 @@ protected override BoundExpression FramePointer(SyntaxNode syntax, NamedTypeSymb
             F.Syntax = oldSyntax;
             return result;
         }
-#nullable enable
-        protected void AddResumableState(SyntaxNode awaitOrYieldReturnSyntax, out int stateNumber, out GeneratedLabelSymbol resumeLabel)
-            => AddResumableState(_resumableStateAllocator, awaitOrYieldReturnSyntax, out stateNumber, out resumeLabel);
 
-        protected void AddResumableState(ResumableStateMachineStateAllocator allocator, SyntaxNode awaitOrYieldReturnSyntax, out int stateNumber, out GeneratedLabelSymbol resumeLabel)
+        protected void AddState(out int stateNumber, out GeneratedLabelSymbol resumeLabel)
         {
-            stateNumber = allocator.AllocateState(awaitOrYieldReturnSyntax);
-            AddStateDebugInfo(awaitOrYieldReturnSyntax, stateNumber);
+            stateNumber = _nextState++;
             AddState(stateNumber, out resumeLabel);
         }
 
-        protected void AddStateDebugInfo(SyntaxNode node, int stateNumber)
-        {
-            Debug.Assert(SyntaxBindingUtilities.BindsToResumableStateMachineState(node) || SyntaxBindingUtilities.BindsToTryStatement(node), $"Unexpected syntax: {node.Kind()}");
-
-            int syntaxOffset = CurrentMethod.CalculateLocalSyntaxOffset(node.SpanStart, node.SyntaxTree);
-            _stateDebugInfoBuilder.Add(new StateMachineStateDebugInfo(syntaxOffset, stateNumber));
-        }
-
         protected void AddState(int stateNumber, out GeneratedLabelSymbol resumeLabel)
         {
-            _dispatches ??= new Dictionary<LabelSymbol, List<int>>();
+            if (_dispatches == null)
+            {
+                _dispatches = new Dictionary<LabelSymbol, List<int>>();
+            }
 
             resumeLabel = F.GenerateLabel("stateMachine");
-            _dispatches.Add(resumeLabel, new List<int> { stateNumber });
+            var states = new List<int>();
+            states.Add(stateNumber);
+            _dispatches.Add(resumeLabel, states);
         }
 
-        /// <summary>
-        /// Generates code that switches over states and jumps to the target labels listed in <see cref="_dispatches"/>.
-        /// </summary>
-        /// <param name="isOutermost">
-        /// If this is the outermost state dispatch switching over all states of the state machine - i.e. not state dispatch generated for a try-block.
-        /// </param>
-        protected BoundStatement Dispatch(bool isOutermost)
-        {
-            var sections = from kv in _dispatches orderby kv.Value[0] select F.SwitchSection(kv.Value, F.Goto(kv.Key));
-            var result = F.Switch(F.Local(cachedState), sections.ToImmutableArray());
-
-            // Suspension states that were generated for any previous generation of the state machine
-            // but are not present in the current version (awaits/yields have been deleted) need to be dispatched to a throw expression.
-            // When an instance of previous version of the state machine is suspended in a state that does not exist anymore
-            // in the current version dispatch that state to a throw expression. We do not know for sure where to resume in the new version of the method.
-            // Guessing would likely result in unexpected behavior. Resuming in an incorrect point might result in an execution of code that
-            // has already been executed or skipping code that initializes some user state.
-            if (isOutermost)
-            {
-                var missingStateDispatch = GenerateMissingStateDispatch();
-                if (missingStateDispatch != null)
-                {
-                    result = F.Block(result, missingStateDispatch);
-                }
-            }
-
-            return result;
+        protected BoundStatement Dispatch()
+        {
+            return F.Switch(F.Local(cachedState),
+                    (from kv in _dispatches orderby kv.Value[0] select F.SwitchSection(kv.Value, F.Goto(kv.Key))).ToImmutableArray()
+                    );
         }
 
-        protected virtual BoundStatement? GenerateMissingStateDispatch()
-            => _resumableStateAllocator.GenerateThrowMissingStateDispatch(F, F.Local(cachedState), EncMissingStateMessage);
-
-#nullable disable
 #if DEBUG
         public override BoundNode VisitSequence(BoundSequence node)
         {
@@ -831,7 +775,7 @@ public override BoundNode VisitTryStatement(BoundTryStatement node)
 
                 tryBlock = F.Block(
                     F.HiddenSequencePoint(),
-                    Dispatch(isOutermost: false),
+                    Dispatch(),
                     tryBlock);
 
                 oldDispatches ??= new Dictionary<LabelSymbol, List<int>>();
diff --git a/src/Compilers/CSharp/Portable/Lowering/StateMachineRewriter/ResumableStateMachineStateAllocator.cs b/src/Compilers/CSharp/Portable/Lowering/StateMachineRewriter/ResumableStateMachineStateAllocator.cs
deleted file mode 100644
index edb186992cd70..0000000000000
--- a/src/Compilers/CSharp/Portable/Lowering/StateMachineRewriter/ResumableStateMachineStateAllocator.cs
+++ /dev/null
@@ -1,95 +0,0 @@
-// Licensed to the .NET Foundation under one or more agreements.
-// The .NET Foundation licenses this file to you under the MIT license.
-// See the LICENSE file in the project root for more information.
-
-using System;
-using System.Diagnostics;
-using Microsoft.CodeAnalysis.CodeGen;
-using Microsoft.CodeAnalysis.CSharp.Syntax;
-
-namespace Microsoft.CodeAnalysis.CSharp
-{
-    /// <summary>
-    /// Allocates resumable states, i.e. states that resume execution of the state machine after await expression or yield return.
-    /// </summary>
-    internal sealed class ResumableStateMachineStateAllocator
-    {
-        private readonly VariableSlotAllocator? _slotAllocator;
-        private readonly bool _increasing;
-        private readonly int _firstState;
-
-        /// <summary>
-        /// The number of the next generated resumable state (i.e. state that resumes execution of the state machine after await expression or yield return).
-        /// </summary>
-        private int _nextState;
-
-#if DEBUG
-        /// <summary>
-        /// EnC support: states in this state machine that were matched to states of the previous generation state machine.
-        /// </summary>
-        private BitVector _matchedStates = BitVector.Empty;
-#endif
-        /// <summary>
-        /// EnC support: number of states in this state machine that match states of the previous generation state machine.
-        /// </summary>
-        private int _matchedStateCount;
-
-        public ResumableStateMachineStateAllocator(VariableSlotAllocator? slotAllocator, int firstState, bool increasing)
-        {
-            _increasing = increasing;
-            _slotAllocator = slotAllocator;
-            _matchedStateCount = 0;
-            _firstState = firstState;
-            _nextState = slotAllocator?.GetFirstUnusedStateMachineState(increasing) ?? firstState;
-        }
-
-        public int AllocateState(SyntaxNode awaitOrYieldReturnSyntax)
-        {
-            Debug.Assert(SyntaxBindingUtilities.BindsToResumableStateMachineState(awaitOrYieldReturnSyntax));
-
-            int direction = _increasing ? +1 : -1;
-
-            if (_slotAllocator?.TryGetPreviousStateMachineState(awaitOrYieldReturnSyntax, out var stateNumber) == true)
-            {
-#if DEBUG
-                // two states of the new state machine should not match the same state of the previous machine:
-                Debug.Assert(!_matchedStates[stateNumber * direction]);
-                _matchedStates[stateNumber * direction] = true;
-#endif
-                _matchedStateCount++;
-            }
-            else
-            {
-                stateNumber = _nextState;
-                _nextState += direction;
-            }
-
-            return stateNumber;
-        }
-
-        /// <summary>
-        /// True if any of the states generated for any previous state machine has not been allocated in this version.
-        /// </summary>
-        public bool HasMissingStates
-            => _matchedStateCount < Math.Abs((_slotAllocator?.GetFirstUnusedStateMachineState(_increasing) ?? _firstState) - _firstState);
-
-        public BoundStatement? GenerateThrowMissingStateDispatch(SyntheticBoundNodeFactory f, BoundExpression cachedState, string message)
-        {
-            if (!HasMissingStates)
-            {
-                return null;
-            }
-
-            return f.If(
-                f.Binary(
-                    _increasing ? BinaryOperatorKind.IntGreaterThanOrEqual : BinaryOperatorKind.IntLessThanOrEqual,
-                    f.SpecialType(SpecialType.System_Boolean),
-                    cachedState,
-                    f.Literal(_firstState)),
-                f.Throw(
-                    f.New(
-                        f.WellKnownMethod(WellKnownMember.System_InvalidOperationException__ctorString),
-                        f.StringLiteral(ConstantValue.Create(message)))));
-        }
-    }
-}
diff --git a/src/Compilers/CSharp/Portable/Lowering/StateMachineRewriter/StateMachineRewriter.cs b/src/Compilers/CSharp/Portable/Lowering/StateMachineRewriter/StateMachineRewriter.cs
index 0ef6f322a3bd2..0616f66995d3a 100644
--- a/src/Compilers/CSharp/Portable/Lowering/StateMachineRewriter/StateMachineRewriter.cs
+++ b/src/Compilers/CSharp/Portable/Lowering/StateMachineRewriter/StateMachineRewriter.cs
@@ -25,7 +25,6 @@ internal abstract class StateMachineRewriter
         protected readonly SynthesizedContainer stateMachineType;
         protected readonly VariableSlotAllocator slotAllocatorOpt;
         protected readonly SynthesizedLocalOrdinalsDispenser synthesizedLocalOrdinals;
-        protected readonly ArrayBuilder<StateMachineStateDebugInfo> stateMachineStateDebugInfoBuilder;
 
         protected FieldSymbol stateField;
         protected IReadOnlyDictionary<Symbol, CapturedSymbolReplacement> nonReusableLocalProxies;
@@ -38,7 +37,6 @@ protected StateMachineRewriter(
             BoundStatement body,
             MethodSymbol method,
             SynthesizedContainer stateMachineType,
-            ArrayBuilder<StateMachineStateDebugInfo> stateMachineStateDebugInfoBuilder,
             VariableSlotAllocator slotAllocatorOpt,
             TypeCompilationState compilationState,
             BindingDiagnosticBag diagnostics)
@@ -49,12 +47,10 @@ protected StateMachineRewriter(
             Debug.Assert(compilationState != null);
             Debug.Assert(diagnostics != null);
             Debug.Assert(diagnostics.DiagnosticBag != null);
-            Debug.Assert(stateMachineStateDebugInfoBuilder.IsEmpty());
 
             this.body = body;
             this.method = method;
             this.stateMachineType = stateMachineType;
-            this.stateMachineStateDebugInfoBuilder = stateMachineStateDebugInfoBuilder;
             this.slotAllocatorOpt = slotAllocatorOpt;
             this.synthesizedLocalOrdinals = new SynthesizedLocalOrdinalsDispenser();
             this.diagnostics = diagnostics;
@@ -437,7 +433,7 @@ protected SynthesizedImplementationMethod GenerateIteratorGetEnumerator(MethodSy
                 makeIterator = F.If(
                     // if (this.state == -2 && this.initialThreadId == Thread.CurrentThread.ManagedThreadId)
                     condition: F.LogicalAnd(
-                        F.IntEqual(F.Field(F.This(), stateField), F.Literal(StateMachineStates.FinishedState)),
+                        F.IntEqual(F.Field(F.This(), stateField), F.Literal(StateMachineStates.FinishedStateMachine)),
                         F.IntEqual(F.Field(F.This(), initialThreadIdField), managedThreadId)),
                     thenClause: F.Block(thenBuilder.ToImmutableAndFree()),
                     elseClauseOpt: makeIterator);
diff --git a/src/Compilers/CSharp/Portable/Lowering/StateMachineRewriter/StateMachineStates.cs b/src/Compilers/CSharp/Portable/Lowering/StateMachineRewriter/StateMachineStates.cs
index 2f17bf33c8c4b..debc8437de81e 100644
--- a/src/Compilers/CSharp/Portable/Lowering/StateMachineRewriter/StateMachineStates.cs
+++ b/src/Compilers/CSharp/Portable/Lowering/StateMachineRewriter/StateMachineStates.cs
@@ -2,38 +2,17 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 // See the LICENSE file in the project root for more information.
 
+#nullable disable
+
 namespace Microsoft.CodeAnalysis.CSharp
 {
     internal static class StateMachineStates
     {
-        internal const int FirstIteratorFinalizeState = -3;
-
-        internal const int FinishedState = -2;
-        internal const int NotStartedOrRunningState = -1;
+        internal const int FinishedStateMachine = -2;
+        internal const int NotStartedStateMachine = -1;
         internal const int FirstUnusedState = 0;
 
-        /// <summary>
-        /// First state in async state machine that is used to resume the machine after await.
-        /// </summary>
-        internal const int FirstResumableAsyncState = 0;
-
-        internal const int InitialIteratorState = 0;
-
-        /// <summary>
-        /// First state in iterator state machine that is used to resume the machine after yield return.
-        /// Initial state is not used to resume state machine that yielded.
-        /// </summary>
-        internal const int FirstResumableIteratorState = InitialIteratorState + 1;
-
-        /// <summary>
-        /// Used for async-iterators to distinguish initial state from <see cref="NotStartedOrRunningState"/> so that DisposeAsync can throw in latter case.
-        /// </summary>
-        internal const int InitialAsyncIteratorState = -3;
-
-        /// <summary>
-        /// First state in async iterator state machine that is used to resume the machine after yield return.
-        /// Initial state is not used to resume state machine that yielded.
-        /// </summary>
-        internal const int FirstResumableAsyncIteratorState = InitialAsyncIteratorState - 1;
+        // used for async-iterators to distinguish initial state from running state (-1) so that DisposeAsync can throw in latter case
+        internal const int InitialAsyncIteratorStateMachine = -3;
     }
 }
diff --git a/src/Compilers/CSharp/Portable/Lowering/SyntheticBoundNodeFactory.cs b/src/Compilers/CSharp/Portable/Lowering/SyntheticBoundNodeFactory.cs
index 520961b991669..0e80a7df79155 100644
--- a/src/Compilers/CSharp/Portable/Lowering/SyntheticBoundNodeFactory.cs
+++ b/src/Compilers/CSharp/Portable/Lowering/SyntheticBoundNodeFactory.cs
@@ -983,9 +983,7 @@ public BoundStatement Switch(BoundExpression ex, ImmutableArray<SyntheticSwitchS
             }
 
             CheckSwitchSections(sections);
-
             GeneratedLabelSymbol breakLabel = new GeneratedLabelSymbol("break");
-
             var caseBuilder = ArrayBuilder<(ConstantValue Value, LabelSymbol label)>.GetInstance();
             var statements = ArrayBuilder<BoundStatement>.GetInstance();
             statements.Add(null!); // placeholder at statements[0] for the dispatch
diff --git a/src/Compilers/CSharp/Portable/Symbols/Synthesized/GeneratedNames.cs b/src/Compilers/CSharp/Portable/Symbols/Synthesized/GeneratedNames.cs
index cf9acb4bcd6e0..bb89a163099c0 100644
--- a/src/Compilers/CSharp/Portable/Symbols/Synthesized/GeneratedNames.cs
+++ b/src/Compilers/CSharp/Portable/Symbols/Synthesized/GeneratedNames.cs
@@ -26,14 +26,16 @@ internal static string MakeBackingFieldName(string propertyName)
             return "<" + propertyName + ">k__BackingField";
         }
 
-        internal static string MakeIteratorFinallyMethodName(int finalizeState)
-        {
-            Debug.Assert(finalizeState < -2);
-
-            // It is important that the name is only derived from the finalizeState, so that when 
-            // editing method during EnC the Finally methods corresponding to matching states have matching names.
+        internal static string MakeIteratorFinallyMethodName(int iteratorState)
+        {
+            // we can pick any name, but we will try to do
+            // <>m__Finally1
+            // <>m__Finally2
+            // <>m__Finally3
+            // . . . 
+            // that will roughly match native naming scheme and may also be easier when need to debug.
             Debug.Assert((char)GeneratedNameKind.IteratorFinallyMethod == 'm');
-            return "<>m__Finally" + StringExtensions.GetNumeral(-(finalizeState + 2));
+            return "<>m__Finally" + StringExtensions.GetNumeral(Math.Abs(iteratorState + 2));
         }
 
         internal static string MakeStaticLambdaDisplayClassName(int methodOrdinal, int generation)
diff --git a/src/Compilers/CSharp/Portable/Syntax/SyntaxBindingUtilities.cs b/src/Compilers/CSharp/Portable/Syntax/SyntaxBindingUtilities.cs
deleted file mode 100644
index 16800dd4ecb8e..0000000000000
--- a/src/Compilers/CSharp/Portable/Syntax/SyntaxBindingUtilities.cs
+++ /dev/null
@@ -1,27 +0,0 @@
-// Licensed to the .NET Foundation under one or more agreements.
-// The .NET Foundation licenses this file to you under the MIT license.
-// See the LICENSE file in the project root for more information.
-
-using System;
-using System.Collections.Generic;
-using System.Text;
-
-namespace Microsoft.CodeAnalysis.CSharp.Syntax
-{
-    internal static class SyntaxBindingUtilities
-    {
-        public static bool BindsToResumableStateMachineState(SyntaxNode node)
-            => node.IsKind(SyntaxKind.YieldReturnStatement) ||
-               node.IsKind(SyntaxKind.AwaitExpression) ||
-               node is CommonForEachStatementSyntax { AwaitKeyword.RawKind: not 0 }
-                    or VariableDeclaratorSyntax { Parent.Parent: UsingStatementSyntax { AwaitKeyword.RawKind: not 0 } or LocalDeclarationStatementSyntax { AwaitKeyword.RawKind: not 0 } }
-                    or UsingStatementSyntax { Expression: not null, AwaitKeyword.RawKind: not 0 };
-
-        public static bool BindsToTryStatement(SyntaxNode node)
-            => node is VariableDeclaratorSyntax { Parent.Parent: UsingStatementSyntax { } or LocalDeclarationStatementSyntax { UsingKeyword.RawKind: not 0 } }
-                    or UsingStatementSyntax { Expression: not null }
-                    or CommonForEachStatementSyntax
-                    or TryStatementSyntax
-                    or LockStatementSyntax;
-    }
-}
diff --git a/src/Compilers/CSharp/Test/Emit/CodeGen/CodeGenAsyncEHTests.cs b/src/Compilers/CSharp/Test/Emit/CodeGen/CodeGenAsyncEHTests.cs
index 74d72686e20ea..7d612c9e4f045 100644
--- a/src/Compilers/CSharp/Test/Emit/CodeGen/CodeGenAsyncEHTests.cs
+++ b/src/Compilers/CSharp/Test/Emit/CodeGen/CodeGenAsyncEHTests.cs
@@ -973,10 +973,6 @@ public static void Main()
           <slot kind=""28"" offset=""156"" />
           <slot kind=""28"" offset=""156"" ordinal=""1"" />
         </encLocalSlotMap>
-        <encStateMachineStateMap>
-          <state number=""0"" offset=""65"" />
-          <state number=""1"" offset=""156"" />
-        </encStateMachineStateMap>
       </customDebugInfo>
     </method>
   </methods>
diff --git a/src/Compilers/CSharp/Test/Emit/CodeGen/CodeGenAsyncLocalsTests.cs b/src/Compilers/CSharp/Test/Emit/CodeGen/CodeGenAsyncLocalsTests.cs
index d4349b1c7f0dd..ceecdf8225a84 100644
--- a/src/Compilers/CSharp/Test/Emit/CodeGen/CodeGenAsyncLocalsTests.cs
+++ b/src/Compilers/CSharp/Test/Emit/CodeGen/CodeGenAsyncLocalsTests.cs
@@ -364,14 +364,6 @@ public async Task M(IDisposable disposable)
               <slot kind=""3"" offset=""410"" />
               <slot kind=""2"" offset=""410"" />
             </encLocalSlotMap>
-            <encStateMachineStateMap>
-              <state number=""0"" offset=""74"" />
-              <state number=""1"" offset=""172"" />
-              <state number=""2"" offset=""281"" />
-              <state number=""3"" offset=""261"" />
-              <state number=""4"" offset=""241"" />
-              <state number=""5"" offset=""328"" />
-            </encStateMachineStateMap>
           </customDebugInfo>
         </method>
       </methods>
diff --git a/src/Compilers/CSharp/Test/Emit/Emit/EditAndContinue/EditAndContinuePdbTests.cs b/src/Compilers/CSharp/Test/Emit/Emit/EditAndContinue/EditAndContinuePdbTests.cs
index 5b12f12413060..76f7d9a55e97e 100644
--- a/src/Compilers/CSharp/Test/Emit/Emit/EditAndContinue/EditAndContinuePdbTests.cs
+++ b/src/Compilers/CSharp/Test/Emit/Emit/EditAndContinue/EditAndContinuePdbTests.cs
@@ -23,7 +23,7 @@ public class EditAndContinuePdbTests : EditAndContinueTestBase
         [MemberData(nameof(ExternalPdbFormats))]
         public void MethodExtents(DebugInformationFormat format)
         {
-            var source0 = MarkedSource(@"#pragma checksum ""C:\Enc1.cs"" ""{ff1816ec-aa5e-4d10-87f7-6f4963833460}"" ""1111111111111111111111111111111111111111""
+            var source0 = MarkedSource(WithWindowsLineBreaks(@"#pragma checksum ""C:\Enc1.cs"" ""{ff1816ec-aa5e-4d10-87f7-6f4963833460}"" ""1111111111111111111111111111111111111111""
 using System;
 
 public class C
@@ -52,9 +52,9 @@ void G()
         }</N:1>;
     }
 }                              
-", fileName: @"C:\Enc1.cs");
+"), fileName: @"C:\Enc1.cs");
 
-            var source1 = MarkedSource(@"#pragma checksum ""C:\Enc1.cs"" ""{ff1816ec-aa5e-4d10-87f7-6f4963833460}"" ""2222222222222222222222222222222222222222""
+            var source1 = MarkedSource(WithWindowsLineBreaks(@"#pragma checksum ""C:\Enc1.cs"" ""{ff1816ec-aa5e-4d10-87f7-6f4963833460}"" ""2222222222222222222222222222222222222222""
 using System;
 
 public class C
@@ -83,9 +83,9 @@ void G()
 
     int E() => 1;
 }
-", fileName: @"C:\Enc1.cs");
+"), fileName: @"C:\Enc1.cs");
 
-            var source2 = MarkedSource(@"#pragma checksum ""C:\Enc1.cs"" ""{ff1816ec-aa5e-4d10-87f7-6f4963833460}"" ""3333333333333333333333333333333333333333""
+            var source2 = MarkedSource(WithWindowsLineBreaks(@"#pragma checksum ""C:\Enc1.cs"" ""{ff1816ec-aa5e-4d10-87f7-6f4963833460}"" ""3333333333333333333333333333333333333333""
 using System;
 
 public class C
@@ -116,7 +116,7 @@ void G()
 
     int B() => 4;
 }
-", fileName: @"C:\Enc1.cs");
+"), fileName: @"C:\Enc1.cs");
 
             var compilation0 = CreateCompilation(source0.Tree, options: ComSafeDebugDll.WithMetadataImportOptions(MetadataImportOptions.All), assemblyName: "EncMethodExtents");
             var compilation1 = compilation0.WithSource(source1.Tree);
diff --git a/src/Compilers/CSharp/Test/Emit/Emit/EditAndContinue/EditAndContinueStateMachineTests.cs b/src/Compilers/CSharp/Test/Emit/Emit/EditAndContinue/EditAndContinueStateMachineTests.cs
index de960ec8f4dac..4db804c90174b 100644
--- a/src/Compilers/CSharp/Test/Emit/Emit/EditAndContinue/EditAndContinueStateMachineTests.cs
+++ b/src/Compilers/CSharp/Test/Emit/Emit/EditAndContinue/EditAndContinueStateMachineTests.cs
@@ -345,78 +345,78 @@ static IEnumerable<int> F()
 
             var v0 = CompileAndVerify(compilation0);
 
-            using var md0 = ModuleMetadata.CreateFromImage(v0.EmittedAssemblyData);
-            var method0 = compilation0.GetMember<MethodSymbol>("C.F");
-            var method1 = compilation1.GetMember<MethodSymbol>("C.F");
-
-            var generation0 = EmitBaseline.CreateInitialBaseline(md0, EmptyLocalsProvider);
-            var diff1 = compilation1.EmitDifference(
-                generation0,
-                ImmutableArray.Create(SemanticEdit.Create(SemanticEditKind.Update, method0, method1)));
+            using (var md0 = ModuleMetadata.CreateFromImage(v0.EmittedAssemblyData))
+            {
+                var method0 = compilation0.GetMember<MethodSymbol>("C.F");
+                var method1 = compilation1.GetMember<MethodSymbol>("C.F");
 
-            diff1.VerifySynthesizedMembers(
-                "C: {<F>d__0#1}",
-                "C.<F>d__0#1: {<>1__state, <>2__current, <>l__initialThreadId, System.IDisposable.Dispose, MoveNext, System.Collections.Generic.IEnumerator<System.Int32>.get_Current, System.Collections.IEnumerator.Reset, System.Collections.IEnumerator.get_Current, System.Collections.Generic.IEnumerable<System.Int32>.GetEnumerator, System.Collections.IEnumerable.GetEnumerator, System.Collections.Generic.IEnumerator<System.Int32>.Current, System.Collections.IEnumerator.Current}");
+                var generation0 = EmitBaseline.CreateInitialBaseline(md0, EmptyLocalsProvider);
+                var diff1 = compilation1.EmitDifference(
+                    generation0,
+                    ImmutableArray.Create(SemanticEdit.Create(SemanticEditKind.Update, method0, method1)));
 
-            using var md1 = diff1.GetMetadata();
-            CheckEncLogDefinitions(md1.Reader,
-                Row(2, TableIndex.StandAloneSig, EditAndContinueOperation.Default),
-                Row(3, TableIndex.StandAloneSig, EditAndContinueOperation.Default),
-                Row(5, TableIndex.TypeDef, EditAndContinueOperation.Default),
-                Row(1, TableIndex.PropertyMap, EditAndContinueOperation.Default),
-                Row(5, TableIndex.TypeDef, EditAndContinueOperation.AddField),
-                Row(2, TableIndex.Field, EditAndContinueOperation.Default),
-                Row(5, TableIndex.TypeDef, EditAndContinueOperation.AddField),
-                Row(3, TableIndex.Field, EditAndContinueOperation.Default),
-                Row(5, TableIndex.TypeDef, EditAndContinueOperation.AddField),
-                Row(4, TableIndex.Field, EditAndContinueOperation.Default),
-                Row(1, TableIndex.MethodDef, EditAndContinueOperation.Default),
-                Row(5, TableIndex.TypeDef, EditAndContinueOperation.AddMethod),
-                Row(3, TableIndex.MethodDef, EditAndContinueOperation.Default),
-                Row(5, TableIndex.TypeDef, EditAndContinueOperation.AddMethod),
-                Row(4, TableIndex.MethodDef, EditAndContinueOperation.Default),
-                Row(5, TableIndex.TypeDef, EditAndContinueOperation.AddMethod),
-                Row(5, TableIndex.MethodDef, EditAndContinueOperation.Default),
-                Row(5, TableIndex.TypeDef, EditAndContinueOperation.AddMethod),
-                Row(6, TableIndex.MethodDef, EditAndContinueOperation.Default),
-                Row(5, TableIndex.TypeDef, EditAndContinueOperation.AddMethod),
-                Row(7, TableIndex.MethodDef, EditAndContinueOperation.Default),
-                Row(5, TableIndex.TypeDef, EditAndContinueOperation.AddMethod),
-                Row(8, TableIndex.MethodDef, EditAndContinueOperation.Default),
-                Row(5, TableIndex.TypeDef, EditAndContinueOperation.AddMethod),
-                Row(9, TableIndex.MethodDef, EditAndContinueOperation.Default),
-                Row(5, TableIndex.TypeDef, EditAndContinueOperation.AddMethod),
-                Row(10, TableIndex.MethodDef, EditAndContinueOperation.Default),
-                Row(1, TableIndex.PropertyMap, EditAndContinueOperation.AddProperty),
-                Row(1, TableIndex.Property, EditAndContinueOperation.Default),
-                Row(1, TableIndex.PropertyMap, EditAndContinueOperation.AddProperty),
-                Row(2, TableIndex.Property, EditAndContinueOperation.Default),
-                Row(3, TableIndex.MethodDef, EditAndContinueOperation.AddParameter),
-                Row(1, TableIndex.Param, EditAndContinueOperation.Default),
-                Row(5, TableIndex.CustomAttribute, EditAndContinueOperation.Default),
-                Row(6, TableIndex.CustomAttribute, EditAndContinueOperation.Default),
-                Row(7, TableIndex.CustomAttribute, EditAndContinueOperation.Default),
-                Row(8, TableIndex.CustomAttribute, EditAndContinueOperation.Default),
-                Row(9, TableIndex.CustomAttribute, EditAndContinueOperation.Default),
-                Row(10, TableIndex.CustomAttribute, EditAndContinueOperation.Default),
-                Row(11, TableIndex.CustomAttribute, EditAndContinueOperation.Default),
-                Row(12, TableIndex.CustomAttribute, EditAndContinueOperation.Default),
-                Row(13, TableIndex.CustomAttribute, EditAndContinueOperation.Default),
-                Row(1, TableIndex.MethodSemantics, EditAndContinueOperation.Default),
-                Row(2, TableIndex.MethodSemantics, EditAndContinueOperation.Default),
-                Row(1, TableIndex.MethodImpl, EditAndContinueOperation.Default),
-                Row(2, TableIndex.MethodImpl, EditAndContinueOperation.Default),
-                Row(3, TableIndex.MethodImpl, EditAndContinueOperation.Default),
-                Row(4, TableIndex.MethodImpl, EditAndContinueOperation.Default),
-                Row(5, TableIndex.MethodImpl, EditAndContinueOperation.Default),
-                Row(6, TableIndex.MethodImpl, EditAndContinueOperation.Default),
-                Row(7, TableIndex.MethodImpl, EditAndContinueOperation.Default),
-                Row(2, TableIndex.NestedClass, EditAndContinueOperation.Default),
-                Row(1, TableIndex.InterfaceImpl, EditAndContinueOperation.Default),
-                Row(2, TableIndex.InterfaceImpl, EditAndContinueOperation.Default),
-                Row(3, TableIndex.InterfaceImpl, EditAndContinueOperation.Default),
-                Row(4, TableIndex.InterfaceImpl, EditAndContinueOperation.Default),
-                Row(5, TableIndex.InterfaceImpl, EditAndContinueOperation.Default));
+                using (var md1 = diff1.GetMetadata())
+                {
+                    CheckEncLogDefinitions(md1.Reader,
+                        Row(2, TableIndex.StandAloneSig, EditAndContinueOperation.Default),
+                        Row(3, TableIndex.StandAloneSig, EditAndContinueOperation.Default),
+                        Row(5, TableIndex.TypeDef, EditAndContinueOperation.Default),
+                        Row(1, TableIndex.PropertyMap, EditAndContinueOperation.Default),
+                        Row(5, TableIndex.TypeDef, EditAndContinueOperation.AddField),
+                        Row(2, TableIndex.Field, EditAndContinueOperation.Default),
+                        Row(5, TableIndex.TypeDef, EditAndContinueOperation.AddField),
+                        Row(3, TableIndex.Field, EditAndContinueOperation.Default),
+                        Row(5, TableIndex.TypeDef, EditAndContinueOperation.AddField),
+                        Row(4, TableIndex.Field, EditAndContinueOperation.Default),
+                        Row(1, TableIndex.MethodDef, EditAndContinueOperation.Default),
+                        Row(5, TableIndex.TypeDef, EditAndContinueOperation.AddMethod),
+                        Row(3, TableIndex.MethodDef, EditAndContinueOperation.Default),
+                        Row(5, TableIndex.TypeDef, EditAndContinueOperation.AddMethod),
+                        Row(4, TableIndex.MethodDef, EditAndContinueOperation.Default),
+                        Row(5, TableIndex.TypeDef, EditAndContinueOperation.AddMethod),
+                        Row(5, TableIndex.MethodDef, EditAndContinueOperation.Default),
+                        Row(5, TableIndex.TypeDef, EditAndContinueOperation.AddMethod),
+                        Row(6, TableIndex.MethodDef, EditAndContinueOperation.Default),
+                        Row(5, TableIndex.TypeDef, EditAndContinueOperation.AddMethod),
+                        Row(7, TableIndex.MethodDef, EditAndContinueOperation.Default),
+                        Row(5, TableIndex.TypeDef, EditAndContinueOperation.AddMethod),
+                        Row(8, TableIndex.MethodDef, EditAndContinueOperation.Default),
+                        Row(5, TableIndex.TypeDef, EditAndContinueOperation.AddMethod),
+                        Row(9, TableIndex.MethodDef, EditAndContinueOperation.Default),
+                        Row(5, TableIndex.TypeDef, EditAndContinueOperation.AddMethod),
+                        Row(10, TableIndex.MethodDef, EditAndContinueOperation.Default),
+                        Row(1, TableIndex.PropertyMap, EditAndContinueOperation.AddProperty),
+                        Row(1, TableIndex.Property, EditAndContinueOperation.Default),
+                        Row(1, TableIndex.PropertyMap, EditAndContinueOperation.AddProperty),
+                        Row(2, TableIndex.Property, EditAndContinueOperation.Default),
+                        Row(3, TableIndex.MethodDef, EditAndContinueOperation.AddParameter),
+                        Row(1, TableIndex.Param, EditAndContinueOperation.Default),
+                        Row(5, TableIndex.CustomAttribute, EditAndContinueOperation.Default),
+                        Row(6, TableIndex.CustomAttribute, EditAndContinueOperation.Default),
+                        Row(7, TableIndex.CustomAttribute, EditAndContinueOperation.Default),
+                        Row(8, TableIndex.CustomAttribute, EditAndContinueOperation.Default),
+                        Row(9, TableIndex.CustomAttribute, EditAndContinueOperation.Default),
+                        Row(10, TableIndex.CustomAttribute, EditAndContinueOperation.Default),
+                        Row(11, TableIndex.CustomAttribute, EditAndContinueOperation.Default),
+                        Row(12, TableIndex.CustomAttribute, EditAndContinueOperation.Default),
+                        Row(13, TableIndex.CustomAttribute, EditAndContinueOperation.Default),
+                        Row(1, TableIndex.MethodSemantics, EditAndContinueOperation.Default),
+                        Row(2, TableIndex.MethodSemantics, EditAndContinueOperation.Default),
+                        Row(1, TableIndex.MethodImpl, EditAndContinueOperation.Default),
+                        Row(2, TableIndex.MethodImpl, EditAndContinueOperation.Default),
+                        Row(3, TableIndex.MethodImpl, EditAndContinueOperation.Default),
+                        Row(4, TableIndex.MethodImpl, EditAndContinueOperation.Default),
+                        Row(5, TableIndex.MethodImpl, EditAndContinueOperation.Default),
+                        Row(6, TableIndex.MethodImpl, EditAndContinueOperation.Default),
+                        Row(7, TableIndex.MethodImpl, EditAndContinueOperation.Default),
+                        Row(2, TableIndex.NestedClass, EditAndContinueOperation.Default),
+                        Row(1, TableIndex.InterfaceImpl, EditAndContinueOperation.Default),
+                        Row(2, TableIndex.InterfaceImpl, EditAndContinueOperation.Default),
+                        Row(3, TableIndex.InterfaceImpl, EditAndContinueOperation.Default),
+                        Row(4, TableIndex.InterfaceImpl, EditAndContinueOperation.Default),
+                        Row(5, TableIndex.InterfaceImpl, EditAndContinueOperation.Default));
+                }
+            }
         }
 
         [Fact]
@@ -447,49 +447,49 @@ static async Task<int> F()
 
             var v0 = CompileAndVerify(compilation0);
 
-            using var md0 = ModuleMetadata.CreateFromImage(v0.EmittedAssemblyData);
-            var method0 = compilation0.GetMember<MethodSymbol>("C.F");
-            var method1 = compilation1.GetMember<MethodSymbol>("C.F");
-
-            var generation0 = EmitBaseline.CreateInitialBaseline(md0, v0.CreateSymReader().GetEncMethodDebugInfo);
-            var diff1 = compilation1.EmitDifference(
-                generation0,
-                ImmutableArray.Create(SemanticEdit.Create(SemanticEditKind.Update, method0, method1)));
+            using (var md0 = ModuleMetadata.CreateFromImage(v0.EmittedAssemblyData))
+            {
+                var method0 = compilation0.GetMember<MethodSymbol>("C.F");
+                var method1 = compilation1.GetMember<MethodSymbol>("C.F");
 
-            diff1.VerifySynthesizedMembers(
-                "C.<F>d__0#1: {<>1__state, <>t__builder, <>s__1, <>u__1, MoveNext, SetStateMachine}",
-                "C: {<F>d__0#1}");
+                var generation0 = EmitBaseline.CreateInitialBaseline(md0, EmptyLocalsProvider);
+                var diff1 = compilation1.EmitDifference(
+                    generation0,
+                    ImmutableArray.Create(SemanticEdit.Create(SemanticEditKind.Update, method0, method1)));
 
-            using var md1 = diff1.GetMetadata();
-            CheckEncLogDefinitions(md1.Reader,
-                Row(2, TableIndex.StandAloneSig, EditAndContinueOperation.Default),
-                Row(3, TableIndex.StandAloneSig, EditAndContinueOperation.Default),
-                Row(3, TableIndex.TypeDef, EditAndContinueOperation.Default),
-                Row(3, TableIndex.TypeDef, EditAndContinueOperation.AddField),
-                Row(1, TableIndex.Field, EditAndContinueOperation.Default),
-                Row(3, TableIndex.TypeDef, EditAndContinueOperation.AddField),
-                Row(2, TableIndex.Field, EditAndContinueOperation.Default),
-                Row(3, TableIndex.TypeDef, EditAndContinueOperation.AddField),
-                Row(3, TableIndex.Field, EditAndContinueOperation.Default),
-                Row(3, TableIndex.TypeDef, EditAndContinueOperation.AddField),
-                Row(4, TableIndex.Field, EditAndContinueOperation.Default),
-                Row(1, TableIndex.MethodDef, EditAndContinueOperation.Default),
-                Row(3, TableIndex.TypeDef, EditAndContinueOperation.AddMethod),
-                Row(3, TableIndex.MethodDef, EditAndContinueOperation.Default),
-                Row(3, TableIndex.TypeDef, EditAndContinueOperation.AddMethod),
-                Row(4, TableIndex.MethodDef, EditAndContinueOperation.Default),
-                Row(3, TableIndex.TypeDef, EditAndContinueOperation.AddMethod),
-                Row(5, TableIndex.MethodDef, EditAndContinueOperation.Default),
-                Row(5, TableIndex.MethodDef, EditAndContinueOperation.AddParameter),
-                Row(1, TableIndex.Param, EditAndContinueOperation.Default),
-                Row(4, TableIndex.CustomAttribute, EditAndContinueOperation.Default),
-                Row(5, TableIndex.CustomAttribute, EditAndContinueOperation.Default),
-                Row(6, TableIndex.CustomAttribute, EditAndContinueOperation.Default),
-                Row(7, TableIndex.CustomAttribute, EditAndContinueOperation.Default),
-                Row(1, TableIndex.MethodImpl, EditAndContinueOperation.Default),
-                Row(2, TableIndex.MethodImpl, EditAndContinueOperation.Default),
-                Row(1, TableIndex.NestedClass, EditAndContinueOperation.Default),
-                Row(1, TableIndex.InterfaceImpl, EditAndContinueOperation.Default));
+                using (var md1 = diff1.GetMetadata())
+                {
+                    CheckEncLogDefinitions(md1.Reader,
+                        Row(2, TableIndex.StandAloneSig, EditAndContinueOperation.Default),
+                        Row(3, TableIndex.StandAloneSig, EditAndContinueOperation.Default),
+                        Row(3, TableIndex.TypeDef, EditAndContinueOperation.Default),
+                        Row(3, TableIndex.TypeDef, EditAndContinueOperation.AddField),
+                        Row(1, TableIndex.Field, EditAndContinueOperation.Default),
+                        Row(3, TableIndex.TypeDef, EditAndContinueOperation.AddField),
+                        Row(2, TableIndex.Field, EditAndContinueOperation.Default),
+                        Row(3, TableIndex.TypeDef, EditAndContinueOperation.AddField),
+                        Row(3, TableIndex.Field, EditAndContinueOperation.Default),
+                        Row(3, TableIndex.TypeDef, EditAndContinueOperation.AddField),
+                        Row(4, TableIndex.Field, EditAndContinueOperation.Default),
+                        Row(1, TableIndex.MethodDef, EditAndContinueOperation.Default),
+                        Row(3, TableIndex.TypeDef, EditAndContinueOperation.AddMethod),
+                        Row(3, TableIndex.MethodDef, EditAndContinueOperation.Default),
+                        Row(3, TableIndex.TypeDef, EditAndContinueOperation.AddMethod),
+                        Row(4, TableIndex.MethodDef, EditAndContinueOperation.Default),
+                        Row(3, TableIndex.TypeDef, EditAndContinueOperation.AddMethod),
+                        Row(5, TableIndex.MethodDef, EditAndContinueOperation.Default),
+                        Row(5, TableIndex.MethodDef, EditAndContinueOperation.AddParameter),
+                        Row(1, TableIndex.Param, EditAndContinueOperation.Default),
+                        Row(4, TableIndex.CustomAttribute, EditAndContinueOperation.Default),
+                        Row(5, TableIndex.CustomAttribute, EditAndContinueOperation.Default),
+                        Row(6, TableIndex.CustomAttribute, EditAndContinueOperation.Default),
+                        Row(7, TableIndex.CustomAttribute, EditAndContinueOperation.Default),
+                        Row(1, TableIndex.MethodImpl, EditAndContinueOperation.Default),
+                        Row(2, TableIndex.MethodImpl, EditAndContinueOperation.Default),
+                        Row(1, TableIndex.NestedClass, EditAndContinueOperation.Default),
+                        Row(1, TableIndex.InterfaceImpl, EditAndContinueOperation.Default));
+                }
+            }
         }
 
         [Fact]
@@ -571,26 +571,28 @@ static Task<int> F()
 
             var v0 = CompileAndVerify(compilation0);
 
-            using var md0 = ModuleMetadata.CreateFromImage(v0.EmittedAssemblyData);
-            var method0 = compilation0.GetMember<MethodSymbol>("C.F");
-            var method1 = compilation1.GetMember<MethodSymbol>("C.F");
+            using (var md0 = ModuleMetadata.CreateFromImage(v0.EmittedAssemblyData))
+            {
+                var method0 = compilation0.GetMember<MethodSymbol>("C.F");
+                var method1 = compilation1.GetMember<MethodSymbol>("C.F");
 
-            var generation0 = EmitBaseline.CreateInitialBaseline(md0, EmptyLocalsProvider);
-            var diff1 = compilation1.EmitDifference(
-                generation0,
-                ImmutableArray.Create(SemanticEdit.Create(SemanticEditKind.Update, method0, method1)));
+                var generation0 = EmitBaseline.CreateInitialBaseline(md0, EmptyLocalsProvider);
+                var diff1 = compilation1.EmitDifference(
+                    generation0,
+                    ImmutableArray.Create(SemanticEdit.Create(SemanticEditKind.Update, method0, method1)));
 
-            using (var md1 = diff1.GetMetadata())
-            {
-                CheckAttributes(md1.Reader,
-                    new CustomAttributeRow(Handle(0, TableIndex.MethodDef), Handle(0, TableIndex.MemberRef)),  // row id 0 == delete
-                    new CustomAttributeRow(Handle(0, TableIndex.MethodDef), Handle(0, TableIndex.MemberRef))); // row id 0 == delete
-
-                CheckEncLogDefinitions(md1.Reader,
-                    Row(3, TableIndex.StandAloneSig, EditAndContinueOperation.Default),
-                    Row(1, TableIndex.MethodDef, EditAndContinueOperation.Default),
-                    Row(1, TableIndex.CustomAttribute, EditAndContinueOperation.Default),  // Delete AsyncStateMachineAttribute
-                    Row(2, TableIndex.CustomAttribute, EditAndContinueOperation.Default));  // Delete DebuggerStepThroughAttribute
+                using (var md1 = diff1.GetMetadata())
+                {
+                    CheckAttributes(md1.Reader,
+                        new CustomAttributeRow(Handle(0, TableIndex.MethodDef), Handle(0, TableIndex.MemberRef)),  // row id 0 == delete
+                        new CustomAttributeRow(Handle(0, TableIndex.MethodDef), Handle(0, TableIndex.MemberRef))); // row id 0 == delete
+
+                    CheckEncLogDefinitions(md1.Reader,
+                        Row(3, TableIndex.StandAloneSig, EditAndContinueOperation.Default),
+                        Row(1, TableIndex.MethodDef, EditAndContinueOperation.Default),
+                        Row(1, TableIndex.CustomAttribute, EditAndContinueOperation.Default),  // Delete AsyncStateMachineAttribute
+                        Row(2, TableIndex.CustomAttribute, EditAndContinueOperation.Default));  // Delete DebuggerStepThroughAttribute
+                }
             }
         }
 
@@ -642,50 +644,53 @@ static async Task<int> F(int a)
 
             var v0 = CompileAndVerify(compilation0);
 
-            using var md0 = ModuleMetadata.CreateFromImage(v0.EmittedAssemblyData);
-            var methodShort0 = compilation0.GetMembers("C.F").Single(m => m.ToTestDisplayString() == "System.Threading.Tasks.Task<System.Int32> C.F(System.Int16 a)");
-            var methodShort1 = compilation1.GetMembers("C.F").Single(m => m.ToTestDisplayString() == "System.Threading.Tasks.Task<System.Int32> C.F(System.Int16 a)");
-
-            var methodInt0 = compilation0.GetMembers("C.F").Single(m => m.ToTestDisplayString() == "System.Threading.Tasks.Task<System.Int32> C.F(System.Int32 a)");
-            var methodInt1 = compilation1.GetMembers("C.F").Single(m => m.ToTestDisplayString() == "System.Threading.Tasks.Task<System.Int32> C.F(System.Int32 a)");
+            using (var md0 = ModuleMetadata.CreateFromImage(v0.EmittedAssemblyData))
+            {
+                var methodShort0 = compilation0.GetMembers("C.F").Single(m => m.ToTestDisplayString() == "System.Threading.Tasks.Task<System.Int32> C.F(System.Int16 a)");
+                var methodShort1 = compilation1.GetMembers("C.F").Single(m => m.ToTestDisplayString() == "System.Threading.Tasks.Task<System.Int32> C.F(System.Int16 a)");
 
-            var methodLong0 = compilation0.GetMembers("C.F").Single(m => m.ToTestDisplayString() == "System.Threading.Tasks.Task<System.Int32> C.F(System.Int64 a)");
-            var methodLong1 = compilation1.GetMembers("C.F").Single(m => m.ToTestDisplayString() == "System.Threading.Tasks.Task<System.Int32> C.F(System.Int64 a)");
+                var methodInt0 = compilation0.GetMembers("C.F").Single(m => m.ToTestDisplayString() == "System.Threading.Tasks.Task<System.Int32> C.F(System.Int32 a)");
+                var methodInt1 = compilation1.GetMembers("C.F").Single(m => m.ToTestDisplayString() == "System.Threading.Tasks.Task<System.Int32> C.F(System.Int32 a)");
 
-            var generation0 = EmitBaseline.CreateInitialBaseline(md0, v0.CreateSymReader().GetEncMethodDebugInfo);
-            var diff1 = compilation1.EmitDifference(
-                generation0,
-                ImmutableArray.Create(
-                    SemanticEdit.Create(SemanticEditKind.Update, methodShort0, methodShort1, preserveLocalVariables: true),
-                    SemanticEdit.Create(SemanticEditKind.Update, methodInt0, methodInt1, preserveLocalVariables: true),
-                    SemanticEdit.Create(SemanticEditKind.Update, methodLong0, methodLong1, preserveLocalVariables: true)
-                ));
+                var methodLong0 = compilation0.GetMembers("C.F").Single(m => m.ToTestDisplayString() == "System.Threading.Tasks.Task<System.Int32> C.F(System.Int64 a)");
+                var methodLong1 = compilation1.GetMembers("C.F").Single(m => m.ToTestDisplayString() == "System.Threading.Tasks.Task<System.Int32> C.F(System.Int64 a)");
 
-            using var md1 = diff1.GetMetadata();
+                var generation0 = EmitBaseline.CreateInitialBaseline(md0, EmptyLocalsProvider);
+                var diff1 = compilation1.EmitDifference(
+                    generation0,
+                    ImmutableArray.Create(
+                        SemanticEdit.Create(SemanticEditKind.Update, methodShort0, methodShort1, preserveLocalVariables: true),
+                        SemanticEdit.Create(SemanticEditKind.Update, methodInt0, methodInt1, preserveLocalVariables: true),
+                        SemanticEdit.Create(SemanticEditKind.Update, methodLong0, methodLong1, preserveLocalVariables: true)
+                    ));
 
-            // notice no TypeDefs, FieldDefs
-            CheckEncLogDefinitions(md1.Reader,
-                Row(7, TableIndex.StandAloneSig, EditAndContinueOperation.Default),
-                Row(8, TableIndex.StandAloneSig, EditAndContinueOperation.Default),
-                Row(9, TableIndex.StandAloneSig, EditAndContinueOperation.Default),
-                Row(10, TableIndex.StandAloneSig, EditAndContinueOperation.Default),
-                Row(11, TableIndex.StandAloneSig, EditAndContinueOperation.Default),
-                Row(12, TableIndex.StandAloneSig, EditAndContinueOperation.Default),
-                Row(1, TableIndex.MethodDef, EditAndContinueOperation.Default),
-                Row(2, TableIndex.MethodDef, EditAndContinueOperation.Default),
-                Row(3, TableIndex.MethodDef, EditAndContinueOperation.Default),
-                Row(6, TableIndex.MethodDef, EditAndContinueOperation.Default),
-                Row(9, TableIndex.MethodDef, EditAndContinueOperation.Default),
-                Row(12, TableIndex.MethodDef, EditAndContinueOperation.Default),
-                Row(1, TableIndex.Param, EditAndContinueOperation.Default),
-                Row(2, TableIndex.Param, EditAndContinueOperation.Default),
-                Row(3, TableIndex.Param, EditAndContinueOperation.Default),
-                Row(1, TableIndex.CustomAttribute, EditAndContinueOperation.Default),
-                Row(2, TableIndex.CustomAttribute, EditAndContinueOperation.Default),
-                Row(6, TableIndex.CustomAttribute, EditAndContinueOperation.Default),
-                Row(7, TableIndex.CustomAttribute, EditAndContinueOperation.Default),
-                Row(8, TableIndex.CustomAttribute, EditAndContinueOperation.Default),
-                Row(9, TableIndex.CustomAttribute, EditAndContinueOperation.Default));
+                using (var md1 = diff1.GetMetadata())
+                {
+                    // notice no TypeDefs, FieldDefs
+                    CheckEncLogDefinitions(md1.Reader,
+                        Row(7, TableIndex.StandAloneSig, EditAndContinueOperation.Default),
+                        Row(8, TableIndex.StandAloneSig, EditAndContinueOperation.Default),
+                        Row(9, TableIndex.StandAloneSig, EditAndContinueOperation.Default),
+                        Row(10, TableIndex.StandAloneSig, EditAndContinueOperation.Default),
+                        Row(11, TableIndex.StandAloneSig, EditAndContinueOperation.Default),
+                        Row(12, TableIndex.StandAloneSig, EditAndContinueOperation.Default),
+                        Row(1, TableIndex.MethodDef, EditAndContinueOperation.Default),
+                        Row(2, TableIndex.MethodDef, EditAndContinueOperation.Default),
+                        Row(3, TableIndex.MethodDef, EditAndContinueOperation.Default),
+                        Row(6, TableIndex.MethodDef, EditAndContinueOperation.Default),
+                        Row(9, TableIndex.MethodDef, EditAndContinueOperation.Default),
+                        Row(12, TableIndex.MethodDef, EditAndContinueOperation.Default),
+                        Row(1, TableIndex.Param, EditAndContinueOperation.Default),
+                        Row(2, TableIndex.Param, EditAndContinueOperation.Default),
+                        Row(3, TableIndex.Param, EditAndContinueOperation.Default),
+                        Row(1, TableIndex.CustomAttribute, EditAndContinueOperation.Default),
+                        Row(2, TableIndex.CustomAttribute, EditAndContinueOperation.Default),
+                        Row(6, TableIndex.CustomAttribute, EditAndContinueOperation.Default),
+                        Row(7, TableIndex.CustomAttribute, EditAndContinueOperation.Default),
+                        Row(8, TableIndex.CustomAttribute, EditAndContinueOperation.Default),
+                        Row(9, TableIndex.CustomAttribute, EditAndContinueOperation.Default));
+                }
+            }
         }
 
         [Fact]
@@ -1094,5015 +1099,715 @@ .locals init (int V_0,
         }
 
         [Fact]
-        public void UpdateAsync_Await_Add()
+        public void UpdateIterator_UserDefinedVariables_NoChange()
         {
-            var source0 = MarkedSource(@"
-using System.Threading.Tasks;
+            var source0 = @"
+using System.Collections.Generic;
 
 class C
 {
-    static Task M1() => null;
-    static Task M2() => null;
-    static Task M3() => null;
-    static void End() {}
-
-    static async Task F() 
+    static IEnumerable<int> F(int p) 
     {
-        <N:0>await M1()</N:0>;
-        <N:1>await M2()</N:1>;
-        End();
+        int x = p;
+        yield return 1;
     }
-}");
-            var source1 = MarkedSource(@"
-using System.Threading.Tasks;
+}";
+            var source1 = @"
+using System.Collections.Generic;
 
 class C
 {
-    static Task M1() => null;
-    static Task M2() => null;
-    static Task M3() => null;
-    static void End() {}
-
-    static async Task F() 
+    static IEnumerable<int> F(int p) 
     {
-        <N:0>await M1()</N:0>;
-        <N:2>await M3()</N:2>;
-        <N:1>await M2()</N:1>;
-        End();
+        int x = p;
+        yield return 2;
     }
-}");
-            var compilation0 = CreateCompilationWithMscorlib45(new[] { source0.Tree }, new[] { SystemCoreRef, CSharpRef }, options: ComSafeDebugDll);
-            var compilation1 = compilation0.WithSource(source1.Tree);
+}";
+            var compilation0 = CreateCompilationWithMscorlib45(source0, options: ComSafeDebugDll);
+            var compilation1 = compilation0.WithSource(source1);
 
             var v0 = CompileAndVerify(compilation0);
-            v0.VerifyDiagnostics();
-            var md0 = ModuleMetadata.CreateFromImage(v0.EmittedAssemblyData);
+            var symReader = v0.CreateSymReader();
 
-            var f0 = compilation0.GetMember<MethodSymbol>("C.F");
-            var f1 = compilation1.GetMember<MethodSymbol>("C.F");
+            using (var md0 = ModuleMetadata.CreateFromImage(v0.EmittedAssemblyData))
+            {
+                var method0 = compilation0.GetMember<MethodSymbol>("C.F");
+                var method1 = compilation1.GetMember<MethodSymbol>("C.F");
 
-            var generation0 = EmitBaseline.CreateInitialBaseline(md0, v0.CreateSymReader().GetEncMethodDebugInfo);
+                var generation0 = EmitBaseline.CreateInitialBaseline(md0, symReader.GetEncMethodDebugInfo);
 
-            var diff1 = compilation1.EmitDifference(
-                 generation0,
-                 ImmutableArray.Create(
-                     SemanticEdit.Create(SemanticEditKind.Update, f0, f1, GetSyntaxMapFromMarkers(source0, source1), preserveLocalVariables: true)));
+                var diff1 = compilation1.EmitDifference(
+                    generation0,
+                    ImmutableArray.Create(SemanticEdit.Create(SemanticEditKind.Update, method0, method1, GetEquivalentNodesMap(method1, method0), preserveLocalVariables: true)));
 
-            v0.VerifyPdb("C.F", @"
-<symbols>
-  <files>
-    <file id=""1"" name="""" language=""C#"" />
-  </files>
-  <methods>
-    <method containingType=""C"" name=""F"">
-      <customDebugInfo>
-        <forwardIterator name=""&lt;F&gt;d__4"" />
-        <encStateMachineStateMap>
-          <state number=""0"" offset=""16"" />
-          <state number=""1"" offset=""48"" />
-        </encStateMachineStateMap>
-      </customDebugInfo>
-    </method>
-  </methods>
-</symbols>
-");
-            v0.VerifyPdb("C+<F>d__4.MoveNext", @"
-  <symbols>
-  <files>
-    <file id=""1"" name="""" language=""C#"" />
-  </files>
-  <methods>
-    <method containingType=""C+&lt;F&gt;d__4"" name=""MoveNext"">
-      <customDebugInfo>
-        <forward declaringType=""C"" methodName=""M1"" />
-        <encLocalSlotMap>
-          <slot kind=""27"" offset=""0"" />
-          <slot kind=""33"" offset=""16"" />
-          <slot kind=""temp"" />
-          <slot kind=""33"" offset=""48"" />
-          <slot kind=""temp"" />
-        </encLocalSlotMap>
-      </customDebugInfo>
-      <asyncInfo>
-        <kickoffMethod declaringType=""C"" methodName=""F"" />
-        <await yield=""0x37"" resume=""0x55"" declaringType=""C+&lt;F&gt;d__4"" methodName=""MoveNext"" />
-        <await yield=""0x96"" resume=""0xb1"" declaringType=""C+&lt;F&gt;d__4"" methodName=""MoveNext"" />
-      </asyncInfo>
-    </method>
-  </methods>
-</symbols>
-", options: PdbValidationOptions.ExcludeSequencePoints);
+                // Verify delta metadata contains expected rows.
+                using (var md1 = diff1.GetMetadata())
+                {
+                    // Verify that no new TypeDefs, FieldDefs or MethodDefs were added,
+                    // 3 methods were updated: 
+                    // - the kick-off method (might be changed if the method previously wasn't an iterator)
+                    // - Finally method
+                    // - MoveNext method
+                    CheckEncLogDefinitions(md1.Reader,
+                        Row(3, TableIndex.StandAloneSig, EditAndContinueOperation.Default),
+                        Row(1, TableIndex.MethodDef, EditAndContinueOperation.Default),
+                        Row(4, TableIndex.MethodDef, EditAndContinueOperation.Default),
+                        Row(5, TableIndex.MethodDef, EditAndContinueOperation.Default),
+                        Row(1, TableIndex.Param, EditAndContinueOperation.Default),
+                        Row(1, TableIndex.CustomAttribute, EditAndContinueOperation.Default),
+                        Row(7, TableIndex.CustomAttribute, EditAndContinueOperation.Default));
 
-            v0.VerifyIL("C.<F>d__4.System.Runtime.CompilerServices.IAsyncStateMachine.MoveNext", @"
+                    diff1.VerifyIL("C.<F>d__0.System.Collections.IEnumerator.MoveNext", @"
 {
-  // Code size      268 (0x10c)
-  .maxstack  3
-  .locals init (int V_0,
-                System.Runtime.CompilerServices.TaskAwaiter V_1,
-                C.<F>d__4 V_2,
-                System.Runtime.CompilerServices.TaskAwaiter V_3,
-                System.Exception V_4)
-  IL_0000:  ldarg.0
-  IL_0001:  ldfld      ""int C.<F>d__4.<>1__state""
-  IL_0006:  stloc.0
-  .try
-  {
-    IL_0007:  ldloc.0
-    IL_0008:  brfalse.s  IL_0012
-    IL_000a:  br.s       IL_000c
-    IL_000c:  ldloc.0
-    IL_000d:  ldc.i4.1
-    IL_000e:  beq.s      IL_0014
-    IL_0010:  br.s       IL_0019
-    IL_0012:  br.s       IL_0055
-    IL_0014:  br         IL_00b1
-
-    IL_0019:  nop
-    IL_001a:  call       ""System.Threading.Tasks.Task C.M1()""
-    IL_001f:  callvirt   ""System.Runtime.CompilerServices.TaskAwaiter System.Threading.Tasks.Task.GetAwaiter()""
-    IL_0024:  stloc.1
-    IL_0025:  ldloca.s   V_1
-    IL_0027:  call       ""bool System.Runtime.CompilerServices.TaskAwaiter.IsCompleted.get""
-    IL_002c:  brtrue.s   IL_0071
-
-    IL_002e:  ldarg.0
-    IL_002f:  ldc.i4.0
-    IL_0030:  dup
-    IL_0031:  stloc.0
-    IL_0032:  stfld      ""int C.<F>d__4.<>1__state""
-    IL_0037:  ldarg.0
-    IL_0038:  ldloc.1
-    IL_0039:  stfld      ""System.Runtime.CompilerServices.TaskAwaiter C.<F>d__4.<>u__1""
-    IL_003e:  ldarg.0
-    IL_003f:  stloc.2
-    IL_0040:  ldarg.0
-    IL_0041:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder C.<F>d__4.<>t__builder""
-    IL_0046:  ldloca.s   V_1
-    IL_0048:  ldloca.s   V_2
-    IL_004a:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.AwaitUnsafeOnCompleted<System.Runtime.CompilerServices.TaskAwaiter, C.<F>d__4>(ref System.Runtime.CompilerServices.TaskAwaiter, ref C.<F>d__4)""
-    IL_004f:  nop
-    IL_0050:  leave      IL_010b
-
-    IL_0055:  ldarg.0
-    IL_0056:  ldfld      ""System.Runtime.CompilerServices.TaskAwaiter C.<F>d__4.<>u__1""
-    IL_005b:  stloc.1
-    IL_005c:  ldarg.0
-    IL_005d:  ldflda     ""System.Runtime.CompilerServices.TaskAwaiter C.<F>d__4.<>u__1""
-    IL_0062:  initobj    ""System.Runtime.CompilerServices.TaskAwaiter""
-    IL_0068:  ldarg.0
-    IL_0069:  ldc.i4.m1
-    IL_006a:  dup
-    IL_006b:  stloc.0
-    IL_006c:  stfld      ""int C.<F>d__4.<>1__state""
-
-    IL_0071:  ldloca.s   V_1
-    IL_0073:  call       ""void System.Runtime.CompilerServices.TaskAwaiter.GetResult()""
-    IL_0078:  nop
-    IL_0079:  call       ""System.Threading.Tasks.Task C.M2()""
-    IL_007e:  callvirt   ""System.Runtime.CompilerServices.TaskAwaiter System.Threading.Tasks.Task.GetAwaiter()""
-    IL_0083:  stloc.3
-    IL_0084:  ldloca.s   V_3
-    IL_0086:  call       ""bool System.Runtime.CompilerServices.TaskAwaiter.IsCompleted.get""
-    IL_008b:  brtrue.s   IL_00cd
-
-    IL_008d:  ldarg.0
-    IL_008e:  ldc.i4.1
-    IL_008f:  dup
-    IL_0090:  stloc.0
-    IL_0091:  stfld      ""int C.<F>d__4.<>1__state""
-    IL_0096:  ldarg.0
-    IL_0097:  ldloc.3
-    IL_0098:  stfld      ""System.Runtime.CompilerServices.TaskAwaiter C.<F>d__4.<>u__1""
-    IL_009d:  ldarg.0
-    IL_009e:  stloc.2
-    IL_009f:  ldarg.0
-    IL_00a0:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder C.<F>d__4.<>t__builder""
-    IL_00a5:  ldloca.s   V_3
-    IL_00a7:  ldloca.s   V_2
-    IL_00a9:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.AwaitUnsafeOnCompleted<System.Runtime.CompilerServices.TaskAwaiter, C.<F>d__4>(ref System.Runtime.CompilerServices.TaskAwaiter, ref C.<F>d__4)""
-    IL_00ae:  nop
-    IL_00af:  leave.s    IL_010b
-
-    IL_00b1:  ldarg.0
-    IL_00b2:  ldfld      ""System.Runtime.CompilerServices.TaskAwaiter C.<F>d__4.<>u__1""
-    IL_00b7:  stloc.3
-    IL_00b8:  ldarg.0
-    IL_00b9:  ldflda     ""System.Runtime.CompilerServices.TaskAwaiter C.<F>d__4.<>u__1""
-    IL_00be:  initobj    ""System.Runtime.CompilerServices.TaskAwaiter""
-    IL_00c4:  ldarg.0
-    IL_00c5:  ldc.i4.m1
-    IL_00c6:  dup
-    IL_00c7:  stloc.0
-    IL_00c8:  stfld      ""int C.<F>d__4.<>1__state""
-
-    IL_00cd:  ldloca.s   V_3
-    IL_00cf:  call       ""void System.Runtime.CompilerServices.TaskAwaiter.GetResult()""
-    IL_00d4:  nop
-    IL_00d5:  call       ""void C.End()""
-    IL_00da:  nop
-    IL_00db:  leave.s    IL_00f7
-  }
-  catch System.Exception
-  {
-    IL_00dd:  stloc.s    V_4
-    IL_00df:  ldarg.0
-    IL_00e0:  ldc.i4.s   -2
-    IL_00e2:  stfld      ""int C.<F>d__4.<>1__state""
-    IL_00e7:  ldarg.0
-    IL_00e8:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder C.<F>d__4.<>t__builder""
-    IL_00ed:  ldloc.s    V_4
-    IL_00ef:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetException(System.Exception)""
-    IL_00f4:  nop
-    IL_00f5:  leave.s    IL_010b
-  }
-  IL_00f7:  ldarg.0
-  IL_00f8:  ldc.i4.s   -2
-  IL_00fa:  stfld      ""int C.<F>d__4.<>1__state""
-  IL_00ff:  ldarg.0
-  IL_0100:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder C.<F>d__4.<>t__builder""
-  IL_0105:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetResult()""
-  IL_010a:  nop
-  IL_010b:  ret
-}
-");
-
-            diff1.VerifyIL("C.<F>d__4.System.Runtime.CompilerServices.IAsyncStateMachine.MoveNext", @"
-{
-  // Code size      380 (0x17c)
-  .maxstack  3
-  .locals init (int V_0,
-                System.Runtime.CompilerServices.TaskAwaiter V_1,
-                C.<F>d__4 V_2,
-                System.Runtime.CompilerServices.TaskAwaiter V_3,
-                System.Runtime.CompilerServices.TaskAwaiter V_4,
-                System.Exception V_5)
-  IL_0000:  ldarg.0
-  IL_0001:  ldfld      ""int C.<F>d__4.<>1__state""
-  IL_0006:  stloc.0
-  .try
-  {
-    IL_0007:  ldloc.0
-    IL_0008:  switch    (
-        IL_001b,
-        IL_001d,
-        IL_0022)
-    IL_0019:  br.s       IL_0027
-    IL_001b:  br.s       IL_0063
-    IL_001d:  br         IL_0120
-    IL_0022:  br         IL_00c2
-
-    IL_0027:  nop
-    IL_0028:  call       ""System.Threading.Tasks.Task C.M1()""
-    IL_002d:  callvirt   ""System.Runtime.CompilerServices.TaskAwaiter System.Threading.Tasks.Task.GetAwaiter()""
-    IL_0032:  stloc.1
-    IL_0033:  ldloca.s   V_1
-    IL_0035:  call       ""bool System.Runtime.CompilerServices.TaskAwaiter.IsCompleted.get""
-    IL_003a:  brtrue.s   IL_007f
-
-    IL_003c:  ldarg.0
-    IL_003d:  ldc.i4.0
-    IL_003e:  dup
-    IL_003f:  stloc.0
-    IL_0040:  stfld      ""int C.<F>d__4.<>1__state""
-    IL_0045:  ldarg.0
-    IL_0046:  ldloc.1
-    IL_0047:  stfld      ""System.Runtime.CompilerServices.TaskAwaiter C.<F>d__4.<>u__1""
-    IL_004c:  ldarg.0
-    IL_004d:  stloc.2
-    IL_004e:  ldarg.0
-    IL_004f:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder C.<F>d__4.<>t__builder""
-    IL_0054:  ldloca.s   V_1
-    IL_0056:  ldloca.s   V_2
-    IL_0058:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.AwaitUnsafeOnCompleted<System.Runtime.CompilerServices.TaskAwaiter, C.<F>d__4>(ref System.Runtime.CompilerServices.TaskAwaiter, ref C.<F>d__4)""
-    IL_005d:  nop
-    IL_005e:  leave      IL_017b
-
-    IL_0063:  ldarg.0
-    IL_0064:  ldfld      ""System.Runtime.CompilerServices.TaskAwaiter C.<F>d__4.<>u__1""
-    IL_0069:  stloc.1
-    IL_006a:  ldarg.0
-    IL_006b:  ldflda     ""System.Runtime.CompilerServices.TaskAwaiter C.<F>d__4.<>u__1""
-    IL_0070:  initobj    ""System.Runtime.CompilerServices.TaskAwaiter""
-    IL_0076:  ldarg.0
-    IL_0077:  ldc.i4.m1
-    IL_0078:  dup
-    IL_0079:  stloc.0
-    IL_007a:  stfld      ""int C.<F>d__4.<>1__state""
-
-    IL_007f:  ldloca.s   V_1
-    IL_0081:  call       ""void System.Runtime.CompilerServices.TaskAwaiter.GetResult()""
-    IL_0086:  nop
-    IL_0087:  call       ""System.Threading.Tasks.Task C.M3()""
-    IL_008c:  callvirt   ""System.Runtime.CompilerServices.TaskAwaiter System.Threading.Tasks.Task.GetAwaiter()""
-    IL_0091:  stloc.3
-    IL_0092:  ldloca.s   V_3
-    IL_0094:  call       ""bool System.Runtime.CompilerServices.TaskAwaiter.IsCompleted.get""
-    IL_0099:  brtrue.s   IL_00de
-
-    IL_009b:  ldarg.0
-    IL_009c:  ldc.i4.2
-    IL_009d:  dup
-    IL_009e:  stloc.0
-    IL_009f:  stfld      ""int C.<F>d__4.<>1__state""
-    IL_00a4:  ldarg.0
-    IL_00a5:  ldloc.3
-    IL_00a6:  stfld      ""System.Runtime.CompilerServices.TaskAwaiter C.<F>d__4.<>u__1""
-    IL_00ab:  ldarg.0
-    IL_00ac:  stloc.2
-    IL_00ad:  ldarg.0
-    IL_00ae:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder C.<F>d__4.<>t__builder""
-    IL_00b3:  ldloca.s   V_3
-    IL_00b5:  ldloca.s   V_2
-    IL_00b7:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.AwaitUnsafeOnCompleted<System.Runtime.CompilerServices.TaskAwaiter, C.<F>d__4>(ref System.Runtime.CompilerServices.TaskAwaiter, ref C.<F>d__4)""
-    IL_00bc:  nop
-    IL_00bd:  leave      IL_017b
-
-    IL_00c2:  ldarg.0
-    IL_00c3:  ldfld      ""System.Runtime.CompilerServices.TaskAwaiter C.<F>d__4.<>u__1""
-    IL_00c8:  stloc.3
-    IL_00c9:  ldarg.0
-    IL_00ca:  ldflda     ""System.Runtime.CompilerServices.TaskAwaiter C.<F>d__4.<>u__1""
-    IL_00cf:  initobj    ""System.Runtime.CompilerServices.TaskAwaiter""
-    IL_00d5:  ldarg.0
-    IL_00d6:  ldc.i4.m1
-    IL_00d7:  dup
-    IL_00d8:  stloc.0
-    IL_00d9:  stfld      ""int C.<F>d__4.<>1__state""
-
-    IL_00de:  ldloca.s   V_3
-    IL_00e0:  call       ""void System.Runtime.CompilerServices.TaskAwaiter.GetResult()""
-    IL_00e5:  nop
-    IL_00e6:  call       ""System.Threading.Tasks.Task C.M2()""
-    IL_00eb:  callvirt   ""System.Runtime.CompilerServices.TaskAwaiter System.Threading.Tasks.Task.GetAwaiter()""
-    IL_00f0:  stloc.s    V_4
-    IL_00f2:  ldloca.s   V_4
-    IL_00f4:  call       ""bool System.Runtime.CompilerServices.TaskAwaiter.IsCompleted.get""
-    IL_00f9:  brtrue.s   IL_013d
-
-    IL_00fb:  ldarg.0
-    IL_00fc:  ldc.i4.1
-    IL_00fd:  dup
-    IL_00fe:  stloc.0
-    IL_00ff:  stfld      ""int C.<F>d__4.<>1__state""
-    IL_0104:  ldarg.0
-    IL_0105:  ldloc.s    V_4
-    IL_0107:  stfld      ""System.Runtime.CompilerServices.TaskAwaiter C.<F>d__4.<>u__1""
-    IL_010c:  ldarg.0
-    IL_010d:  stloc.2
-    IL_010e:  ldarg.0
-    IL_010f:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder C.<F>d__4.<>t__builder""
-    IL_0114:  ldloca.s   V_4
-    IL_0116:  ldloca.s   V_2
-    IL_0118:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.AwaitUnsafeOnCompleted<System.Runtime.CompilerServices.TaskAwaiter, C.<F>d__4>(ref System.Runtime.CompilerServices.TaskAwaiter, ref C.<F>d__4)""
-    IL_011d:  nop
-    IL_011e:  leave.s    IL_017b
-
-    IL_0120:  ldarg.0
-    IL_0121:  ldfld      ""System.Runtime.CompilerServices.TaskAwaiter C.<F>d__4.<>u__1""
-    IL_0126:  stloc.s    V_4
-    IL_0128:  ldarg.0
-    IL_0129:  ldflda     ""System.Runtime.CompilerServices.TaskAwaiter C.<F>d__4.<>u__1""
-    IL_012e:  initobj    ""System.Runtime.CompilerServices.TaskAwaiter""
-    IL_0134:  ldarg.0
-    IL_0135:  ldc.i4.m1
-    IL_0136:  dup
-    IL_0137:  stloc.0
-    IL_0138:  stfld      ""int C.<F>d__4.<>1__state""
-
-    IL_013d:  ldloca.s   V_4
-    IL_013f:  call       ""void System.Runtime.CompilerServices.TaskAwaiter.GetResult()""
-    IL_0144:  nop
-    IL_0145:  call       ""void C.End()""
-    IL_014a:  nop
-    IL_014b:  leave.s    IL_0167
-  }
-  catch System.Exception
-  {
-    IL_014d:  stloc.s    V_5
-    IL_014f:  ldarg.0
-    IL_0150:  ldc.i4.s   -2
-    IL_0152:  stfld      ""int C.<F>d__4.<>1__state""
-    IL_0157:  ldarg.0
-    IL_0158:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder C.<F>d__4.<>t__builder""
-    IL_015d:  ldloc.s    V_5
-    IL_015f:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetException(System.Exception)""
-    IL_0164:  nop
-    IL_0165:  leave.s    IL_017b
-  }
-  IL_0167:  ldarg.0
-  IL_0168:  ldc.i4.s   -2
-  IL_016a:  stfld      ""int C.<F>d__4.<>1__state""
-  IL_016f:  ldarg.0
-  IL_0170:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder C.<F>d__4.<>t__builder""
-  IL_0175:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetResult()""
-  IL_017a:  nop
-  IL_017b:  ret
-}
-");
-        }
-
-        [Fact]
-        public void UpdateAsync_Await_Remove_RemoveAdd()
-        {
-            var source0 = MarkedSource(@"
-using System.Threading.Tasks;
-
-class C
-{
-    static Task M1() => null;
-    static Task M2() => null;
-    static Task M3() => null;
-    static void End() {}
-
-    static async Task F() 
-    {
-        <N:0>await M1()</N:0>;
-        <N:1>await M3()</N:1>;
-        <N:2>await M2()</N:2>;
-        End();
-    }
-}");
-            var source1 = MarkedSource(@"
-using System.Threading.Tasks;
-
-class C
-{
-    static Task M1() => null;
-    static Task M2() => null;
-    static Task M3() => null;
-    static void End() {}
-
-    static async Task F() 
-    {
-        <N:0>await M1()</N:0>;
-        <N:2>await M2()</N:2>;
-        End();
-    }
-}");
-            var source2 = MarkedSource(@"
-using System.Threading.Tasks;
-
-class C
-{
-    static Task M1() => null;
-    static Task M2() => null;
-    static Task M3() => null;
-    static void End() {}
-
-    static async Task F() 
-    {
-        await M3();
-        <N:0>await M1()</N:0>;
-        End();
-    }
-}");
-            var compilation0 = CreateCompilationWithMscorlib45(new[] { source0.Tree }, new[] { SystemCoreRef, CSharpRef }, options: ComSafeDebugDll);
-            var compilation1 = compilation0.WithSource(source1.Tree);
-            var compilation2 = compilation0.WithSource(source2.Tree);
-
-            var v0 = CompileAndVerify(compilation0);
-            v0.VerifyDiagnostics();
-            var md0 = ModuleMetadata.CreateFromImage(v0.EmittedAssemblyData);
-
-            var f0 = compilation0.GetMember<MethodSymbol>("C.F");
-            var f1 = compilation1.GetMember<MethodSymbol>("C.F");
-            var f2 = compilation2.GetMember<MethodSymbol>("C.F");
-
-            var generation0 = EmitBaseline.CreateInitialBaseline(md0, v0.CreateSymReader().GetEncMethodDebugInfo);
-
-            var diff1 = compilation1.EmitDifference(
-                 generation0,
-                 ImmutableArray.Create(
-                     SemanticEdit.Create(SemanticEditKind.Update, f0, f1, GetSyntaxMapFromMarkers(source0, source1), preserveLocalVariables: true)));
-
-            var diff2 = compilation2.EmitDifference(
-                 diff1.NextGeneration,
-                 ImmutableArray.Create(
-                     SemanticEdit.Create(SemanticEditKind.Update, f1, f2, GetSyntaxMapFromMarkers(source1, source2), preserveLocalVariables: true)));
-
-            v0.VerifyPdb("C.F", @"
-<symbols>
-  <files>
-    <file id=""1"" name="""" language=""C#"" />
-  </files>
-  <methods>
-    <method containingType=""C"" name=""F"">
-      <customDebugInfo>
-        <forwardIterator name=""&lt;F&gt;d__4"" />
-        <encStateMachineStateMap>
-          <state number=""0"" offset=""16"" />
-          <state number=""1"" offset=""48"" />
-          <state number=""2"" offset=""80"" />
-        </encStateMachineStateMap>
-      </customDebugInfo>
-    </method>
-  </methods>
-</symbols>
-");
-            v0.VerifyPdb("C+<F>d__4.MoveNext", @"
-  <symbols>
-  <files>
-    <file id=""1"" name="""" language=""C#"" />
-  </files>
-  <methods>
-    <method containingType=""C+&lt;F&gt;d__4"" name=""MoveNext"">
-      <customDebugInfo>
-        <forward declaringType=""C"" methodName=""M1"" />
-        <encLocalSlotMap>
-          <slot kind=""27"" offset=""0"" />
-          <slot kind=""33"" offset=""16"" />
-          <slot kind=""temp"" />
-          <slot kind=""33"" offset=""48"" />
-          <slot kind=""33"" offset=""80"" />
-          <slot kind=""temp"" />
-        </encLocalSlotMap>
-      </customDebugInfo>
-      <asyncInfo>
-        <kickoffMethod declaringType=""C"" methodName=""F"" />
-        <await yield=""0x45"" resume=""0x63"" declaringType=""C+&lt;F&gt;d__4"" methodName=""MoveNext"" />
-        <await yield=""0xa4"" resume=""0xc2"" declaringType=""C+&lt;F&gt;d__4"" methodName=""MoveNext"" />
-        <await yield=""0x104"" resume=""0x120"" declaringType=""C+&lt;F&gt;d__4"" methodName=""MoveNext"" />
-      </asyncInfo>
-    </method>
-  </methods>
-</symbols>
-", options: PdbValidationOptions.ExcludeSequencePoints);
-
-            v0.VerifyIL("C.<F>d__4.System.Runtime.CompilerServices.IAsyncStateMachine.MoveNext", @"
-{
-  // Code size      380 (0x17c)
-  .maxstack  3
-  .locals init (int V_0,
-                System.Runtime.CompilerServices.TaskAwaiter V_1,
-                C.<F>d__4 V_2,
-                System.Runtime.CompilerServices.TaskAwaiter V_3,
-                System.Runtime.CompilerServices.TaskAwaiter V_4,
-                System.Exception V_5)
-  IL_0000:  ldarg.0
-  IL_0001:  ldfld      ""int C.<F>d__4.<>1__state""
-  IL_0006:  stloc.0
-  .try
-  {
-    IL_0007:  ldloc.0
-    IL_0008:  switch    (
-        IL_001b,
-        IL_001d,
-        IL_0022)
-    IL_0019:  br.s       IL_0027
-    IL_001b:  br.s       IL_0063
-    IL_001d:  br         IL_00c2
-    IL_0022:  br         IL_0120
-
-    IL_0027:  nop
-    IL_0028:  call       ""System.Threading.Tasks.Task C.M1()""
-    IL_002d:  callvirt   ""System.Runtime.CompilerServices.TaskAwaiter System.Threading.Tasks.Task.GetAwaiter()""
-    IL_0032:  stloc.1
-    IL_0033:  ldloca.s   V_1
-    IL_0035:  call       ""bool System.Runtime.CompilerServices.TaskAwaiter.IsCompleted.get""
-    IL_003a:  brtrue.s   IL_007f
-
-    IL_003c:  ldarg.0
-    IL_003d:  ldc.i4.0
-    IL_003e:  dup
-    IL_003f:  stloc.0
-    IL_0040:  stfld      ""int C.<F>d__4.<>1__state""
-    IL_0045:  ldarg.0
-    IL_0046:  ldloc.1
-    IL_0047:  stfld      ""System.Runtime.CompilerServices.TaskAwaiter C.<F>d__4.<>u__1""
-    IL_004c:  ldarg.0
-    IL_004d:  stloc.2
-    IL_004e:  ldarg.0
-    IL_004f:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder C.<F>d__4.<>t__builder""
-    IL_0054:  ldloca.s   V_1
-    IL_0056:  ldloca.s   V_2
-    IL_0058:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.AwaitUnsafeOnCompleted<System.Runtime.CompilerServices.TaskAwaiter, C.<F>d__4>(ref System.Runtime.CompilerServices.TaskAwaiter, ref C.<F>d__4)""
-    IL_005d:  nop
-    IL_005e:  leave      IL_017b
-
-    IL_0063:  ldarg.0
-    IL_0064:  ldfld      ""System.Runtime.CompilerServices.TaskAwaiter C.<F>d__4.<>u__1""
-    IL_0069:  stloc.1
-    IL_006a:  ldarg.0
-    IL_006b:  ldflda     ""System.Runtime.CompilerServices.TaskAwaiter C.<F>d__4.<>u__1""
-    IL_0070:  initobj    ""System.Runtime.CompilerServices.TaskAwaiter""
-    IL_0076:  ldarg.0
-    IL_0077:  ldc.i4.m1
-    IL_0078:  dup
-    IL_0079:  stloc.0
-    IL_007a:  stfld      ""int C.<F>d__4.<>1__state""
-
-    IL_007f:  ldloca.s   V_1
-    IL_0081:  call       ""void System.Runtime.CompilerServices.TaskAwaiter.GetResult()""
-    IL_0086:  nop
-    IL_0087:  call       ""System.Threading.Tasks.Task C.M3()""
-    IL_008c:  callvirt   ""System.Runtime.CompilerServices.TaskAwaiter System.Threading.Tasks.Task.GetAwaiter()""
-    IL_0091:  stloc.3
-    IL_0092:  ldloca.s   V_3
-    IL_0094:  call       ""bool System.Runtime.CompilerServices.TaskAwaiter.IsCompleted.get""
-    IL_0099:  brtrue.s   IL_00de
-
-    IL_009b:  ldarg.0
-    IL_009c:  ldc.i4.1
-    IL_009d:  dup
-    IL_009e:  stloc.0
-    IL_009f:  stfld      ""int C.<F>d__4.<>1__state""
-    IL_00a4:  ldarg.0
-    IL_00a5:  ldloc.3
-    IL_00a6:  stfld      ""System.Runtime.CompilerServices.TaskAwaiter C.<F>d__4.<>u__1""
-    IL_00ab:  ldarg.0
-    IL_00ac:  stloc.2
-    IL_00ad:  ldarg.0
-    IL_00ae:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder C.<F>d__4.<>t__builder""
-    IL_00b3:  ldloca.s   V_3
-    IL_00b5:  ldloca.s   V_2
-    IL_00b7:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.AwaitUnsafeOnCompleted<System.Runtime.CompilerServices.TaskAwaiter, C.<F>d__4>(ref System.Runtime.CompilerServices.TaskAwaiter, ref C.<F>d__4)""
-    IL_00bc:  nop
-    IL_00bd:  leave      IL_017b
-
-    IL_00c2:  ldarg.0
-    IL_00c3:  ldfld      ""System.Runtime.CompilerServices.TaskAwaiter C.<F>d__4.<>u__1""
-    IL_00c8:  stloc.3
-    IL_00c9:  ldarg.0
-    IL_00ca:  ldflda     ""System.Runtime.CompilerServices.TaskAwaiter C.<F>d__4.<>u__1""
-    IL_00cf:  initobj    ""System.Runtime.CompilerServices.TaskAwaiter""
-    IL_00d5:  ldarg.0
-    IL_00d6:  ldc.i4.m1
-    IL_00d7:  dup
-    IL_00d8:  stloc.0
-    IL_00d9:  stfld      ""int C.<F>d__4.<>1__state""
-
-    IL_00de:  ldloca.s   V_3
-    IL_00e0:  call       ""void System.Runtime.CompilerServices.TaskAwaiter.GetResult()""
-    IL_00e5:  nop
-    IL_00e6:  call       ""System.Threading.Tasks.Task C.M2()""
-    IL_00eb:  callvirt   ""System.Runtime.CompilerServices.TaskAwaiter System.Threading.Tasks.Task.GetAwaiter()""
-    IL_00f0:  stloc.s    V_4
-    IL_00f2:  ldloca.s   V_4
-    IL_00f4:  call       ""bool System.Runtime.CompilerServices.TaskAwaiter.IsCompleted.get""
-    IL_00f9:  brtrue.s   IL_013d
-
-    IL_00fb:  ldarg.0
-    IL_00fc:  ldc.i4.2
-    IL_00fd:  dup
-    IL_00fe:  stloc.0
-    IL_00ff:  stfld      ""int C.<F>d__4.<>1__state""
-    IL_0104:  ldarg.0
-    IL_0105:  ldloc.s    V_4
-    IL_0107:  stfld      ""System.Runtime.CompilerServices.TaskAwaiter C.<F>d__4.<>u__1""
-    IL_010c:  ldarg.0
-    IL_010d:  stloc.2
-    IL_010e:  ldarg.0
-    IL_010f:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder C.<F>d__4.<>t__builder""
-    IL_0114:  ldloca.s   V_4
-    IL_0116:  ldloca.s   V_2
-    IL_0118:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.AwaitUnsafeOnCompleted<System.Runtime.CompilerServices.TaskAwaiter, C.<F>d__4>(ref System.Runtime.CompilerServices.TaskAwaiter, ref C.<F>d__4)""
-    IL_011d:  nop
-    IL_011e:  leave.s    IL_017b
-
-    IL_0120:  ldarg.0
-    IL_0121:  ldfld      ""System.Runtime.CompilerServices.TaskAwaiter C.<F>d__4.<>u__1""
-    IL_0126:  stloc.s    V_4
-    IL_0128:  ldarg.0
-    IL_0129:  ldflda     ""System.Runtime.CompilerServices.TaskAwaiter C.<F>d__4.<>u__1""
-    IL_012e:  initobj    ""System.Runtime.CompilerServices.TaskAwaiter""
-    IL_0134:  ldarg.0
-    IL_0135:  ldc.i4.m1
-    IL_0136:  dup
-    IL_0137:  stloc.0
-    IL_0138:  stfld      ""int C.<F>d__4.<>1__state""
-
-    IL_013d:  ldloca.s   V_4
-    IL_013f:  call       ""void System.Runtime.CompilerServices.TaskAwaiter.GetResult()""
-    IL_0144:  nop
-    IL_0145:  call       ""void C.End()""
-    IL_014a:  nop
-    IL_014b:  leave.s    IL_0167
-  }
-  catch System.Exception
-  {
-    IL_014d:  stloc.s    V_5
-    IL_014f:  ldarg.0
-    IL_0150:  ldc.i4.s   -2
-    IL_0152:  stfld      ""int C.<F>d__4.<>1__state""
-    IL_0157:  ldarg.0
-    IL_0158:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder C.<F>d__4.<>t__builder""
-    IL_015d:  ldloc.s    V_5
-    IL_015f:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetException(System.Exception)""
-    IL_0164:  nop
-    IL_0165:  leave.s    IL_017b
-  }
-  IL_0167:  ldarg.0
-  IL_0168:  ldc.i4.s   -2
-  IL_016a:  stfld      ""int C.<F>d__4.<>1__state""
-  IL_016f:  ldarg.0
-  IL_0170:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder C.<F>d__4.<>t__builder""
-  IL_0175:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetResult()""
-  IL_017a:  nop
-  IL_017b:  ret
-}
-");
-
-            diff1.VerifyIL("C.<F>d__4.System.Runtime.CompilerServices.IAsyncStateMachine.MoveNext", @"
-{
-  // Code size      283 (0x11b)
-  .maxstack  3
-  .locals init (int V_0,
-                System.Runtime.CompilerServices.TaskAwaiter V_1,
-                C.<F>d__4 V_2,
-                System.Runtime.CompilerServices.TaskAwaiter V_3,
-                System.Exception V_4)
-  IL_0000:  ldarg.0
-  IL_0001:  ldfld      ""int C.<F>d__4.<>1__state""
-  IL_0006:  stloc.0
-  .try
-  {
-    IL_0007:  ldloc.0
-    IL_0008:  brfalse.s  IL_0012
-    IL_000a:  br.s       IL_000c
-    IL_000c:  ldloc.0
-    IL_000d:  ldc.i4.2
-    IL_000e:  beq.s      IL_0014
-    IL_0010:  br.s       IL_0019
-    IL_0012:  br.s       IL_0064
-    IL_0014:  br         IL_00c0
-    IL_0019:  ldloc.0
-    IL_001a:  ldc.i4.0
-    IL_001b:  blt.s      IL_0028
-    IL_001d:  ldstr      """ + CodeAnalysisResources.EncCannotResumeSuspendedAsyncMethod + @"""
-    IL_0022:  newobj     ""System.InvalidOperationException..ctor(string)""
-    IL_0027:  throw
-
-    IL_0028:  nop
-    IL_0029:  call       ""System.Threading.Tasks.Task C.M1()""
-    IL_002e:  callvirt   ""System.Runtime.CompilerServices.TaskAwaiter System.Threading.Tasks.Task.GetAwaiter()""
-    IL_0033:  stloc.1
-    IL_0034:  ldloca.s   V_1
-    IL_0036:  call       ""bool System.Runtime.CompilerServices.TaskAwaiter.IsCompleted.get""
-    IL_003b:  brtrue.s   IL_0080
-
-    IL_003d:  ldarg.0
-    IL_003e:  ldc.i4.0
-    IL_003f:  dup
-    IL_0040:  stloc.0
-    IL_0041:  stfld      ""int C.<F>d__4.<>1__state""
-    IL_0046:  ldarg.0
-    IL_0047:  ldloc.1
-    IL_0048:  stfld      ""System.Runtime.CompilerServices.TaskAwaiter C.<F>d__4.<>u__1""
-    IL_004d:  ldarg.0
-    IL_004e:  stloc.2
-    IL_004f:  ldarg.0
-    IL_0050:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder C.<F>d__4.<>t__builder""
-    IL_0055:  ldloca.s   V_1
-    IL_0057:  ldloca.s   V_2
-    IL_0059:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.AwaitUnsafeOnCompleted<System.Runtime.CompilerServices.TaskAwaiter, C.<F>d__4>(ref System.Runtime.CompilerServices.TaskAwaiter, ref C.<F>d__4)""
-    IL_005e:  nop
-    IL_005f:  leave      IL_011a
-
-    IL_0064:  ldarg.0
-    IL_0065:  ldfld      ""System.Runtime.CompilerServices.TaskAwaiter C.<F>d__4.<>u__1""
-    IL_006a:  stloc.1
-    IL_006b:  ldarg.0
-    IL_006c:  ldflda     ""System.Runtime.CompilerServices.TaskAwaiter C.<F>d__4.<>u__1""
-    IL_0071:  initobj    ""System.Runtime.CompilerServices.TaskAwaiter""
-    IL_0077:  ldarg.0
-    IL_0078:  ldc.i4.m1
-    IL_0079:  dup
-    IL_007a:  stloc.0
-    IL_007b:  stfld      ""int C.<F>d__4.<>1__state""
-    IL_0080:  ldloca.s   V_1
-    IL_0082:  call       ""void System.Runtime.CompilerServices.TaskAwaiter.GetResult()""
-    IL_0087:  nop
-    IL_0088:  call       ""System.Threading.Tasks.Task C.M2()""
-    IL_008d:  callvirt   ""System.Runtime.CompilerServices.TaskAwaiter System.Threading.Tasks.Task.GetAwaiter()""
-    IL_0092:  stloc.3
-    IL_0093:  ldloca.s   V_3
-    IL_0095:  call       ""bool System.Runtime.CompilerServices.TaskAwaiter.IsCompleted.get""
-    IL_009a:  brtrue.s   IL_00dc
-
-    IL_009c:  ldarg.0
-    IL_009d:  ldc.i4.2
-    IL_009e:  dup
-    IL_009f:  stloc.0
-    IL_00a0:  stfld      ""int C.<F>d__4.<>1__state""
-    IL_00a5:  ldarg.0
-    IL_00a6:  ldloc.3
-    IL_00a7:  stfld      ""System.Runtime.CompilerServices.TaskAwaiter C.<F>d__4.<>u__1""
-    IL_00ac:  ldarg.0
-    IL_00ad:  stloc.2
-    IL_00ae:  ldarg.0
-    IL_00af:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder C.<F>d__4.<>t__builder""
-    IL_00b4:  ldloca.s   V_3
-    IL_00b6:  ldloca.s   V_2
-    IL_00b8:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.AwaitUnsafeOnCompleted<System.Runtime.CompilerServices.TaskAwaiter, C.<F>d__4>(ref System.Runtime.CompilerServices.TaskAwaiter, ref C.<F>d__4)""
-    IL_00bd:  nop
-    IL_00be:  leave.s    IL_011a
-
-    IL_00c0:  ldarg.0
-    IL_00c1:  ldfld      ""System.Runtime.CompilerServices.TaskAwaiter C.<F>d__4.<>u__1""
-    IL_00c6:  stloc.3
-    IL_00c7:  ldarg.0
-    IL_00c8:  ldflda     ""System.Runtime.CompilerServices.TaskAwaiter C.<F>d__4.<>u__1""
-    IL_00cd:  initobj    ""System.Runtime.CompilerServices.TaskAwaiter""
-    IL_00d3:  ldarg.0
-    IL_00d4:  ldc.i4.m1
-    IL_00d5:  dup
-    IL_00d6:  stloc.0
-    IL_00d7:  stfld      ""int C.<F>d__4.<>1__state""
-
-    IL_00dc:  ldloca.s   V_3
-    IL_00de:  call       ""void System.Runtime.CompilerServices.TaskAwaiter.GetResult()""
-    IL_00e3:  nop
-    IL_00e4:  call       ""void C.End()""
-    IL_00e9:  nop
-    IL_00ea:  leave.s    IL_0106
-  }
-  catch System.Exception
-  {
-    IL_00ec:  stloc.s    V_4
-    IL_00ee:  ldarg.0
-    IL_00ef:  ldc.i4.s   -2
-    IL_00f1:  stfld      ""int C.<F>d__4.<>1__state""
-    IL_00f6:  ldarg.0
-    IL_00f7:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder C.<F>d__4.<>t__builder""
-    IL_00fc:  ldloc.s    V_4
-    IL_00fe:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetException(System.Exception)""
-    IL_0103:  nop
-    IL_0104:  leave.s    IL_011a
-  }
-  IL_0106:  ldarg.0
-  IL_0107:  ldc.i4.s   -2
-  IL_0109:  stfld      ""int C.<F>d__4.<>1__state""
-  IL_010e:  ldarg.0
-  IL_010f:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder C.<F>d__4.<>t__builder""
-  IL_0114:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetResult()""
-  IL_0119:  nop
-  IL_011a:  ret
-}
-");
-            // note that CDI is not emitted to the delta since we already have the information captured in changed symbols:
-            diff1.VerifyPdb(Enumerable.Range(1, 20).Select(MetadataTokens.MethodDefinitionHandle), @"
-<symbols>
-    <files>
-      <file id=""1"" name="""" language=""C#"" />
-    </files>
-    <methods>
-    <method token=""0x6000008"">
-      <sequencePoints>
-        <entry offset=""0x0"" hidden=""true"" document=""1"" />
-        <entry offset=""0x7"" hidden=""true"" document=""1"" />
-        <entry offset=""0x28"" startLine=""12"" startColumn=""5"" endLine=""12"" endColumn=""6"" document=""1"" />
-        <entry offset=""0x29"" startLine=""13"" startColumn=""14"" endLine=""13"" endColumn=""31"" document=""1"" />
-        <entry offset=""0x34"" hidden=""true"" document=""1"" />
-        <entry offset=""0x88"" startLine=""14"" startColumn=""14"" endLine=""14"" endColumn=""31"" document=""1"" />
-        <entry offset=""0x93"" hidden=""true"" document=""1"" />
-        <entry offset=""0xe4"" startLine=""15"" startColumn=""9"" endLine=""15"" endColumn=""15"" document=""1"" />
-        <entry offset=""0xec"" hidden=""true"" document=""1"" />
-        <entry offset=""0x106"" startLine=""16"" startColumn=""5"" endLine=""16"" endColumn=""6"" document=""1"" />
-        <entry offset=""0x10e"" hidden=""true"" document=""1"" />
-      </sequencePoints>
-      <asyncInfo>
-        <kickoffMethod token=""0x6000005"" />
-        <await yield=""0x46"" resume=""0x64"" token=""0x6000008"" />
-        <await yield=""0xa5"" resume=""0xc0"" token=""0x6000008"" />
-      </asyncInfo>
-    </method>
-    </methods>
-</symbols>
-");
-            diff2.VerifyIL("C.<F>d__4.System.Runtime.CompilerServices.IAsyncStateMachine.MoveNext", @"
-{
-  // Code size      283 (0x11b)
-  .maxstack  3
-  .locals init (int V_0,
-                System.Runtime.CompilerServices.TaskAwaiter V_1,
-                C.<F>d__4 V_2,
-                System.Runtime.CompilerServices.TaskAwaiter V_3,
-                System.Exception V_4)
-  IL_0000:  ldarg.0
-  IL_0001:  ldfld      ""int C.<F>d__4.<>1__state""
-  IL_0006:  stloc.0
-  .try
-  {
-    IL_0007:  ldloc.0
-    IL_0008:  brfalse.s  IL_0012
-    IL_000a:  br.s       IL_000c
-    IL_000c:  ldloc.0
-    IL_000d:  ldc.i4.3
-    IL_000e:  beq.s      IL_0017
-    IL_0010:  br.s       IL_0019
-    IL_0012:  br         IL_00c0
-    IL_0017:  br.s       IL_0064
-    IL_0019:  ldloc.0
-    IL_001a:  ldc.i4.0
-    IL_001b:  blt.s      IL_0028
-    IL_001d:  ldstr      """ + CodeAnalysisResources.EncCannotResumeSuspendedAsyncMethod + @"""
-    IL_0022:  newobj     ""System.InvalidOperationException..ctor(string)""
-    IL_0027:  throw
-
-    IL_0028:  nop
-    IL_0029:  call       ""System.Threading.Tasks.Task C.M3()""
-    IL_002e:  callvirt   ""System.Runtime.CompilerServices.TaskAwaiter System.Threading.Tasks.Task.GetAwaiter()""
-    IL_0033:  stloc.1
-    IL_0034:  ldloca.s   V_1
-    IL_0036:  call       ""bool System.Runtime.CompilerServices.TaskAwaiter.IsCompleted.get""
-    IL_003b:  brtrue.s   IL_0080
-
-    IL_003d:  ldarg.0
-    IL_003e:  ldc.i4.3
-    IL_003f:  dup
-    IL_0040:  stloc.0
-    IL_0041:  stfld      ""int C.<F>d__4.<>1__state""
-    IL_0046:  ldarg.0
-    IL_0047:  ldloc.1
-    IL_0048:  stfld      ""System.Runtime.CompilerServices.TaskAwaiter C.<F>d__4.<>u__1""
-    IL_004d:  ldarg.0
-    IL_004e:  stloc.2
-    IL_004f:  ldarg.0
-    IL_0050:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder C.<F>d__4.<>t__builder""
-    IL_0055:  ldloca.s   V_1
-    IL_0057:  ldloca.s   V_2
-    IL_0059:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.AwaitUnsafeOnCompleted<System.Runtime.CompilerServices.TaskAwaiter, C.<F>d__4>(ref System.Runtime.CompilerServices.TaskAwaiter, ref C.<F>d__4)""
-    IL_005e:  nop
-    IL_005f:  leave      IL_011a
-
-    IL_0064:  ldarg.0
-    IL_0065:  ldfld      ""System.Runtime.CompilerServices.TaskAwaiter C.<F>d__4.<>u__1""
-    IL_006a:  stloc.1
-    IL_006b:  ldarg.0
-    IL_006c:  ldflda     ""System.Runtime.CompilerServices.TaskAwaiter C.<F>d__4.<>u__1""
-    IL_0071:  initobj    ""System.Runtime.CompilerServices.TaskAwaiter""
-    IL_0077:  ldarg.0
-    IL_0078:  ldc.i4.m1
-    IL_0079:  dup
-    IL_007a:  stloc.0
-    IL_007b:  stfld      ""int C.<F>d__4.<>1__state""
-
-    IL_0080:  ldloca.s   V_1
-    IL_0082:  call       ""void System.Runtime.CompilerServices.TaskAwaiter.GetResult()""
-    IL_0087:  nop
-    IL_0088:  call       ""System.Threading.Tasks.Task C.M1()""
-    IL_008d:  callvirt   ""System.Runtime.CompilerServices.TaskAwaiter System.Threading.Tasks.Task.GetAwaiter()""
-    IL_0092:  stloc.3
-    IL_0093:  ldloca.s   V_3
-    IL_0095:  call       ""bool System.Runtime.CompilerServices.TaskAwaiter.IsCompleted.get""
-    IL_009a:  brtrue.s   IL_00dc
-
-    IL_009c:  ldarg.0
-    IL_009d:  ldc.i4.0
-    IL_009e:  dup
-    IL_009f:  stloc.0
-    IL_00a0:  stfld      ""int C.<F>d__4.<>1__state""
-    IL_00a5:  ldarg.0
-    IL_00a6:  ldloc.3
-    IL_00a7:  stfld      ""System.Runtime.CompilerServices.TaskAwaiter C.<F>d__4.<>u__1""
-    IL_00ac:  ldarg.0
-    IL_00ad:  stloc.2
-    IL_00ae:  ldarg.0
-    IL_00af:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder C.<F>d__4.<>t__builder""
-    IL_00b4:  ldloca.s   V_3
-    IL_00b6:  ldloca.s   V_2
-    IL_00b8:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.AwaitUnsafeOnCompleted<System.Runtime.CompilerServices.TaskAwaiter, C.<F>d__4>(ref System.Runtime.CompilerServices.TaskAwaiter, ref C.<F>d__4)""
-    IL_00bd:  nop
-    IL_00be:  leave.s    IL_011a
-
-    IL_00c0:  ldarg.0
-    IL_00c1:  ldfld      ""System.Runtime.CompilerServices.TaskAwaiter C.<F>d__4.<>u__1""
-    IL_00c6:  stloc.3
-    IL_00c7:  ldarg.0
-    IL_00c8:  ldflda     ""System.Runtime.CompilerServices.TaskAwaiter C.<F>d__4.<>u__1""
-    IL_00cd:  initobj    ""System.Runtime.CompilerServices.TaskAwaiter""
-    IL_00d3:  ldarg.0
-    IL_00d4:  ldc.i4.m1
-    IL_00d5:  dup
-    IL_00d6:  stloc.0
-    IL_00d7:  stfld      ""int C.<F>d__4.<>1__state""
-
-    IL_00dc:  ldloca.s   V_3
-    IL_00de:  call       ""void System.Runtime.CompilerServices.TaskAwaiter.GetResult()""
-    IL_00e3:  nop
-    IL_00e4:  call       ""void C.End()""
-    IL_00e9:  nop
-    IL_00ea:  leave.s    IL_0106
-  }
-  catch System.Exception
-  {
-    IL_00ec:  stloc.s    V_4
-    IL_00ee:  ldarg.0
-    IL_00ef:  ldc.i4.s   -2
-    IL_00f1:  stfld      ""int C.<F>d__4.<>1__state""
-    IL_00f6:  ldarg.0
-    IL_00f7:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder C.<F>d__4.<>t__builder""
-    IL_00fc:  ldloc.s    V_4
-    IL_00fe:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetException(System.Exception)""
-    IL_0103:  nop
-    IL_0104:  leave.s    IL_011a
-  }
-  IL_0106:  ldarg.0
-  IL_0107:  ldc.i4.s   -2
-  IL_0109:  stfld      ""int C.<F>d__4.<>1__state""
-  IL_010e:  ldarg.0
-  IL_010f:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder C.<F>d__4.<>t__builder""
-  IL_0114:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetResult()""
-  IL_0119:  nop
-  IL_011a:  ret
-}
-");
-        }
-
-        [Fact]
-        public void UpdateAsync_Await_Remove_FirstAndLast()
-        {
-            var source0 = MarkedSource(@"
-using System.Threading.Tasks;
-
-class C
-{
-    static Task M1() => null;
-    static Task M2() => null;
-    static Task M3() => null;
-    static void End() {}
-
-    static async Task F() 
-    {
-        <N:0>await M1()</N:0>;
-        <N:1>await M2()</N:1>;
-        <N:2>await M3()</N:2>;
-        End();
-    }
-}");
-            var source1 = MarkedSource(@"
-using System.Threading.Tasks;
-
-class C
-{
-    static Task M1() => null;
-    static Task M2() => null;
-    static Task M3() => null;
-    static void End() {}
-
-    static async Task F() 
-    {
-        <N:1>await M2()</N:1>;
-        End();
-    }
-}");
-            var compilation0 = CreateCompilationWithMscorlib45(new[] { source0.Tree }, new[] { SystemCoreRef, CSharpRef }, options: ComSafeDebugDll);
-            var compilation1 = compilation0.WithSource(source1.Tree);
-
-            var v0 = CompileAndVerify(compilation0);
-            v0.VerifyDiagnostics();
-            var md0 = ModuleMetadata.CreateFromImage(v0.EmittedAssemblyData);
-
-            var f0 = compilation0.GetMember<MethodSymbol>("C.F");
-            var f1 = compilation1.GetMember<MethodSymbol>("C.F");
-
-            var generation0 = EmitBaseline.CreateInitialBaseline(md0, v0.CreateSymReader().GetEncMethodDebugInfo);
-
-            var diff1 = compilation1.EmitDifference(
-                 generation0,
-                 ImmutableArray.Create(
-                     SemanticEdit.Create(SemanticEditKind.Update, f0, f1, GetSyntaxMapFromMarkers(source0, source1), preserveLocalVariables: true)));
-
-            diff1.VerifyIL("C.<F>d__4.System.Runtime.CompilerServices.IAsyncStateMachine.MoveNext", @"
-{
-  // Code size      176 (0xb0)
-  .maxstack  3
-  .locals init (int V_0,
-                System.Runtime.CompilerServices.TaskAwaiter V_1,
-                C.<F>d__4 V_2,
-                System.Exception V_3)
-  IL_0000:  ldarg.0
-  IL_0001:  ldfld      ""int C.<F>d__4.<>1__state""
-  IL_0006:  stloc.0
-  .try
-  {
-    IL_0007:  ldloc.0
-    IL_0008:  ldc.i4.1
-    IL_0009:  beq.s      IL_000d
-    IL_000b:  br.s       IL_000f
-    IL_000d:  br.s       IL_0057
-    IL_000f:  ldloc.0
-    IL_0010:  ldc.i4.0
-    IL_0011:  blt.s      IL_001e
-    IL_0013:  ldstr      """ + CodeAnalysisResources.EncCannotResumeSuspendedAsyncMethod + @"""
-    IL_0018:  newobj     ""System.InvalidOperationException..ctor(string)""
-    IL_001d:  throw
-
-    IL_001e:  nop
-    IL_001f:  call       ""System.Threading.Tasks.Task C.M2()""
-    IL_0024:  callvirt   ""System.Runtime.CompilerServices.TaskAwaiter System.Threading.Tasks.Task.GetAwaiter()""
-    IL_0029:  stloc.1
-    IL_002a:  ldloca.s   V_1
-    IL_002c:  call       ""bool System.Runtime.CompilerServices.TaskAwaiter.IsCompleted.get""
-    IL_0031:  brtrue.s   IL_0073
-
-    IL_0033:  ldarg.0
-    IL_0034:  ldc.i4.1
-    IL_0035:  dup
-    IL_0036:  stloc.0
-    IL_0037:  stfld      ""int C.<F>d__4.<>1__state""
-    IL_003c:  ldarg.0
-    IL_003d:  ldloc.1
-    IL_003e:  stfld      ""System.Runtime.CompilerServices.TaskAwaiter C.<F>d__4.<>u__1""
-    IL_0043:  ldarg.0
-    IL_0044:  stloc.2
-    IL_0045:  ldarg.0
-    IL_0046:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder C.<F>d__4.<>t__builder""
-    IL_004b:  ldloca.s   V_1
-    IL_004d:  ldloca.s   V_2
-    IL_004f:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.AwaitUnsafeOnCompleted<System.Runtime.CompilerServices.TaskAwaiter, C.<F>d__4>(ref System.Runtime.CompilerServices.TaskAwaiter, ref C.<F>d__4)""
-    IL_0054:  nop
-    IL_0055:  leave.s    IL_00af
-
-    IL_0057:  ldarg.0
-    IL_0058:  ldfld      ""System.Runtime.CompilerServices.TaskAwaiter C.<F>d__4.<>u__1""
-    IL_005d:  stloc.1
-    IL_005e:  ldarg.0
-    IL_005f:  ldflda     ""System.Runtime.CompilerServices.TaskAwaiter C.<F>d__4.<>u__1""
-    IL_0064:  initobj    ""System.Runtime.CompilerServices.TaskAwaiter""
-    IL_006a:  ldarg.0
-    IL_006b:  ldc.i4.m1
-    IL_006c:  dup
-    IL_006d:  stloc.0
-    IL_006e:  stfld      ""int C.<F>d__4.<>1__state""
-
-    IL_0073:  ldloca.s   V_1
-    IL_0075:  call       ""void System.Runtime.CompilerServices.TaskAwaiter.GetResult()""
-    IL_007a:  nop
-    IL_007b:  call       ""void C.End()""
-    IL_0080:  nop
-    IL_0081:  leave.s    IL_009b
-  }
-  catch System.Exception
-  {
-    IL_0083:  stloc.3
-    IL_0084:  ldarg.0
-    IL_0085:  ldc.i4.s   -2
-    IL_0087:  stfld      ""int C.<F>d__4.<>1__state""
-    IL_008c:  ldarg.0
-    IL_008d:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder C.<F>d__4.<>t__builder""
-    IL_0092:  ldloc.3
-    IL_0093:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetException(System.Exception)""
-    IL_0098:  nop
-    IL_0099:  leave.s    IL_00af
-  }
-  IL_009b:  ldarg.0
-  IL_009c:  ldc.i4.s   -2
-  IL_009e:  stfld      ""int C.<F>d__4.<>1__state""
-  IL_00a3:  ldarg.0
-  IL_00a4:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder C.<F>d__4.<>t__builder""
-  IL_00a9:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetResult()""
-  IL_00ae:  nop
-  IL_00af:  ret
-}
-");
-        }
-
-        [Fact]
-        public void UpdateAsync_Await_Remove_TryBlock()
-        {
-            var source0 = MarkedSource(@"
-using System.Threading.Tasks;
-
-class C
-{
-    static void Start() {}
-    static Task M1() => null;
-    static Task M2() => null;
-    static Task M3() => null;
-    static Task M4() => null;
-    static Task M5() => null;
-    static void End() {}
-
-    static async Task F() 
-    {
-        Start();
-        <N:0>await M1()</N:0>;
-        try
-        {
-            <N:1>await M2()</N:1>;
-            <N:2>await M3()</N:2>;
-        }
-        catch
-        {
-            <N:3>await M4()</N:3>;
-            <N:4>await M5()</N:4>;
-        }
-        End();
-    }
-}");
-            var source1 = MarkedSource(@"
-using System.Threading.Tasks;
-
-class C
-{
-    static void Start() {}
-    static Task M1() => null;
-    static Task M2() => null;
-    static Task M3() => null;
-    static Task M4() => null;
-    static Task M5() => null;
-    static void End() {}
-
-    static async Task F() 
-    {
-        Start();
-        try
-        {
-            <N:1>await M2()</N:1>;
-        }
-        catch
-        {
-            <N:2>await M4()</N:2>;
-        }
-        End();
-    }
-}");
-            var compilation0 = CreateCompilationWithMscorlib45(new[] { source0.Tree }, new[] { SystemCoreRef, CSharpRef }, options: ComSafeDebugDll);
-            var compilation1 = compilation0.WithSource(source1.Tree);
-
-            var v0 = CompileAndVerify(compilation0);
-            v0.VerifyDiagnostics();
-            var md0 = ModuleMetadata.CreateFromImage(v0.EmittedAssemblyData);
-
-            var f0 = compilation0.GetMember<MethodSymbol>("C.F");
-            var f1 = compilation1.GetMember<MethodSymbol>("C.F");
-
-            var generation0 = EmitBaseline.CreateInitialBaseline(md0, v0.CreateSymReader().GetEncMethodDebugInfo);
-
-            var diff1 = compilation1.EmitDifference(
-                 generation0,
-                 ImmutableArray.Create(
-                     SemanticEdit.Create(SemanticEditKind.Update, f0, f1, GetSyntaxMapFromMarkers(source0, source1), preserveLocalVariables: true)));
-
-            v0.VerifyIL("C.<F>d__7.System.Runtime.CompilerServices.IAsyncStateMachine.MoveNext", @"
-{
-  // Code size      671 (0x29f)
-  .maxstack  3
-  .locals init (int V_0,
-                System.Runtime.CompilerServices.TaskAwaiter V_1,
-                C.<F>d__7 V_2,
-                System.Runtime.CompilerServices.TaskAwaiter V_3,
-                System.Runtime.CompilerServices.TaskAwaiter V_4,
-                object V_5,
-                int V_6,
-                System.Runtime.CompilerServices.TaskAwaiter V_7,
-                System.Runtime.CompilerServices.TaskAwaiter V_8,
-                System.Exception V_9)
-  IL_0000:  ldarg.0
-  IL_0001:  ldfld      ""int C.<F>d__7.<>1__state""
-  IL_0006:  stloc.0
-  .try
-  {
-    IL_0007:  ldloc.0
-    IL_0008:  switch    (
-        IL_0023,
-        IL_0025,
-        IL_0025,
-        IL_0027,
-        IL_002c)
-    IL_0021:  br.s       IL_0031
-    IL_0023:  br.s       IL_0073
-    IL_0025:  br.s       IL_009e
-    IL_0027:  br         IL_01da
-    IL_002c:  br         IL_0239
-
-    IL_0031:  nop
-    IL_0032:  call       ""void C.Start()""
-    IL_0037:  nop
-    IL_0038:  call       ""System.Threading.Tasks.Task C.M1()""
-    IL_003d:  callvirt   ""System.Runtime.CompilerServices.TaskAwaiter System.Threading.Tasks.Task.GetAwaiter()""
-    IL_0042:  stloc.1
-    IL_0043:  ldloca.s   V_1
-    IL_0045:  call       ""bool System.Runtime.CompilerServices.TaskAwaiter.IsCompleted.get""
-    IL_004a:  brtrue.s   IL_008f
-
-    IL_004c:  ldarg.0
-    IL_004d:  ldc.i4.0
-    IL_004e:  dup
-    IL_004f:  stloc.0
-    IL_0050:  stfld      ""int C.<F>d__7.<>1__state""
-    IL_0055:  ldarg.0
-    IL_0056:  ldloc.1
-    IL_0057:  stfld      ""System.Runtime.CompilerServices.TaskAwaiter C.<F>d__7.<>u__1""
-    IL_005c:  ldarg.0
-    IL_005d:  stloc.2
-    IL_005e:  ldarg.0
-    IL_005f:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder C.<F>d__7.<>t__builder""
-    IL_0064:  ldloca.s   V_1
-    IL_0066:  ldloca.s   V_2
-    IL_0068:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.AwaitUnsafeOnCompleted<System.Runtime.CompilerServices.TaskAwaiter, C.<F>d__7>(ref System.Runtime.CompilerServices.TaskAwaiter, ref C.<F>d__7)""
-    IL_006d:  nop
-    IL_006e:  leave      IL_029e
-
-    IL_0073:  ldarg.0
-    IL_0074:  ldfld      ""System.Runtime.CompilerServices.TaskAwaiter C.<F>d__7.<>u__1""
-    IL_0079:  stloc.1
-    IL_007a:  ldarg.0
-    IL_007b:  ldflda     ""System.Runtime.CompilerServices.TaskAwaiter C.<F>d__7.<>u__1""
-    IL_0080:  initobj    ""System.Runtime.CompilerServices.TaskAwaiter""
-    IL_0086:  ldarg.0
-    IL_0087:  ldc.i4.m1
-    IL_0088:  dup
-    IL_0089:  stloc.0
-    IL_008a:  stfld      ""int C.<F>d__7.<>1__state""
-
-    IL_008f:  ldloca.s   V_1
-    IL_0091:  call       ""void System.Runtime.CompilerServices.TaskAwaiter.GetResult()""
-    IL_0096:  nop
-    IL_0097:  ldarg.0
-    IL_0098:  ldc.i4.0
-    IL_0099:  stfld      ""int C.<F>d__7.<>s__2""
-
-    IL_009e:  nop
-    .try
-    {
-      IL_009f:  ldloc.0
-      IL_00a0:  ldc.i4.1
-      IL_00a1:  beq.s      IL_00ab
-      IL_00a3:  br.s       IL_00a5
-      IL_00a5:  ldloc.0
-      IL_00a6:  ldc.i4.2
-      IL_00a7:  beq.s      IL_00ad
-      IL_00a9:  br.s       IL_00b2
-      IL_00ab:  br.s       IL_00ee
-      IL_00ad:  br         IL_014f
-
-      IL_00b2:  nop
-      IL_00b3:  call       ""System.Threading.Tasks.Task C.M2()""
-      IL_00b8:  callvirt   ""System.Runtime.CompilerServices.TaskAwaiter System.Threading.Tasks.Task.GetAwaiter()""
-      IL_00bd:  stloc.3
-      IL_00be:  ldloca.s   V_3
-      IL_00c0:  call       ""bool System.Runtime.CompilerServices.TaskAwaiter.IsCompleted.get""
-      IL_00c5:  brtrue.s   IL_010a
-
-      IL_00c7:  ldarg.0
-      IL_00c8:  ldc.i4.1
-      IL_00c9:  dup
-      IL_00ca:  stloc.0
-      IL_00cb:  stfld      ""int C.<F>d__7.<>1__state""
-      IL_00d0:  ldarg.0
-      IL_00d1:  ldloc.3
-      IL_00d2:  stfld      ""System.Runtime.CompilerServices.TaskAwaiter C.<F>d__7.<>u__1""
-      IL_00d7:  ldarg.0
-      IL_00d8:  stloc.2
-      IL_00d9:  ldarg.0
-      IL_00da:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder C.<F>d__7.<>t__builder""
-      IL_00df:  ldloca.s   V_3
-      IL_00e1:  ldloca.s   V_2
-      IL_00e3:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.AwaitUnsafeOnCompleted<System.Runtime.CompilerServices.TaskAwaiter, C.<F>d__7>(ref System.Runtime.CompilerServices.TaskAwaiter, ref C.<F>d__7)""
-      IL_00e8:  nop
-      IL_00e9:  leave      IL_029e
-
-      IL_00ee:  ldarg.0
-      IL_00ef:  ldfld      ""System.Runtime.CompilerServices.TaskAwaiter C.<F>d__7.<>u__1""
-      IL_00f4:  stloc.3
-      IL_00f5:  ldarg.0
-      IL_00f6:  ldflda     ""System.Runtime.CompilerServices.TaskAwaiter C.<F>d__7.<>u__1""
-      IL_00fb:  initobj    ""System.Runtime.CompilerServices.TaskAwaiter""
-      IL_0101:  ldarg.0
-      IL_0102:  ldc.i4.m1
-      IL_0103:  dup
-      IL_0104:  stloc.0
-      IL_0105:  stfld      ""int C.<F>d__7.<>1__state""
-
-      IL_010a:  ldloca.s   V_3
-      IL_010c:  call       ""void System.Runtime.CompilerServices.TaskAwaiter.GetResult()""
-      IL_0111:  nop
-      IL_0112:  call       ""System.Threading.Tasks.Task C.M3()""
-      IL_0117:  callvirt   ""System.Runtime.CompilerServices.TaskAwaiter System.Threading.Tasks.Task.GetAwaiter()""
-      IL_011c:  stloc.s    V_4
-      IL_011e:  ldloca.s   V_4
-      IL_0120:  call       ""bool System.Runtime.CompilerServices.TaskAwaiter.IsCompleted.get""
-      IL_0125:  brtrue.s   IL_016c
-
-      IL_0127:  ldarg.0
-      IL_0128:  ldc.i4.2
-      IL_0129:  dup
-      IL_012a:  stloc.0
-      IL_012b:  stfld      ""int C.<F>d__7.<>1__state""
-      IL_0130:  ldarg.0
-      IL_0131:  ldloc.s    V_4
-      IL_0133:  stfld      ""System.Runtime.CompilerServices.TaskAwaiter C.<F>d__7.<>u__1""
-      IL_0138:  ldarg.0
-      IL_0139:  stloc.2
-      IL_013a:  ldarg.0
-      IL_013b:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder C.<F>d__7.<>t__builder""
-      IL_0140:  ldloca.s   V_4
-      IL_0142:  ldloca.s   V_2
-      IL_0144:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.AwaitUnsafeOnCompleted<System.Runtime.CompilerServices.TaskAwaiter, C.<F>d__7>(ref System.Runtime.CompilerServices.TaskAwaiter, ref C.<F>d__7)""
-      IL_0149:  nop
-      IL_014a:  leave      IL_029e
-
-      IL_014f:  ldarg.0
-      IL_0150:  ldfld      ""System.Runtime.CompilerServices.TaskAwaiter C.<F>d__7.<>u__1""
-      IL_0155:  stloc.s    V_4
-      IL_0157:  ldarg.0
-      IL_0158:  ldflda     ""System.Runtime.CompilerServices.TaskAwaiter C.<F>d__7.<>u__1""
-      IL_015d:  initobj    ""System.Runtime.CompilerServices.TaskAwaiter""
-      IL_0163:  ldarg.0
-      IL_0164:  ldc.i4.m1
-      IL_0165:  dup
-      IL_0166:  stloc.0
-      IL_0167:  stfld      ""int C.<F>d__7.<>1__state""
-
-      IL_016c:  ldloca.s   V_4
-      IL_016e:  call       ""void System.Runtime.CompilerServices.TaskAwaiter.GetResult()""
-      IL_0173:  nop
-      IL_0174:  nop
-      IL_0175:  leave.s    IL_018a
-    }
-    catch object
-    {
-      IL_0177:  stloc.s    V_5
-      IL_0179:  ldarg.0
-      IL_017a:  ldloc.s    V_5
-      IL_017c:  stfld      ""object C.<F>d__7.<>s__1""
-      IL_0181:  ldarg.0
-      IL_0182:  ldc.i4.1
-      IL_0183:  stfld      ""int C.<F>d__7.<>s__2""
-      IL_0188:  leave.s    IL_018a
-    }
-    IL_018a:  ldarg.0
-    IL_018b:  ldfld      ""int C.<F>d__7.<>s__2""
-    IL_0190:  stloc.s    V_6
-    IL_0192:  ldloc.s    V_6
-    IL_0194:  ldc.i4.1
-    IL_0195:  beq.s      IL_019c
-    IL_0197:  br         IL_0261
-
-    IL_019c:  nop
-    IL_019d:  call       ""System.Threading.Tasks.Task C.M4()""
-    IL_01a2:  callvirt   ""System.Runtime.CompilerServices.TaskAwaiter System.Threading.Tasks.Task.GetAwaiter()""
-    IL_01a7:  stloc.s    V_7
-    IL_01a9:  ldloca.s   V_7
-    IL_01ab:  call       ""bool System.Runtime.CompilerServices.TaskAwaiter.IsCompleted.get""
-    IL_01b0:  brtrue.s   IL_01f7
-
-    IL_01b2:  ldarg.0
-    IL_01b3:  ldc.i4.3
-    IL_01b4:  dup
-    IL_01b5:  stloc.0
-    IL_01b6:  stfld      ""int C.<F>d__7.<>1__state""
-    IL_01bb:  ldarg.0
-    IL_01bc:  ldloc.s    V_7
-    IL_01be:  stfld      ""System.Runtime.CompilerServices.TaskAwaiter C.<F>d__7.<>u__1""
-    IL_01c3:  ldarg.0
-    IL_01c4:  stloc.2
-    IL_01c5:  ldarg.0
-    IL_01c6:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder C.<F>d__7.<>t__builder""
-    IL_01cb:  ldloca.s   V_7
-    IL_01cd:  ldloca.s   V_2
-    IL_01cf:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.AwaitUnsafeOnCompleted<System.Runtime.CompilerServices.TaskAwaiter, C.<F>d__7>(ref System.Runtime.CompilerServices.TaskAwaiter, ref C.<F>d__7)""
-    IL_01d4:  nop
-    IL_01d5:  leave      IL_029e
-
-    IL_01da:  ldarg.0
-    IL_01db:  ldfld      ""System.Runtime.CompilerServices.TaskAwaiter C.<F>d__7.<>u__1""
-    IL_01e0:  stloc.s    V_7
-    IL_01e2:  ldarg.0
-    IL_01e3:  ldflda     ""System.Runtime.CompilerServices.TaskAwaiter C.<F>d__7.<>u__1""
-    IL_01e8:  initobj    ""System.Runtime.CompilerServices.TaskAwaiter""
-    IL_01ee:  ldarg.0
-    IL_01ef:  ldc.i4.m1
-    IL_01f0:  dup
-    IL_01f1:  stloc.0
-    IL_01f2:  stfld      ""int C.<F>d__7.<>1__state""
-
-    IL_01f7:  ldloca.s   V_7
-    IL_01f9:  call       ""void System.Runtime.CompilerServices.TaskAwaiter.GetResult()""
-    IL_01fe:  nop
-    IL_01ff:  call       ""System.Threading.Tasks.Task C.M5()""
-    IL_0204:  callvirt   ""System.Runtime.CompilerServices.TaskAwaiter System.Threading.Tasks.Task.GetAwaiter()""
-    IL_0209:  stloc.s    V_8
-    IL_020b:  ldloca.s   V_8
-    IL_020d:  call       ""bool System.Runtime.CompilerServices.TaskAwaiter.IsCompleted.get""
-    IL_0212:  brtrue.s   IL_0256
-
-    IL_0214:  ldarg.0
-    IL_0215:  ldc.i4.4
-    IL_0216:  dup
-    IL_0217:  stloc.0
-    IL_0218:  stfld      ""int C.<F>d__7.<>1__state""
-    IL_021d:  ldarg.0
-    IL_021e:  ldloc.s    V_8
-    IL_0220:  stfld      ""System.Runtime.CompilerServices.TaskAwaiter C.<F>d__7.<>u__1""
-    IL_0225:  ldarg.0
-    IL_0226:  stloc.2
-    IL_0227:  ldarg.0
-    IL_0228:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder C.<F>d__7.<>t__builder""
-    IL_022d:  ldloca.s   V_8
-    IL_022f:  ldloca.s   V_2
-    IL_0231:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.AwaitUnsafeOnCompleted<System.Runtime.CompilerServices.TaskAwaiter, C.<F>d__7>(ref System.Runtime.CompilerServices.TaskAwaiter, ref C.<F>d__7)""
-    IL_0236:  nop
-    IL_0237:  leave.s    IL_029e
-
-    IL_0239:  ldarg.0
-    IL_023a:  ldfld      ""System.Runtime.CompilerServices.TaskAwaiter C.<F>d__7.<>u__1""
-    IL_023f:  stloc.s    V_8
-    IL_0241:  ldarg.0
-    IL_0242:  ldflda     ""System.Runtime.CompilerServices.TaskAwaiter C.<F>d__7.<>u__1""
-    IL_0247:  initobj    ""System.Runtime.CompilerServices.TaskAwaiter""
-    IL_024d:  ldarg.0
-    IL_024e:  ldc.i4.m1
-    IL_024f:  dup
-    IL_0250:  stloc.0
-    IL_0251:  stfld      ""int C.<F>d__7.<>1__state""
-
-    IL_0256:  ldloca.s   V_8
-    IL_0258:  call       ""void System.Runtime.CompilerServices.TaskAwaiter.GetResult()""
-    IL_025d:  nop
-    IL_025e:  nop
-    IL_025f:  br.s       IL_0261
-
-    IL_0261:  ldarg.0
-    IL_0262:  ldnull
-    IL_0263:  stfld      ""object C.<F>d__7.<>s__1""
-    IL_0268:  call       ""void C.End()""
-    IL_026d:  nop
-    IL_026e:  leave.s    IL_028a
-  }
-  catch System.Exception
-  {
-    IL_0270:  stloc.s    V_9
-    IL_0272:  ldarg.0
-    IL_0273:  ldc.i4.s   -2
-    IL_0275:  stfld      ""int C.<F>d__7.<>1__state""
-    IL_027a:  ldarg.0
-    IL_027b:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder C.<F>d__7.<>t__builder""
-    IL_0280:  ldloc.s    V_9
-    IL_0282:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetException(System.Exception)""
-    IL_0287:  nop
-    IL_0288:  leave.s    IL_029e
-  }
-  IL_028a:  ldarg.0
-  IL_028b:  ldc.i4.s   -2
-  IL_028d:  stfld      ""int C.<F>d__7.<>1__state""
-  IL_0292:  ldarg.0
-  IL_0293:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder C.<F>d__7.<>t__builder""
-  IL_0298:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetResult()""
-  IL_029d:  nop
-  IL_029e:  ret
-}
-");
-
-            diff1.VerifyIL("C.<F>d__7.System.Runtime.CompilerServices.IAsyncStateMachine.MoveNext", @"
-{
-  // Code size      356 (0x164)
-  .maxstack  3
-  .locals init (int V_0,
-                System.Runtime.CompilerServices.TaskAwaiter V_1,
-                C.<F>d__7 V_2,
-                object V_3,
-                int V_4,
-                System.Runtime.CompilerServices.TaskAwaiter V_5,
-                System.Exception V_6)
-  IL_0000:  ldarg.0
-  IL_0001:  ldfld      ""int C.<F>d__7.<>1__state""
-  IL_0006:  stloc.0
-  .try
-  {
-    IL_0007:  ldloc.0
-    IL_0008:  ldc.i4.1
-    IL_0009:  beq.s      IL_0013
-    IL_000b:  br.s       IL_000d
-    IL_000d:  ldloc.0
-    IL_000e:  ldc.i4.2
-    IL_000f:  beq.s      IL_0015
-    IL_0011:  br.s       IL_001a
-    IL_0013:  br.s       IL_0037
-    IL_0015:  br         IL_00fe
-    IL_001a:  ldloc.0
-    IL_001b:  ldc.i4.0
-    IL_001c:  blt.s      IL_0029
-    IL_001e:  ldstr      """ + CodeAnalysisResources.EncCannotResumeSuspendedAsyncMethod + @"""
-    IL_0023:  newobj     ""System.InvalidOperationException..ctor(string)""
-    IL_0028:  throw
-
-    IL_0029:  nop
-    IL_002a:  call       ""void C.Start()""
-    IL_002f:  nop
-    IL_0030:  ldarg.0
-    IL_0031:  ldc.i4.0
-    IL_0032:  stfld      ""int C.<F>d__7.<>s__4""
-
-    IL_0037:  nop
-    .try
-    {
-      IL_0038:  ldloc.0
-      IL_0039:  ldc.i4.1
-      IL_003a:  beq.s      IL_003e
-      IL_003c:  br.s       IL_0040
-      IL_003e:  br.s       IL_007c
-
-      IL_0040:  nop
-      IL_0041:  call       ""System.Threading.Tasks.Task C.M2()""
-      IL_0046:  callvirt   ""System.Runtime.CompilerServices.TaskAwaiter System.Threading.Tasks.Task.GetAwaiter()""
-      IL_004b:  stloc.1
-      IL_004c:  ldloca.s   V_1
-      IL_004e:  call       ""bool System.Runtime.CompilerServices.TaskAwaiter.IsCompleted.get""
-      IL_0053:  brtrue.s   IL_0098
-
-      IL_0055:  ldarg.0
-      IL_0056:  ldc.i4.1
-      IL_0057:  dup
-      IL_0058:  stloc.0
-      IL_0059:  stfld      ""int C.<F>d__7.<>1__state""
-      IL_005e:  ldarg.0
-      IL_005f:  ldloc.1
-      IL_0060:  stfld      ""System.Runtime.CompilerServices.TaskAwaiter C.<F>d__7.<>u__1""
-      IL_0065:  ldarg.0
-      IL_0066:  stloc.2
-      IL_0067:  ldarg.0
-      IL_0068:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder C.<F>d__7.<>t__builder""
-      IL_006d:  ldloca.s   V_1
-      IL_006f:  ldloca.s   V_2
-      IL_0071:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.AwaitUnsafeOnCompleted<System.Runtime.CompilerServices.TaskAwaiter, C.<F>d__7>(ref System.Runtime.CompilerServices.TaskAwaiter, ref C.<F>d__7)""
-      IL_0076:  nop
-      IL_0077:  leave      IL_0163
-
-      IL_007c:  ldarg.0
-      IL_007d:  ldfld      ""System.Runtime.CompilerServices.TaskAwaiter C.<F>d__7.<>u__1""
-      IL_0082:  stloc.1
-      IL_0083:  ldarg.0
-      IL_0084:  ldflda     ""System.Runtime.CompilerServices.TaskAwaiter C.<F>d__7.<>u__1""
-      IL_0089:  initobj    ""System.Runtime.CompilerServices.TaskAwaiter""
-      IL_008f:  ldarg.0
-      IL_0090:  ldc.i4.m1
-      IL_0091:  dup
-      IL_0092:  stloc.0
-      IL_0093:  stfld      ""int C.<F>d__7.<>1__state""
-      IL_0098:  ldloca.s   V_1
-      IL_009a:  call       ""void System.Runtime.CompilerServices.TaskAwaiter.GetResult()""
-      IL_009f:  nop
-      IL_00a0:  nop
-      IL_00a1:  leave.s    IL_00b4
-    }
-    catch object
-    {
-      IL_00a3:  stloc.3
-      IL_00a4:  ldarg.0
-      IL_00a5:  ldloc.3
-      IL_00a6:  stfld      ""object C.<F>d__7.<>s__3""
-      IL_00ab:  ldarg.0
-      IL_00ac:  ldc.i4.1
-      IL_00ad:  stfld      ""int C.<F>d__7.<>s__4""
-      IL_00b2:  leave.s    IL_00b4
-    }
-    IL_00b4:  ldarg.0
-    IL_00b5:  ldfld      ""int C.<F>d__7.<>s__4""
-    IL_00ba:  stloc.s    V_4
-    IL_00bc:  ldloc.s    V_4
-    IL_00be:  ldc.i4.1
-    IL_00bf:  beq.s      IL_00c3
-    IL_00c1:  br.s       IL_0126
-
-    IL_00c3:  nop
-    IL_00c4:  call       ""System.Threading.Tasks.Task C.M4()""
-    IL_00c9:  callvirt   ""System.Runtime.CompilerServices.TaskAwaiter System.Threading.Tasks.Task.GetAwaiter()""
-    IL_00ce:  stloc.s    V_5
-    IL_00d0:  ldloca.s   V_5
-    IL_00d2:  call       ""bool System.Runtime.CompilerServices.TaskAwaiter.IsCompleted.get""
-    IL_00d7:  brtrue.s   IL_011b
-
-    IL_00d9:  ldarg.0
-    IL_00da:  ldc.i4.2
-    IL_00db:  dup
-    IL_00dc:  stloc.0
-    IL_00dd:  stfld      ""int C.<F>d__7.<>1__state""
-    IL_00e2:  ldarg.0
-    IL_00e3:  ldloc.s    V_5
-    IL_00e5:  stfld      ""System.Runtime.CompilerServices.TaskAwaiter C.<F>d__7.<>u__1""
-    IL_00ea:  ldarg.0
-    IL_00eb:  stloc.2
-    IL_00ec:  ldarg.0
-    IL_00ed:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder C.<F>d__7.<>t__builder""
-    IL_00f2:  ldloca.s   V_5
-    IL_00f4:  ldloca.s   V_2
-    IL_00f6:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.AwaitUnsafeOnCompleted<System.Runtime.CompilerServices.TaskAwaiter, C.<F>d__7>(ref System.Runtime.CompilerServices.TaskAwaiter, ref C.<F>d__7)""
-    IL_00fb:  nop
-    IL_00fc:  leave.s    IL_0163
-
-    IL_00fe:  ldarg.0
-    IL_00ff:  ldfld      ""System.Runtime.CompilerServices.TaskAwaiter C.<F>d__7.<>u__1""
-    IL_0104:  stloc.s    V_5
-    IL_0106:  ldarg.0
-    IL_0107:  ldflda     ""System.Runtime.CompilerServices.TaskAwaiter C.<F>d__7.<>u__1""
-    IL_010c:  initobj    ""System.Runtime.CompilerServices.TaskAwaiter""
-    IL_0112:  ldarg.0
-    IL_0113:  ldc.i4.m1
-    IL_0114:  dup
-    IL_0115:  stloc.0
-    IL_0116:  stfld      ""int C.<F>d__7.<>1__state""
-
-    IL_011b:  ldloca.s   V_5
-    IL_011d:  call       ""void System.Runtime.CompilerServices.TaskAwaiter.GetResult()""
-    IL_0122:  nop
-    IL_0123:  nop
-    IL_0124:  br.s       IL_0126
-
-    IL_0126:  ldarg.0
-    IL_0127:  ldnull
-    IL_0128:  stfld      ""object C.<F>d__7.<>s__3""
-    IL_012d:  call       ""void C.End()""
-    IL_0132:  nop
-    IL_0133:  leave.s    IL_014f
-  }
-  catch System.Exception
-  {
-    IL_0135:  stloc.s    V_6
-    IL_0137:  ldarg.0
-    IL_0138:  ldc.i4.s   -2
-    IL_013a:  stfld      ""int C.<F>d__7.<>1__state""
-    IL_013f:  ldarg.0
-    IL_0140:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder C.<F>d__7.<>t__builder""
-    IL_0145:  ldloc.s    V_6
-    IL_0147:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetException(System.Exception)""
-    IL_014c:  nop
-    IL_014d:  leave.s    IL_0163
-  }
-  IL_014f:  ldarg.0
-  IL_0150:  ldc.i4.s   -2
-  IL_0152:  stfld      ""int C.<F>d__7.<>1__state""
-  IL_0157:  ldarg.0
-  IL_0158:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder C.<F>d__7.<>t__builder""
-  IL_015d:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetResult()""
-  IL_0162:  nop
-  IL_0163:  ret
-}
-");
-        }
-
-        [Fact]
-        public void UpdateAsync_AwaitDeclarationMappedToNonAwait()
-        {
-            var source0 = MarkedSource(@"
-using System;
-using System.Threading.Tasks;
-
-class C
-{
-    static async Task F() 
-    {
-        <N:0>await Task.CompletedTask</N:0>;
-        IAsyncDisposable <N:1>x = G()</N:1>, <N:2>y = G()</N:2>;
-    }
-
-    static IAsyncDisposable G() => null; 
-}");
-            var source1 = MarkedSource(@"
-using System;
-using System.Threading.Tasks;
-
-class C
-{
-    static async Task F() 
-    {
-        <N:0>await Task.CompletedTask</N:0>;
-        await using IAsyncDisposable <N:1>x = G()</N:1>, <N:2>y = G()</N:2>;
-    }
-
-    static IAsyncDisposable G() => null; 
-}");
-            var asyncStreamsTree = Parse(AsyncStreamsTypes);
-
-            var compilation0 = CreateCompilationWithTasksExtensions(new[] { source0.Tree, asyncStreamsTree }, options: ComSafeDebugDll);
-            var compilation1 = compilation0.WithSource(new[] { source1.Tree, asyncStreamsTree });
-
-            var v0 = CompileAndVerify(compilation0);
-            v0.VerifyDiagnostics();
-            var md0 = ModuleMetadata.CreateFromImage(v0.EmittedAssemblyData);
-
-            var f0 = compilation0.GetMember<MethodSymbol>("C.F");
-            var f1 = compilation1.GetMember<MethodSymbol>("C.F");
-
-            var generation0 = EmitBaseline.CreateInitialBaseline(md0, v0.CreateSymReader().GetEncMethodDebugInfo);
-
-            var diff1 = compilation1.EmitDifference(
-                 generation0,
-                 ImmutableArray.Create(
-                     SemanticEdit.Create(SemanticEditKind.Update, f0, f1, GetSyntaxMapFromMarkers(source0, source1), preserveLocalVariables: true)));
-
-            // Note that the CDI contains local variable declaration mapping to facilitate local variable slot allocation,
-            // but these are not included in the state machine map since the V0 version of the local declaration statement does not have "await" keyword.
-            // Therefore, the V1 version will not be able ot match the local declaration statements to their previous versions when emitting
-            // state machine states and create new states for them as expected.
-            v0.VerifyPdb("C.F", @"
-<symbols>
-  <files>
-    <file id=""1"" name="""" language=""C#"" />
-  </files>
-  <methods>
-    <method containingType=""C"" name=""F"">
-      <customDebugInfo>
-        <forwardIterator name=""&lt;F&gt;d__0"" />
-        <encLocalSlotMap>
-          <slot kind=""0"" offset=""79"" />
-          <slot kind=""0"" offset=""99"" />
-        </encLocalSlotMap>
-        <encStateMachineStateMap>
-          <state number=""0"" offset=""16"" />
-        </encStateMachineStateMap>
-      </customDebugInfo>
-    </method>
-  </methods>
-</symbols>");
-
-            // note preserved hoisted variables x, y:
-
-            v0.VerifySynthesizedFields("C.<F>d__0",
-                "int <>1__state",
-                "System.Runtime.CompilerServices.AsyncTaskMethodBuilder <>t__builder",
-                "System.IAsyncDisposable <x>5__1",
-                "System.IAsyncDisposable <y>5__2",
-                "System.Runtime.CompilerServices.TaskAwaiter <>u__1");
-
-            diff1.VerifySynthesizedFields("C.<F>d__0",
-                "<>1__state: int",
-                "<>t__builder: System.Runtime.CompilerServices.AsyncTaskMethodBuilder",
-                "<x>5__1: System.IAsyncDisposable",
-                "<y>5__2: System.IAsyncDisposable",
-                "<>s__3: object",
-                "<>s__4: int",
-                "<>s__5: object",
-                "<>s__6: int",
-                "<>u__1: System.Runtime.CompilerServices.TaskAwaiter",
-                "<>u__2: System.Runtime.CompilerServices.ValueTaskAwaiter");
-
-            diff1.VerifyIL("C.<F>d__0.System.Runtime.CompilerServices.IAsyncStateMachine.MoveNext", @"
-{
-  // Code size      678 (0x2a6)
-  .maxstack  3
-  .locals init (int V_0,
-                System.Runtime.CompilerServices.TaskAwaiter V_1,
-                C.<F>d__0 V_2,
-                object V_3,
-                System.Runtime.CompilerServices.ValueTaskAwaiter V_4,
-                System.Threading.Tasks.ValueTask V_5,
-                System.Exception V_6,
-                int V_7,
-                System.Runtime.CompilerServices.ValueTaskAwaiter V_8)
-  IL_0000:  ldarg.0
-  IL_0001:  ldfld      ""int C.<F>d__0.<>1__state""
-  IL_0006:  stloc.0
-  .try
-  {
-    IL_0007:  ldloc.0
-    IL_0008:  switch    (
-        IL_001b,
-        IL_001d,
-        IL_001f)
-    IL_0019:  br.s       IL_0024
-    IL_001b:  br.s       IL_0060
-    IL_001d:  br.s       IL_009d
-    IL_001f:  br         IL_01e9
-    IL_0024:  nop
-    IL_0025:  call       ""System.Threading.Tasks.Task System.Threading.Tasks.Task.CompletedTask.get""
-    IL_002a:  callvirt   ""System.Runtime.CompilerServices.TaskAwaiter System.Threading.Tasks.Task.GetAwaiter()""
-    IL_002f:  stloc.1
-    IL_0030:  ldloca.s   V_1
-    IL_0032:  call       ""bool System.Runtime.CompilerServices.TaskAwaiter.IsCompleted.get""
-    IL_0037:  brtrue.s   IL_007c
-    IL_0039:  ldarg.0
-    IL_003a:  ldc.i4.0
-    IL_003b:  dup
-    IL_003c:  stloc.0
-    IL_003d:  stfld      ""int C.<F>d__0.<>1__state""
-    IL_0042:  ldarg.0
-    IL_0043:  ldloc.1
-    IL_0044:  stfld      ""System.Runtime.CompilerServices.TaskAwaiter C.<F>d__0.<>u__1""
-    IL_0049:  ldarg.0
-    IL_004a:  stloc.2
-    IL_004b:  ldarg.0
-    IL_004c:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder C.<F>d__0.<>t__builder""
-    IL_0051:  ldloca.s   V_1
-    IL_0053:  ldloca.s   V_2
-    IL_0055:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.AwaitUnsafeOnCompleted<System.Runtime.CompilerServices.TaskAwaiter, C.<F>d__0>(ref System.Runtime.CompilerServices.TaskAwaiter, ref C.<F>d__0)""
-    IL_005a:  nop
-    IL_005b:  leave      IL_02a5
-    IL_0060:  ldarg.0
-    IL_0061:  ldfld      ""System.Runtime.CompilerServices.TaskAwaiter C.<F>d__0.<>u__1""
-    IL_0066:  stloc.1
-    IL_0067:  ldarg.0
-    IL_0068:  ldflda     ""System.Runtime.CompilerServices.TaskAwaiter C.<F>d__0.<>u__1""
-    IL_006d:  initobj    ""System.Runtime.CompilerServices.TaskAwaiter""
-    IL_0073:  ldarg.0
-    IL_0074:  ldc.i4.m1
-    IL_0075:  dup
-    IL_0076:  stloc.0
-    IL_0077:  stfld      ""int C.<F>d__0.<>1__state""
-    IL_007c:  ldloca.s   V_1
-    IL_007e:  call       ""void System.Runtime.CompilerServices.TaskAwaiter.GetResult()""
-    IL_0083:  nop
-    IL_0084:  ldarg.0
-    IL_0085:  call       ""System.IAsyncDisposable C.G()""
-    IL_008a:  stfld      ""System.IAsyncDisposable C.<F>d__0.<x>5__1""
-    IL_008f:  ldarg.0
-    IL_0090:  ldnull
-    IL_0091:  stfld      ""object C.<F>d__0.<>s__3""
-    IL_0096:  ldarg.0
-    IL_0097:  ldc.i4.0
-    IL_0098:  stfld      ""int C.<F>d__0.<>s__4""
-    IL_009d:  nop
-    .try
-    {
-      IL_009e:  ldloc.0
-      IL_009f:  ldc.i4.1
-      IL_00a0:  beq.s      IL_00a4
-      IL_00a2:  br.s       IL_00a6
-      IL_00a4:  br.s       IL_0123
-      IL_00a6:  ldarg.0
-      IL_00a7:  call       ""System.IAsyncDisposable C.G()""
-      IL_00ac:  stfld      ""System.IAsyncDisposable C.<F>d__0.<y>5__2""
-      IL_00b1:  ldarg.0
-      IL_00b2:  ldnull
-      IL_00b3:  stfld      ""object C.<F>d__0.<>s__5""
-      IL_00b8:  ldarg.0
-      IL_00b9:  ldc.i4.0
-      IL_00ba:  stfld      ""int C.<F>d__0.<>s__6""
-      .try
-      {
-        IL_00bf:  br.s       IL_00c1
-        IL_00c1:  ldarg.0
-        IL_00c2:  ldc.i4.1
-        IL_00c3:  stfld      ""int C.<F>d__0.<>s__6""
-        IL_00c8:  leave.s    IL_00d4
-      }
-      catch object
-      {
-        IL_00ca:  stloc.3
-        IL_00cb:  ldarg.0
-        IL_00cc:  ldloc.3
-        IL_00cd:  stfld      ""object C.<F>d__0.<>s__5""
-        IL_00d2:  leave.s    IL_00d4
-      }
-      IL_00d4:  ldarg.0
-      IL_00d5:  ldfld      ""System.IAsyncDisposable C.<F>d__0.<y>5__2""
-      IL_00da:  brfalse.s  IL_0148
-      IL_00dc:  ldarg.0
-      IL_00dd:  ldfld      ""System.IAsyncDisposable C.<F>d__0.<y>5__2""
-      IL_00e2:  callvirt   ""System.Threading.Tasks.ValueTask System.IAsyncDisposable.DisposeAsync()""
-      IL_00e7:  stloc.s    V_5
-      IL_00e9:  ldloca.s   V_5
-      IL_00eb:  call       ""System.Runtime.CompilerServices.ValueTaskAwaiter System.Threading.Tasks.ValueTask.GetAwaiter()""
-      IL_00f0:  stloc.s    V_4
-      IL_00f2:  ldloca.s   V_4
-      IL_00f4:  call       ""bool System.Runtime.CompilerServices.ValueTaskAwaiter.IsCompleted.get""
-      IL_00f9:  brtrue.s   IL_0140
-      IL_00fb:  ldarg.0
-      IL_00fc:  ldc.i4.1
-      IL_00fd:  dup
-      IL_00fe:  stloc.0
-      IL_00ff:  stfld      ""int C.<F>d__0.<>1__state""
-      IL_0104:  ldarg.0
-      IL_0105:  ldloc.s    V_4
-      IL_0107:  stfld      ""System.Runtime.CompilerServices.ValueTaskAwaiter C.<F>d__0.<>u__2""
-      IL_010c:  ldarg.0
-      IL_010d:  stloc.2
-      IL_010e:  ldarg.0
-      IL_010f:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder C.<F>d__0.<>t__builder""
-      IL_0114:  ldloca.s   V_4
-      IL_0116:  ldloca.s   V_2
-      IL_0118:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.AwaitUnsafeOnCompleted<System.Runtime.CompilerServices.ValueTaskAwaiter, C.<F>d__0>(ref System.Runtime.CompilerServices.ValueTaskAwaiter, ref C.<F>d__0)""
-      IL_011d:  nop
-      IL_011e:  leave      IL_02a5
-      IL_0123:  ldarg.0
-      IL_0124:  ldfld      ""System.Runtime.CompilerServices.ValueTaskAwaiter C.<F>d__0.<>u__2""
-      IL_0129:  stloc.s    V_4
-      IL_012b:  ldarg.0
-      IL_012c:  ldflda     ""System.Runtime.CompilerServices.ValueTaskAwaiter C.<F>d__0.<>u__2""
-      IL_0131:  initobj    ""System.Runtime.CompilerServices.ValueTaskAwaiter""
-      IL_0137:  ldarg.0
-      IL_0138:  ldc.i4.m1
-      IL_0139:  dup
-      IL_013a:  stloc.0
-      IL_013b:  stfld      ""int C.<F>d__0.<>1__state""
-      IL_0140:  ldloca.s   V_4
-      IL_0142:  call       ""void System.Runtime.CompilerServices.ValueTaskAwaiter.GetResult()""
-      IL_0147:  nop
-      IL_0148:  ldarg.0
-      IL_0149:  ldfld      ""object C.<F>d__0.<>s__5""
-      IL_014e:  stloc.3
-      IL_014f:  ldloc.3
-      IL_0150:  brfalse.s  IL_016d
-      IL_0152:  ldloc.3
-      IL_0153:  isinst     ""System.Exception""
-      IL_0158:  stloc.s    V_6
-      IL_015a:  ldloc.s    V_6
-      IL_015c:  brtrue.s   IL_0160
-      IL_015e:  ldloc.3
-      IL_015f:  throw
-      IL_0160:  ldloc.s    V_6
-      IL_0162:  call       ""System.Runtime.ExceptionServices.ExceptionDispatchInfo System.Runtime.ExceptionServices.ExceptionDispatchInfo.Capture(System.Exception)""
-      IL_0167:  callvirt   ""void System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()""
-      IL_016c:  nop
-      IL_016d:  ldarg.0
-      IL_016e:  ldfld      ""int C.<F>d__0.<>s__6""
-      IL_0173:  stloc.s    V_7
-      IL_0175:  ldloc.s    V_7
-      IL_0177:  ldc.i4.1
-      IL_0178:  beq.s      IL_017c
-      IL_017a:  br.s       IL_017e
-      IL_017c:  br.s       IL_0187
-      IL_017e:  ldarg.0
-      IL_017f:  ldnull
-      IL_0180:  stfld      ""object C.<F>d__0.<>s__5""
-      IL_0185:  leave.s    IL_019a
-      IL_0187:  ldarg.0
-      IL_0188:  ldc.i4.1
-      IL_0189:  stfld      ""int C.<F>d__0.<>s__4""
-      IL_018e:  leave.s    IL_019a
-    }
-    catch object
-    {
-      IL_0190:  stloc.3
-      IL_0191:  ldarg.0
-      IL_0192:  ldloc.3
-      IL_0193:  stfld      ""object C.<F>d__0.<>s__3""
-      IL_0198:  leave.s    IL_019a
-    }
-    IL_019a:  ldarg.0
-    IL_019b:  ldfld      ""System.IAsyncDisposable C.<F>d__0.<x>5__1""
-    IL_01a0:  brfalse.s  IL_020e
-    IL_01a2:  ldarg.0
-    IL_01a3:  ldfld      ""System.IAsyncDisposable C.<F>d__0.<x>5__1""
-    IL_01a8:  callvirt   ""System.Threading.Tasks.ValueTask System.IAsyncDisposable.DisposeAsync()""
-    IL_01ad:  stloc.s    V_5
-    IL_01af:  ldloca.s   V_5
-    IL_01b1:  call       ""System.Runtime.CompilerServices.ValueTaskAwaiter System.Threading.Tasks.ValueTask.GetAwaiter()""
-    IL_01b6:  stloc.s    V_8
-    IL_01b8:  ldloca.s   V_8
-    IL_01ba:  call       ""bool System.Runtime.CompilerServices.ValueTaskAwaiter.IsCompleted.get""
-    IL_01bf:  brtrue.s   IL_0206
-    IL_01c1:  ldarg.0
-    IL_01c2:  ldc.i4.2
-    IL_01c3:  dup
-    IL_01c4:  stloc.0
-    IL_01c5:  stfld      ""int C.<F>d__0.<>1__state""
-    IL_01ca:  ldarg.0
-    IL_01cb:  ldloc.s    V_8
-    IL_01cd:  stfld      ""System.Runtime.CompilerServices.ValueTaskAwaiter C.<F>d__0.<>u__2""
-    IL_01d2:  ldarg.0
-    IL_01d3:  stloc.2
-    IL_01d4:  ldarg.0
-    IL_01d5:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder C.<F>d__0.<>t__builder""
-    IL_01da:  ldloca.s   V_8
-    IL_01dc:  ldloca.s   V_2
-    IL_01de:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.AwaitUnsafeOnCompleted<System.Runtime.CompilerServices.ValueTaskAwaiter, C.<F>d__0>(ref System.Runtime.CompilerServices.ValueTaskAwaiter, ref C.<F>d__0)""
-    IL_01e3:  nop
-    IL_01e4:  leave      IL_02a5
-    IL_01e9:  ldarg.0
-    IL_01ea:  ldfld      ""System.Runtime.CompilerServices.ValueTaskAwaiter C.<F>d__0.<>u__2""
-    IL_01ef:  stloc.s    V_8
-    IL_01f1:  ldarg.0
-    IL_01f2:  ldflda     ""System.Runtime.CompilerServices.ValueTaskAwaiter C.<F>d__0.<>u__2""
-    IL_01f7:  initobj    ""System.Runtime.CompilerServices.ValueTaskAwaiter""
-    IL_01fd:  ldarg.0
-    IL_01fe:  ldc.i4.m1
-    IL_01ff:  dup
-    IL_0200:  stloc.0
-    IL_0201:  stfld      ""int C.<F>d__0.<>1__state""
-    IL_0206:  ldloca.s   V_8
-    IL_0208:  call       ""void System.Runtime.CompilerServices.ValueTaskAwaiter.GetResult()""
-    IL_020d:  nop
-    IL_020e:  ldarg.0
-    IL_020f:  ldfld      ""object C.<F>d__0.<>s__3""
-    IL_0214:  stloc.3
-    IL_0215:  ldloc.3
-    IL_0216:  brfalse.s  IL_0233
-    IL_0218:  ldloc.3
-    IL_0219:  isinst     ""System.Exception""
-    IL_021e:  stloc.s    V_6
-    IL_0220:  ldloc.s    V_6
-    IL_0222:  brtrue.s   IL_0226
-    IL_0224:  ldloc.3
-    IL_0225:  throw
-    IL_0226:  ldloc.s    V_6
-    IL_0228:  call       ""System.Runtime.ExceptionServices.ExceptionDispatchInfo System.Runtime.ExceptionServices.ExceptionDispatchInfo.Capture(System.Exception)""
-    IL_022d:  callvirt   ""void System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()""
-    IL_0232:  nop
-    IL_0233:  ldarg.0
-    IL_0234:  ldfld      ""int C.<F>d__0.<>s__4""
-    IL_0239:  stloc.s    V_7
-    IL_023b:  ldloc.s    V_7
-    IL_023d:  ldc.i4.1
-    IL_023e:  beq.s      IL_0242
-    IL_0240:  br.s       IL_0244
-    IL_0242:  leave.s    IL_0283
-    IL_0244:  ldarg.0
-    IL_0245:  ldnull
-    IL_0246:  stfld      ""object C.<F>d__0.<>s__3""
-    IL_024b:  ldarg.0
-    IL_024c:  ldnull
-    IL_024d:  stfld      ""System.IAsyncDisposable C.<F>d__0.<x>5__1""
-    IL_0252:  ldarg.0
-    IL_0253:  ldnull
-    IL_0254:  stfld      ""System.IAsyncDisposable C.<F>d__0.<y>5__2""
-    IL_0259:  leave.s    IL_0283
-  }
-  catch System.Exception
-  {
-    IL_025b:  stloc.s    V_6
-    IL_025d:  ldarg.0
-    IL_025e:  ldc.i4.s   -2
-    IL_0260:  stfld      ""int C.<F>d__0.<>1__state""
-    IL_0265:  ldarg.0
-    IL_0266:  ldnull
-    IL_0267:  stfld      ""System.IAsyncDisposable C.<F>d__0.<x>5__1""
-    IL_026c:  ldarg.0
-    IL_026d:  ldnull
-    IL_026e:  stfld      ""System.IAsyncDisposable C.<F>d__0.<y>5__2""
-    IL_0273:  ldarg.0
-    IL_0274:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder C.<F>d__0.<>t__builder""
-    IL_0279:  ldloc.s    V_6
-    IL_027b:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetException(System.Exception)""
-    IL_0280:  nop
-    IL_0281:  leave.s    IL_02a5
-  }
-  IL_0283:  ldarg.0
-  IL_0284:  ldc.i4.s   -2
-  IL_0286:  stfld      ""int C.<F>d__0.<>1__state""
-  IL_028b:  ldarg.0
-  IL_028c:  ldnull
-  IL_028d:  stfld      ""System.IAsyncDisposable C.<F>d__0.<x>5__1""
-  IL_0292:  ldarg.0
-  IL_0293:  ldnull
-  IL_0294:  stfld      ""System.IAsyncDisposable C.<F>d__0.<y>5__2""
-  IL_0299:  ldarg.0
-  IL_029a:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder C.<F>d__0.<>t__builder""
-  IL_029f:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetResult()""
-  IL_02a4:  nop
-  IL_02a5:  ret
-}");
-        }
-
-        [Fact]
-        public void UpdateIterator_UserDefinedVariables_NoChange()
-        {
-            var source0 = MarkedSource(@"
-using System.Collections.Generic;
-
-class C
-{
-    static IEnumerable<int> F(int p) 
-    {
-        int <N:0>x = p</N:0>;
-        <N:1>yield return 1</N:1>;
-    }
-}");
-            var source1 = MarkedSource(@"
-using System.Collections.Generic;
-
-class C
-{
-    static IEnumerable<int> F(int p) 
-    {
-        int <N:0>x = p</N:0>;
-        <N:1>yield return 2</N:1>;
-    }
-}");
-            var compilation0 = CreateCompilationWithMscorlib45(source0.Tree, options: ComSafeDebugDll);
-            var compilation1 = compilation0.WithSource(source1.Tree);
-
-            var v0 = CompileAndVerify(compilation0);
-            var symReader = v0.CreateSymReader();
-
-            using var md0 = ModuleMetadata.CreateFromImage(v0.EmittedAssemblyData);
-            var method0 = compilation0.GetMember<MethodSymbol>("C.F");
-            var method1 = compilation1.GetMember<MethodSymbol>("C.F");
-
-            var generation0 = EmitBaseline.CreateInitialBaseline(md0, symReader.GetEncMethodDebugInfo);
-
-            var diff1 = compilation1.EmitDifference(
-                generation0,
-                ImmutableArray.Create(SemanticEdit.Create(SemanticEditKind.Update, method0, method1, GetSyntaxMapFromMarkers(source0, source1), preserveLocalVariables: true)));
-
-            // Verify delta metadata contains expected rows.
-            using var md1 = diff1.GetMetadata();
-
-            // Verify that no new TypeDefs, FieldDefs or MethodDefs were added,
-            // 3 methods were updated: 
-            // - the kick-off method (might be changed if the method previously wasn't an iterator)
-            // - Finally method
-            // - MoveNext method
-            CheckEncLogDefinitions(md1.Reader,
-                Row(3, TableIndex.StandAloneSig, EditAndContinueOperation.Default),
-                Row(1, TableIndex.MethodDef, EditAndContinueOperation.Default),
-                Row(4, TableIndex.MethodDef, EditAndContinueOperation.Default),
-                Row(5, TableIndex.MethodDef, EditAndContinueOperation.Default),
-                Row(1, TableIndex.Param, EditAndContinueOperation.Default),
-                Row(1, TableIndex.CustomAttribute, EditAndContinueOperation.Default),
-                Row(7, TableIndex.CustomAttribute, EditAndContinueOperation.Default));
-
-            diff1.VerifyIL("C.<F>d__0.System.Collections.IEnumerator.MoveNext", @"
-{
-  // Code size       69 (0x45)
-  .maxstack  2
-  .locals init (int V_0)
-  IL_0000:  ldarg.0
-  IL_0001:  ldfld      ""int C.<F>d__0.<>1__state""
-  IL_0006:  stloc.0
-  IL_0007:  ldloc.0
-  IL_0008:  brfalse.s  IL_0012
-  IL_000a:  br.s       IL_000c
-  IL_000c:  ldloc.0
-  IL_000d:  ldc.i4.1
-  IL_000e:  beq.s      IL_0014
-  IL_0010:  br.s       IL_0016
-  IL_0012:  br.s       IL_0018
-  IL_0014:  br.s       IL_003c
-  IL_0016:  ldc.i4.0
-  IL_0017:  ret
-  IL_0018:  ldarg.0
-  IL_0019:  ldc.i4.m1
-  IL_001a:  stfld      ""int C.<F>d__0.<>1__state""
-  IL_001f:  nop
-  IL_0020:  ldarg.0
-  IL_0021:  ldarg.0
-  IL_0022:  ldfld      ""int C.<F>d__0.p""
-  IL_0027:  stfld      ""int C.<F>d__0.<x>5__1""
-  IL_002c:  ldarg.0
-  IL_002d:  ldc.i4.2
-  IL_002e:  stfld      ""int C.<F>d__0.<>2__current""
-  IL_0033:  ldarg.0
-  IL_0034:  ldc.i4.1
-  IL_0035:  stfld      ""int C.<F>d__0.<>1__state""
-  IL_003a:  ldc.i4.1
-  IL_003b:  ret
-  IL_003c:  ldarg.0
-  IL_003d:  ldc.i4.m1
-  IL_003e:  stfld      ""int C.<F>d__0.<>1__state""
-  IL_0043:  ldc.i4.0
-  IL_0044:  ret
-}");
-        }
-
-        [Fact]
-        public void UpdateIterator_UserDefinedVariables_AddVariable()
-        {
-            var source0 = MarkedSource(@"
-using System;
-using System.Collections.Generic;
-
-class C
-{
-    static IEnumerable<int> F(int p) 
-    {
-        int <N:0>x = p</N:0>;
-        <N:1>yield return x;</N:1>
-    }
-}");
-            var source1 = MarkedSource(@"
-using System;
-using System.Collections.Generic;
-
-class C
-{
-    static IEnumerable<int> F(int p) 
-    {
-        int y = 1234;
-        int <N:0>x = p</N:0>;
-        <N:1>yield return y</N:1>;
-        Console.WriteLine(x);
-    }
-}");
-            var compilation0 = CreateCompilationWithMscorlib45(source0.Tree, options: ComSafeDebugDll);
-            var compilation1 = compilation0.WithSource(source1.Tree);
-
-            var v0 = CompileAndVerify(compilation0);
-            var symReader = v0.CreateSymReader();
-
-            using var md0 = ModuleMetadata.CreateFromImage(v0.EmittedAssemblyData);
-            var method0 = compilation0.GetMember<MethodSymbol>("C.F");
-            var method1 = compilation1.GetMember<MethodSymbol>("C.F");
-
-            var generation0 = EmitBaseline.CreateInitialBaseline(md0, symReader.GetEncMethodDebugInfo);
-            var diff1 = compilation1.EmitDifference(
-                generation0,
-                ImmutableArray.Create(SemanticEdit.Create(SemanticEditKind.Update, method0, method1, GetSyntaxMapFromMarkers(source0, source1), preserveLocalVariables: true)));
-
-            // Verify delta metadata contains expected rows.
-            using var md1 = diff1.GetMetadata();
-
-            // 1 field def added & 3 methods updated
-            CheckEncLogDefinitions(md1.Reader,
-                Row(3, TableIndex.StandAloneSig, EditAndContinueOperation.Default),
-                Row(3, TableIndex.TypeDef, EditAndContinueOperation.AddField),
-                Row(7, TableIndex.Field, EditAndContinueOperation.Default),
-                Row(1, TableIndex.MethodDef, EditAndContinueOperation.Default),
-                Row(4, TableIndex.MethodDef, EditAndContinueOperation.Default),
-                Row(5, TableIndex.MethodDef, EditAndContinueOperation.Default),
-                Row(1, TableIndex.Param, EditAndContinueOperation.Default),
-                Row(1, TableIndex.CustomAttribute, EditAndContinueOperation.Default),
-                Row(7, TableIndex.CustomAttribute, EditAndContinueOperation.Default));
-
-            diff1.VerifyIL("C.<F>d__0.System.Collections.IEnumerator.MoveNext", @"
-{
-  // Code size       97 (0x61)
-  .maxstack  2
-  .locals init (int V_0)
-  IL_0000:  ldarg.0
-  IL_0001:  ldfld      ""int C.<F>d__0.<>1__state""
-  IL_0006:  stloc.0
-  IL_0007:  ldloc.0
-  IL_0008:  brfalse.s  IL_0012
-  IL_000a:  br.s       IL_000c
-  IL_000c:  ldloc.0
-  IL_000d:  ldc.i4.1
-  IL_000e:  beq.s      IL_0014
-  IL_0010:  br.s       IL_0016
-  IL_0012:  br.s       IL_0018
-  IL_0014:  br.s       IL_004c
-  IL_0016:  ldc.i4.0
-  IL_0017:  ret
-  IL_0018:  ldarg.0
-  IL_0019:  ldc.i4.m1
-  IL_001a:  stfld      ""int C.<F>d__0.<>1__state""
-  IL_001f:  nop
-  IL_0020:  ldarg.0
-  IL_0021:  ldc.i4     0x4d2
-  IL_0026:  stfld      ""int C.<F>d__0.<y>5__2""
-  IL_002b:  ldarg.0
-  IL_002c:  ldarg.0
-  IL_002d:  ldfld      ""int C.<F>d__0.p""
-  IL_0032:  stfld      ""int C.<F>d__0.<x>5__1""
-  IL_0037:  ldarg.0
-  IL_0038:  ldarg.0
-  IL_0039:  ldfld      ""int C.<F>d__0.<y>5__2""
-  IL_003e:  stfld      ""int C.<F>d__0.<>2__current""
-  IL_0043:  ldarg.0
-  IL_0044:  ldc.i4.1
-  IL_0045:  stfld      ""int C.<F>d__0.<>1__state""
-  IL_004a:  ldc.i4.1
-  IL_004b:  ret
-  IL_004c:  ldarg.0
-  IL_004d:  ldc.i4.m1
-  IL_004e:  stfld      ""int C.<F>d__0.<>1__state""
-  IL_0053:  ldarg.0
-  IL_0054:  ldfld      ""int C.<F>d__0.<x>5__1""
-  IL_0059:  call       ""void System.Console.WriteLine(int)""
-  IL_005e:  nop
-  IL_005f:  ldc.i4.0
-  IL_0060:  ret
-}");
-        }
-
-        [Fact]
-        public void UpdateIterator_UserDefinedVariables_AddAndRemoveVariable()
-        {
-            var source0 = MarkedSource(@"
-using System;
-using System.Collections.Generic;
-
-class C
-{
-    static IEnumerable<int> F(int p) 
-    {
-        int x = p;
-        <N:0>yield return x;</N:0>
-    }
-}");
-            var source1 = MarkedSource(@"
-using System;
-using System.Collections.Generic;
-
-class C
-{
-    static IEnumerable<int> F(int p) 
-    {
-        int y = 1234;
-        <N:0>yield return y;</N:0>
-        Console.WriteLine(p);
-    }
-}");
-            var compilation0 = CreateCompilationWithMscorlib45(source0.Tree, options: ComSafeDebugDll);
-            var compilation1 = compilation0.WithSource(source1.Tree);
-
-            var v0 = CompileAndVerify(compilation0);
-            var symReader = v0.CreateSymReader();
-
-            using var md0 = ModuleMetadata.CreateFromImage(v0.EmittedAssemblyData);
-            var method0 = compilation0.GetMember<MethodSymbol>("C.F");
-            var method1 = compilation1.GetMember<MethodSymbol>("C.F");
-
-            var generation0 = EmitBaseline.CreateInitialBaseline(md0, symReader.GetEncMethodDebugInfo);
-            var diff1 = compilation1.EmitDifference(
-                generation0,
-                ImmutableArray.Create(SemanticEdit.Create(SemanticEditKind.Update, method0, method1, GetSyntaxMapFromMarkers(source0, source1), preserveLocalVariables: true)));
-
-            // Verify delta metadata contains expected rows.
-            using var md1 = diff1.GetMetadata();
-
-            // 1 field def added & 3 methods updated
-            CheckEncLogDefinitions(md1.Reader,
-                Row(3, TableIndex.StandAloneSig, EditAndContinueOperation.Default),
-                Row(3, TableIndex.TypeDef, EditAndContinueOperation.AddField),
-                Row(7, TableIndex.Field, EditAndContinueOperation.Default),
-                Row(1, TableIndex.MethodDef, EditAndContinueOperation.Default),
-                Row(4, TableIndex.MethodDef, EditAndContinueOperation.Default),
-                Row(5, TableIndex.MethodDef, EditAndContinueOperation.Default),
-                Row(1, TableIndex.Param, EditAndContinueOperation.Default),
-                Row(1, TableIndex.CustomAttribute, EditAndContinueOperation.Default),
-                Row(7, TableIndex.CustomAttribute, EditAndContinueOperation.Default));
-
-            diff1.VerifyIL("C.<F>d__0.System.Collections.IEnumerator.MoveNext", @"
-{
-  // Code size       85 (0x55)
-  .maxstack  2
-  .locals init (int V_0)
-  IL_0000:  ldarg.0
-  IL_0001:  ldfld      ""int C.<F>d__0.<>1__state""
-  IL_0006:  stloc.0
-  IL_0007:  ldloc.0
-  IL_0008:  brfalse.s  IL_0012
-  IL_000a:  br.s       IL_000c
-  IL_000c:  ldloc.0
-  IL_000d:  ldc.i4.1
-  IL_000e:  beq.s      IL_0014
-  IL_0010:  br.s       IL_0016
-  IL_0012:  br.s       IL_0018
-  IL_0014:  br.s       IL_0040
-  IL_0016:  ldc.i4.0
-  IL_0017:  ret
-  IL_0018:  ldarg.0
-  IL_0019:  ldc.i4.m1
-  IL_001a:  stfld      ""int C.<F>d__0.<>1__state""
-  IL_001f:  nop
-  IL_0020:  ldarg.0
-  IL_0021:  ldc.i4     0x4d2
-  IL_0026:  stfld      ""int C.<F>d__0.<y>5__2""
-  IL_002b:  ldarg.0
-  IL_002c:  ldarg.0
-  IL_002d:  ldfld      ""int C.<F>d__0.<y>5__2""
-  IL_0032:  stfld      ""int C.<F>d__0.<>2__current""
-  IL_0037:  ldarg.0
-  IL_0038:  ldc.i4.1
-  IL_0039:  stfld      ""int C.<F>d__0.<>1__state""
-  IL_003e:  ldc.i4.1
-  IL_003f:  ret
-  IL_0040:  ldarg.0
-  IL_0041:  ldc.i4.m1
-  IL_0042:  stfld      ""int C.<F>d__0.<>1__state""
-  IL_0047:  ldarg.0
-  IL_0048:  ldfld      ""int C.<F>d__0.p""
-  IL_004d:  call       ""void System.Console.WriteLine(int)""
-  IL_0052:  nop
-  IL_0053:  ldc.i4.0
-  IL_0054:  ret
-}");
-        }
-
-        [Fact]
-        public void UpdateIterator_UserDefinedVariables_ChangeVariableType()
-        {
-            var source0 = MarkedSource(@"
-using System;
-using System.Collections.Generic;
-
-class C
-{
-    static IEnumerable<int> F() 
-    {
-        var <N:0>x = 1</N:0>;
-        <N:1>yield return 1</N:1>;
-        Console.WriteLine(x);
-    }
-}");
-            var source1 = MarkedSource(@"
-using System;
-using System.Collections.Generic;
-
-class C
-{
-    static IEnumerable<int> F() 
-    {
-        var <N:0>x = 1.0</N:0>;
-        <N:1>yield return 2</N:1>;
-        Console.WriteLine(x);
-    }
-}");
-            var compilation0 = CreateCompilationWithMscorlib45(source0.Tree, options: ComSafeDebugDll);
-            var compilation1 = compilation0.WithSource(source1.Tree);
-
-            var v0 = CompileAndVerify(compilation0);
-            var symReader = v0.CreateSymReader();
-
-            using var md0 = ModuleMetadata.CreateFromImage(v0.EmittedAssemblyData);
-            var method0 = compilation0.GetMember<MethodSymbol>("C.F");
-            var method1 = compilation1.GetMember<MethodSymbol>("C.F");
-
-            var generation0 = EmitBaseline.CreateInitialBaseline(md0, symReader.GetEncMethodDebugInfo);
-            var diff1 = compilation1.EmitDifference(
-                generation0,
-                ImmutableArray.Create(SemanticEdit.Create(SemanticEditKind.Update, method0, method1, GetSyntaxMapFromMarkers(source0, source1), preserveLocalVariables: true)));
-
-            // Verify delta metadata contains expected rows.
-            using var md1 = diff1.GetMetadata();
-
-            // 1 field def added & 3 methods updated
-            CheckEncLogDefinitions(md1.Reader,
-                Row(3, TableIndex.StandAloneSig, EditAndContinueOperation.Default),
-                Row(3, TableIndex.TypeDef, EditAndContinueOperation.AddField),
-                Row(5, TableIndex.Field, EditAndContinueOperation.Default),
-                Row(1, TableIndex.MethodDef, EditAndContinueOperation.Default),
-                Row(4, TableIndex.MethodDef, EditAndContinueOperation.Default),
-                Row(5, TableIndex.MethodDef, EditAndContinueOperation.Default),
-                Row(1, TableIndex.CustomAttribute, EditAndContinueOperation.Default),
-                Row(7, TableIndex.CustomAttribute, EditAndContinueOperation.Default));
-
-            diff1.VerifyIL("C.<F>d__0.System.Collections.IEnumerator.MoveNext", @"
-{
-  // Code size       84 (0x54)
-  .maxstack  2
-  .locals init (int V_0)
-  IL_0000:  ldarg.0
-  IL_0001:  ldfld      ""int C.<F>d__0.<>1__state""
-  IL_0006:  stloc.0
-  IL_0007:  ldloc.0
-  IL_0008:  brfalse.s  IL_0012
-  IL_000a:  br.s       IL_000c
-  IL_000c:  ldloc.0
-  IL_000d:  ldc.i4.1
-  IL_000e:  beq.s      IL_0014
-  IL_0010:  br.s       IL_0016
-  IL_0012:  br.s       IL_0018
-  IL_0014:  br.s       IL_003f
-  IL_0016:  ldc.i4.0
-  IL_0017:  ret
-  IL_0018:  ldarg.0
-  IL_0019:  ldc.i4.m1
-  IL_001a:  stfld      ""int C.<F>d__0.<>1__state""
-  IL_001f:  nop
-  IL_0020:  ldarg.0
-  IL_0021:  ldc.r8     1
-  IL_002a:  stfld      ""double C.<F>d__0.<x>5__2""
-  IL_002f:  ldarg.0
-  IL_0030:  ldc.i4.2
-  IL_0031:  stfld      ""int C.<F>d__0.<>2__current""
-  IL_0036:  ldarg.0
-  IL_0037:  ldc.i4.1
-  IL_0038:  stfld      ""int C.<F>d__0.<>1__state""
-  IL_003d:  ldc.i4.1
-  IL_003e:  ret
-  IL_003f:  ldarg.0
-  IL_0040:  ldc.i4.m1
-  IL_0041:  stfld      ""int C.<F>d__0.<>1__state""
-  IL_0046:  ldarg.0
-  IL_0047:  ldfld      ""double C.<F>d__0.<x>5__2""
-  IL_004c:  call       ""void System.Console.WriteLine(double)""
-  IL_0051:  nop
-  IL_0052:  ldc.i4.0
-  IL_0053:  ret
-}");
-        }
-
-        [Fact]
-        public void UpdateIterator_SynthesizedVariables_ChangeVariableType()
-        {
-            var source0 = MarkedSource(@"
-using System;
-using System.Collections.Generic;
-
-class C
-{
-    static IEnumerable<int> F() 
-    {
-        <N:0>foreach</N:0> (object item in new[] { 1 }) { <N:1>yield return 1;</N:1> }
-    }
-}");
-            var source1 = MarkedSource(@"
-using System;
-using System.Collections.Generic;
-
-class C
-{
-    static IEnumerable<int> F() 
-    {
-        <N:0>foreach</N:0> (object item in new[] { 1.0 }) { <N:1>yield return 1;</N:1> }
-    }
-}");
-            // Rude edit but the compiler should handle it.
-
-            var compilation0 = CreateCompilationWithMscorlib45(source0.Tree, options: ComSafeDebugDll.WithMetadataImportOptions(MetadataImportOptions.All));
-            var compilation1 = compilation0.WithSource(source1.Tree);
-
-            var v0 = CompileAndVerify(compilation0, symbolValidator: module =>
-            {
-                Assert.Equal(new[]
-                {
-                    "<>1__state: int",
-                    "<>2__current: int",
-                    "<>l__initialThreadId: int",
-                    "<>s__1: int[]",
-                    "<>s__2: int",
-                    "<item>5__3: object"
-                }, module.GetFieldNamesAndTypes("C.<F>d__0"));
-            });
-
-            var symReader = v0.CreateSymReader();
-
-            using var md0 = ModuleMetadata.CreateFromImage(v0.EmittedAssemblyData);
-            var method0 = compilation0.GetMember<MethodSymbol>("C.F");
-            var method1 = compilation1.GetMember<MethodSymbol>("C.F");
-
-            var generation0 = EmitBaseline.CreateInitialBaseline(md0, symReader.GetEncMethodDebugInfo);
-            var diff1 = compilation1.EmitDifference(
-                generation0,
-                ImmutableArray.Create(SemanticEdit.Create(SemanticEditKind.Update, method0, method1, GetSyntaxMapFromMarkers(source0, source1), preserveLocalVariables: true)));
-
-            // Verify delta metadata contains expected rows.
-            using var md1 = diff1.GetMetadata();
-
-            // 1 field def added & 3 methods updated
-            CheckEncLogDefinitions(md1.Reader,
-                Row(3, TableIndex.StandAloneSig, EditAndContinueOperation.Default),
-                Row(3, TableIndex.TypeDef, EditAndContinueOperation.AddField),
-                Row(7, TableIndex.Field, EditAndContinueOperation.Default),
-                Row(1, TableIndex.MethodDef, EditAndContinueOperation.Default),
-                Row(4, TableIndex.MethodDef, EditAndContinueOperation.Default),
-                Row(5, TableIndex.MethodDef, EditAndContinueOperation.Default),
-                Row(1, TableIndex.CustomAttribute, EditAndContinueOperation.Default),
-                Row(7, TableIndex.CustomAttribute, EditAndContinueOperation.Default));
-
-            diff1.VerifyIL("C.<F>d__0.System.Collections.IEnumerator.MoveNext", @"
-{
-  // Code size      161 (0xa1)
-  .maxstack  5
-  .locals init (int V_0)
-  IL_0000:  ldarg.0
-  IL_0001:  ldfld      ""int C.<F>d__0.<>1__state""
-  IL_0006:  stloc.0
-  IL_0007:  ldloc.0
-  IL_0008:  brfalse.s  IL_0012
-  IL_000a:  br.s       IL_000c
-  IL_000c:  ldloc.0
-  IL_000d:  ldc.i4.1
-  IL_000e:  beq.s      IL_0014
-  IL_0010:  br.s       IL_0016
-  IL_0012:  br.s       IL_0018
-  IL_0014:  br.s       IL_006b
-  IL_0016:  ldc.i4.0
-  IL_0017:  ret
-  IL_0018:  ldarg.0
-  IL_0019:  ldc.i4.m1
-  IL_001a:  stfld      ""int C.<F>d__0.<>1__state""
-  IL_001f:  nop
-  IL_0020:  nop
-  IL_0021:  ldarg.0
-  IL_0022:  ldc.i4.1
-  IL_0023:  newarr     ""double""
-  IL_0028:  dup
-  IL_0029:  ldc.i4.0
-  IL_002a:  ldc.r8     1
-  IL_0033:  stelem.r8
-  IL_0034:  stfld      ""double[] C.<F>d__0.<>s__4""
-  IL_0039:  ldarg.0
-  IL_003a:  ldc.i4.0
-  IL_003b:  stfld      ""int C.<F>d__0.<>s__2""
-  IL_0040:  br.s       IL_0088
-  IL_0042:  ldarg.0
-  IL_0043:  ldarg.0
-  IL_0044:  ldfld      ""double[] C.<F>d__0.<>s__4""
-  IL_0049:  ldarg.0
-  IL_004a:  ldfld      ""int C.<F>d__0.<>s__2""
-  IL_004f:  ldelem.r8
-  IL_0050:  box        ""double""
-  IL_0055:  stfld      ""object C.<F>d__0.<item>5__3""
-  IL_005a:  nop
-  IL_005b:  ldarg.0
-  IL_005c:  ldc.i4.1
-  IL_005d:  stfld      ""int C.<F>d__0.<>2__current""
-  IL_0062:  ldarg.0
-  IL_0063:  ldc.i4.1
-  IL_0064:  stfld      ""int C.<F>d__0.<>1__state""
-  IL_0069:  ldc.i4.1
-  IL_006a:  ret
-  IL_006b:  ldarg.0
-  IL_006c:  ldc.i4.m1
-  IL_006d:  stfld      ""int C.<F>d__0.<>1__state""
-  IL_0072:  nop
-  IL_0073:  ldarg.0
-  IL_0074:  ldnull
-  IL_0075:  stfld      ""object C.<F>d__0.<item>5__3""
-  IL_007a:  ldarg.0
-  IL_007b:  ldarg.0
-  IL_007c:  ldfld      ""int C.<F>d__0.<>s__2""
-  IL_0081:  ldc.i4.1
-  IL_0082:  add
-  IL_0083:  stfld      ""int C.<F>d__0.<>s__2""
-  IL_0088:  ldarg.0
-  IL_0089:  ldfld      ""int C.<F>d__0.<>s__2""
-  IL_008e:  ldarg.0
-  IL_008f:  ldfld      ""double[] C.<F>d__0.<>s__4""
-  IL_0094:  ldlen
-  IL_0095:  conv.i4
-  IL_0096:  blt.s      IL_0042
-  IL_0098:  ldarg.0
-  IL_0099:  ldnull
-  IL_009a:  stfld      ""double[] C.<F>d__0.<>s__4""
-  IL_009f:  ldc.i4.0
-  IL_00a0:  ret
-}");
-        }
-
-        [Fact]
-        public void UpdateIterator_YieldReturn_Add()
-        {
-            var source0 = MarkedSource(@"
-using System.Collections.Generic;
-
-class C
-{
-    static int M1() => 1;
-    static int M2() => 2;
-    static int M3() => 3;
-    static int M4() => 4;
-    static void End() {}
-
-    static IEnumerable<int> F() 
-    {
-        <N:0>yield return M1();</N:0>
-        <N:1>yield return M2();</N:1>
-        End();
-    }
-}");
-            var source1 = MarkedSource(@"
-using System.Collections.Generic;
-
-class C
-{
-    static int M1() => 1;
-    static int M2() => 2;
-    static int M3() => 3;
-    static int M4() => 4;
-    static void End() {}
-
-    static IEnumerable<int> F() 
-    {
-        <N:0>yield return M1();</N:0>
-        <N:2>yield return M3();</N:2>
-        <N:3>yield return M4();</N:3>
-        <N:1>yield return M2();</N:1>   
-        End();
-    }
-}");
-            var compilation0 = CreateCompilationWithMscorlib45(new[] { source0.Tree }, new[] { SystemCoreRef, CSharpRef }, options: ComSafeDebugDll);
-            var compilation1 = compilation0.WithSource(source1.Tree);
-
-            var v0 = CompileAndVerify(compilation0);
-            v0.VerifyDiagnostics();
-            var md0 = ModuleMetadata.CreateFromImage(v0.EmittedAssemblyData);
-
-            var f0 = compilation0.GetMember<MethodSymbol>("C.F");
-            var f1 = compilation1.GetMember<MethodSymbol>("C.F");
-
-            var generation0 = EmitBaseline.CreateInitialBaseline(md0, v0.CreateSymReader().GetEncMethodDebugInfo);
-
-            var diff1 = compilation1.EmitDifference(
-                 generation0,
-                 ImmutableArray.Create(
-                     SemanticEdit.Create(SemanticEditKind.Update, f0, f1, GetSyntaxMapFromMarkers(source0, source1), preserveLocalVariables: true)));
-
-            v0.VerifyPdb("C.F", @"
-<symbols>
-  <files>
-    <file id=""1"" name="""" language=""C#"" />
-  </files>
-  <methods>
-    <method containingType=""C"" name=""F"">
-      <customDebugInfo>
-        <forwardIterator name=""&lt;F&gt;d__5"" />
-        <encStateMachineStateMap>
-          <state number=""1"" offset=""16"" />
-          <state number=""2"" offset=""55"" />
-        </encStateMachineStateMap>
-      </customDebugInfo>
-    </method>
-  </methods>
-</symbols>
-");
-            v0.VerifyPdb("C+<F>d__5.MoveNext", @"
-  <symbols>
-  <files>
-    <file id=""1"" name="""" language=""C#"" />
-  </files>
-  <methods>
-    <method containingType=""C+&lt;F&gt;d__5"" name=""MoveNext"">
-      <customDebugInfo>
-        <forward declaringType=""C"" methodName=""M1"" />
-        <encLocalSlotMap>
-          <slot kind=""27"" offset=""0"" />
-        </encLocalSlotMap>
-      </customDebugInfo>
-    </method>
-  </methods>
-</symbols>
-", options: PdbValidationOptions.ExcludeSequencePoints);
-
-            v0.VerifyIL("C.<F>d__5.System.Collections.IEnumerator.MoveNext", @"
- {
-  // Code size      105 (0x69)
-  .maxstack  2
-  .locals init (int V_0)
-  IL_0000:  ldarg.0
-  IL_0001:  ldfld      ""int C.<F>d__5.<>1__state""
-  IL_0006:  stloc.0
-  IL_0007:  ldloc.0
-  IL_0008:  switch    (
-        IL_001b,
-        IL_001d,
-        IL_001f)
-  IL_0019:  br.s       IL_0021
-  IL_001b:  br.s       IL_0023
-  IL_001d:  br.s       IL_003f
-  IL_001f:  br.s       IL_005a
-
-  IL_0021:  ldc.i4.0
-  IL_0022:  ret
-
-  IL_0023:  ldarg.0
-  IL_0024:  ldc.i4.m1
-  IL_0025:  stfld      ""int C.<F>d__5.<>1__state""
-  IL_002a:  nop
-  IL_002b:  ldarg.0
-  IL_002c:  call       ""int C.M1()""
-  IL_0031:  stfld      ""int C.<F>d__5.<>2__current""
-  IL_0036:  ldarg.0
-  IL_0037:  ldc.i4.1
-  IL_0038:  stfld      ""int C.<F>d__5.<>1__state""
-  IL_003d:  ldc.i4.1
-  IL_003e:  ret
-
-  IL_003f:  ldarg.0
-  IL_0040:  ldc.i4.m1
-  IL_0041:  stfld      ""int C.<F>d__5.<>1__state""
-  IL_0046:  ldarg.0
-  IL_0047:  call       ""int C.M2()""
-  IL_004c:  stfld      ""int C.<F>d__5.<>2__current""
-  IL_0051:  ldarg.0
-  IL_0052:  ldc.i4.2
-  IL_0053:  stfld      ""int C.<F>d__5.<>1__state""
-  IL_0058:  ldc.i4.1
-  IL_0059:  ret
-
-  IL_005a:  ldarg.0
-  IL_005b:  ldc.i4.m1
-  IL_005c:  stfld      ""int C.<F>d__5.<>1__state""
-  IL_0061:  call       ""void C.End()""
-  IL_0066:  nop
-  IL_0067:  ldc.i4.0
-  IL_0068:  ret
-}");
-
-            diff1.VerifyIL("C.<F>d__5.System.Collections.IEnumerator.MoveNext", @"
-{
-  // Code size      171 (0xab)
-  .maxstack  2
-  .locals init (int V_0)
-  IL_0000:  ldarg.0
-  IL_0001:  ldfld      ""int C.<F>d__5.<>1__state""
-  IL_0006:  stloc.0
-  IL_0007:  ldloc.0
-  IL_0008:  switch    (
-        IL_0023,
-        IL_0025,
-        IL_0027,
-        IL_0029,
-        IL_002b)
-  IL_0021:  br.s       IL_002d
-  IL_0023:  br.s       IL_002f
-  IL_0025:  br.s       IL_004b
-  IL_0027:  br.s       IL_009c
-  IL_0029:  br.s       IL_0066
-  IL_002b:  br.s       IL_0081
-
-  IL_002d:  ldc.i4.0
-  IL_002e:  ret
-
-  IL_002f:  ldarg.0
-  IL_0030:  ldc.i4.m1
-  IL_0031:  stfld      ""int C.<F>d__5.<>1__state""
-  IL_0036:  nop
-  IL_0037:  ldarg.0
-  IL_0038:  call       ""int C.M1()""
-  IL_003d:  stfld      ""int C.<F>d__5.<>2__current""
-  IL_0042:  ldarg.0
-  IL_0043:  ldc.i4.1
-  IL_0044:  stfld      ""int C.<F>d__5.<>1__state""
-  IL_0049:  ldc.i4.1
-  IL_004a:  ret
-
-  IL_004b:  ldarg.0
-  IL_004c:  ldc.i4.m1
-  IL_004d:  stfld      ""int C.<F>d__5.<>1__state""
-  IL_0052:  ldarg.0
-  IL_0053:  call       ""int C.M3()""
-  IL_0058:  stfld      ""int C.<F>d__5.<>2__current""
-  IL_005d:  ldarg.0
-  IL_005e:  ldc.i4.3
-  IL_005f:  stfld      ""int C.<F>d__5.<>1__state""
-  IL_0064:  ldc.i4.1
-  IL_0065:  ret
-
-  IL_0066:  ldarg.0
-  IL_0067:  ldc.i4.m1
-  IL_0068:  stfld      ""int C.<F>d__5.<>1__state""
-  IL_006d:  ldarg.0
-  IL_006e:  call       ""int C.M4()""
-  IL_0073:  stfld      ""int C.<F>d__5.<>2__current""
-  IL_0078:  ldarg.0
-  IL_0079:  ldc.i4.4
-  IL_007a:  stfld      ""int C.<F>d__5.<>1__state""
-  IL_007f:  ldc.i4.1
-  IL_0080:  ret
-
-  IL_0081:  ldarg.0
-  IL_0082:  ldc.i4.m1
-  IL_0083:  stfld      ""int C.<F>d__5.<>1__state""
-  IL_0088:  ldarg.0
-  IL_0089:  call       ""int C.M2()""
-  IL_008e:  stfld      ""int C.<F>d__5.<>2__current""
-  IL_0093:  ldarg.0
-  IL_0094:  ldc.i4.2
-  IL_0095:  stfld      ""int C.<F>d__5.<>1__state""
-  IL_009a:  ldc.i4.1
-  IL_009b:  ret
-
-  IL_009c:  ldarg.0
-  IL_009d:  ldc.i4.m1
-  IL_009e:  stfld      ""int C.<F>d__5.<>1__state""
-  IL_00a3:  call       ""void C.End()""
-  IL_00a8:  nop
-  IL_00a9:  ldc.i4.0
-  IL_00aa:  ret
-}
-");
-        }
-
-        [Fact]
-        public void UpdateIterator_YieldReturn_Remove()
-        {
-            var source0 = MarkedSource(@"
-using System.Collections.Generic;
-
-class C
-{
-    static int M1() => 1;
-    static int M2() => 2;
-    static int M3() => 3;
-    static int M4() => 4;
-    static void End() {}
-
-    static IEnumerable<int> F() 
-    {
-        <N:0>yield return M1();</N:0>
-        <N:1>yield return M2();</N:1>
-        <N:2>yield return M3();</N:2>
-        <N:3>yield return M4();</N:3>
-        End();
-    }
-}");
-            var source1 = MarkedSource(@"
-using System.Collections.Generic;
-
-class C
-{
-    static int M1() => 1;
-    static int M2() => 2;
-    static int M3() => 3;
-    static int M4() => 4;
-    static void End() {}
-
-    static IEnumerable<int> F() 
-    {
-        <N:1>yield return M2();</N:1>
-        <N:2>yield return M3();</N:2>
-        End();
-    }
-}");
-            var compilation0 = CreateCompilationWithMscorlib45(new[] { source0.Tree }, new[] { SystemCoreRef, CSharpRef }, options: ComSafeDebugDll);
-            var compilation1 = compilation0.WithSource(source1.Tree);
-
-            var v0 = CompileAndVerify(compilation0);
-            v0.VerifyDiagnostics();
-            var md0 = ModuleMetadata.CreateFromImage(v0.EmittedAssemblyData);
-
-            var f0 = compilation0.GetMember<MethodSymbol>("C.F");
-            var f1 = compilation1.GetMember<MethodSymbol>("C.F");
-
-            var generation0 = EmitBaseline.CreateInitialBaseline(md0, v0.CreateSymReader().GetEncMethodDebugInfo);
-
-            var diff1 = compilation1.EmitDifference(
-                 generation0,
-                 ImmutableArray.Create(
-                     SemanticEdit.Create(SemanticEditKind.Update, f0, f1, GetSyntaxMapFromMarkers(source0, source1), preserveLocalVariables: true)));
-
-            diff1.VerifyIL("C.<F>d__5.System.Collections.IEnumerator.MoveNext", @"
-{
-  // Code size      124 (0x7c)
-  .maxstack  2
-  .locals init (int V_0)
-  IL_0000:  ldarg.0
-  IL_0001:  ldfld      ""int C.<F>d__5.<>1__state""
-  IL_0006:  stloc.0
-  IL_0007:  ldloc.0
-  IL_0008:  switch    (
-        IL_001f,
-        IL_0025,
-        IL_0021,
-        IL_0023)
-  IL_001d:  br.s       IL_0025
-  IL_001f:  br.s       IL_0036
-  IL_0021:  br.s       IL_0052
-  IL_0023:  br.s       IL_006d
-  IL_0025:  ldloc.0
-  IL_0026:  ldc.i4.1
-  IL_0027:  blt.s      IL_0034
-  IL_0029:  ldstr      """ + CodeAnalysisResources.EncCannotResumeSuspendedIteratorMethod + @"""
-  IL_002e:  newobj     ""System.InvalidOperationException..ctor(string)""
-  IL_0033:  throw
-
-  IL_0034:  ldc.i4.0
-  IL_0035:  ret
-
-  IL_0036:  ldarg.0
-  IL_0037:  ldc.i4.m1
-  IL_0038:  stfld      ""int C.<F>d__5.<>1__state""
-  IL_003d:  nop
-  IL_003e:  ldarg.0
-  IL_003f:  call       ""int C.M2()""
-  IL_0044:  stfld      ""int C.<F>d__5.<>2__current""
-  IL_0049:  ldarg.0
-  IL_004a:  ldc.i4.2
-  IL_004b:  stfld      ""int C.<F>d__5.<>1__state""
-  IL_0050:  ldc.i4.1
-  IL_0051:  ret
-
-  IL_0052:  ldarg.0
-  IL_0053:  ldc.i4.m1
-  IL_0054:  stfld      ""int C.<F>d__5.<>1__state""
-  IL_0059:  ldarg.0
-  IL_005a:  call       ""int C.M3()""
-  IL_005f:  stfld      ""int C.<F>d__5.<>2__current""
-  IL_0064:  ldarg.0
-  IL_0065:  ldc.i4.3
-  IL_0066:  stfld      ""int C.<F>d__5.<>1__state""
-  IL_006b:  ldc.i4.1
-  IL_006c:  ret
-
-  IL_006d:  ldarg.0
-  IL_006e:  ldc.i4.m1
-  IL_006f:  stfld      ""int C.<F>d__5.<>1__state""
-  IL_0074:  call       ""void C.End()""
-  IL_0079:  nop
-  IL_007a:  ldc.i4.0
-  IL_007b:  ret
-}
-");
-        }
-
-        [Fact]
-        public void UpdateIterator_YieldReturn_Add_Finally_Try()
-        {
-            var source0 = MarkedSource(@"
-using System.Collections.Generic;
-
-class C
-{
-    static IEnumerable<int> F() 
-    {
-        <N:0>yield return M1();</N:0>
-
-        <N:3>try</N:3>
-        {
-            <N:1>yield return M2();</N:1>
-        }
-        finally
-        {
-            Finally1(0);
-        }
-
-        <N:2>yield return M3();</N:2>
-
-        End();
-    }
-
-    static int M1() => 1;
-    static int M2() => 2;
-    static int M3() => 3;
-    static int M4() => 4;
-    static void End() {}
-    static void Finally1(int gen) {}
-    static void Finally2(int gen) {}
-    static void Finally3(int gen) {}
-}");
-            var source1 = MarkedSource(@"
-using System.Collections.Generic;
-
-class C
-{
-    static IEnumerable<int> F() 
-    {
-        try
-        {
-            <N:0>yield return M1();</N:0>
-        }
-        finally
-        {
-            Finally2(1);
-        }
-
-        <N:3>try</N:3>
-        {
-            <N:1>yield return M2();</N:1>
-            try
-            {
-                <N:4>yield return M4();</N:4>
-            }
-            finally 
-            {
-                Finally3(1);
-            }
-        }
-        finally
-        {
-            Finally1(1);
-        }
-
-        <N:2>yield return M3();</N:2>
-
-        End();
-    }
-
-    static int M1() => 1;
-    static int M2() => 2;
-    static int M3() => 3;
-    static int M4() => 4;
-    static void End() {}
-    static void Finally1(int gen) {}
-    static void Finally2(int gen) {}
-    static void Finally3(int gen) {}
-}");
-            var compilation0 = CreateCompilationWithMscorlib45(new[] { source0.Tree }, new[] { SystemCoreRef, CSharpRef }, options: ComSafeDebugDll);
-            var compilation1 = compilation0.WithSource(source1.Tree);
-
-            var v0 = CompileAndVerify(compilation0);
-            v0.VerifyDiagnostics();
-            var md0 = ModuleMetadata.CreateFromImage(v0.EmittedAssemblyData);
-
-            var f0 = compilation0.GetMember<MethodSymbol>("C.F");
-            var f1 = compilation1.GetMember<MethodSymbol>("C.F");
-
-            var generation0 = EmitBaseline.CreateInitialBaseline(md0, v0.CreateSymReader().GetEncMethodDebugInfo);
-
-            var diff1 = compilation1.EmitDifference(
-                 generation0,
-                 ImmutableArray.Create(
-                     SemanticEdit.Create(SemanticEditKind.Update, f0, f1, GetSyntaxMapFromMarkers(source0, source1), preserveLocalVariables: true)));
-
-            v0.VerifyPdb("C.F", @"
-<symbols>
-  <files>
-    <file id=""1"" name="""" language=""C#"" />
-  </files>
-  <methods>
-    <method containingType=""C"" name=""F"">
-        <customDebugInfo>
-        <forwardIterator name=""&lt;F&gt;d__0"" />
-        <encStateMachineStateMap>
-            <state number=""1"" offset=""16"" />
-            <state number=""-3"" offset=""57"" />
-            <state number=""2"" offset=""96"" />
-            <state number=""3"" offset=""213"" />
-        </encStateMachineStateMap>
-        </customDebugInfo>
-    </method>
-  </methods>
-</symbols>");
-
-            diff1.VerifySynthesizedMembers(
-               "C: {<F>d__0}",
-               "C.<F>d__0: {" + string.Join(", ", new[]
-               {
-                    "<>1__state",
-                    "<>2__current",
-                    "<>l__initialThreadId",
-                    "System.IDisposable.Dispose",
-                    "MoveNext",
-                    "<>m__Finally2",
-                    "<>m__Finally1",
-                    "<>m__Finally3",
-                    "System.Collections.Generic.IEnumerator<System.Int32>.get_Current",
-                    "System.Collections.IEnumerator.Reset, System.Collections.IEnumerator.get_Current",
-                    "System.Collections.Generic.IEnumerable<System.Int32>.GetEnumerator",
-                    "System.Collections.IEnumerable.GetEnumerator",
-                    "System.Collections.Generic.IEnumerator<System.Int32>.Current",
-                    "System.Collections.IEnumerator.Current"
-               }) + "}");
-
-            diff1.VerifyIL("C.<F>d__0.<>m__Finally1", @"
-{
-  // Code size       17 (0x11)
-  .maxstack  2
-  IL_0000:  ldarg.0
-  IL_0001:  ldc.i4.m1
-  IL_0002:  stfld      ""int C.<F>d__0.<>1__state""
-  IL_0007:  nop
-  IL_0008:  ldc.i4.1
-  IL_0009:  call       ""void C.Finally1(int)""
-  IL_000e:  nop
-  IL_000f:  nop
-  IL_0010:  ret
-}
-");
-            diff1.VerifyIL("C.<F>d__0.<>m__Finally2", @"
-{
-  // Code size       17 (0x11)
-  .maxstack  2
-  IL_0000:  ldarg.0
-  IL_0001:  ldc.i4.m1
-  IL_0002:  stfld      ""int C.<F>d__0.<>1__state""
-  IL_0007:  nop
-  IL_0008:  ldc.i4.1
-  IL_0009:  call       ""void C.Finally2(int)""
-  IL_000e:  nop
-  IL_000f:  nop
-  IL_0010:  ret
-}
-");
-            diff1.VerifyIL("C.<F>d__0.<>m__Finally3", @"
-{
-  // Code size       18 (0x12)
-  .maxstack  2
-  IL_0000:  ldarg.0
-  IL_0001:  ldc.i4.s   -3
-  IL_0003:  stfld      ""int C.<F>d__0.<>1__state""
-  IL_0008:  nop
-  IL_0009:  ldc.i4.1
-  IL_000a:  call       ""void C.Finally3(int)""
-  IL_000f:  nop
-  IL_0010:  nop
-  IL_0011:  ret
-}
-");
-
-            v0.VerifyIL("C.<F>d__0.System.IDisposable.Dispose", @"
-{
-  // Code size       33 (0x21)
-  .maxstack  2
-  .locals init (int V_0)
-  IL_0000:  ldarg.0
-  IL_0001:  ldfld      ""int C.<F>d__0.<>1__state""
-  IL_0006:  stloc.0
-  IL_0007:  ldloc.0
-  IL_0008:  ldc.i4.s   -3
-  IL_000a:  beq.s      IL_0014
-  IL_000c:  br.s       IL_000e
-  IL_000e:  ldloc.0
-  IL_000f:  ldc.i4.2
-  IL_0010:  beq.s      IL_0014
-  IL_0012:  br.s       IL_0020
-  IL_0014:  nop
-  .try
-  {
-    IL_0015:  leave.s    IL_001e
-  }
-  finally
-  {
-    IL_0017:  ldarg.0
-    IL_0018:  call       ""void C.<F>d__0.<>m__Finally1()""
-    IL_001d:  endfinally
-  }
-  IL_001e:  br.s       IL_0020
-  IL_0020:  ret
-}
-");
-            diff1.VerifyIL("C.<F>d__0.System.IDisposable.Dispose", @"
-{
-  // Code size      108 (0x6c)
+  // Code size       69 (0x45)
   .maxstack  2
   .locals init (int V_0)
   IL_0000:  ldarg.0
   IL_0001:  ldfld      ""int C.<F>d__0.<>1__state""
   IL_0006:  stloc.0
   IL_0007:  ldloc.0
-  IL_0008:  ldc.i4.s   -5
-  IL_000a:  sub
-  IL_000b:  switch    (
-        IL_0046,
-        IL_003a,
-        IL_0046,
-        IL_006b,
-        IL_006b,
-        IL_006b,
-        IL_003a,
-        IL_0046,
-        IL_006b,
-        IL_0046)
-  IL_0038:  br.s       IL_006b
-  IL_003a:  nop
-  .try
-  {
-    IL_003b:  leave.s    IL_0044
-  }
-  finally
-  {
-    IL_003d:  ldarg.0
-    IL_003e:  call       ""void C.<F>d__0.<>m__Finally2()""
-    IL_0043:  endfinally
-  }
-  IL_0044:  br.s       IL_006b
-  IL_0046:  nop
-  .try
-  {
-    IL_0047:  ldloc.0
-    IL_0048:  ldc.i4.s   -5
-    IL_004a:  beq.s      IL_0054
-    IL_004c:  br.s       IL_004e
-    IL_004e:  ldloc.0
-    IL_004f:  ldc.i4.4
-    IL_0050:  beq.s      IL_0054
-    IL_0052:  br.s       IL_0060
-    IL_0054:  nop
-    .try
-    {
-      IL_0055:  leave.s    IL_005e
-    }
-    finally
-    {
-      IL_0057:  ldarg.0
-      IL_0058:  call       ""void C.<F>d__0.<>m__Finally3()""
-      IL_005d:  endfinally
-    }
-    IL_005e:  br.s       IL_0060
-    IL_0060:  leave.s    IL_0069
-  }
-  finally
-  {
-    IL_0062:  ldarg.0
-    IL_0063:  call       ""void C.<F>d__0.<>m__Finally1()""
-    IL_0068:  endfinally
-  }
-  IL_0069:  br.s       IL_006b
-  IL_006b:  ret
-}
-");
-
-            v0.VerifyIL("C.<F>d__0.System.Collections.IEnumerator.MoveNext", @"
-{
-  // Code size      179 (0xb3)
-  .maxstack  2
-  .locals init (bool V_0,
-                int V_1)
-  .try
-  {
-    IL_0000:  ldarg.0
-    IL_0001:  ldfld      ""int C.<F>d__0.<>1__state""
-    IL_0006:  stloc.1
-    IL_0007:  ldloc.1
-    IL_0008:  switch    (
-        IL_001f,
-        IL_0021,
-        IL_0023,
-        IL_0025)
-    IL_001d:  br.s       IL_0027
-    IL_001f:  br.s       IL_002e
-    IL_0021:  br.s       IL_004c
-    IL_0023:  br.s       IL_0072
-    IL_0025:  br.s       IL_0098
-    IL_0027:  ldc.i4.0
-    IL_0028:  stloc.0
-    IL_0029:  leave      IL_00b1
-    IL_002e:  ldarg.0
-    IL_002f:  ldc.i4.m1
-    IL_0030:  stfld      ""int C.<F>d__0.<>1__state""
-    IL_0035:  nop
-    IL_0036:  ldarg.0
-    IL_0037:  call       ""int C.M1()""
-    IL_003c:  stfld      ""int C.<F>d__0.<>2__current""
-    IL_0041:  ldarg.0
-    IL_0042:  ldc.i4.1
-    IL_0043:  stfld      ""int C.<F>d__0.<>1__state""
-    IL_0048:  ldc.i4.1
-    IL_0049:  stloc.0
-    IL_004a:  leave.s    IL_00b1
-    IL_004c:  ldarg.0
-    IL_004d:  ldc.i4.m1
-    IL_004e:  stfld      ""int C.<F>d__0.<>1__state""
-    IL_0053:  ldarg.0
-    IL_0054:  ldc.i4.s   -3
-    IL_0056:  stfld      ""int C.<F>d__0.<>1__state""
-    IL_005b:  nop
-    IL_005c:  ldarg.0
-    IL_005d:  call       ""int C.M2()""
-    IL_0062:  stfld      ""int C.<F>d__0.<>2__current""
-    IL_0067:  ldarg.0
-    IL_0068:  ldc.i4.2
-    IL_0069:  stfld      ""int C.<F>d__0.<>1__state""
-    IL_006e:  ldc.i4.1
-    IL_006f:  stloc.0
-    IL_0070:  leave.s    IL_00b1
-    IL_0072:  ldarg.0
-    IL_0073:  ldc.i4.s   -3
-    IL_0075:  stfld      ""int C.<F>d__0.<>1__state""
-    IL_007a:  nop
-    IL_007b:  ldarg.0
-    IL_007c:  call       ""void C.<F>d__0.<>m__Finally1()""
-    IL_0081:  nop
-    IL_0082:  ldarg.0
-    IL_0083:  call       ""int C.M3()""
-    IL_0088:  stfld      ""int C.<F>d__0.<>2__current""
-    IL_008d:  ldarg.0
-    IL_008e:  ldc.i4.3
-    IL_008f:  stfld      ""int C.<F>d__0.<>1__state""
-    IL_0094:  ldc.i4.1
-    IL_0095:  stloc.0
-    IL_0096:  leave.s    IL_00b1
-    IL_0098:  ldarg.0
-    IL_0099:  ldc.i4.m1
-    IL_009a:  stfld      ""int C.<F>d__0.<>1__state""
-    IL_009f:  call       ""void C.End()""
-    IL_00a4:  nop
-    IL_00a5:  ldc.i4.0
-    IL_00a6:  stloc.0
-    IL_00a7:  leave.s    IL_00b1
-  }
-  fault
-  {
-    IL_00a9:  ldarg.0
-    IL_00aa:  call       ""void C.<F>d__0.Dispose()""
-    IL_00af:  nop
-    IL_00b0:  endfinally
-  }
-  IL_00b1:  ldloc.0
-  IL_00b2:  ret
-} 
-");
-
-            diff1.VerifyIL("C.<F>d__0.System.Collections.IEnumerator.MoveNext", @"
-{
-  // Code size      259 (0x103)
-  .maxstack  2
-  .locals init (bool V_0,
-                int V_1)
-  .try
-  {
-    IL_0000:  ldarg.0
-    IL_0001:  ldfld      ""int C.<F>d__0.<>1__state""
-    IL_0006:  stloc.1
-    IL_0007:  ldloc.1
-    IL_0008:  switch    (
-        IL_0023,
-        IL_0025,
-        IL_0027,
-        IL_0029,
-        IL_002e)
-    IL_0021:  br.s       IL_0033
-    IL_0023:  br.s       IL_003a
-    IL_0025:  br.s       IL_0064
-    IL_0027:  br.s       IL_0093
-    IL_0029:  br         IL_00e8
-    IL_002e:  br         IL_00ba
-    IL_0033:  ldc.i4.0
-    IL_0034:  stloc.0
-    IL_0035:  leave      IL_0101
-    IL_003a:  ldarg.0
-    IL_003b:  ldc.i4.m1
-    IL_003c:  stfld      ""int C.<F>d__0.<>1__state""
-    IL_0041:  nop
-    IL_0042:  ldarg.0
-    IL_0043:  ldc.i4.s   -4
-    IL_0045:  stfld      ""int C.<F>d__0.<>1__state""
-    IL_004a:  nop
-    IL_004b:  ldarg.0
-    IL_004c:  call       ""int C.M1()""
-    IL_0051:  stfld      ""int C.<F>d__0.<>2__current""
-    IL_0056:  ldarg.0
-    IL_0057:  ldc.i4.1
-    IL_0058:  stfld      ""int C.<F>d__0.<>1__state""
-    IL_005d:  ldc.i4.1
-    IL_005e:  stloc.0
-    IL_005f:  leave      IL_0101
-    IL_0064:  ldarg.0
-    IL_0065:  ldc.i4.s   -4
-    IL_0067:  stfld      ""int C.<F>d__0.<>1__state""
-    IL_006c:  nop
-    IL_006d:  ldarg.0
-    IL_006e:  call       ""void C.<F>d__0.<>m__Finally2()""
-    IL_0073:  nop
-    IL_0074:  ldarg.0
-    IL_0075:  ldc.i4.s   -3
-    IL_0077:  stfld      ""int C.<F>d__0.<>1__state""
-    IL_007c:  nop
-    IL_007d:  ldarg.0
-    IL_007e:  call       ""int C.M2()""
-    IL_0083:  stfld      ""int C.<F>d__0.<>2__current""
-    IL_0088:  ldarg.0
-    IL_0089:  ldc.i4.2
-    IL_008a:  stfld      ""int C.<F>d__0.<>1__state""
-    IL_008f:  ldc.i4.1
-    IL_0090:  stloc.0
-    IL_0091:  leave.s    IL_0101
-    IL_0093:  ldarg.0
-    IL_0094:  ldc.i4.s   -3
-    IL_0096:  stfld      ""int C.<F>d__0.<>1__state""
-    IL_009b:  ldarg.0
-    IL_009c:  ldc.i4.s   -5
-    IL_009e:  stfld      ""int C.<F>d__0.<>1__state""
-    IL_00a3:  nop
-    IL_00a4:  ldarg.0
-    IL_00a5:  call       ""int C.M4()""
-    IL_00aa:  stfld      ""int C.<F>d__0.<>2__current""
-    IL_00af:  ldarg.0
-    IL_00b0:  ldc.i4.4
-    IL_00b1:  stfld      ""int C.<F>d__0.<>1__state""
-    IL_00b6:  ldc.i4.1
-    IL_00b7:  stloc.0
-    IL_00b8:  leave.s    IL_0101
-    IL_00ba:  ldarg.0
-    IL_00bb:  ldc.i4.s   -5
-    IL_00bd:  stfld      ""int C.<F>d__0.<>1__state""
-    IL_00c2:  nop
-    IL_00c3:  ldarg.0
-    IL_00c4:  call       ""void C.<F>d__0.<>m__Finally3()""
-    IL_00c9:  nop
-    IL_00ca:  nop
-    IL_00cb:  ldarg.0
-    IL_00cc:  call       ""void C.<F>d__0.<>m__Finally1()""
-    IL_00d1:  nop
-    IL_00d2:  ldarg.0
-    IL_00d3:  call       ""int C.M3()""
-    IL_00d8:  stfld      ""int C.<F>d__0.<>2__current""
-    IL_00dd:  ldarg.0
-    IL_00de:  ldc.i4.3
-    IL_00df:  stfld      ""int C.<F>d__0.<>1__state""
-    IL_00e4:  ldc.i4.1
-    IL_00e5:  stloc.0
-    IL_00e6:  leave.s    IL_0101
-    IL_00e8:  ldarg.0
-    IL_00e9:  ldc.i4.m1
-    IL_00ea:  stfld      ""int C.<F>d__0.<>1__state""
-    IL_00ef:  call       ""void C.End()""
-    IL_00f4:  nop
-    IL_00f5:  ldc.i4.0
-    IL_00f6:  stloc.0
-    IL_00f7:  leave.s    IL_0101
-  }
-  fault
-  {
-    IL_00f9:  ldarg.0
-    IL_00fa:  call       ""void C.<F>d__0.Dispose()""
-    IL_00ff:  nop
-    IL_0100:  endfinally
-  }
-  IL_0101:  ldloc.0
-  IL_0102:  ret
+  IL_0008:  brfalse.s  IL_0012
+  IL_000a:  br.s       IL_000c
+  IL_000c:  ldloc.0
+  IL_000d:  ldc.i4.1
+  IL_000e:  beq.s      IL_0014
+  IL_0010:  br.s       IL_0016
+  IL_0012:  br.s       IL_0018
+  IL_0014:  br.s       IL_003c
+  IL_0016:  ldc.i4.0
+  IL_0017:  ret
+  IL_0018:  ldarg.0
+  IL_0019:  ldc.i4.m1
+  IL_001a:  stfld      ""int C.<F>d__0.<>1__state""
+  IL_001f:  nop
+  IL_0020:  ldarg.0
+  IL_0021:  ldarg.0
+  IL_0022:  ldfld      ""int C.<F>d__0.p""
+  IL_0027:  stfld      ""int C.<F>d__0.<x>5__1""
+  IL_002c:  ldarg.0
+  IL_002d:  ldc.i4.2
+  IL_002e:  stfld      ""int C.<F>d__0.<>2__current""
+  IL_0033:  ldarg.0
+  IL_0034:  ldc.i4.1
+  IL_0035:  stfld      ""int C.<F>d__0.<>1__state""
+  IL_003a:  ldc.i4.1
+  IL_003b:  ret
+  IL_003c:  ldarg.0
+  IL_003d:  ldc.i4.m1
+  IL_003e:  stfld      ""int C.<F>d__0.<>1__state""
+  IL_0043:  ldc.i4.0
+  IL_0044:  ret
 }");
+                }
+            }
         }
 
         [Fact]
-        public void UpdateIterator_YieldReturn_Add_Finally_UsingDeclaration()
+        public void UpdateIterator_UserDefinedVariables_AddVariable()
         {
-            var source0 = MarkedSource(@"
+            var source0 = @"
 using System;
 using System.Collections.Generic;
 
 class C
 {
-    static IEnumerable<int> F() 
+    static IEnumerable<int> F(int p) 
     {
-        using var <N:0>x = M1()</N:0>;
-        <N:1>yield return M2();</N:1>
-        End();
+        int x = p;
+        yield return x;
     }
-
-    static IDisposable M1() => null;
-    static int M2() => 0;
-    static int M3() => 0;
-    static void End() {}
-}");
-            var source1 = MarkedSource(@"
+}";
+            var source1 = @"
 using System;
 using System.Collections.Generic;
 
 class C
 {
-    static IEnumerable<int> F() 
+    static IEnumerable<int> F(int p) 
     {
-        using var <N:0>x = M1()</N:0>;
-        <N:1>yield return M2();</N:1>
-        yield return M3();
-        End();
+        int y = 1234;
+        int x = p;
+        yield return y;
+        Console.WriteLine(x);
     }
-
-    static IDisposable M1() => null;
-    static int M2() => 0;
-    static int M3() => 0;
-    static void End() {}
-}");
-            var compilation0 = CreateCompilationWithMscorlib45(new[] { source0.Tree }, new[] { SystemCoreRef, CSharpRef }, options: ComSafeDebugDll);
-            var compilation1 = compilation0.WithSource(source1.Tree);
+}";
+            var compilation0 = CreateCompilationWithMscorlib45(source0, options: ComSafeDebugDll);
+            var compilation1 = compilation0.WithSource(source1);
 
             var v0 = CompileAndVerify(compilation0);
-            v0.VerifyDiagnostics();
-            var md0 = ModuleMetadata.CreateFromImage(v0.EmittedAssemblyData);
-
-            var f0 = compilation0.GetMember<MethodSymbol>("C.F");
-            var f1 = compilation1.GetMember<MethodSymbol>("C.F");
-
-            var generation0 = EmitBaseline.CreateInitialBaseline(md0, v0.CreateSymReader().GetEncMethodDebugInfo);
+            var symReader = v0.CreateSymReader();
 
-            var diff1 = compilation1.EmitDifference(
-                 generation0,
-                 ImmutableArray.Create(
-                     SemanticEdit.Create(SemanticEditKind.Update, f0, f1, GetSyntaxMapFromMarkers(source0, source1), preserveLocalVariables: true)));
+            using (var md0 = ModuleMetadata.CreateFromImage(v0.EmittedAssemblyData))
+            {
+                var method0 = compilation0.GetMember<MethodSymbol>("C.F");
+                var method1 = compilation1.GetMember<MethodSymbol>("C.F");
 
-            v0.VerifyPdb("C.F", @"
-<symbols>
-  <files>
-    <file id=""1"" name="""" language=""C#"" />
-  </files>
-  <methods>
-    <method containingType=""C"" name=""F"">
-      <customDebugInfo>
-        <forwardIterator name=""&lt;F&gt;d__0"" />
-        <encLocalSlotMap>
-          <slot kind=""0"" offset=""26"" />
-        </encLocalSlotMap>
-        <encStateMachineStateMap>
-          <state number=""-3"" offset=""26"" />
-          <state number=""1"" offset=""56"" />
-        </encStateMachineStateMap>
-      </customDebugInfo>
-    </method>
-  </methods>
-</symbols>");
+                var generation0 = EmitBaseline.CreateInitialBaseline(md0, symReader.GetEncMethodDebugInfo);
+                var diff1 = compilation1.EmitDifference(
+                    generation0,
+                    ImmutableArray.Create(SemanticEdit.Create(SemanticEditKind.Update, method0, method1, GetEquivalentNodesMap(method1, method0), preserveLocalVariables: true)));
 
-            diff1.VerifySynthesizedMembers(
-               "C: {<F>d__0}",
-               "C.<F>d__0: {" + string.Join(", ", new[]
-               {
-                    "<>1__state",
-                    "<>2__current",
-                    "<>l__initialThreadId",
-                    "<x>5__1",
-                    "System.IDisposable.Dispose",
-                    "MoveNext",
-                    "<>m__Finally1",
-                    "System.Collections.Generic.IEnumerator<System.Int32>.get_Current",
-                    "System.Collections.IEnumerator.Reset, System.Collections.IEnumerator.get_Current",
-                    "System.Collections.Generic.IEnumerable<System.Int32>.GetEnumerator",
-                    "System.Collections.IEnumerable.GetEnumerator",
-                    "System.Collections.Generic.IEnumerator<System.Int32>.Current",
-                    "System.Collections.IEnumerator.Current"
-               }) + "}");
-
-            diff1.VerifyIL("C.<F>d__0.<>m__Finally1", @"
-{
-  // Code size       28 (0x1c)
-  .maxstack  2
-  IL_0000:  ldarg.0
-  IL_0001:  ldc.i4.m1
-  IL_0002:  stfld      ""int C.<F>d__0.<>1__state""
-  IL_0007:  ldarg.0
-  IL_0008:  ldfld      ""System.IDisposable C.<F>d__0.<x>5__1""
-  IL_000d:  brfalse.s  IL_001b
-  IL_000f:  ldarg.0
-  IL_0010:  ldfld      ""System.IDisposable C.<F>d__0.<x>5__1""
-  IL_0015:  callvirt   ""void System.IDisposable.Dispose()""
-  IL_001a:  nop
-  IL_001b:  ret
-}
-");
+                // Verify delta metadata contains expected rows.
+                using (var md1 = diff1.GetMetadata())
+                {
+                    // 1 field def added & 3 methods updated
+                    CheckEncLogDefinitions(md1.Reader,
+                        Row(3, TableIndex.StandAloneSig, EditAndContinueOperation.Default),
+                        Row(3, TableIndex.TypeDef, EditAndContinueOperation.AddField),
+                        Row(7, TableIndex.Field, EditAndContinueOperation.Default),
+                        Row(1, TableIndex.MethodDef, EditAndContinueOperation.Default),
+                        Row(4, TableIndex.MethodDef, EditAndContinueOperation.Default),
+                        Row(5, TableIndex.MethodDef, EditAndContinueOperation.Default),
+                        Row(1, TableIndex.Param, EditAndContinueOperation.Default),
+                        Row(1, TableIndex.CustomAttribute, EditAndContinueOperation.Default),
+                        Row(7, TableIndex.CustomAttribute, EditAndContinueOperation.Default));
 
-            v0.VerifyIL("C.<F>d__0.System.IDisposable.Dispose", @"
-{
-  // Code size       33 (0x21)
-  .maxstack  2
-  .locals init (int V_0)
-  IL_0000:  ldarg.0
-  IL_0001:  ldfld      ""int C.<F>d__0.<>1__state""
-  IL_0006:  stloc.0
-  IL_0007:  ldloc.0
-  IL_0008:  ldc.i4.s   -3
-  IL_000a:  beq.s      IL_0014
-  IL_000c:  br.s       IL_000e
-  IL_000e:  ldloc.0
-  IL_000f:  ldc.i4.1
-  IL_0010:  beq.s      IL_0014
-  IL_0012:  br.s       IL_0020
-  IL_0014:  nop
-  .try
-  {
-    IL_0015:  leave.s    IL_001e
-  }
-  finally
-  {
-    IL_0017:  ldarg.0
-    IL_0018:  call       ""void C.<F>d__0.<>m__Finally1()""
-    IL_001d:  endfinally
-  }
-  IL_001e:  br.s       IL_0020
-  IL_0020:  ret
-}
-");
-            diff1.VerifyIL("C.<F>d__0.System.IDisposable.Dispose", @"
+                    diff1.VerifyIL("C.<F>d__0.System.Collections.IEnumerator.MoveNext", @"
 {
-  // Code size       35 (0x23)
+  // Code size       97 (0x61)
   .maxstack  2
   .locals init (int V_0)
   IL_0000:  ldarg.0
   IL_0001:  ldfld      ""int C.<F>d__0.<>1__state""
   IL_0006:  stloc.0
   IL_0007:  ldloc.0
-  IL_0008:  ldc.i4.s   -3
-  IL_000a:  beq.s      IL_0016
-  IL_000c:  br.s       IL_000e
-  IL_000e:  ldloc.0
-  IL_000f:  ldc.i4.1
-  IL_0010:  sub
-  IL_0011:  ldc.i4.1
-  IL_0012:  ble.un.s   IL_0016
-  IL_0014:  br.s       IL_0022
-  IL_0016:  nop
-  .try
-  {
-    IL_0017:  leave.s    IL_0020
-  }
-  finally
-  {
-    IL_0019:  ldarg.0
-    IL_001a:  call       ""void C.<F>d__0.<>m__Finally1()""
-    IL_001f:  endfinally
-  }
-  IL_0020:  br.s       IL_0022
-  IL_0022:  ret
-}
-");
-
-            v0.VerifyIL("C.<F>d__0.System.Collections.IEnumerator.MoveNext", @"
- {
-  // Code size      112 (0x70)
-  .maxstack  2
-  .locals init (bool V_0,
-                int V_1)
-  .try
-  {
-    IL_0000:  ldarg.0
-    IL_0001:  ldfld      ""int C.<F>d__0.<>1__state""
-    IL_0006:  stloc.1
-    IL_0007:  ldloc.1
-    IL_0008:  brfalse.s  IL_0012
-    IL_000a:  br.s       IL_000c
-    IL_000c:  ldloc.1
-    IL_000d:  ldc.i4.1
-    IL_000e:  beq.s      IL_0014
-    IL_0010:  br.s       IL_0016
-    IL_0012:  br.s       IL_001a
-    IL_0014:  br.s       IL_004b
-    IL_0016:  ldc.i4.0
-    IL_0017:  stloc.0
-    IL_0018:  leave.s    IL_006e
-    IL_001a:  ldarg.0
-    IL_001b:  ldc.i4.m1
-    IL_001c:  stfld      ""int C.<F>d__0.<>1__state""
-    IL_0021:  nop
-    IL_0022:  ldarg.0
-    IL_0023:  call       ""System.IDisposable C.M1()""
-    IL_0028:  stfld      ""System.IDisposable C.<F>d__0.<x>5__1""
-    IL_002d:  ldarg.0
-    IL_002e:  ldc.i4.s   -3
-    IL_0030:  stfld      ""int C.<F>d__0.<>1__state""
-    IL_0035:  ldarg.0
-    IL_0036:  call       ""int C.M2()""
-    IL_003b:  stfld      ""int C.<F>d__0.<>2__current""
-    IL_0040:  ldarg.0
-    IL_0041:  ldc.i4.1
-    IL_0042:  stfld      ""int C.<F>d__0.<>1__state""
-    IL_0047:  ldc.i4.1
-    IL_0048:  stloc.0
-    IL_0049:  leave.s    IL_006e
-    IL_004b:  ldarg.0
-    IL_004c:  ldc.i4.s   -3
-    IL_004e:  stfld      ""int C.<F>d__0.<>1__state""
-    IL_0053:  call       ""void C.End()""
-    IL_0058:  nop
-    IL_0059:  ldc.i4.0
-    IL_005a:  stloc.0
-    IL_005b:  br.s       IL_005d
-    IL_005d:  ldarg.0
-    IL_005e:  call       ""void C.<F>d__0.<>m__Finally1()""
-    IL_0063:  nop
-    IL_0064:  leave.s    IL_006e
-  }
-  fault
-  {
-    IL_0066:  ldarg.0
-    IL_0067:  call       ""void C.<F>d__0.Dispose()""
-    IL_006c:  nop
-    IL_006d:  endfinally
-  }
-  IL_006e:  ldloc.0
-  IL_006f:  ret
-}
-");
-
-            diff1.VerifyIL("C.<F>d__0.System.Collections.IEnumerator.MoveNext", @"
-{
-  // Code size      153 (0x99)
-  .maxstack  2
-  .locals init (bool V_0,
-                int V_1)
-  .try
-  {
-    IL_0000:  ldarg.0
-    IL_0001:  ldfld      ""int C.<F>d__0.<>1__state""
-    IL_0006:  stloc.1
-    IL_0007:  ldloc.1
-    IL_0008:  switch    (
-        IL_001b,
-        IL_001d,
-        IL_001f)
-    IL_0019:  br.s       IL_0021
-    IL_001b:  br.s       IL_0025
-    IL_001d:  br.s       IL_0056
-    IL_001f:  br.s       IL_0074
-    IL_0021:  ldc.i4.0
-    IL_0022:  stloc.0
-    IL_0023:  leave.s    IL_0097
-    IL_0025:  ldarg.0
-    IL_0026:  ldc.i4.m1
-    IL_0027:  stfld      ""int C.<F>d__0.<>1__state""
-    IL_002c:  nop
-    IL_002d:  ldarg.0
-    IL_002e:  call       ""System.IDisposable C.M1()""
-    IL_0033:  stfld      ""System.IDisposable C.<F>d__0.<x>5__1""
-    IL_0038:  ldarg.0
-    IL_0039:  ldc.i4.s   -3
-    IL_003b:  stfld      ""int C.<F>d__0.<>1__state""
-    IL_0040:  ldarg.0
-    IL_0041:  call       ""int C.M2()""
-    IL_0046:  stfld      ""int C.<F>d__0.<>2__current""
-    IL_004b:  ldarg.0
-    IL_004c:  ldc.i4.1
-    IL_004d:  stfld      ""int C.<F>d__0.<>1__state""
-    IL_0052:  ldc.i4.1
-    IL_0053:  stloc.0
-    IL_0054:  leave.s    IL_0097
-    IL_0056:  ldarg.0
-    IL_0057:  ldc.i4.s   -3
-    IL_0059:  stfld      ""int C.<F>d__0.<>1__state""
-    IL_005e:  ldarg.0
-    IL_005f:  call       ""int C.M3()""
-    IL_0064:  stfld      ""int C.<F>d__0.<>2__current""
-    IL_0069:  ldarg.0
-    IL_006a:  ldc.i4.2
-    IL_006b:  stfld      ""int C.<F>d__0.<>1__state""
-    IL_0070:  ldc.i4.1
-    IL_0071:  stloc.0
-    IL_0072:  leave.s    IL_0097
-    IL_0074:  ldarg.0
-    IL_0075:  ldc.i4.s   -3
-    IL_0077:  stfld      ""int C.<F>d__0.<>1__state""
-    IL_007c:  call       ""void C.End()""
-    IL_0081:  nop
-    IL_0082:  ldc.i4.0
-    IL_0083:  stloc.0
-    IL_0084:  br.s       IL_0086
-    IL_0086:  ldarg.0
-    IL_0087:  call       ""void C.<F>d__0.<>m__Finally1()""
-    IL_008c:  nop
-    IL_008d:  leave.s    IL_0097
-  }
-  fault
-  {
-    IL_008f:  ldarg.0
-    IL_0090:  call       ""void C.<F>d__0.Dispose()""
-    IL_0095:  nop
-    IL_0096:  endfinally
-  }
-  IL_0097:  ldloc.0
-  IL_0098:  ret
+  IL_0008:  brfalse.s  IL_0012
+  IL_000a:  br.s       IL_000c
+  IL_000c:  ldloc.0
+  IL_000d:  ldc.i4.1
+  IL_000e:  beq.s      IL_0014
+  IL_0010:  br.s       IL_0016
+  IL_0012:  br.s       IL_0018
+  IL_0014:  br.s       IL_004c
+  IL_0016:  ldc.i4.0
+  IL_0017:  ret
+  IL_0018:  ldarg.0
+  IL_0019:  ldc.i4.m1
+  IL_001a:  stfld      ""int C.<F>d__0.<>1__state""
+  IL_001f:  nop
+  IL_0020:  ldarg.0
+  IL_0021:  ldc.i4     0x4d2
+  IL_0026:  stfld      ""int C.<F>d__0.<y>5__2""
+  IL_002b:  ldarg.0
+  IL_002c:  ldarg.0
+  IL_002d:  ldfld      ""int C.<F>d__0.p""
+  IL_0032:  stfld      ""int C.<F>d__0.<x>5__1""
+  IL_0037:  ldarg.0
+  IL_0038:  ldarg.0
+  IL_0039:  ldfld      ""int C.<F>d__0.<y>5__2""
+  IL_003e:  stfld      ""int C.<F>d__0.<>2__current""
+  IL_0043:  ldarg.0
+  IL_0044:  ldc.i4.1
+  IL_0045:  stfld      ""int C.<F>d__0.<>1__state""
+  IL_004a:  ldc.i4.1
+  IL_004b:  ret
+  IL_004c:  ldarg.0
+  IL_004d:  ldc.i4.m1
+  IL_004e:  stfld      ""int C.<F>d__0.<>1__state""
+  IL_0053:  ldarg.0
+  IL_0054:  ldfld      ""int C.<F>d__0.<x>5__1""
+  IL_0059:  call       ""void System.Console.WriteLine(int)""
+  IL_005e:  nop
+  IL_005f:  ldc.i4.0
+  IL_0060:  ret
 }");
+                }
+            }
         }
 
         [Fact]
-        public void UpdateIterator_YieldReturn_Add_Finally_Foreach_ForEachVar_Using_Lock()
+        public void UpdateIterator_UserDefinedVariables_AddAndRemoveVariable()
         {
-            var source0 = MarkedSource(@"
+            var source0 = @"
 using System;
 using System.Collections.Generic;
 
 class C
 {
-    static IEnumerable<int> F() 
+    static IEnumerable<int> F(int p) 
     {
-        using IDisposable <N:0>x1 = D()</N:0>, <N:1>x2 = D()</N:1>;
-
-        <N:2>using (D())</N:2>
-            using (IDisposable <N:3>y1 = D()</N:3>, <N:4>y2 = D()</N:4>)
-                <N:5>foreach</N:5> (var z in E())
-                    <N:6>foreach</N:6> (var (u, w) in E())
-                        <N:7>lock</N:7> (D())
-                        {
-                            <N:8>yield return 1;</N:8>
-                        }
+        int x = p;
+        yield return x;
     }
-
-    static IDisposable D() => null;
-    static IEnumerable<(int, int)> E() => null;
-}");
-            var source1 = MarkedSource(@"
+}";
+            var source1 = @"
 using System;
 using System.Collections.Generic;
 
 class C
 {
-    static IEnumerable<int> F() 
+    static IEnumerable<int> F(int p) 
     {
-        using IDisposable <N:0>x1 = D()</N:0>, <N:1>x2 = D()</N:1>;
-
-        <N:2>using (D())</N:2>
-            using (IDisposable <N:3>y1 = D()</N:3>, <N:4>y2 = D()</N:4>)
-                <N:5>foreach</N:5> (var z in E())
-                    <N:6>foreach</N:6> (var (u, w) in E())
-                        <N:7>lock</N:7> (D())
-                        {
-                            <N:8>yield return 1;</N:8>
-                            yield return 2;
-                        }
+        int y = 1234;
+        yield return y;
+        Console.WriteLine(p);
     }
-
-    static IDisposable D() => null;
-    static IEnumerable<(int, int)> E() => null;
-}");
-            var compilation0 = CreateCompilationWithMscorlib45(new[] { source0.Tree }, new[] { SystemRuntimeFacadeRef, ValueTupleRef }, options: ComSafeDebugDll);
-            var compilation1 = compilation0.WithSource(source1.Tree);
+}";
+            var compilation0 = CreateCompilationWithMscorlib45(source0, options: ComSafeDebugDll);
+            var compilation1 = compilation0.WithSource(source1);
 
             var v0 = CompileAndVerify(compilation0);
-            v0.VerifyDiagnostics();
-            var md0 = ModuleMetadata.CreateFromImage(v0.EmittedAssemblyData);
-
-            var f0 = compilation0.GetMember<MethodSymbol>("C.F");
-            var f1 = compilation1.GetMember<MethodSymbol>("C.F");
+            var symReader = v0.CreateSymReader();
 
-            var generation0 = EmitBaseline.CreateInitialBaseline(md0, v0.CreateSymReader().GetEncMethodDebugInfo);
+            using (var md0 = ModuleMetadata.CreateFromImage(v0.EmittedAssemblyData))
+            {
+                var method0 = compilation0.GetMember<MethodSymbol>("C.F");
+                var method1 = compilation1.GetMember<MethodSymbol>("C.F");
 
-            var diff1 = compilation1.EmitDifference(
-                 generation0,
-                 ImmutableArray.Create(
-                     SemanticEdit.Create(SemanticEditKind.Update, f0, f1, GetSyntaxMapFromMarkers(source0, source1), preserveLocalVariables: true)));
+                var generation0 = EmitBaseline.CreateInitialBaseline(md0, symReader.GetEncMethodDebugInfo);
+                var diff1 = compilation1.EmitDifference(
+                    generation0,
+                    ImmutableArray.Create(SemanticEdit.Create(SemanticEditKind.Update, method0, method1, GetEquivalentNodesMap(method1, method0), preserveLocalVariables: true)));
 
-            v0.VerifyPdb("C.F", @"
-<symbols>
-  <files>
-    <file id=""1"" name="""" language=""C#"" />
-  </files>
-  <methods>
-    <method containingType=""C"" name=""F"">
-      <customDebugInfo>
-        <forwardIterator name=""&lt;F&gt;d__0"" />
-        <encLocalSlotMap>
-          <slot kind=""0"" offset=""34"" />
-          <slot kind=""0"" offset=""55"" />
-          <slot kind=""4"" offset=""87"" />
-          <slot kind=""0"" offset=""142"" />
-          <slot kind=""0"" offset=""163"" />
-          <slot kind=""5"" offset=""201"" />
-          <slot kind=""0"" offset=""201"" />
-          <slot kind=""5"" offset=""256"" />
-          <slot kind=""0"" offset=""276"" />
-          <slot kind=""0"" offset=""279"" />
-          <slot kind=""3"" offset=""320"" />
-          <slot kind=""2"" offset=""320"" />
-        </encLocalSlotMap>
-        <encStateMachineStateMap>
-          <state number=""-3"" offset=""34"" />
-          <state number=""-4"" offset=""55"" />
-          <state number=""-5"" offset=""87"" />
-          <state number=""-6"" offset=""142"" />
-          <state number=""-7"" offset=""163"" />
-          <state number=""-8"" offset=""201"" />
-          <state number=""-9"" offset=""256"" />
-          <state number=""-10"" offset=""320"" />
-          <state number=""1"" offset=""398"" />
-        </encStateMachineStateMap>
-      </customDebugInfo>
-    </method>
-  </methods>
-</symbols>");
+                // Verify delta metadata contains expected rows.
+                using (var md1 = diff1.GetMetadata())
+                {
+                    // 1 field def added & 3 methods updated
+                    CheckEncLogDefinitions(md1.Reader,
+                        Row(3, TableIndex.StandAloneSig, EditAndContinueOperation.Default),
+                        Row(3, TableIndex.TypeDef, EditAndContinueOperation.AddField),
+                        Row(7, TableIndex.Field, EditAndContinueOperation.Default),
+                        Row(1, TableIndex.MethodDef, EditAndContinueOperation.Default),
+                        Row(4, TableIndex.MethodDef, EditAndContinueOperation.Default),
+                        Row(5, TableIndex.MethodDef, EditAndContinueOperation.Default),
+                        Row(1, TableIndex.Param, EditAndContinueOperation.Default),
+                        Row(1, TableIndex.CustomAttribute, EditAndContinueOperation.Default),
+                        Row(7, TableIndex.CustomAttribute, EditAndContinueOperation.Default));
 
-            diff1.VerifyIL("C.<F>d__0.System.Collections.IEnumerator.MoveNext", @"
+                    diff1.VerifyIL("C.<F>d__0.System.Collections.IEnumerator.MoveNext", @"
 {
-  // Code size      526 (0x20e)
+  // Code size       85 (0x55)
   .maxstack  2
-  .locals init (bool V_0,
-                int V_1,
-                System.ValueTuple<int, int> V_2)
-  .try
-  {
-    IL_0000:  ldarg.0
-    IL_0001:  ldfld      ""int C.<F>d__0.<>1__state""
-    IL_0006:  stloc.1
-    IL_0007:  ldloc.1
-    IL_0008:  switch    (
-        IL_001b,
-        IL_001d,
-        IL_0022)
-    IL_0019:  br.s       IL_0027
-    IL_001b:  br.s       IL_002e
-    IL_001d:  br         IL_0148
-    IL_0022:  br         IL_0165
-    IL_0027:  ldc.i4.0
-    IL_0028:  stloc.0
-    IL_0029:  leave      IL_020c
-    IL_002e:  ldarg.0
-    IL_002f:  ldc.i4.m1
-    IL_0030:  stfld      ""int C.<F>d__0.<>1__state""
-    IL_0035:  nop
-    IL_0036:  ldarg.0
-    IL_0037:  call       ""System.IDisposable C.D()""
-    IL_003c:  stfld      ""System.IDisposable C.<F>d__0.<x1>5__1""
-    IL_0041:  ldarg.0
-    IL_0042:  ldc.i4.s   -3
-    IL_0044:  stfld      ""int C.<F>d__0.<>1__state""
-    IL_0049:  ldarg.0
-    IL_004a:  call       ""System.IDisposable C.D()""
-    IL_004f:  stfld      ""System.IDisposable C.<F>d__0.<x2>5__2""
-    IL_0054:  ldarg.0
-    IL_0055:  ldc.i4.s   -4
-    IL_0057:  stfld      ""int C.<F>d__0.<>1__state""
-    IL_005c:  ldarg.0
-    IL_005d:  call       ""System.IDisposable C.D()""
-    IL_0062:  stfld      ""System.IDisposable C.<F>d__0.<>s__3""
-    IL_0067:  ldarg.0
-    IL_0068:  ldc.i4.s   -5
-    IL_006a:  stfld      ""int C.<F>d__0.<>1__state""
-    IL_006f:  ldarg.0
-    IL_0070:  call       ""System.IDisposable C.D()""
-    IL_0075:  stfld      ""System.IDisposable C.<F>d__0.<y1>5__4""
-    IL_007a:  ldarg.0
-    IL_007b:  ldc.i4.s   -6
-    IL_007d:  stfld      ""int C.<F>d__0.<>1__state""
-    IL_0082:  ldarg.0
-    IL_0083:  call       ""System.IDisposable C.D()""
-    IL_0088:  stfld      ""System.IDisposable C.<F>d__0.<y2>5__5""
-    IL_008d:  ldarg.0
-    IL_008e:  ldc.i4.s   -7
-    IL_0090:  stfld      ""int C.<F>d__0.<>1__state""
-    IL_0095:  nop
-    IL_0096:  ldarg.0
-    IL_0097:  call       ""System.Collections.Generic.IEnumerable<System.ValueTuple<int, int>> C.E()""
-    IL_009c:  callvirt   ""System.Collections.Generic.IEnumerator<System.ValueTuple<int, int>> System.Collections.Generic.IEnumerable<System.ValueTuple<int, int>>.GetEnumerator()""
-    IL_00a1:  stfld      ""System.Collections.Generic.IEnumerator<System.ValueTuple<int, int>> C.<F>d__0.<>s__6""
-    IL_00a6:  ldarg.0
-    IL_00a7:  ldc.i4.s   -8
-    IL_00a9:  stfld      ""int C.<F>d__0.<>1__state""
-    IL_00ae:  br         IL_01a6
-    IL_00b3:  ldarg.0
-    IL_00b4:  ldarg.0
-    IL_00b5:  ldfld      ""System.Collections.Generic.IEnumerator<System.ValueTuple<int, int>> C.<F>d__0.<>s__6""
-    IL_00ba:  callvirt   ""System.ValueTuple<int, int> System.Collections.Generic.IEnumerator<System.ValueTuple<int, int>>.Current.get""
-    IL_00bf:  stfld      ""System.ValueTuple<int, int> C.<F>d__0.<z>5__7""
-    IL_00c4:  nop
-    IL_00c5:  ldarg.0
-    IL_00c6:  call       ""System.Collections.Generic.IEnumerable<System.ValueTuple<int, int>> C.E()""
-    IL_00cb:  callvirt   ""System.Collections.Generic.IEnumerator<System.ValueTuple<int, int>> System.Collections.Generic.IEnumerable<System.ValueTuple<int, int>>.GetEnumerator()""
-    IL_00d0:  stfld      ""System.Collections.Generic.IEnumerator<System.ValueTuple<int, int>> C.<F>d__0.<>s__8""
-    IL_00d5:  ldarg.0
-    IL_00d6:  ldc.i4.s   -9
-    IL_00d8:  stfld      ""int C.<F>d__0.<>1__state""
-    IL_00dd:  br         IL_017c
-    IL_00e2:  ldarg.0
-    IL_00e3:  ldfld      ""System.Collections.Generic.IEnumerator<System.ValueTuple<int, int>> C.<F>d__0.<>s__8""
-    IL_00e8:  callvirt   ""System.ValueTuple<int, int> System.Collections.Generic.IEnumerator<System.ValueTuple<int, int>>.Current.get""
-    IL_00ed:  stloc.2
-    IL_00ee:  ldarg.0
-    IL_00ef:  ldloc.2
-    IL_00f0:  ldfld      ""int System.ValueTuple<int, int>.Item1""
-    IL_00f5:  stfld      ""int C.<F>d__0.<u>5__13""
-    IL_00fa:  ldarg.0
-    IL_00fb:  ldloc.2
-    IL_00fc:  ldfld      ""int System.ValueTuple<int, int>.Item2""
-    IL_0101:  stfld      ""int C.<F>d__0.<w>5__14""
-    IL_0106:  ldarg.0
-    IL_0107:  call       ""System.IDisposable C.D()""
-    IL_010c:  stfld      ""System.IDisposable C.<F>d__0.<>s__11""
-    IL_0111:  ldarg.0
-    IL_0112:  ldc.i4.0
-    IL_0113:  stfld      ""bool C.<F>d__0.<>s__12""
-    IL_0118:  ldarg.0
-    IL_0119:  ldc.i4.s   -10
-    IL_011b:  stfld      ""int C.<F>d__0.<>1__state""
-    IL_0120:  ldarg.0
-    IL_0121:  ldfld      ""System.IDisposable C.<F>d__0.<>s__11""
-    IL_0126:  ldarg.0
-    IL_0127:  ldflda     ""bool C.<F>d__0.<>s__12""
-    IL_012c:  call       ""void System.Threading.Monitor.Enter(object, ref bool)""
-    IL_0131:  nop
-    IL_0132:  nop
-    IL_0133:  ldarg.0
-    IL_0134:  ldc.i4.1
-    IL_0135:  stfld      ""int C.<F>d__0.<>2__current""
-    IL_013a:  ldarg.0
-    IL_013b:  ldc.i4.1
-    IL_013c:  stfld      ""int C.<F>d__0.<>1__state""
-    IL_0141:  ldc.i4.1
-    IL_0142:  stloc.0
-    IL_0143:  leave      IL_020c
-    IL_0148:  ldarg.0
-    IL_0149:  ldc.i4.s   -10
-    IL_014b:  stfld      ""int C.<F>d__0.<>1__state""
-    IL_0150:  ldarg.0
-    IL_0151:  ldc.i4.2
-    IL_0152:  stfld      ""int C.<F>d__0.<>2__current""
-    IL_0157:  ldarg.0
-    IL_0158:  ldc.i4.2
-    IL_0159:  stfld      ""int C.<F>d__0.<>1__state""
-    IL_015e:  ldc.i4.1
-    IL_015f:  stloc.0
-    IL_0160:  leave      IL_020c
-    IL_0165:  ldarg.0
-    IL_0166:  ldc.i4.s   -10
-    IL_0168:  stfld      ""int C.<F>d__0.<>1__state""
-    IL_016d:  nop
-    IL_016e:  ldarg.0
-    IL_016f:  call       ""void C.<F>d__0.<>m__Finally8()""
-    IL_0174:  nop
-    IL_0175:  ldarg.0
-    IL_0176:  ldnull
-    IL_0177:  stfld      ""System.IDisposable C.<F>d__0.<>s__11""
-    IL_017c:  ldarg.0
-    IL_017d:  ldfld      ""System.Collections.Generic.IEnumerator<System.ValueTuple<int, int>> C.<F>d__0.<>s__8""
-    IL_0182:  callvirt   ""bool System.Collections.IEnumerator.MoveNext()""
-    IL_0187:  brtrue     IL_00e2
-    IL_018c:  ldarg.0
-    IL_018d:  call       ""void C.<F>d__0.<>m__Finally7()""
-    IL_0192:  nop
-    IL_0193:  ldarg.0
-    IL_0194:  ldnull
-    IL_0195:  stfld      ""System.Collections.Generic.IEnumerator<System.ValueTuple<int, int>> C.<F>d__0.<>s__8""
-    IL_019a:  ldarg.0
-    IL_019b:  ldflda     ""System.ValueTuple<int, int> C.<F>d__0.<z>5__7""
-    IL_01a0:  initobj    ""System.ValueTuple<int, int>""
-    IL_01a6:  ldarg.0
-    IL_01a7:  ldfld      ""System.Collections.Generic.IEnumerator<System.ValueTuple<int, int>> C.<F>d__0.<>s__6""
-    IL_01ac:  callvirt   ""bool System.Collections.IEnumerator.MoveNext()""
-    IL_01b1:  brtrue     IL_00b3
-    IL_01b6:  ldarg.0
-    IL_01b7:  call       ""void C.<F>d__0.<>m__Finally6()""
-    IL_01bc:  nop
-    IL_01bd:  ldarg.0
-    IL_01be:  ldnull
-    IL_01bf:  stfld      ""System.Collections.Generic.IEnumerator<System.ValueTuple<int, int>> C.<F>d__0.<>s__6""
-    IL_01c4:  ldarg.0
-    IL_01c5:  call       ""void C.<F>d__0.<>m__Finally5()""
-    IL_01ca:  nop
-    IL_01cb:  ldarg.0
-    IL_01cc:  call       ""void C.<F>d__0.<>m__Finally4()""
-    IL_01d1:  nop
-    IL_01d2:  ldarg.0
-    IL_01d3:  ldnull
-    IL_01d4:  stfld      ""System.IDisposable C.<F>d__0.<y1>5__4""
-    IL_01d9:  ldarg.0
-    IL_01da:  ldnull
-    IL_01db:  stfld      ""System.IDisposable C.<F>d__0.<y2>5__5""
-    IL_01e0:  ldarg.0
-    IL_01e1:  call       ""void C.<F>d__0.<>m__Finally3()""
-    IL_01e6:  nop
-    IL_01e7:  ldarg.0
-    IL_01e8:  ldnull
-    IL_01e9:  stfld      ""System.IDisposable C.<F>d__0.<>s__3""
-    IL_01ee:  ldc.i4.0
-    IL_01ef:  stloc.0
-    IL_01f0:  br.s       IL_01f2
-    IL_01f2:  ldarg.0
-    IL_01f3:  call       ""void C.<F>d__0.<>m__Finally2()""
-    IL_01f8:  nop
-    IL_01f9:  br.s       IL_01fb
-    IL_01fb:  ldarg.0
-    IL_01fc:  call       ""void C.<F>d__0.<>m__Finally1()""
-    IL_0201:  nop
-    IL_0202:  leave.s    IL_020c
-  }
-  fault
-  {
-    IL_0204:  ldarg.0
-    IL_0205:  call       ""void C.<F>d__0.Dispose()""
-    IL_020a:  nop
-    IL_020b:  endfinally
-  }
-  IL_020c:  ldloc.0
-  IL_020d:  ret
+  .locals init (int V_0)
+  IL_0000:  ldarg.0
+  IL_0001:  ldfld      ""int C.<F>d__0.<>1__state""
+  IL_0006:  stloc.0
+  IL_0007:  ldloc.0
+  IL_0008:  brfalse.s  IL_0012
+  IL_000a:  br.s       IL_000c
+  IL_000c:  ldloc.0
+  IL_000d:  ldc.i4.1
+  IL_000e:  beq.s      IL_0014
+  IL_0010:  br.s       IL_0016
+  IL_0012:  br.s       IL_0018
+  IL_0014:  br.s       IL_0040
+  IL_0016:  ldc.i4.0
+  IL_0017:  ret
+  IL_0018:  ldarg.0
+  IL_0019:  ldc.i4.m1
+  IL_001a:  stfld      ""int C.<F>d__0.<>1__state""
+  IL_001f:  nop
+  IL_0020:  ldarg.0
+  IL_0021:  ldc.i4     0x4d2
+  IL_0026:  stfld      ""int C.<F>d__0.<y>5__2""
+  IL_002b:  ldarg.0
+  IL_002c:  ldarg.0
+  IL_002d:  ldfld      ""int C.<F>d__0.<y>5__2""
+  IL_0032:  stfld      ""int C.<F>d__0.<>2__current""
+  IL_0037:  ldarg.0
+  IL_0038:  ldc.i4.1
+  IL_0039:  stfld      ""int C.<F>d__0.<>1__state""
+  IL_003e:  ldc.i4.1
+  IL_003f:  ret
+  IL_0040:  ldarg.0
+  IL_0041:  ldc.i4.m1
+  IL_0042:  stfld      ""int C.<F>d__0.<>1__state""
+  IL_0047:  ldarg.0
+  IL_0048:  ldfld      ""int C.<F>d__0.p""
+  IL_004d:  call       ""void System.Console.WriteLine(int)""
+  IL_0052:  nop
+  IL_0053:  ldc.i4.0
+  IL_0054:  ret
 }");
+                }
+            }
         }
 
         [Fact]
-        public void UpdateAsyncEnumerable_AwaitAndYield_AddAndRemove()
+        public void UpdateIterator_UserDefinedVariables_ChangeVariableType()
         {
-            var source0 = MarkedSource(@"
+            var source0 = @"
+using System;
 using System.Collections.Generic;
-using System.Threading.Tasks;
 
 class C
 {
-    async IAsyncEnumerable<int> F()
+    static IEnumerable<int> F() 
     {
-        <N:0>yield return F1();</N:0>
-        <N:1>await Task.FromResult(1)</N:1>;
-        End();
+        var x = 1;
+        yield return 1;
+        Console.WriteLine(x);
     }
-
-    static int F1() => 1;
-    static int F2() => 1;
-    static void End() { }
-}
-");
-            var source1 = MarkedSource(@"
+}";
+            var source1 = @"
+using System;
 using System.Collections.Generic;
-using System.Threading.Tasks;
 
 class C
 {
-    async IAsyncEnumerable<int> F()
+    static IEnumerable<int> F() 
     {
-        <N:2>yield return F2();</N:2>
-        <N:3>await Task.FromResult(2)</N:3>;
-        <N:0>yield return F1();</N:0>
-        <N:1>await Task.FromResult(1)</N:1>;
-        End();
+        var x = 1.0;
+        yield return 2;
+        Console.WriteLine(x);
     }
+}";
+            var compilation0 = CreateCompilationWithMscorlib45(source0, options: ComSafeDebugDll);
+            var compilation1 = compilation0.WithSource(source1);
 
-    static int F1() => 1;
-    static int F2() => 1;
-    static void End() { }
-}");
-            var source2 = MarkedSource(@"
-using System.Collections.Generic;
-using System.Threading.Tasks;
+            var v0 = CompileAndVerify(compilation0);
+            var symReader = v0.CreateSymReader();
 
-class C
-{
-    async IAsyncEnumerable<int> F()
-    {
-        <N:2>yield return F2();</N:2>
-        <N:3>await Task.FromResult(2)</N:3>;
-        <N:1>await Task.FromResult(1)</N:1>;
-        End();
-    }
+            using (var md0 = ModuleMetadata.CreateFromImage(v0.EmittedAssemblyData))
+            {
+                var method0 = compilation0.GetMember<MethodSymbol>("C.F");
+                var method1 = compilation1.GetMember<MethodSymbol>("C.F");
+
+                var generation0 = EmitBaseline.CreateInitialBaseline(md0, symReader.GetEncMethodDebugInfo);
+                var diff1 = compilation1.EmitDifference(
+                    generation0,
+                    ImmutableArray.Create(SemanticEdit.Create(SemanticEditKind.Update, method0, method1, GetEquivalentNodesMap(method1, method0), preserveLocalVariables: true)));
+
+                // Verify delta metadata contains expected rows.
+                using (var md1 = diff1.GetMetadata())
+                {
+                    // 1 field def added & 3 methods updated
+                    CheckEncLogDefinitions(md1.Reader,
+                        Row(3, TableIndex.StandAloneSig, EditAndContinueOperation.Default),
+                        Row(3, TableIndex.TypeDef, EditAndContinueOperation.AddField),
+                        Row(5, TableIndex.Field, EditAndContinueOperation.Default),
+                        Row(1, TableIndex.MethodDef, EditAndContinueOperation.Default),
+                        Row(4, TableIndex.MethodDef, EditAndContinueOperation.Default),
+                        Row(5, TableIndex.MethodDef, EditAndContinueOperation.Default),
+                        Row(1, TableIndex.CustomAttribute, EditAndContinueOperation.Default),
+                        Row(7, TableIndex.CustomAttribute, EditAndContinueOperation.Default));
 
-    static int F1() => 1;
-    static int F2() => 1;
-    static void End() { }
+                    diff1.VerifyIL("C.<F>d__0.System.Collections.IEnumerator.MoveNext", @"
+{
+  // Code size       84 (0x54)
+  .maxstack  2
+  .locals init (int V_0)
+  IL_0000:  ldarg.0
+  IL_0001:  ldfld      ""int C.<F>d__0.<>1__state""
+  IL_0006:  stloc.0
+  IL_0007:  ldloc.0
+  IL_0008:  brfalse.s  IL_0012
+  IL_000a:  br.s       IL_000c
+  IL_000c:  ldloc.0
+  IL_000d:  ldc.i4.1
+  IL_000e:  beq.s      IL_0014
+  IL_0010:  br.s       IL_0016
+  IL_0012:  br.s       IL_0018
+  IL_0014:  br.s       IL_003f
+  IL_0016:  ldc.i4.0
+  IL_0017:  ret
+  IL_0018:  ldarg.0
+  IL_0019:  ldc.i4.m1
+  IL_001a:  stfld      ""int C.<F>d__0.<>1__state""
+  IL_001f:  nop
+  IL_0020:  ldarg.0
+  IL_0021:  ldc.r8     1
+  IL_002a:  stfld      ""double C.<F>d__0.<x>5__2""
+  IL_002f:  ldarg.0
+  IL_0030:  ldc.i4.2
+  IL_0031:  stfld      ""int C.<F>d__0.<>2__current""
+  IL_0036:  ldarg.0
+  IL_0037:  ldc.i4.1
+  IL_0038:  stfld      ""int C.<F>d__0.<>1__state""
+  IL_003d:  ldc.i4.1
+  IL_003e:  ret
+  IL_003f:  ldarg.0
+  IL_0040:  ldc.i4.m1
+  IL_0041:  stfld      ""int C.<F>d__0.<>1__state""
+  IL_0046:  ldarg.0
+  IL_0047:  ldfld      ""double C.<F>d__0.<x>5__2""
+  IL_004c:  call       ""void System.Console.WriteLine(double)""
+  IL_0051:  nop
+  IL_0052:  ldc.i4.0
+  IL_0053:  ret
 }");
-            var source3 = MarkedSource(@"
+                }
+            }
+        }
+
+        [Fact]
+        public void UpdateIterator_SynthesizedVariables_ChangeVariableType()
+        {
+            var source0 = @"
+using System;
 using System.Collections.Generic;
-using System.Threading.Tasks;
 
 class C
 {
-    async IAsyncEnumerable<int> F()
+    static IEnumerable<int> F() 
     {
-        <N:2>yield return F2();</N:2>
-        <N:1>await Task.FromResult(1)</N:1>;
-        End();
+        foreach (object item in new[] { 1 }) { yield return 1; }
     }
+}";
+            var source1 = @"
+using System;
+using System.Collections.Generic;
 
-    static int F1() => 1;
-    static int F2() => 1;
-    static void End() { }
-}");
-            var asyncStreamsTree = Parse(AsyncStreamsTypes);
-
-            var compilation0 = CreateCompilationWithTasksExtensions(new[] { source0.Tree, asyncStreamsTree }, options: ComSafeDebugDll);
-            var compilation1 = compilation0.WithSource(new[] { source1.Tree, asyncStreamsTree });
-            var compilation2 = compilation1.WithSource(new[] { source2.Tree, asyncStreamsTree });
-            var compilation3 = compilation2.WithSource(new[] { source3.Tree, asyncStreamsTree });
-
-            var v0 = CompileAndVerify(compilation0);
-            v0.VerifyDiagnostics();
-            var md0 = ModuleMetadata.CreateFromImage(v0.EmittedAssemblyData);
-
-            var f0 = compilation0.GetMember<MethodSymbol>("C.F");
-            var f1 = compilation1.GetMember<MethodSymbol>("C.F");
-            var f2 = compilation2.GetMember<MethodSymbol>("C.F");
-            var f3 = compilation3.GetMember<MethodSymbol>("C.F");
-
-            var generation0 = EmitBaseline.CreateInitialBaseline(md0, v0.CreateSymReader().GetEncMethodDebugInfo);
+class C
+{
+    static IEnumerable<int> F() 
+    {
+        foreach (object item in new[] { 1.0 }) { yield return 1; }
+    }
+}";
+            // Rude edit but the compiler should handle it.
 
-            var diff1 = compilation1.EmitDifference(
-                 generation0,
-                 ImmutableArray.Create(
-                     SemanticEdit.Create(SemanticEditKind.Update, f0, f1, GetSyntaxMapFromMarkers(source0, source1), preserveLocalVariables: true)));
+            var compilation0 = CreateCompilationWithMscorlib45(source0, options: ComSafeDebugDll.WithMetadataImportOptions(MetadataImportOptions.All));
+            var compilation1 = compilation0.WithSource(source1);
 
-            var diff2 = compilation2.EmitDifference(
-                 diff1.NextGeneration,
-                 ImmutableArray.Create(
-                     SemanticEdit.Create(SemanticEditKind.Update, f1, f2, GetSyntaxMapFromMarkers(source1, source2), preserveLocalVariables: true)));
+            var v0 = CompileAndVerify(compilation0, symbolValidator: module =>
+            {
+                Assert.Equal(new[]
+                {
+                    "<>1__state: int",
+                    "<>2__current: int",
+                    "<>l__initialThreadId: int",
+                    "<>s__1: int[]",
+                    "<>s__2: int",
+                    "<item>5__3: object"
+                }, module.GetFieldNamesAndTypes("C.<F>d__0"));
+            });
 
-            var diff3 = compilation3.EmitDifference(
-                 diff2.NextGeneration,
-                 ImmutableArray.Create(
-                     SemanticEdit.Create(SemanticEditKind.Update, f2, f3, GetSyntaxMapFromMarkers(source2, source3), preserveLocalVariables: true)));
+            var symReader = v0.CreateSymReader();
 
-            v0.VerifyPdb("C.F", @"
-<symbols>
-  <files>
-    <file id=""1"" name="""" language=""C#"" />
-  </files>
-  <methods>
-    <method containingType=""C"" name=""F"">
-      <customDebugInfo>
-        <forwardIterator name=""&lt;F&gt;d__0"" />
-        <encStateMachineStateMap>
-          <state number=""-4"" offset=""16"" />
-          <state number=""0"" offset=""55"" />
-        </encStateMachineStateMap>
-      </customDebugInfo>
-    </method>
-  </methods>
-</symbols>
-");
+            using (var md0 = ModuleMetadata.CreateFromImage(v0.EmittedAssemblyData))
+            {
+                var method0 = compilation0.GetMember<MethodSymbol>("C.F");
+                var method1 = compilation1.GetMember<MethodSymbol>("C.F");
 
-            diff1.VerifyIL("C.<F>d__0.System.Runtime.CompilerServices.IAsyncStateMachine.MoveNext", @"
-{
-  // Code size      484 (0x1e4)
-  .maxstack  3
-  .locals init (int V_0,
-                System.Runtime.CompilerServices.TaskAwaiter<int> V_1,
-                C.<F>d__0 V_2,
-                System.Runtime.CompilerServices.TaskAwaiter<int> V_3,
-                System.Exception V_4)
-  IL_0000:  ldarg.0
-  IL_0001:  ldfld      ""int C.<F>d__0.<>1__state""
-  IL_0006:  stloc.0
-  .try
-  {
-    IL_0007:  ldloc.0
-    IL_0008:  ldc.i4.s   -5
-    IL_000a:  sub
-    IL_000b:  switch    (
-        IL_002e,
-        IL_0030,
-        IL_0035,
-        IL_0041,
-        IL_0041,
-        IL_0037,
-        IL_003c)
-    IL_002c:  br.s       IL_0041
-    IL_002e:  br.s       IL_0072
-    IL_0030:  br         IL_0102
-    IL_0035:  br.s       IL_0041
-    IL_0037:  br         IL_0154
-    IL_003c:  br         IL_00c4
-    IL_0041:  ldarg.0
-    IL_0042:  ldfld      ""bool C.<F>d__0.<>w__disposeMode""
-    IL_0047:  brfalse.s  IL_004e
-    IL_0049:  leave      IL_01ad
-    IL_004e:  ldarg.0
-    IL_004f:  ldc.i4.m1
-    IL_0050:  dup
-    IL_0051:  stloc.0
-    IL_0052:  stfld      ""int C.<F>d__0.<>1__state""
-    IL_0057:  nop
-    IL_0058:  ldarg.0
-    IL_0059:  call       ""int C.F2()""
-    IL_005e:  stfld      ""int C.<F>d__0.<>2__current""
-    IL_0063:  ldarg.0
-    IL_0064:  ldc.i4.s   -5
-    IL_0066:  dup
-    IL_0067:  stloc.0
-    IL_0068:  stfld      ""int C.<F>d__0.<>1__state""
-    IL_006d:  leave      IL_01d6
-    IL_0072:  ldarg.0
-    IL_0073:  ldc.i4.m1
-    IL_0074:  dup
-    IL_0075:  stloc.0
-    IL_0076:  stfld      ""int C.<F>d__0.<>1__state""
-    IL_007b:  ldarg.0
-    IL_007c:  ldfld      ""bool C.<F>d__0.<>w__disposeMode""
-    IL_0081:  brfalse.s  IL_0088
-    IL_0083:  leave      IL_01ad
-    IL_0088:  ldc.i4.2
-    IL_0089:  call       ""System.Threading.Tasks.Task<int> System.Threading.Tasks.Task.FromResult<int>(int)""
-    IL_008e:  callvirt   ""System.Runtime.CompilerServices.TaskAwaiter<int> System.Threading.Tasks.Task<int>.GetAwaiter()""
-    IL_0093:  stloc.1
-    IL_0094:  ldloca.s   V_1
-    IL_0096:  call       ""bool System.Runtime.CompilerServices.TaskAwaiter<int>.IsCompleted.get""
-    IL_009b:  brtrue.s   IL_00e0
-    IL_009d:  ldarg.0
-    IL_009e:  ldc.i4.1
-    IL_009f:  dup
-    IL_00a0:  stloc.0
-    IL_00a1:  stfld      ""int C.<F>d__0.<>1__state""
-    IL_00a6:  ldarg.0
-    IL_00a7:  ldloc.1
-    IL_00a8:  stfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> C.<F>d__0.<>u__1""
-    IL_00ad:  ldarg.0
-    IL_00ae:  stloc.2
-    IL_00af:  ldarg.0
-    IL_00b0:  ldflda     ""System.Runtime.CompilerServices.AsyncIteratorMethodBuilder C.<F>d__0.<>t__builder""
-    IL_00b5:  ldloca.s   V_1
-    IL_00b7:  ldloca.s   V_2
-    IL_00b9:  call       ""void System.Runtime.CompilerServices.AsyncIteratorMethodBuilder.AwaitUnsafeOnCompleted<System.Runtime.CompilerServices.TaskAwaiter<int>, C.<F>d__0>(ref System.Runtime.CompilerServices.TaskAwaiter<int>, ref C.<F>d__0)""
-    IL_00be:  nop
-    IL_00bf:  leave      IL_01e3
-    IL_00c4:  ldarg.0
-    IL_00c5:  ldfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> C.<F>d__0.<>u__1""
-    IL_00ca:  stloc.1
-    IL_00cb:  ldarg.0
-    IL_00cc:  ldflda     ""System.Runtime.CompilerServices.TaskAwaiter<int> C.<F>d__0.<>u__1""
-    IL_00d1:  initobj    ""System.Runtime.CompilerServices.TaskAwaiter<int>""
-    IL_00d7:  ldarg.0
-    IL_00d8:  ldc.i4.m1
-    IL_00d9:  dup
-    IL_00da:  stloc.0
-    IL_00db:  stfld      ""int C.<F>d__0.<>1__state""
-    IL_00e0:  ldloca.s   V_1
-    IL_00e2:  call       ""int System.Runtime.CompilerServices.TaskAwaiter<int>.GetResult()""
-    IL_00e7:  pop
-    IL_00e8:  ldarg.0
-    IL_00e9:  call       ""int C.F1()""
-    IL_00ee:  stfld      ""int C.<F>d__0.<>2__current""
-    IL_00f3:  ldarg.0
-    IL_00f4:  ldc.i4.s   -4
-    IL_00f6:  dup
-    IL_00f7:  stloc.0
-    IL_00f8:  stfld      ""int C.<F>d__0.<>1__state""
-    IL_00fd:  leave      IL_01d6
-    IL_0102:  ldarg.0
-    IL_0103:  ldc.i4.m1
-    IL_0104:  dup
-    IL_0105:  stloc.0
-    IL_0106:  stfld      ""int C.<F>d__0.<>1__state""
-    IL_010b:  ldarg.0
-    IL_010c:  ldfld      ""bool C.<F>d__0.<>w__disposeMode""
-    IL_0111:  brfalse.s  IL_0118
-    IL_0113:  leave      IL_01ad
-    IL_0118:  ldc.i4.1
-    IL_0119:  call       ""System.Threading.Tasks.Task<int> System.Threading.Tasks.Task.FromResult<int>(int)""
-    IL_011e:  callvirt   ""System.Runtime.CompilerServices.TaskAwaiter<int> System.Threading.Tasks.Task<int>.GetAwaiter()""
-    IL_0123:  stloc.3
-    IL_0124:  ldloca.s   V_3
-    IL_0126:  call       ""bool System.Runtime.CompilerServices.TaskAwaiter<int>.IsCompleted.get""
-    IL_012b:  brtrue.s   IL_0170
-    IL_012d:  ldarg.0
-    IL_012e:  ldc.i4.0
-    IL_012f:  dup
-    IL_0130:  stloc.0
-    IL_0131:  stfld      ""int C.<F>d__0.<>1__state""
-    IL_0136:  ldarg.0
-    IL_0137:  ldloc.3
-    IL_0138:  stfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> C.<F>d__0.<>u__1""
-    IL_013d:  ldarg.0
-    IL_013e:  stloc.2
-    IL_013f:  ldarg.0
-    IL_0140:  ldflda     ""System.Runtime.CompilerServices.AsyncIteratorMethodBuilder C.<F>d__0.<>t__builder""
-    IL_0145:  ldloca.s   V_3
-    IL_0147:  ldloca.s   V_2
-    IL_0149:  call       ""void System.Runtime.CompilerServices.AsyncIteratorMethodBuilder.AwaitUnsafeOnCompleted<System.Runtime.CompilerServices.TaskAwaiter<int>, C.<F>d__0>(ref System.Runtime.CompilerServices.TaskAwaiter<int>, ref C.<F>d__0)""
-    IL_014e:  nop
-    IL_014f:  leave      IL_01e3
-    IL_0154:  ldarg.0
-    IL_0155:  ldfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> C.<F>d__0.<>u__1""
-    IL_015a:  stloc.3
-    IL_015b:  ldarg.0
-    IL_015c:  ldflda     ""System.Runtime.CompilerServices.TaskAwaiter<int> C.<F>d__0.<>u__1""
-    IL_0161:  initobj    ""System.Runtime.CompilerServices.TaskAwaiter<int>""
-    IL_0167:  ldarg.0
-    IL_0168:  ldc.i4.m1
-    IL_0169:  dup
-    IL_016a:  stloc.0
-    IL_016b:  stfld      ""int C.<F>d__0.<>1__state""
-    IL_0170:  ldloca.s   V_3
-    IL_0172:  call       ""int System.Runtime.CompilerServices.TaskAwaiter<int>.GetResult()""
-    IL_0177:  pop
-    IL_0178:  call       ""void C.End()""
-    IL_017d:  nop
-    IL_017e:  leave.s    IL_01ad
-  }
-  catch System.Exception
-  {
-    IL_0180:  stloc.s    V_4
-    IL_0182:  ldarg.0
-    IL_0183:  ldc.i4.s   -2
-    IL_0185:  stfld      ""int C.<F>d__0.<>1__state""
-    IL_018a:  ldarg.0
-    IL_018b:  ldc.i4.0
-    IL_018c:  stfld      ""int C.<F>d__0.<>2__current""
-    IL_0191:  ldarg.0
-    IL_0192:  ldflda     ""System.Runtime.CompilerServices.AsyncIteratorMethodBuilder C.<F>d__0.<>t__builder""
-    IL_0197:  call       ""void System.Runtime.CompilerServices.AsyncIteratorMethodBuilder.Complete()""
-    IL_019c:  nop
-    IL_019d:  ldarg.0
-    IL_019e:  ldflda     ""System.Threading.Tasks.Sources.ManualResetValueTaskSourceCore<bool> C.<F>d__0.<>v__promiseOfValueOrEnd""
-    IL_01a3:  ldloc.s    V_4
-    IL_01a5:  call       ""void System.Threading.Tasks.Sources.ManualResetValueTaskSourceCore<bool>.SetException(System.Exception)""
-    IL_01aa:  nop
-    IL_01ab:  leave.s    IL_01e3
-  }
-  IL_01ad:  ldarg.0
-  IL_01ae:  ldc.i4.s   -2
-  IL_01b0:  stfld      ""int C.<F>d__0.<>1__state""
-  IL_01b5:  ldarg.0
-  IL_01b6:  ldc.i4.0
-  IL_01b7:  stfld      ""int C.<F>d__0.<>2__current""
-  IL_01bc:  ldarg.0
-  IL_01bd:  ldflda     ""System.Runtime.CompilerServices.AsyncIteratorMethodBuilder C.<F>d__0.<>t__builder""
-  IL_01c2:  call       ""void System.Runtime.CompilerServices.AsyncIteratorMethodBuilder.Complete()""
-  IL_01c7:  nop
-  IL_01c8:  ldarg.0
-  IL_01c9:  ldflda     ""System.Threading.Tasks.Sources.ManualResetValueTaskSourceCore<bool> C.<F>d__0.<>v__promiseOfValueOrEnd""
-  IL_01ce:  ldc.i4.0
-  IL_01cf:  call       ""void System.Threading.Tasks.Sources.ManualResetValueTaskSourceCore<bool>.SetResult(bool)""
-  IL_01d4:  nop
-  IL_01d5:  ret
-  IL_01d6:  ldarg.0
-  IL_01d7:  ldflda     ""System.Threading.Tasks.Sources.ManualResetValueTaskSourceCore<bool> C.<F>d__0.<>v__promiseOfValueOrEnd""
-  IL_01dc:  ldc.i4.1
-  IL_01dd:  call       ""void System.Threading.Tasks.Sources.ManualResetValueTaskSourceCore<bool>.SetResult(bool)""
-  IL_01e2:  nop
-  IL_01e3:  ret
-}
-");
+                var generation0 = EmitBaseline.CreateInitialBaseline(md0, symReader.GetEncMethodDebugInfo);
+                var diff1 = compilation1.EmitDifference(
+                    generation0,
+                    ImmutableArray.Create(SemanticEdit.Create(SemanticEditKind.Update, method0, method1, GetSyntaxMapByKind(method0, SyntaxKind.ForEachStatement), preserveLocalVariables: true)));
 
-            diff2.VerifyIL("C.<F>d__0.System.Runtime.CompilerServices.IAsyncStateMachine.MoveNext", @"
-{
-  // Code size      447 (0x1bf)
-  .maxstack  3
-  .locals init (int V_0,
-                System.Runtime.CompilerServices.TaskAwaiter<int> V_1,
-                C.<F>d__0 V_2,
-                System.Runtime.CompilerServices.TaskAwaiter<int> V_3,
-                System.Exception V_4)
-  IL_0000:  ldarg.0
-  IL_0001:  ldfld      ""int C.<F>d__0.<>1__state""
-  IL_0006:  stloc.0
-  .try
-  {
-    IL_0007:  ldloc.0
-    IL_0008:  ldc.i4.s   -5
-    IL_000a:  sub
-    IL_000b:  switch    (
-        IL_002e,
-        IL_003c,
-        IL_0030,
-        IL_003c,
-        IL_003c,
-        IL_0032,
-        IL_0037)
-    IL_002c:  br.s       IL_003c
-    IL_002e:  br.s       IL_007d
-    IL_0030:  br.s       IL_004c
-    IL_0032:  br         IL_012f
-    IL_0037:  br         IL_00cf
-    IL_003c:  ldloc.0
-    IL_003d:  ldc.i4.s   -4
-    IL_003f:  bgt.s      IL_004c
-    IL_0041:  ldstr      """ + CodeAnalysisResources.EncCannotResumeSuspendedIteratorMethod + @"""
-    IL_0046:  newobj     ""System.InvalidOperationException..ctor(string)""
-    IL_004b:  throw
-    IL_004c:  ldarg.0
-    IL_004d:  ldfld      ""bool C.<F>d__0.<>w__disposeMode""
-    IL_0052:  brfalse.s  IL_0059
-    IL_0054:  leave      IL_0188
-    IL_0059:  ldarg.0
-    IL_005a:  ldc.i4.m1
-    IL_005b:  dup
-    IL_005c:  stloc.0
-    IL_005d:  stfld      ""int C.<F>d__0.<>1__state""
-    IL_0062:  nop
-    IL_0063:  ldarg.0
-    IL_0064:  call       ""int C.F2()""
-    IL_0069:  stfld      ""int C.<F>d__0.<>2__current""
-    IL_006e:  ldarg.0
-    IL_006f:  ldc.i4.s   -5
-    IL_0071:  dup
-    IL_0072:  stloc.0
-    IL_0073:  stfld      ""int C.<F>d__0.<>1__state""
-    IL_0078:  leave      IL_01b1
-    IL_007d:  ldarg.0
-    IL_007e:  ldc.i4.m1
-    IL_007f:  dup
-    IL_0080:  stloc.0
-    IL_0081:  stfld      ""int C.<F>d__0.<>1__state""
-    IL_0086:  ldarg.0
-    IL_0087:  ldfld      ""bool C.<F>d__0.<>w__disposeMode""
-    IL_008c:  brfalse.s  IL_0093
-    IL_008e:  leave      IL_0188
-    IL_0093:  ldc.i4.2
-    IL_0094:  call       ""System.Threading.Tasks.Task<int> System.Threading.Tasks.Task.FromResult<int>(int)""
-    IL_0099:  callvirt   ""System.Runtime.CompilerServices.TaskAwaiter<int> System.Threading.Tasks.Task<int>.GetAwaiter()""
-    IL_009e:  stloc.1
-    IL_009f:  ldloca.s   V_1
-    IL_00a1:  call       ""bool System.Runtime.CompilerServices.TaskAwaiter<int>.IsCompleted.get""
-    IL_00a6:  brtrue.s   IL_00eb
-    IL_00a8:  ldarg.0
-    IL_00a9:  ldc.i4.1
-    IL_00aa:  dup
-    IL_00ab:  stloc.0
-    IL_00ac:  stfld      ""int C.<F>d__0.<>1__state""
-    IL_00b1:  ldarg.0
-    IL_00b2:  ldloc.1
-    IL_00b3:  stfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> C.<F>d__0.<>u__1""
-    IL_00b8:  ldarg.0
-    IL_00b9:  stloc.2
-    IL_00ba:  ldarg.0
-    IL_00bb:  ldflda     ""System.Runtime.CompilerServices.AsyncIteratorMethodBuilder C.<F>d__0.<>t__builder""
-    IL_00c0:  ldloca.s   V_1
-    IL_00c2:  ldloca.s   V_2
-    IL_00c4:  call       ""void System.Runtime.CompilerServices.AsyncIteratorMethodBuilder.AwaitUnsafeOnCompleted<System.Runtime.CompilerServices.TaskAwaiter<int>, C.<F>d__0>(ref System.Runtime.CompilerServices.TaskAwaiter<int>, ref C.<F>d__0)""
-    IL_00c9:  nop
-    IL_00ca:  leave      IL_01be
-    IL_00cf:  ldarg.0
-    IL_00d0:  ldfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> C.<F>d__0.<>u__1""
-    IL_00d5:  stloc.1
-    IL_00d6:  ldarg.0
-    IL_00d7:  ldflda     ""System.Runtime.CompilerServices.TaskAwaiter<int> C.<F>d__0.<>u__1""
-    IL_00dc:  initobj    ""System.Runtime.CompilerServices.TaskAwaiter<int>""
-    IL_00e2:  ldarg.0
-    IL_00e3:  ldc.i4.m1
-    IL_00e4:  dup
-    IL_00e5:  stloc.0
-    IL_00e6:  stfld      ""int C.<F>d__0.<>1__state""
-    IL_00eb:  ldloca.s   V_1
-    IL_00ed:  call       ""int System.Runtime.CompilerServices.TaskAwaiter<int>.GetResult()""
-    IL_00f2:  pop
-    IL_00f3:  ldc.i4.1
-    IL_00f4:  call       ""System.Threading.Tasks.Task<int> System.Threading.Tasks.Task.FromResult<int>(int)""
-    IL_00f9:  callvirt   ""System.Runtime.CompilerServices.TaskAwaiter<int> System.Threading.Tasks.Task<int>.GetAwaiter()""
-    IL_00fe:  stloc.3
-    IL_00ff:  ldloca.s   V_3
-    IL_0101:  call       ""bool System.Runtime.CompilerServices.TaskAwaiter<int>.IsCompleted.get""
-    IL_0106:  brtrue.s   IL_014b
-    IL_0108:  ldarg.0
-    IL_0109:  ldc.i4.0
-    IL_010a:  dup
-    IL_010b:  stloc.0
-    IL_010c:  stfld      ""int C.<F>d__0.<>1__state""
-    IL_0111:  ldarg.0
-    IL_0112:  ldloc.3
-    IL_0113:  stfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> C.<F>d__0.<>u__1""
-    IL_0118:  ldarg.0
-    IL_0119:  stloc.2
-    IL_011a:  ldarg.0
-    IL_011b:  ldflda     ""System.Runtime.CompilerServices.AsyncIteratorMethodBuilder C.<F>d__0.<>t__builder""
-    IL_0120:  ldloca.s   V_3
-    IL_0122:  ldloca.s   V_2
-    IL_0124:  call       ""void System.Runtime.CompilerServices.AsyncIteratorMethodBuilder.AwaitUnsafeOnCompleted<System.Runtime.CompilerServices.TaskAwaiter<int>, C.<F>d__0>(ref System.Runtime.CompilerServices.TaskAwaiter<int>, ref C.<F>d__0)""
-    IL_0129:  nop
-    IL_012a:  leave      IL_01be
-    IL_012f:  ldarg.0
-    IL_0130:  ldfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> C.<F>d__0.<>u__1""
-    IL_0135:  stloc.3
-    IL_0136:  ldarg.0
-    IL_0137:  ldflda     ""System.Runtime.CompilerServices.TaskAwaiter<int> C.<F>d__0.<>u__1""
-    IL_013c:  initobj    ""System.Runtime.CompilerServices.TaskAwaiter<int>""
-    IL_0142:  ldarg.0
-    IL_0143:  ldc.i4.m1
-    IL_0144:  dup
-    IL_0145:  stloc.0
-    IL_0146:  stfld      ""int C.<F>d__0.<>1__state""
-    IL_014b:  ldloca.s   V_3
-    IL_014d:  call       ""int System.Runtime.CompilerServices.TaskAwaiter<int>.GetResult()""
-    IL_0152:  pop
-    IL_0153:  call       ""void C.End()""
-    IL_0158:  nop
-    IL_0159:  leave.s    IL_0188
-  }
-  catch System.Exception
-  {
-    IL_015b:  stloc.s    V_4
-    IL_015d:  ldarg.0
-    IL_015e:  ldc.i4.s   -2
-    IL_0160:  stfld      ""int C.<F>d__0.<>1__state""
-    IL_0165:  ldarg.0
-    IL_0166:  ldc.i4.0
-    IL_0167:  stfld      ""int C.<F>d__0.<>2__current""
-    IL_016c:  ldarg.0
-    IL_016d:  ldflda     ""System.Runtime.CompilerServices.AsyncIteratorMethodBuilder C.<F>d__0.<>t__builder""
-    IL_0172:  call       ""void System.Runtime.CompilerServices.AsyncIteratorMethodBuilder.Complete()""
-    IL_0177:  nop
-    IL_0178:  ldarg.0
-    IL_0179:  ldflda     ""System.Threading.Tasks.Sources.ManualResetValueTaskSourceCore<bool> C.<F>d__0.<>v__promiseOfValueOrEnd""
-    IL_017e:  ldloc.s    V_4
-    IL_0180:  call       ""void System.Threading.Tasks.Sources.ManualResetValueTaskSourceCore<bool>.SetException(System.Exception)""
-    IL_0185:  nop
-    IL_0186:  leave.s    IL_01be
-  }
-  IL_0188:  ldarg.0
-  IL_0189:  ldc.i4.s   -2
-  IL_018b:  stfld      ""int C.<F>d__0.<>1__state""
-  IL_0190:  ldarg.0
-  IL_0191:  ldc.i4.0
-  IL_0192:  stfld      ""int C.<F>d__0.<>2__current""
-  IL_0197:  ldarg.0
-  IL_0198:  ldflda     ""System.Runtime.CompilerServices.AsyncIteratorMethodBuilder C.<F>d__0.<>t__builder""
-  IL_019d:  call       ""void System.Runtime.CompilerServices.AsyncIteratorMethodBuilder.Complete()""
-  IL_01a2:  nop
-  IL_01a3:  ldarg.0
-  IL_01a4:  ldflda     ""System.Threading.Tasks.Sources.ManualResetValueTaskSourceCore<bool> C.<F>d__0.<>v__promiseOfValueOrEnd""
-  IL_01a9:  ldc.i4.0
-  IL_01aa:  call       ""void System.Threading.Tasks.Sources.ManualResetValueTaskSourceCore<bool>.SetResult(bool)""
-  IL_01af:  nop
-  IL_01b0:  ret
-  IL_01b1:  ldarg.0
-  IL_01b2:  ldflda     ""System.Threading.Tasks.Sources.ManualResetValueTaskSourceCore<bool> C.<F>d__0.<>v__promiseOfValueOrEnd""
-  IL_01b7:  ldc.i4.1
-  IL_01b8:  call       ""void System.Threading.Tasks.Sources.ManualResetValueTaskSourceCore<bool>.SetResult(bool)""
-  IL_01bd:  nop
-  IL_01be:  ret
-}");
-            diff3.VerifyIL("C.<F>d__0.System.Runtime.CompilerServices.IAsyncStateMachine.MoveNext", @"
+                // Verify delta metadata contains expected rows.
+                using (var md1 = diff1.GetMetadata())
+                {
+                    // 1 field def added & 3 methods updated
+                    CheckEncLogDefinitions(md1.Reader,
+                        Row(3, TableIndex.StandAloneSig, EditAndContinueOperation.Default),
+                        Row(3, TableIndex.TypeDef, EditAndContinueOperation.AddField),
+                        Row(7, TableIndex.Field, EditAndContinueOperation.Default),
+                        Row(1, TableIndex.MethodDef, EditAndContinueOperation.Default),
+                        Row(4, TableIndex.MethodDef, EditAndContinueOperation.Default),
+                        Row(5, TableIndex.MethodDef, EditAndContinueOperation.Default),
+                        Row(1, TableIndex.CustomAttribute, EditAndContinueOperation.Default),
+                        Row(7, TableIndex.CustomAttribute, EditAndContinueOperation.Default));
+
+                    diff1.VerifyIL("C.<F>d__0.System.Collections.IEnumerator.MoveNext", @"
 {
-  // Code size      339 (0x153)
-  .maxstack  3
-  .locals init (int V_0,
-                System.Runtime.CompilerServices.TaskAwaiter<int> V_1,
-                C.<F>d__0 V_2,
-                System.Exception V_3)
+  // Code size      161 (0xa1)
+  .maxstack  5
+  .locals init (int V_0)
   IL_0000:  ldarg.0
   IL_0001:  ldfld      ""int C.<F>d__0.<>1__state""
   IL_0006:  stloc.0
-  .try
-  {
-    IL_0007:  ldloc.0
-    IL_0008:  ldc.i4.s   -5
-    IL_000a:  beq.s      IL_001a
-    IL_000c:  br.s       IL_000e
-    IL_000e:  ldloc.0
-    IL_000f:  ldc.i4.s   -3
-    IL_0011:  beq.s      IL_001c
-    IL_0013:  br.s       IL_0015
-    IL_0015:  ldloc.0
-    IL_0016:  brfalse.s  IL_001e
-    IL_0018:  br.s       IL_0023
-    IL_001a:  br.s       IL_0073
-    IL_001c:  br.s       IL_0042
-    IL_001e:  br         IL_00c5
-
-    IL_0023:  ldloc.0
-    IL_0024:  ldc.i4.0
-    IL_0025:  blt.s      IL_0032
-    IL_0027:  ldstr      """ + CodeAnalysisResources.EncCannotResumeSuspendedAsyncMethod + @"""
-    IL_002c:  newobj     ""System.InvalidOperationException..ctor(string)""
-    IL_0031:  throw
-
-    IL_0032:  ldloc.0
-    IL_0033:  ldc.i4.s   -4
-    IL_0035:  bgt.s      IL_0042
-    IL_0037:  ldstr      """ + CodeAnalysisResources.EncCannotResumeSuspendedIteratorMethod + @"""
-    IL_003c:  newobj     ""System.InvalidOperationException..ctor(string)""
-    IL_0041:  throw
-
-    IL_0042:  ldarg.0
-    IL_0043:  ldfld      ""bool C.<F>d__0.<>w__disposeMode""
-    IL_0048:  brfalse.s  IL_004f
-    IL_004a:  leave      IL_011c
-
-    IL_004f:  ldarg.0
-    IL_0050:  ldc.i4.m1
-    IL_0051:  dup
-    IL_0052:  stloc.0
-    IL_0053:  stfld      ""int C.<F>d__0.<>1__state""
-    IL_0058:  nop
-    IL_0059:  ldarg.0
-    IL_005a:  call       ""int C.F2()""
-    IL_005f:  stfld      ""int C.<F>d__0.<>2__current""
-    IL_0064:  ldarg.0
-    IL_0065:  ldc.i4.s   -5
-    IL_0067:  dup
-    IL_0068:  stloc.0
-    IL_0069:  stfld      ""int C.<F>d__0.<>1__state""
-    IL_006e:  leave      IL_0145
-
-    IL_0073:  ldarg.0
-    IL_0074:  ldc.i4.m1
-    IL_0075:  dup
-    IL_0076:  stloc.0
-    IL_0077:  stfld      ""int C.<F>d__0.<>1__state""
-    IL_007c:  ldarg.0
-    IL_007d:  ldfld      ""bool C.<F>d__0.<>w__disposeMode""
-    IL_0082:  brfalse.s  IL_0089
-    IL_0084:  leave      IL_011c
-
-    IL_0089:  ldc.i4.1
-    IL_008a:  call       ""System.Threading.Tasks.Task<int> System.Threading.Tasks.Task.FromResult<int>(int)""
-    IL_008f:  callvirt   ""System.Runtime.CompilerServices.TaskAwaiter<int> System.Threading.Tasks.Task<int>.GetAwaiter()""
-    IL_0094:  stloc.1
-    IL_0095:  ldloca.s   V_1
-    IL_0097:  call       ""bool System.Runtime.CompilerServices.TaskAwaiter<int>.IsCompleted.get""
-    IL_009c:  brtrue.s   IL_00e1
-
-    IL_009e:  ldarg.0
-    IL_009f:  ldc.i4.0
-    IL_00a0:  dup
-    IL_00a1:  stloc.0
-    IL_00a2:  stfld      ""int C.<F>d__0.<>1__state""
-    IL_00a7:  ldarg.0
-    IL_00a8:  ldloc.1
-    IL_00a9:  stfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> C.<F>d__0.<>u__1""
-    IL_00ae:  ldarg.0
-    IL_00af:  stloc.2
-    IL_00b0:  ldarg.0
-    IL_00b1:  ldflda     ""System.Runtime.CompilerServices.AsyncIteratorMethodBuilder C.<F>d__0.<>t__builder""
-    IL_00b6:  ldloca.s   V_1
-    IL_00b8:  ldloca.s   V_2
-    IL_00ba:  call       ""void System.Runtime.CompilerServices.AsyncIteratorMethodBuilder.AwaitUnsafeOnCompleted<System.Runtime.CompilerServices.TaskAwaiter<int>, C.<F>d__0>(ref System.Runtime.CompilerServices.TaskAwaiter<int>, ref C.<F>d__0)""
-    IL_00bf:  nop
-    IL_00c0:  leave      IL_0152
-
-    IL_00c5:  ldarg.0
-    IL_00c6:  ldfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> C.<F>d__0.<>u__1""
-    IL_00cb:  stloc.1
-    IL_00cc:  ldarg.0
-    IL_00cd:  ldflda     ""System.Runtime.CompilerServices.TaskAwaiter<int> C.<F>d__0.<>u__1""
-    IL_00d2:  initobj    ""System.Runtime.CompilerServices.TaskAwaiter<int>""
-    IL_00d8:  ldarg.0
-    IL_00d9:  ldc.i4.m1
-    IL_00da:  dup
-    IL_00db:  stloc.0
-    IL_00dc:  stfld      ""int C.<F>d__0.<>1__state""
-
-    IL_00e1:  ldloca.s   V_1
-    IL_00e3:  call       ""int System.Runtime.CompilerServices.TaskAwaiter<int>.GetResult()""
-    IL_00e8:  pop
-    IL_00e9:  call       ""void C.End()""
-    IL_00ee:  nop
-    IL_00ef:  leave.s    IL_011c
-  }
-  catch System.Exception
-  {
-    IL_00f1:  stloc.3
-    IL_00f2:  ldarg.0
-    IL_00f3:  ldc.i4.s   -2
-    IL_00f5:  stfld      ""int C.<F>d__0.<>1__state""
-    IL_00fa:  ldarg.0
-    IL_00fb:  ldc.i4.0
-    IL_00fc:  stfld      ""int C.<F>d__0.<>2__current""
-    IL_0101:  ldarg.0
-    IL_0102:  ldflda     ""System.Runtime.CompilerServices.AsyncIteratorMethodBuilder C.<F>d__0.<>t__builder""
-    IL_0107:  call       ""void System.Runtime.CompilerServices.AsyncIteratorMethodBuilder.Complete()""
-    IL_010c:  nop
-    IL_010d:  ldarg.0
-    IL_010e:  ldflda     ""System.Threading.Tasks.Sources.ManualResetValueTaskSourceCore<bool> C.<F>d__0.<>v__promiseOfValueOrEnd""
-    IL_0113:  ldloc.3
-    IL_0114:  call       ""void System.Threading.Tasks.Sources.ManualResetValueTaskSourceCore<bool>.SetException(System.Exception)""
-    IL_0119:  nop
-    IL_011a:  leave.s    IL_0152
-  }
-  IL_011c:  ldarg.0
-  IL_011d:  ldc.i4.s   -2
-  IL_011f:  stfld      ""int C.<F>d__0.<>1__state""
-  IL_0124:  ldarg.0
-  IL_0125:  ldc.i4.0
-  IL_0126:  stfld      ""int C.<F>d__0.<>2__current""
-  IL_012b:  ldarg.0
-  IL_012c:  ldflda     ""System.Runtime.CompilerServices.AsyncIteratorMethodBuilder C.<F>d__0.<>t__builder""
-  IL_0131:  call       ""void System.Runtime.CompilerServices.AsyncIteratorMethodBuilder.Complete()""
-  IL_0136:  nop
-  IL_0137:  ldarg.0
-  IL_0138:  ldflda     ""System.Threading.Tasks.Sources.ManualResetValueTaskSourceCore<bool> C.<F>d__0.<>v__promiseOfValueOrEnd""
-  IL_013d:  ldc.i4.0
-  IL_013e:  call       ""void System.Threading.Tasks.Sources.ManualResetValueTaskSourceCore<bool>.SetResult(bool)""
-  IL_0143:  nop
-  IL_0144:  ret
-
-  IL_0145:  ldarg.0
-  IL_0146:  ldflda     ""System.Threading.Tasks.Sources.ManualResetValueTaskSourceCore<bool> C.<F>d__0.<>v__promiseOfValueOrEnd""
-  IL_014b:  ldc.i4.1
-  IL_014c:  call       ""void System.Threading.Tasks.Sources.ManualResetValueTaskSourceCore<bool>.SetResult(bool)""
-  IL_0151:  nop
-  IL_0152:  ret
+  IL_0007:  ldloc.0
+  IL_0008:  brfalse.s  IL_0012
+  IL_000a:  br.s       IL_000c
+  IL_000c:  ldloc.0
+  IL_000d:  ldc.i4.1
+  IL_000e:  beq.s      IL_0014
+  IL_0010:  br.s       IL_0016
+  IL_0012:  br.s       IL_0018
+  IL_0014:  br.s       IL_006b
+  IL_0016:  ldc.i4.0
+  IL_0017:  ret
+  IL_0018:  ldarg.0
+  IL_0019:  ldc.i4.m1
+  IL_001a:  stfld      ""int C.<F>d__0.<>1__state""
+  IL_001f:  nop
+  IL_0020:  nop
+  IL_0021:  ldarg.0
+  IL_0022:  ldc.i4.1
+  IL_0023:  newarr     ""double""
+  IL_0028:  dup
+  IL_0029:  ldc.i4.0
+  IL_002a:  ldc.r8     1
+  IL_0033:  stelem.r8
+  IL_0034:  stfld      ""double[] C.<F>d__0.<>s__4""
+  IL_0039:  ldarg.0
+  IL_003a:  ldc.i4.0
+  IL_003b:  stfld      ""int C.<F>d__0.<>s__2""
+  IL_0040:  br.s       IL_0088
+  IL_0042:  ldarg.0
+  IL_0043:  ldarg.0
+  IL_0044:  ldfld      ""double[] C.<F>d__0.<>s__4""
+  IL_0049:  ldarg.0
+  IL_004a:  ldfld      ""int C.<F>d__0.<>s__2""
+  IL_004f:  ldelem.r8
+  IL_0050:  box        ""double""
+  IL_0055:  stfld      ""object C.<F>d__0.<item>5__3""
+  IL_005a:  nop
+  IL_005b:  ldarg.0
+  IL_005c:  ldc.i4.1
+  IL_005d:  stfld      ""int C.<F>d__0.<>2__current""
+  IL_0062:  ldarg.0
+  IL_0063:  ldc.i4.1
+  IL_0064:  stfld      ""int C.<F>d__0.<>1__state""
+  IL_0069:  ldc.i4.1
+  IL_006a:  ret
+  IL_006b:  ldarg.0
+  IL_006c:  ldc.i4.m1
+  IL_006d:  stfld      ""int C.<F>d__0.<>1__state""
+  IL_0072:  nop
+  IL_0073:  ldarg.0
+  IL_0074:  ldnull
+  IL_0075:  stfld      ""object C.<F>d__0.<item>5__3""
+  IL_007a:  ldarg.0
+  IL_007b:  ldarg.0
+  IL_007c:  ldfld      ""int C.<F>d__0.<>s__2""
+  IL_0081:  ldc.i4.1
+  IL_0082:  add
+  IL_0083:  stfld      ""int C.<F>d__0.<>s__2""
+  IL_0088:  ldarg.0
+  IL_0089:  ldfld      ""int C.<F>d__0.<>s__2""
+  IL_008e:  ldarg.0
+  IL_008f:  ldfld      ""double[] C.<F>d__0.<>s__4""
+  IL_0094:  ldlen
+  IL_0095:  conv.i4
+  IL_0096:  blt.s      IL_0042
+  IL_0098:  ldarg.0
+  IL_0099:  ldnull
+  IL_009a:  stfld      ""double[] C.<F>d__0.<>s__4""
+  IL_009f:  ldc.i4.0
+  IL_00a0:  ret
 }");
+                }
+            }
         }
 
         [Fact]
         public void HoistedVariables_MultipleGenerations()
         {
-            var source0 = MarkedSource(@"
+            var source0 = @"
 using System.Threading.Tasks;
 
 class C
 {
     static async Task<int> F() // testing type changes G0 -> G1, G1 -> G2
     {
-        bool <N:0>a1 = true</N:0>; 
-        int <N:1>a2 = 3</N:1>;
-        <N:2>await Task.Delay(0)</N:2>;
+        bool a1 = true; 
+        int a2 = 3;
+        await Task.Delay(0);
         return 1;
     }
 
     static async Task<int> G() // testing G1 -> G3
     {
-        C <N:3>c = new C()</N:3>;
-        bool <N:4>a1 = true</N:4>;
-        <N:5>await Task.Delay(0)</N:5>;
+        C c = new C();
+        bool a1 = true;
+        await Task.Delay(0);
         return 1;
     }
 
     static async Task<int> H() // testing G0 -> G3
     {
-        C <N:6>c = new C()</N:6>;
-        bool <N:7>a1 = true</N:7>;
-        <N:8>await Task.Delay(0)</N:8>;
+        C c = new C();
+        bool a1 = true;
+        await Task.Delay(0);
         return 1;
     }
-}");
-            var source1 = MarkedSource(@"
+}";
+            var source1 = @"
 using System.Threading.Tasks;
 
 class C
 {
     static async Task<int> F() // updated 
     {
-        C <N:0>a1 = new C()</N:0>; 
-        int <N:1>a2 = 3</N:1>;
-        <N:2>await Task.Delay(0)</N:2>;
+        C a1 = new C(); 
+        int a2 = 3;
+        await Task.Delay(0);
         return 1;
     }
 
     static async Task<int> G() // updated 
     {
-        C <N:3>c = new C()</N:3>;
-        bool <N:4>a1 = true</N:4>;
-        <N:5>await Task.Delay(0)</N:5>;
+        C c = new C();
+        bool a1 = true;
+        await Task.Delay(0);
         return 2;
     }
 
     static async Task<int> H() 
     {
-        C <N:6>c = new C()</N:6>;
-        bool <N:7>a1 = true</N:7>;
-        <N:8>await Task.Delay(0)</N:8>;
+        C c = new C();
+        bool a1 = true;
+        await Task.Delay(0);
         return 1;
     }
-}");
-            var source2 = MarkedSource(@"
+}";
+            var source2 = @"
 using System.Threading.Tasks;
 
 class C
 {
     static async Task<int> F()  // updated
     {
-        bool <N:0>a1 = true</N:0>;
-        C <N:1>a2 = new C()</N:1>;
-        <N:2>await Task.Delay(0)</N:2>;
+        bool a1 = true; 
+        C a2 = new C();
+        await Task.Delay(0);
         return 1;
     }
 
     static async Task<int> G()
     {
-        C <N:3>c = new C()</N:3>;
-        bool <N:4>a1 = true</N:4>;
-        <N:5>await Task.Delay(0)</N:5>;
+        C c = new C();
+        bool a1 = true;
+        await Task.Delay(0);
         return 2;
     }
 
     static async Task<int> H() 
     {
-        C <N:6>c = new C()</N:6>;
-        bool <N:7>a1 = true</N:7>;
-        <N:8>await Task.Delay(0)</N:8>;
+        C c = new C();
+        bool a1 = true;
+        await Task.Delay(0);
         return 1;
     }
-}");
-            var source3 = MarkedSource(@"
+}";
+            var source3 = @"
 using System.Threading.Tasks;
 
 class C
 {
     static async Task<int> F() 
     {
-        bool <N:0>a1 = true</N:0>;
-        C <N:1>a2 = new C()</N:1>;
-        <N:2>await Task.Delay(0)</N:2>;
+        bool a1 = true; 
+        C a2 = new C();
+        await Task.Delay(0);
         return 1;
     }
 
     static async Task<int> G() // updated
     {
-        C <N:3>c = new C()</N:3>;
-        C <N:4>a1 = new C()</N:4>;
-        <N:5>await Task.Delay(0)</N:5>;
+        C c = new C();
+        C a1 = new C();
+        await Task.Delay(0);
         return 1;
     }
 
     static async Task<int> H() // updated
     {
-        C <N:6>c = new C()</N:6>;
-        C <N:7>a1 = new C()</N:7>;
-        <N:8>await Task.Delay(0)</N:8>;
+        C c = new C();
+        C a1 = new C();
+        await Task.Delay(0);
         return 1;
     }
-}");
+}";
 
             // Rude edit but the compiler should handle it.
 
-            var compilation0 = CreateCompilationWithMscorlib45(source0.Tree, options: ComSafeDebugDll.WithMetadataImportOptions(MetadataImportOptions.All));
-            var compilation1 = compilation0.WithSource(source1.Tree);
-            var compilation2 = compilation1.WithSource(source2.Tree);
-            var compilation3 = compilation2.WithSource(source3.Tree);
+            var compilation0 = CreateCompilationWithMscorlib45(source0, options: ComSafeDebugDll.WithMetadataImportOptions(MetadataImportOptions.All));
+            var compilation1 = compilation0.WithSource(source1);
+            var compilation2 = compilation1.WithSource(source2);
+            var compilation3 = compilation2.WithSource(source3);
 
             var f0 = compilation0.GetMember<MethodSymbol>("C.F");
             var f1 = compilation1.GetMember<MethodSymbol>("C.F");
@@ -6132,36 +1837,34 @@ static async Task<int> H() // updated
             });
 
             var md0 = ModuleMetadata.CreateFromImage(v0.EmittedAssemblyData);
-            var syntaxMap1 = GetSyntaxMapFromMarkers(source0, source1);
+
             var generation0 = EmitBaseline.CreateInitialBaseline(md0, v0.CreateSymReader().GetEncMethodDebugInfo);
             var diff1 = compilation1.EmitDifference(
                 generation0,
                 ImmutableArray.Create(
-                    SemanticEdit.Create(SemanticEditKind.Update, f0, f1, syntaxMap1, preserveLocalVariables: true),
-                    SemanticEdit.Create(SemanticEditKind.Update, g0, g1, syntaxMap1, preserveLocalVariables: true)));
+                    SemanticEdit.Create(SemanticEditKind.Update, f0, f1, GetEquivalentNodesMap(f1, f0), preserveLocalVariables: true),
+                    SemanticEdit.Create(SemanticEditKind.Update, g0, g1, GetEquivalentNodesMap(g1, g0), preserveLocalVariables: true)));
 
             diff1.VerifySynthesizedMembers(
                 "C: {<F>d__0, <G>d__1}",
                 "C.<F>d__0: {<>1__state, <>t__builder, <a1>5__3, <a2>5__2, <>u__1, MoveNext, SetStateMachine}",
                 "C.<G>d__1: {<>1__state, <>t__builder, <c>5__1, <a1>5__2, <>u__1, MoveNext, SetStateMachine}");
 
-            var syntaxMap2 = GetSyntaxMapFromMarkers(source1, source2);
             var diff2 = compilation2.EmitDifference(
                 diff1.NextGeneration,
                 ImmutableArray.Create(
-                    SemanticEdit.Create(SemanticEditKind.Update, f1, f2, syntaxMap2, preserveLocalVariables: true)));
+                    SemanticEdit.Create(SemanticEditKind.Update, f1, f2, GetEquivalentNodesMap(f2, f1), preserveLocalVariables: true)));
 
             diff2.VerifySynthesizedMembers(
                 "C: {<F>d__0, <G>d__1}",
                 "C.<F>d__0: {<>1__state, <>t__builder, <a1>5__4, <a2>5__5, <>u__1, MoveNext, SetStateMachine, <a1>5__3, <a2>5__2}",
                 "C.<G>d__1: {<>1__state, <>t__builder, <c>5__1, <a1>5__2, <>u__1, MoveNext, SetStateMachine}");
 
-            var syntaxMap3 = GetSyntaxMapFromMarkers(source2, source3);
             var diff3 = compilation3.EmitDifference(
                 diff2.NextGeneration,
                 ImmutableArray.Create(
-                    SemanticEdit.Create(SemanticEditKind.Update, g2, g3, syntaxMap3, preserveLocalVariables: true),
-                    SemanticEdit.Create(SemanticEditKind.Update, h2, h3, syntaxMap3, preserveLocalVariables: true)));
+                    SemanticEdit.Create(SemanticEditKind.Update, g2, g3, GetEquivalentNodesMap(g3, g2), preserveLocalVariables: true),
+                    SemanticEdit.Create(SemanticEditKind.Update, h2, h3, GetEquivalentNodesMap(h3, h2), preserveLocalVariables: true)));
 
             diff3.VerifySynthesizedMembers(
                 "C: {<G>d__1, <H>d__2, <F>d__0}",
@@ -6428,7 +2131,7 @@ class C
     public IEnumerable<int> F()
     {
         dynamic <N:0>x = 1</N:0>;
-        <N:1>yield return 1;</N:1>
+        yield return 1;
         Console.WriteLine((int)x + <<VALUE>>);
     }
 }
@@ -6735,7 +2438,7 @@ static async Task<int> G()
         [MemberData(nameof(ExternalPdbFormats))]
         public void Awaiters_MultipleGenerations(DebugInformationFormat format)
         {
-            var source0 = MarkedSource(@"
+            var source0 = @"
 using System.Threading.Tasks;
 
 class C
@@ -6746,24 +2449,24 @@ class C
 
     static async Task<int> F() // testing type changes G0 -> G1, G1 -> G2
     {
-        <N:0>await A1()</N:0>;
-        <N:1>await A2()</N:1>;
+        await A1(); 
+        await A2();
         return 1;
     }
 
     static async Task<int> G() // testing G1 -> G3
     {
-        <N:2>await A1()</N:2>;
+        await A1();
         return 1;
     }
 
     static async Task<int> H() // testing G0 -> G3
     {
-        <N:3>await A1()</N:3>;
+        await A1();
         return 1;
     }
-}");
-            var source1 = MarkedSource(@"
+}";
+            var source1 = @"
 using System.Threading.Tasks;
 
 class C
@@ -6774,24 +2477,24 @@ class C
 
     static async Task<int> F() // updated 
     {
-        <N:0>await A3()</N:0>; 
-        <N:1>await A2()</N:1>;
+        await A3(); 
+        await A2();
         return 1;
     }
 
     static async Task<int> G() // updated 
     {
-        <N:2>await A1()</N:2>;
+        await A1();
         return 2;
     }
 
     static async Task<int> H() 
     {
-        <N:3>await A1()</N:3>;
+        await A1();
         return 1;
     }
-}");
-            var source2 = MarkedSource(@"
+}";
+            var source2 = @"
 using System.Threading.Tasks;
 
 class C
@@ -6802,24 +2505,24 @@ class C
 
     static async Task<int> F()  // updated
     {
-        <N:0>await A1()</N:0>; 
-        <N:1>await A3()</N:1>;
+        await A1(); 
+        await A3();
         return 1;
     }
 
     static async Task<int> G()
     {
-        <N:2>await A1()</N:2>;
+        await A1();
         return 2;
     }
 
     static async Task<int> H() 
     {
-        <N:3>await A1()</N:3>;
+        await A1();
         return 1;
     }
-}");
-            var source3 = MarkedSource(@"
+}";
+            var source3 = @"
 using System.Threading.Tasks;
 
 class C
@@ -6830,30 +2533,30 @@ class C
 
     static async Task<int> F() 
     {
-        <N:0>await A1()</N:0>; 
-        <N:1>await A3()</N:1>;
+        await A1(); 
+        await A3();
         return 1;
     }
 
     static async Task<int> G() // updated
     {
-        <N:2>await A3()</N:2>;
+        await A3();
         return 1;
     }
 
     static async Task<int> H() // updated
     {
-        <N:3>await A3()</N:3>;
+        await A3();
         return 1;
     }
-}");
+}";
 
             // Rude edit but the compiler should handle it.
 
-            var compilation0 = CreateCompilationWithMscorlib45(source0.Tree, options: ComSafeDebugDll.WithMetadataImportOptions(MetadataImportOptions.All), assemblyName: "A");
-            var compilation1 = compilation0.WithSource(source1.Tree);
-            var compilation2 = compilation1.WithSource(source2.Tree);
-            var compilation3 = compilation2.WithSource(source3.Tree);
+            var compilation0 = CreateCompilationWithMscorlib45(source0, options: ComSafeDebugDll.WithMetadataImportOptions(MetadataImportOptions.All), assemblyName: "A");
+            var compilation1 = compilation0.WithSource(source1);
+            var compilation2 = compilation1.WithSource(source2);
+            var compilation3 = compilation2.WithSource(source3);
 
             var f0 = compilation0.GetMember<MethodSymbol>("C.F");
             var f1 = compilation1.GetMember<MethodSymbol>("C.F");
@@ -6884,35 +2587,32 @@ static async Task<int> H() // updated
             var md0 = ModuleMetadata.CreateFromImage(v0.EmittedAssemblyData);
 
             var generation0 = EmitBaseline.CreateInitialBaseline(md0, v0.CreateSymReader().GetEncMethodDebugInfo);
-            var syntaxMap1 = GetSyntaxMapFromMarkers(source0, source1);
             var diff1 = compilation1.EmitDifference(
                 generation0,
                 ImmutableArray.Create(
-                    SemanticEdit.Create(SemanticEditKind.Update, f0, f1, syntaxMap1, preserveLocalVariables: true),
-                    SemanticEdit.Create(SemanticEditKind.Update, g0, g1, syntaxMap1, preserveLocalVariables: true)));
+                    SemanticEdit.Create(SemanticEditKind.Update, f0, f1, GetSyntaxMapByKind(f0, SyntaxKind.Block), preserveLocalVariables: true),
+                    SemanticEdit.Create(SemanticEditKind.Update, g0, g1, GetSyntaxMapByKind(g0, SyntaxKind.Block), preserveLocalVariables: true)));
 
             diff1.VerifySynthesizedMembers(
                 "C: {<F>d__3, <G>d__4}",
                 "C.<F>d__3: {<>1__state, <>t__builder, <>u__3, <>u__2, MoveNext, SetStateMachine}",
                 "C.<G>d__4: {<>1__state, <>t__builder, <>u__1, MoveNext, SetStateMachine}");
 
-            var syntaxMap2 = GetSyntaxMapFromMarkers(source1, source2);
             var diff2 = compilation2.EmitDifference(
                 diff1.NextGeneration,
                 ImmutableArray.Create(
-                    SemanticEdit.Create(SemanticEditKind.Update, f1, f2, syntaxMap2, preserveLocalVariables: true)));
+                    SemanticEdit.Create(SemanticEditKind.Update, f1, f2, GetSyntaxMapByKind(f1, SyntaxKind.Block), preserveLocalVariables: true)));
 
             diff2.VerifySynthesizedMembers(
                 "C: {<F>d__3, <G>d__4}",
                 "C.<F>d__3: {<>1__state, <>t__builder, <>u__4, <>u__3, MoveNext, SetStateMachine, <>u__2}",
                 "C.<G>d__4: {<>1__state, <>t__builder, <>u__1, MoveNext, SetStateMachine}");
 
-            var syntaxMap3 = GetSyntaxMapFromMarkers(source2, source3);
             var diff3 = compilation3.EmitDifference(
                 diff2.NextGeneration,
                 ImmutableArray.Create(
-                    SemanticEdit.Create(SemanticEditKind.Update, g2, g3, syntaxMap3, preserveLocalVariables: true),
-                    SemanticEdit.Create(SemanticEditKind.Update, h2, h3, syntaxMap3, preserveLocalVariables: true)));
+                    SemanticEdit.Create(SemanticEditKind.Update, g2, g3, GetSyntaxMapByKind(g2, SyntaxKind.Block), preserveLocalVariables: true),
+                    SemanticEdit.Create(SemanticEditKind.Update, h2, h3, GetSyntaxMapByKind(h2, SyntaxKind.Block), preserveLocalVariables: true)));
 
             diff3.VerifySynthesizedMembers(
                 "C: {<G>d__4, <H>d__5, <F>d__3}",
@@ -6941,9 +2641,9 @@ static async Task<int> H() // updated
             <entry offset=""0x0"" hidden=""true"" document=""1"" />
             <entry offset=""0x7"" hidden=""true"" document=""1"" />
             <entry offset=""0x19"" startLine=""11"" startColumn=""5"" endLine=""11"" endColumn=""6"" document=""1"" />
-            <entry offset=""0x1a"" startLine=""12"" startColumn=""14"" endLine=""12"" endColumn=""31"" document=""1"" />
+            <entry offset=""0x1a"" startLine=""12"" startColumn=""9"" endLine=""12"" endColumn=""20"" document=""1"" />
             <entry offset=""0x25"" hidden=""true"" document=""1"" />
-            <entry offset=""0x79"" startLine=""13"" startColumn=""14"" endLine=""13"" endColumn=""31"" document=""1"" />
+            <entry offset=""0x79"" startLine=""13"" startColumn=""9"" endLine=""13"" endColumn=""20"" document=""1"" />
             <entry offset=""0x85"" hidden=""true"" document=""1"" />
             <entry offset=""0xd8"" startLine=""14"" startColumn=""9"" endLine=""14"" endColumn=""18"" document=""1"" />
             <entry offset=""0xdc"" hidden=""true"" document=""1"" />
@@ -7133,9 +2833,9 @@ .locals init (int V_0,
             <entry offset=""0x0"" hidden=""true"" document=""1"" />
             <entry offset=""0x7"" hidden=""true"" document=""1"" />
             <entry offset=""0x19"" startLine=""11"" startColumn=""5"" endLine=""11"" endColumn=""6"" document=""1"" />
-            <entry offset=""0x1a"" startLine=""12"" startColumn=""14"" endLine=""12"" endColumn=""31"" document=""1"" />
+            <entry offset=""0x1a"" startLine=""12"" startColumn=""9"" endLine=""12"" endColumn=""20"" document=""1"" />
             <entry offset=""0x25"" hidden=""true"" document=""1"" />
-            <entry offset=""0x79"" startLine=""13"" startColumn=""14"" endLine=""13"" endColumn=""31"" document=""1"" />
+            <entry offset=""0x79"" startLine=""13"" startColumn=""9"" endLine=""13"" endColumn=""20"" document=""1"" />
             <entry offset=""0x85"" hidden=""true"" document=""1"" />
             <entry offset=""0xd8"" startLine=""14"" startColumn=""9"" endLine=""14"" endColumn=""18"" document=""1"" />
             <entry offset=""0xdc"" hidden=""true"" document=""1"" />
@@ -7314,7 +3014,7 @@ .locals init (int V_0,
             <entry offset=""0x0"" hidden=""true"" document=""1"" />
             <entry offset=""0x7"" hidden=""true"" document=""1"" />
             <entry offset=""0xe"" startLine=""24"" startColumn=""5"" endLine=""24"" endColumn=""6"" document=""1"" />
-            <entry offset=""0xf"" startLine=""25"" startColumn=""14"" endLine=""25"" endColumn=""31"" document=""1"" />
+            <entry offset=""0xf"" startLine=""25"" startColumn=""9"" endLine=""25"" endColumn=""20"" document=""1"" />
             <entry offset=""0x1a"" hidden=""true"" document=""1"" />
             <entry offset=""0x6b"" startLine=""26"" startColumn=""9"" endLine=""26"" endColumn=""18"" document=""1"" />
             <entry offset=""0x6f"" hidden=""true"" document=""1"" />
@@ -7637,7 +3337,7 @@ class C
     public IEnumerable<int> F()
     {
         var <N:0>x = new { A = 1 }</N:0>;
-        <N:1>yield return 1;</N:1>
+        yield return 1;
         Console.WriteLine(x.A + 1);
     }
 }
@@ -7651,7 +3351,7 @@ class C
     public IEnumerable<int> F()
     {
         var <N:0>x = new { A = 1 }</N:0>;
-        <N:1>yield return 1;</N:1>
+        yield return 1;
         Console.WriteLine(x.A + 2);
     }
 }
@@ -7665,7 +3365,7 @@ class C
     public IEnumerable<int> F()
     {
         var <N:0>x = new { A = 1 }</N:0>;
-        <N:1>yield return 1;</N:1>
+        yield return 1;
         Console.WriteLine(x.A + 3);
     }
 }
@@ -7786,7 +3486,7 @@ class C
     public IEnumerable<int> F()
     {
         var <N:0>x = new[] { new { A = new { B = 1 } } }</N:0>;
-        <N:1>yield return 1;</N:1>
+        yield return 1;
         Console.WriteLine(x[0].A.B + 1);
     }
 }
@@ -7800,7 +3500,7 @@ class C
     public IEnumerable<int> F()
     {
         var <N:0>x = new[] { new { A = new { B = 1 } } }</N:0>;
-        <N:1>yield return 1;</N:1>
+        yield return 1;
         Console.WriteLine(x[0].A.B + 2);
     }
 }
@@ -7814,7 +3514,7 @@ class C
     public IEnumerable<int> F()
     {
         var <N:0>x = new[] { new { A = new { B = 1 } } }</N:0>;
-        <N:1>yield return 1;</N:1>
+        yield return 1;
         Console.WriteLine(x[0].A.B + 3);
     }
 }
@@ -7936,7 +3636,7 @@ class C
     public IEnumerable<int> F()
     {
         var <N:0>x = new Z<double>.S<int>()</N:0>;
-        <N:1>yield return 1;</N:1>
+        yield return 1;
         Console.WriteLine(x.a + x.b + 1);
     }
 }
@@ -7955,7 +3655,7 @@ class C
     public IEnumerable<int> F()
     {
         var <N:0>x = new Z<double>.S<int>()</N:0>;
-        <N:1>yield return 1;</N:1>
+        yield return 1;
         Console.WriteLine(x.a + x.b + 2);
     }
 }
@@ -7974,7 +3674,7 @@ class C
     public IEnumerable<int> F()
     {
         var <N:0>x = new Z<double>.S<int>()</N:0>;
-        <N:1>yield return 1;</N:1>
+        yield return 1;
         Console.WriteLine(x.a + x.b + 3);
     }
 }
@@ -8082,7 +3782,7 @@ class C
     public IEnumerable<int> F()
     {
         var <N:0>x = new { A = (dynamic)null, B = 1 }</N:0>;
-        <N:1>yield return 1;</N:1>
+        yield return 1;
         Console.WriteLine(x.B + <<VALUE>>);
     }
 }
@@ -9436,7 +5136,7 @@ class C
     public async Task<int> F()
     {
         int <N:0>a = 0</N:0>;
-        <N:1>await new Task<int>()</N:1>;
+        <N:1>await new Task<int>();</N:1>
         return a;
     }
 }
@@ -9454,7 +5154,7 @@ class C
     public async Task<int> F()
     {
         int <N:0>a = 1</N:0>;
-        <N:1>await new Task<int>()</N:1>;
+        <N:1>await new Task<int>();</N:1>
         return a;
     }
 }
@@ -9501,7 +5201,7 @@ class C
     public async Task<int> F()
     {
         int <N:0>a = 0</N:0>;
-        <N:1>await new Task<int>()</N:1>;
+        <N:1>await new Task<int>();</N:1>
         return a;
     }
 }
@@ -9519,7 +5219,7 @@ class C
     public async Task<int> F()
     {
         int <N:0>a = 1</N:0>;
-        <N:1>await new Task<int>()</N:1>;
+        <N:1>await new Task<int>();</N:1>
         return a;
     }
 }
@@ -9558,7 +5258,7 @@ class C
     public Task<int> F()
     {
         int <N:0>a = 0</N:0>;
-        return Task.FromResult(a);
+        <N:1>return Task.FromResult(a);</N:1>
     }
 }
 ");
@@ -9570,7 +5270,7 @@ class C
     public async Task<int> F()
     {
         int <N:0>a = 1</N:0>;
-        return <N:1>await Task.FromResult(a)</N:1>;
+        <N:1>return await Task.FromResult(a);</N:1>
     }
 }
 ");
diff --git a/src/Compilers/CSharp/Test/Emit/Emit/EditAndContinue/EditAndContinueTestBase.cs b/src/Compilers/CSharp/Test/Emit/Emit/EditAndContinue/EditAndContinueTestBase.cs
index 0ffe5bc342333..0690435a76ff7 100644
--- a/src/Compilers/CSharp/Test/Emit/Emit/EditAndContinue/EditAndContinueTestBase.cs
+++ b/src/Compilers/CSharp/Test/Emit/Emit/EditAndContinue/EditAndContinueTestBase.cs
@@ -39,14 +39,14 @@ internal static string Visualize(ModuleMetadata baseline, params PinnedMetadata[
         }
 
         internal static SourceWithMarkedNodes MarkedSource(string markedSource, string fileName = "", CSharpParseOptions options = null, bool removeTags = false)
-            => new SourceWithMarkedNodes(
-                WithWindowsLineBreaks(markedSource),
-                parser: s => Parse(s, fileName, options),
-                getSyntaxKind: s => (int)(SyntaxKind)typeof(SyntaxKind).GetField(s).GetValue(null),
-                removeTags);
+        {
+            return new SourceWithMarkedNodes(markedSource, s => Parse(s, fileName, options), s => (int)(SyntaxKind)typeof(SyntaxKind).GetField(s).GetValue(null), removeTags);
+        }
 
         internal static Func<SyntaxNode, SyntaxNode> GetSyntaxMapFromMarkers(SourceWithMarkedNodes source0, SourceWithMarkedNodes source1)
-            => SourceWithMarkedNodes.GetSyntaxMap(source0, source1);
+        {
+            return SourceWithMarkedNodes.GetSyntaxMap(source0, source1);
+        }
 
         internal static ImmutableArray<SyntaxNode> GetAllLocals(MethodSymbol method)
         {
@@ -284,10 +284,5 @@ internal static CSharpCompilation WithSource(this CSharpCompilation compilation,
         {
             return compilation.RemoveAllSyntaxTrees().AddSyntaxTrees(newTree);
         }
-
-        internal static CSharpCompilation WithSource(this CSharpCompilation compilation, SyntaxTree[] newTrees)
-        {
-            return compilation.RemoveAllSyntaxTrees().AddSyntaxTrees(newTrees);
-        }
     }
 }
diff --git a/src/Compilers/CSharp/Test/Emit/Emit/EditAndContinue/LocalSlotMappingTests.cs b/src/Compilers/CSharp/Test/Emit/Emit/EditAndContinue/LocalSlotMappingTests.cs
index 9c7848bdefe4c..21b020ad0cdb1 100644
--- a/src/Compilers/CSharp/Test/Emit/Emit/EditAndContinue/LocalSlotMappingTests.cs
+++ b/src/Compilers/CSharp/Test/Emit/Emit/EditAndContinue/LocalSlotMappingTests.cs
@@ -403,13 +403,16 @@ static void M()
         [Fact]
         public void Using()
         {
-            var source = WithWindowsLineBreaks(@"
-using System;
-
-class C
+            var source = WithWindowsLineBreaks(
+@"class C : System.IDisposable
 {
-    static IDisposable F() => null;
-
+    public void Dispose()
+    {
+    }
+    static System.IDisposable F()
+    {
+        return new C();
+    }
     static void M()
     {
         using (F())
@@ -500,413 +503,6 @@ .locals init (System.IDisposable V_0,
 }");
         }
 
-        [Fact]
-        public void Using_VariableSwap()
-        {
-            var source0 = MarkedSource(@"
-using System;
-
-class C
-{
-    static IDisposable F() => null;
-
-    static void M()
-    {
-        using (IDisposable <N:0>u = F()</N:0>, <N:1>v = F()</N:1>) { }
-    }
-}");
-            var source1 = MarkedSource(@"
-using System;
-
-class C
-{
-    static IDisposable F() => null;
-
-    static void M()
-    {
-        using (IDisposable <N:1>v = F()</N:1>, <N:0>u = F()</N:0>) { }
-    }
-}");
-            var compilation0 = CreateCompilation(source0.Tree, options: TestOptions.DebugDll);
-            var compilation1 = compilation0.WithSource(source1.Tree);
-
-            var v0 = CompileAndVerify(compilation0);
-            var symReader = v0.CreateSymReader();
-
-            using var md0 = ModuleMetadata.CreateFromImage(v0.EmittedAssemblyData);
-            var method0 = compilation0.GetMember<MethodSymbol>("C.M");
-            var method1 = compilation1.GetMember<MethodSymbol>("C.M");
-
-            var generation0 = EmitBaseline.CreateInitialBaseline(md0, symReader.GetEncMethodDebugInfo);
-
-            var diff1 = compilation1.EmitDifference(
-                generation0,
-                ImmutableArray.Create(SemanticEdit.Create(SemanticEditKind.Update, method0, method1, GetSyntaxMapFromMarkers(source0, source1), preserveLocalVariables: true)));
-
-            v0.VerifyPdb("C.M", @"
- <symbols>
-  <files>
-    <file id=""1"" name="""" language=""C#"" />
-  </files>
-  <methods>
-    <method containingType=""C"" name=""M"">
-      <customDebugInfo>
-        <forward declaringType=""C"" methodName=""F"" />
-        <encLocalSlotMap>
-          <slot kind=""0"" offset=""35"" />
-          <slot kind=""0"" offset=""55"" />
-        </encLocalSlotMap>
-      </customDebugInfo>
-      <scope startOffset=""0x0"" endOffset=""0x2a"">
-        <scope startOffset=""0x1"" endOffset=""0x29"">
-          <local name=""u"" il_index=""0"" il_start=""0x1"" il_end=""0x29"" attributes=""0"" />
-          <local name=""v"" il_index=""1"" il_start=""0x1"" il_end=""0x29"" attributes=""0"" />
-        </scope>
-      </scope>
-    </method>
-  </methods>
-</symbols>
-", options: PdbValidationOptions.ExcludeSequencePoints);
-
-            diff1.VerifyIL("C.M", @"
-{
-  // Code size       42 (0x2a)
-  .maxstack  1
-  .locals init (System.IDisposable V_0, //u
-                System.IDisposable V_1) //v
-  IL_0000:  nop
-  IL_0001:  call       ""System.IDisposable C.F()""
-  IL_0006:  stloc.1
-  .try
-  {
-    IL_0007:  call       ""System.IDisposable C.F()""
-    IL_000c:  stloc.0
-    .try
-    {
-      IL_000d:  nop
-      IL_000e:  nop
-      IL_000f:  leave.s    IL_001c
-    }
-    finally
-    {
-      IL_0011:  ldloc.0
-      IL_0012:  brfalse.s  IL_001b
-      IL_0014:  ldloc.0
-      IL_0015:  callvirt   ""void System.IDisposable.Dispose()""
-      IL_001a:  nop
-      IL_001b:  endfinally
-    }
-    IL_001c:  leave.s    IL_0029
-  }
-  finally
-  {
-    IL_001e:  ldloc.1
-    IL_001f:  brfalse.s  IL_0028
-    IL_0021:  ldloc.1
-    IL_0022:  callvirt   ""void System.IDisposable.Dispose()""
-    IL_0027:  nop
-    IL_0028:  endfinally
-  }
-  IL_0029:  ret
-}
-");
-        }
-
-        [Fact]
-        public void Using_VariableDeclaration_VariableSwap()
-        {
-            var source0 = MarkedSource(@"
-using System;
-
-class C
-{
-    static IDisposable F() => null;
-
-    static void M()
-    {
-        using IDisposable <N:0>u = F()</N:0>, <N:1>v = F()</N:1>;
-    }
-}");
-            var source1 = MarkedSource(@"
-using System;
-
-class C
-{
-    static IDisposable F() => null;
-
-    static void M()
-    {
-        using IDisposable <N:1>v = F()</N:1>, <N:0>u = F()</N:0>;
-    }
-}");
-            var compilation0 = CreateCompilation(source0.Tree, options: TestOptions.DebugDll);
-            var compilation1 = compilation0.WithSource(source1.Tree);
-
-            var v0 = CompileAndVerify(compilation0);
-            var symReader = v0.CreateSymReader();
-
-            using var md0 = ModuleMetadata.CreateFromImage(v0.EmittedAssemblyData);
-            var method0 = compilation0.GetMember<MethodSymbol>("C.M");
-            var method1 = compilation1.GetMember<MethodSymbol>("C.M");
-
-            var generation0 = EmitBaseline.CreateInitialBaseline(md0, symReader.GetEncMethodDebugInfo);
-
-            var diff1 = compilation1.EmitDifference(
-                generation0,
-                ImmutableArray.Create(SemanticEdit.Create(SemanticEditKind.Update, method0, method1, GetSyntaxMapFromMarkers(source0, source1), preserveLocalVariables: true)));
-
-            v0.VerifyPdb("C.M", @"
-<symbols>
-  <files>
-    <file id=""1"" name="""" language=""C#"" />
-  </files>
-  <methods>
-    <method containingType=""C"" name=""M"">
-      <customDebugInfo>
-        <forward declaringType=""C"" methodName=""F"" />
-        <encLocalSlotMap>
-          <slot kind=""0"" offset=""34"" />
-          <slot kind=""0"" offset=""54"" />
-        </encLocalSlotMap>
-      </customDebugInfo>
-      <scope startOffset=""0x0"" endOffset=""0x26"">
-        <local name=""u"" il_index=""0"" il_start=""0x0"" il_end=""0x26"" attributes=""0"" />
-        <local name=""v"" il_index=""1"" il_start=""0x0"" il_end=""0x26"" attributes=""0"" />
-      </scope>
-    </method>
-  </methods>
-</symbols>
-", options: PdbValidationOptions.ExcludeSequencePoints);
-
-            diff1.VerifyIL("C.M", @"
-{
-  // Code size       38 (0x26)
-  .maxstack  1
-  .locals init (System.IDisposable V_0, //u
-                System.IDisposable V_1) //v
-  IL_0000:  nop
-  IL_0001:  call       ""System.IDisposable C.F()""
-  IL_0006:  stloc.1
-  .try
-  {
-    IL_0007:  call       ""System.IDisposable C.F()""
-    IL_000c:  stloc.0
-    .try
-    {
-      IL_000d:  leave.s    IL_0025
-    }
-    finally
-    {
-      IL_000f:  ldloc.0
-      IL_0010:  brfalse.s  IL_0019
-      IL_0012:  ldloc.0
-      IL_0013:  callvirt   ""void System.IDisposable.Dispose()""
-      IL_0018:  nop
-      IL_0019:  endfinally
-    }
-  }
-  finally
-  {
-    IL_001a:  ldloc.1
-    IL_001b:  brfalse.s  IL_0024
-    IL_001d:  ldloc.1
-    IL_001e:  callvirt   ""void System.IDisposable.Dispose()""
-    IL_0023:  nop
-    IL_0024:  endfinally
-  }
-  IL_0025:  ret
-}
-");
-        }
-
-        [Fact]
-        public void AwaitUsing_VariableSwap()
-        {
-            var source0 = MarkedSource(@"
-using System;
-using System.Threading.Tasks;
-
-class C
-{
-    static IAsyncDisposable F() => null;
-
-    static async Task M()
-    {
-        await using (IAsyncDisposable <N:0>u = F()</N:0>, <N:1>v = F()</N:1>) { }
-    }
-}");
-            var source1 = MarkedSource(@"
-using System;
-using System.Threading.Tasks;
-
-class C
-{
-    static IAsyncDisposable F() => null;
-
-    static async Task M()
-    {
-        await using (IAsyncDisposable <N:1>v = F()</N:1>, <N:0>u = F()</N:0>) { }
-    }
-}");
-            var asyncStreamsTree = Parse(AsyncStreamsTypes);
-            var compilation0 = CreateCompilationWithTasksExtensions(new[] { source0.Tree, asyncStreamsTree }, options: TestOptions.DebugDll);
-            var compilation1 = compilation0.WithSource(new[] { source1.Tree, asyncStreamsTree });
-
-            var v0 = CompileAndVerify(compilation0);
-            var symReader = v0.CreateSymReader();
-
-            using var md0 = ModuleMetadata.CreateFromImage(v0.EmittedAssemblyData);
-            var method0 = compilation0.GetMember<MethodSymbol>("C.M");
-            var method1 = compilation1.GetMember<MethodSymbol>("C.M");
-
-            var generation0 = EmitBaseline.CreateInitialBaseline(md0, symReader.GetEncMethodDebugInfo);
-
-            var diff1 = compilation1.EmitDifference(
-                generation0,
-                ImmutableArray.Create(SemanticEdit.Create(SemanticEditKind.Update, method0, method1, GetSyntaxMapFromMarkers(source0, source1), preserveLocalVariables: true)));
-
-            v0.VerifyPdb("C.M", @"
-<symbols>
-  <files>
-    <file id=""1"" name="""" language=""C#"" />
-  </files>
-  <methods>
-    <method containingType=""C"" name=""M"">
-      <customDebugInfo>
-        <forwardIterator name=""&lt;M&gt;d__1"" />
-        <encLocalSlotMap>
-          <slot kind=""0"" offset=""46"" />
-          <slot kind=""0"" offset=""66"" />
-          <slot kind=""22"" offset=""46"" />
-          <slot kind=""23"" offset=""46"" />
-          <slot kind=""22"" offset=""66"" />
-          <slot kind=""23"" offset=""66"" />
-        </encLocalSlotMap>
-        <encStateMachineStateMap>
-          <state number=""0"" offset=""66"" />
-          <state number=""1"" offset=""46"" />
-        </encStateMachineStateMap>
-      </customDebugInfo>
-    </method>
-  </methods>
-</symbols>
-");
-            v0.VerifyLocalSignature("C.<M>d__1.System.Runtime.CompilerServices.IAsyncStateMachine.MoveNext", @"
-.locals init (int V_0,
-              object V_1,
-              System.Runtime.CompilerServices.ValueTaskAwaiter V_2,
-              System.Threading.Tasks.ValueTask V_3,
-              C.<M>d__1 V_4,
-              System.Exception V_5,
-              System.Runtime.CompilerServices.ValueTaskAwaiter V_6)
-");
-
-            diff1.VerifyLocalSignature("C.<M>d__1.System.Runtime.CompilerServices.IAsyncStateMachine.MoveNext", @"
-.locals init (int V_0,
-              object V_1,
-              System.Runtime.CompilerServices.ValueTaskAwaiter V_2,
-              System.Threading.Tasks.ValueTask V_3,
-              C.<M>d__1 V_4,
-              System.Exception V_5,
-              System.Runtime.CompilerServices.ValueTaskAwaiter V_6)
-");
-        }
-
-        [Fact]
-        public void AwaitUsing_VariableDeclaration_VariableSwap()
-        {
-            var source0 = MarkedSource(@"
-using System;
-using System.Threading.Tasks;
-
-class C
-{
-    static IAsyncDisposable F() => null;
-
-    static async Task M()
-    {
-        await using IAsyncDisposable <N:0>u = F()</N:0>, <N:1>v = F()</N:1>;
-    }
-}");
-            var source1 = MarkedSource(@"
-using System;
-using System.Threading.Tasks;
-
-class C
-{
-    static IAsyncDisposable F() => null;
-
-    static async Task M()
-    {
-        await using IAsyncDisposable <N:1>v = F()</N:1>, <N:0>u = F()</N:0>;
-    }
-}");
-            var asyncStreamsTree = Parse(AsyncStreamsTypes);
-            var compilation0 = CreateCompilationWithTasksExtensions(new[] { source0.Tree, asyncStreamsTree }, options: TestOptions.DebugDll);
-            var compilation1 = compilation0.WithSource(new[] { source1.Tree, asyncStreamsTree });
-
-            var v0 = CompileAndVerify(compilation0);
-            var symReader = v0.CreateSymReader();
-
-            using var md0 = ModuleMetadata.CreateFromImage(v0.EmittedAssemblyData);
-            var method0 = compilation0.GetMember<MethodSymbol>("C.M");
-            var method1 = compilation1.GetMember<MethodSymbol>("C.M");
-
-            var generation0 = EmitBaseline.CreateInitialBaseline(md0, symReader.GetEncMethodDebugInfo);
-
-            var diff1 = compilation1.EmitDifference(
-                generation0,
-                ImmutableArray.Create(SemanticEdit.Create(SemanticEditKind.Update, method0, method1, GetSyntaxMapFromMarkers(source0, source1), preserveLocalVariables: true)));
-
-            v0.VerifyPdb("C.M", @"
-<symbols>
-  <files>
-    <file id=""1"" name="""" language=""C#"" />
-  </files>
-  <methods>
-    <method containingType=""C"" name=""M"">
-      <customDebugInfo>
-        <forwardIterator name=""&lt;M&gt;d__1"" />
-        <encLocalSlotMap>
-          <slot kind=""0"" offset=""45"" />
-          <slot kind=""0"" offset=""65"" />
-          <slot kind=""22"" offset=""45"" />
-          <slot kind=""23"" offset=""45"" />
-          <slot kind=""22"" offset=""65"" />
-          <slot kind=""23"" offset=""65"" />
-        </encLocalSlotMap>
-        <encStateMachineStateMap>
-          <state number=""0"" offset=""65"" />
-          <state number=""1"" offset=""45"" />
-        </encStateMachineStateMap>
-      </customDebugInfo>
-    </method>
-  </methods>
-</symbols>
-");
-            v0.VerifyLocalSignature("C.<M>d__1.System.Runtime.CompilerServices.IAsyncStateMachine.MoveNext", @"
-.locals init (int V_0,
-              object V_1,
-              System.Runtime.CompilerServices.ValueTaskAwaiter V_2,
-              System.Threading.Tasks.ValueTask V_3,
-              C.<M>d__1 V_4,
-              System.Exception V_5,
-              int V_6,
-              System.Runtime.CompilerServices.ValueTaskAwaiter V_7)
-");
-
-            diff1.VerifyLocalSignature("C.<M>d__1.System.Runtime.CompilerServices.IAsyncStateMachine.MoveNext", @"
-.locals init (int V_0,
-              object V_1,
-              System.Runtime.CompilerServices.ValueTaskAwaiter V_2,
-              System.Threading.Tasks.ValueTask V_3,
-              C.<M>d__1 V_4,
-              System.Exception V_5,
-              int V_6,
-              System.Runtime.CompilerServices.ValueTaskAwaiter V_7)
-");
-        }
-
         [Fact]
         public void Lock()
         {
diff --git a/src/Compilers/CSharp/Test/Emit/PDB/PDBAsyncTests.cs b/src/Compilers/CSharp/Test/Emit/PDB/PDBAsyncTests.cs
index 0d6bb1d4d51f2..c00ac605dbb53 100644
--- a/src/Compilers/CSharp/Test/Emit/PDB/PDBAsyncTests.cs
+++ b/src/Compilers/CSharp/Test/Emit/PDB/PDBAsyncTests.cs
@@ -201,147 +201,141 @@ .locals init (int V_0,
     sequencePoints: "TestCase+<Run>d__1.MoveNext");
 
                 v.VerifyPdb(@"
-<symbols>
-  <files>
-    <file id=""1"" name="""" language=""C#"" />
-  </files>
-  <methods>
-    <method containingType=""DynamicMembers"" name=""get_Prop"">
-      <sequencePoints>
-        <entry offset=""0x0"" startLine=""8"" startColumn=""35"" endLine=""8"" endColumn=""39"" document=""1"" />
-      </sequencePoints>
-    </method>
-    <method containingType=""DynamicMembers"" name=""set_Prop"" parameterNames=""value"">
-      <sequencePoints>
-        <entry offset=""0x0"" startLine=""8"" startColumn=""40"" endLine=""8"" endColumn=""44"" document=""1"" />
-      </sequencePoints>
-    </method>
-    <method containingType=""TestCase"" name=""Run"">
-      <customDebugInfo>
-        <forwardIterator name=""&lt;Run&gt;d__1"" />
-        <encLocalSlotMap>
-          <slot kind=""0"" offset=""26"" />
-          <slot kind=""0"" offset=""139"" />
-          <slot kind=""28"" offset=""146"" />
-        </encLocalSlotMap>
-        <encLambdaMap>
-          <methodOrdinal>1</methodOrdinal>
-          <lambda offset=""86"" />
-        </encLambdaMap>
-        <encStateMachineStateMap>
-          <state number=""0"" offset=""146"" />
-        </encStateMachineStateMap>
-      </customDebugInfo>
-    </method>
-    <method containingType=""Driver"" name=""Main"">
-      <customDebugInfo>
-        <using>
-          <namespace usingCount=""3"" />
-        </using>
-        <encLocalSlotMap>
-          <slot kind=""0"" offset=""15"" />
-          <slot kind=""21"" offset=""0"" />
-        </encLocalSlotMap>
-      </customDebugInfo>
-      <sequencePoints>
-        <entry offset=""0x0"" startLine=""30"" startColumn=""5"" endLine=""30"" endColumn=""6"" document=""1"" />
-        <entry offset=""0x1"" startLine=""31"" startColumn=""9"" endLine=""31"" endColumn=""32"" document=""1"" />
-        <entry offset=""0x7"" startLine=""32"" startColumn=""9"" endLine=""32"" endColumn=""17"" document=""1"" />
-        <entry offset=""0xe"" startLine=""34"" startColumn=""9"" endLine=""34"" endColumn=""35"" document=""1"" />
-        <entry offset=""0x19"" startLine=""35"" startColumn=""9"" endLine=""35"" endColumn=""30"" document=""1"" />
-        <entry offset=""0x21"" startLine=""36"" startColumn=""5"" endLine=""36"" endColumn=""6"" document=""1"" />
-      </sequencePoints>
-      <scope startOffset=""0x0"" endOffset=""0x23"">
-        <namespace name=""System"" />
-        <namespace name=""System.Threading"" />
-        <namespace name=""System.Threading.Tasks"" />
-        <local name=""t"" il_index=""0"" il_start=""0x0"" il_end=""0x23"" attributes=""0"" />
-      </scope>
-    </method>
-    <method containingType=""Driver"" name="".cctor"">
-      <customDebugInfo>
-        <forward declaringType=""Driver"" methodName=""Main"" />
-      </customDebugInfo>
-      <sequencePoints>
-        <entry offset=""0x0"" startLine=""27"" startColumn=""5"" endLine=""27"" endColumn=""35"" document=""1"" />
-        <entry offset=""0x6"" startLine=""28"" startColumn=""5"" endLine=""28"" endColumn=""78"" document=""1"" />
-      </sequencePoints>
-    </method>
-    <method containingType=""TestCase+&lt;&gt;c"" name=""&lt;Run&gt;b__1_0"">
-      <customDebugInfo>
-        <forwardIterator name=""&lt;&lt;Run&gt;b__1_0&gt;d"" />
-        <encStateMachineStateMap>
-          <state number=""0"" offset=""88"" />
-        </encStateMachineStateMap>
-      </customDebugInfo>
-    </method>
-    <method containingType=""TestCase+&lt;Run&gt;d__1"" name=""MoveNext"">
-      <customDebugInfo>
-        <forward declaringType=""Driver"" methodName=""Main"" />
-        <hoistedLocalScopes>
-          <slot startOffset=""0x0"" endOffset=""0x12f"" />
-          <slot startOffset=""0x0"" endOffset=""0x12f"" />
-        </hoistedLocalScopes>
-        <encLocalSlotMap>
-          <slot kind=""27"" offset=""0"" />
-          <slot kind=""33"" offset=""146"" />
-          <slot kind=""temp"" />
-          <slot kind=""1"" offset=""173"" />
-          <slot kind=""temp"" />
-        </encLocalSlotMap>
-      </customDebugInfo>
-      <sequencePoints>
-        <entry offset=""0x0"" hidden=""true"" document=""1"" />
-        <entry offset=""0x7"" hidden=""true"" document=""1"" />
-        <entry offset=""0xe"" startLine=""14"" startColumn=""5"" endLine=""14"" endColumn=""6"" document=""1"" />
-        <entry offset=""0xf"" startLine=""15"" startColumn=""9"" endLine=""15"" endColumn=""51"" document=""1"" />
-        <entry offset=""0x1a"" startLine=""16"" startColumn=""9"" endLine=""16"" endColumn=""71"" document=""1"" />
-        <entry offset=""0x45"" startLine=""17"" startColumn=""9"" endLine=""17"" endColumn=""37"" document=""1"" />
-        <entry offset=""0x5b"" hidden=""true"" document=""1"" />
-        <entry offset=""0xc0"" startLine=""18"" startColumn=""9"" endLine=""18"" endColumn=""23"" document=""1"" />
-        <entry offset=""0xca"" hidden=""true"" document=""1"" />
-        <entry offset=""0xcd"" startLine=""18"" startColumn=""24"" endLine=""18"" endColumn=""32"" document=""1"" />
-        <entry offset=""0xd9"" startLine=""20"" startColumn=""9"" endLine=""20"" endColumn=""44"" document=""1"" />
-        <entry offset=""0xe5"" startLine=""22"" startColumn=""9"" endLine=""22"" endColumn=""38"" document=""1"" />
-        <entry offset=""0xf2"" hidden=""true"" document=""1"" />
-        <entry offset=""0x113"" startLine=""23"" startColumn=""5"" endLine=""23"" endColumn=""6"" document=""1"" />
-        <entry offset=""0x11b"" hidden=""true"" document=""1"" />
-      </sequencePoints>
-      <asyncInfo>
-        <catchHandler offset=""0xf2"" />
-        <kickoffMethod declaringType=""TestCase"" methodName=""Run"" />
-        <await yield=""0x6d"" resume=""0x8b"" declaringType=""TestCase+&lt;Run&gt;d__1"" methodName=""MoveNext"" />
-      </asyncInfo>
-    </method>
-    <method containingType=""TestCase+&lt;&gt;c+&lt;&lt;Run&gt;b__1_0&gt;d"" name=""MoveNext"">
-      <customDebugInfo>
-        <forward declaringType=""Driver"" methodName=""Main"" />
-        <encLocalSlotMap>
-          <slot kind=""27"" offset=""86"" />
-          <slot kind=""20"" offset=""86"" />
-          <slot kind=""33"" offset=""88"" />
-          <slot kind=""temp"" />
-          <slot kind=""temp"" />
-        </encLocalSlotMap>
-      </customDebugInfo>
-      <sequencePoints>
-        <entry offset=""0x0"" hidden=""true"" document=""1"" />
-        <entry offset=""0x7"" hidden=""true"" document=""1"" />
-        <entry offset=""0xe"" startLine=""16"" startColumn=""32"" endLine=""16"" endColumn=""33"" document=""1"" />
-        <entry offset=""0xf"" startLine=""16"" startColumn=""34"" endLine=""16"" endColumn=""58"" document=""1"" />
-        <entry offset=""0x1f"" hidden=""true"" document=""1"" />
-        <entry offset=""0x70"" startLine=""16"" startColumn=""59"" endLine=""16"" endColumn=""68"" document=""1"" />
-        <entry offset=""0x74"" hidden=""true"" document=""1"" />
-        <entry offset=""0x8e"" startLine=""16"" startColumn=""69"" endLine=""16"" endColumn=""70"" document=""1"" />
-        <entry offset=""0x96"" hidden=""true"" document=""1"" />
-      </sequencePoints>
-      <asyncInfo>
-        <kickoffMethod declaringType=""TestCase+&lt;&gt;c"" methodName=""&lt;Run&gt;b__1_0"" />
-        <await yield=""0x31"" resume=""0x4c"" declaringType=""TestCase+&lt;&gt;c+&lt;&lt;Run&gt;b__1_0&gt;d"" methodName=""MoveNext"" />
-      </asyncInfo>
-    </method>
-  </methods>
-</symbols>");
+    <symbols>
+    <files>
+        <file id=""1"" name="""" language=""C#"" />
+    </files>
+    <methods>
+        <method containingType=""DynamicMembers"" name=""get_Prop"">
+        <sequencePoints>
+            <entry offset=""0x0"" startLine=""8"" startColumn=""35"" endLine=""8"" endColumn=""39"" document=""1"" />
+        </sequencePoints>
+        </method>
+        <method containingType=""DynamicMembers"" name=""set_Prop"" parameterNames=""value"">
+        <sequencePoints>
+            <entry offset=""0x0"" startLine=""8"" startColumn=""40"" endLine=""8"" endColumn=""44"" document=""1"" />
+        </sequencePoints>
+        </method>
+        <method containingType=""TestCase"" name=""Run"">
+        <customDebugInfo>
+            <forwardIterator name=""&lt;Run&gt;d__1"" />
+            <encLocalSlotMap>
+            <slot kind=""0"" offset=""26"" />
+            <slot kind=""0"" offset=""139"" />
+            <slot kind=""28"" offset=""146"" />
+            </encLocalSlotMap>
+            <encLambdaMap>
+            <methodOrdinal>1</methodOrdinal>
+            <lambda offset=""86"" />
+            </encLambdaMap>
+        </customDebugInfo>
+        </method>
+        <method containingType=""Driver"" name=""Main"">
+        <customDebugInfo>
+            <using>
+            <namespace usingCount=""3"" />
+            </using>
+            <encLocalSlotMap>
+            <slot kind=""0"" offset=""15"" />
+            <slot kind=""21"" offset=""0"" />
+            </encLocalSlotMap>
+        </customDebugInfo>
+        <sequencePoints>
+            <entry offset=""0x0"" startLine=""30"" startColumn=""5"" endLine=""30"" endColumn=""6"" document=""1"" />
+            <entry offset=""0x1"" startLine=""31"" startColumn=""9"" endLine=""31"" endColumn=""32"" document=""1"" />
+            <entry offset=""0x7"" startLine=""32"" startColumn=""9"" endLine=""32"" endColumn=""17"" document=""1"" />
+            <entry offset=""0xe"" startLine=""34"" startColumn=""9"" endLine=""34"" endColumn=""35"" document=""1"" />
+            <entry offset=""0x19"" startLine=""35"" startColumn=""9"" endLine=""35"" endColumn=""30"" document=""1"" />
+            <entry offset=""0x21"" startLine=""36"" startColumn=""5"" endLine=""36"" endColumn=""6"" document=""1"" />
+        </sequencePoints>
+        <scope startOffset=""0x0"" endOffset=""0x23"">
+            <namespace name=""System"" />
+            <namespace name=""System.Threading"" />
+            <namespace name=""System.Threading.Tasks"" />
+            <local name=""t"" il_index=""0"" il_start=""0x0"" il_end=""0x23"" attributes=""0"" />
+        </scope>
+        </method>
+        <method containingType=""Driver"" name="".cctor"">
+        <customDebugInfo>
+            <forward declaringType=""Driver"" methodName=""Main"" />
+        </customDebugInfo>
+        <sequencePoints>
+            <entry offset=""0x0"" startLine=""27"" startColumn=""5"" endLine=""27"" endColumn=""35"" document=""1"" />
+            <entry offset=""0x6"" startLine=""28"" startColumn=""5"" endLine=""28"" endColumn=""78"" document=""1"" />
+        </sequencePoints>
+        </method>
+        <method containingType=""TestCase+&lt;&gt;c"" name=""&lt;Run&gt;b__1_0"">
+        <customDebugInfo>
+            <forwardIterator name=""&lt;&lt;Run&gt;b__1_0&gt;d"" />
+        </customDebugInfo>
+        </method>
+        <method containingType=""TestCase+&lt;Run&gt;d__1"" name=""MoveNext"">
+        <customDebugInfo>
+            <forward declaringType=""Driver"" methodName=""Main"" />
+            <hoistedLocalScopes>
+            <slot startOffset=""0x0"" endOffset=""0x12f"" />
+            <slot startOffset=""0x0"" endOffset=""0x12f"" />
+            </hoistedLocalScopes>
+            <encLocalSlotMap>
+            <slot kind=""27"" offset=""0"" />
+            <slot kind=""33"" offset=""146"" />
+            <slot kind=""temp"" />
+            <slot kind=""1"" offset=""173"" />
+            <slot kind=""temp"" />
+            </encLocalSlotMap>
+        </customDebugInfo>
+        <sequencePoints>
+            <entry offset=""0x0"" hidden=""true"" document=""1"" />
+            <entry offset=""0x7"" hidden=""true"" document=""1"" />
+            <entry offset=""0xe"" startLine=""14"" startColumn=""5"" endLine=""14"" endColumn=""6"" document=""1"" />
+            <entry offset=""0xf"" startLine=""15"" startColumn=""9"" endLine=""15"" endColumn=""51"" document=""1"" />
+            <entry offset=""0x1a"" startLine=""16"" startColumn=""9"" endLine=""16"" endColumn=""71"" document=""1"" />
+            <entry offset=""0x45"" startLine=""17"" startColumn=""9"" endLine=""17"" endColumn=""37"" document=""1"" />
+            <entry offset=""0x5b"" hidden=""true"" document=""1"" />
+            <entry offset=""0xc0"" startLine=""18"" startColumn=""9"" endLine=""18"" endColumn=""23"" document=""1"" />
+            <entry offset=""0xca"" hidden=""true"" document=""1"" />
+            <entry offset=""0xcd"" startLine=""18"" startColumn=""24"" endLine=""18"" endColumn=""32"" document=""1"" />
+            <entry offset=""0xd9"" startLine=""20"" startColumn=""9"" endLine=""20"" endColumn=""44"" document=""1"" />
+            <entry offset=""0xe5"" startLine=""22"" startColumn=""9"" endLine=""22"" endColumn=""38"" document=""1"" />
+            <entry offset=""0xf2"" hidden=""true"" document=""1"" />
+            <entry offset=""0x113"" startLine=""23"" startColumn=""5"" endLine=""23"" endColumn=""6"" document=""1"" />
+            <entry offset=""0x11b"" hidden=""true"" document=""1"" />
+        </sequencePoints>
+        <asyncInfo>
+            <catchHandler offset=""0xf2"" />
+            <kickoffMethod declaringType=""TestCase"" methodName=""Run"" />
+            <await yield=""0x6d"" resume=""0x8b"" declaringType=""TestCase+&lt;Run&gt;d__1"" methodName=""MoveNext"" />
+        </asyncInfo>
+        </method>
+        <method containingType=""TestCase+&lt;&gt;c+&lt;&lt;Run&gt;b__1_0&gt;d"" name=""MoveNext"">
+        <customDebugInfo>
+            <forward declaringType=""Driver"" methodName=""Main"" />
+            <encLocalSlotMap>
+            <slot kind=""27"" offset=""86"" />
+            <slot kind=""20"" offset=""86"" />
+            <slot kind=""33"" offset=""88"" />
+            <slot kind=""temp"" />
+            <slot kind=""temp"" />
+            </encLocalSlotMap>
+        </customDebugInfo>
+        <sequencePoints>
+            <entry offset=""0x0"" hidden=""true"" document=""1"" />
+            <entry offset=""0x7"" hidden=""true"" document=""1"" />
+            <entry offset=""0xe"" startLine=""16"" startColumn=""32"" endLine=""16"" endColumn=""33"" document=""1"" />
+            <entry offset=""0xf"" startLine=""16"" startColumn=""34"" endLine=""16"" endColumn=""58"" document=""1"" />
+            <entry offset=""0x1f"" hidden=""true"" document=""1"" />
+            <entry offset=""0x70"" startLine=""16"" startColumn=""59"" endLine=""16"" endColumn=""68"" document=""1"" />
+            <entry offset=""0x74"" hidden=""true"" document=""1"" />
+            <entry offset=""0x8e"" startLine=""16"" startColumn=""69"" endLine=""16"" endColumn=""70"" document=""1"" />
+            <entry offset=""0x96"" hidden=""true"" document=""1"" />
+        </sequencePoints>
+        <asyncInfo>
+            <kickoffMethod declaringType=""TestCase+&lt;&gt;c"" methodName=""&lt;Run&gt;b__1_0"" />
+            <await yield=""0x31"" resume=""0x4c"" declaringType=""TestCase+&lt;&gt;c+&lt;&lt;Run&gt;b__1_0&gt;d"" methodName=""MoveNext"" />
+        </asyncInfo>
+        </method>
+    </methods>
+    </symbols>");
             }
         }
 
@@ -411,9 +405,6 @@ private Task<int> GetNextInt(Random random)
     <method containingType=""ConsoleApplication1.Program"" name=""QBar"">
       <customDebugInfo>
         <forwardIterator name=""&lt;QBar&gt;d__2"" />
-        <encStateMachineStateMap>
-          <state number=""0"" offset=""15"" />
-        </encStateMachineStateMap>
       </customDebugInfo>
     </method>
     <method containingType=""ConsoleApplication1.Program"" name=""ZBar"">
@@ -427,9 +418,6 @@ private Task<int> GetNextInt(Random random)
           <slot kind=""0"" offset=""132"" />
           <slot kind=""28"" offset=""141"" />
         </encLocalSlotMap>
-        <encStateMachineStateMap>
-          <state number=""0"" offset=""141"" />
-        </encStateMachineStateMap>
       </customDebugInfo>
     </method>
     <method containingType=""ConsoleApplication1.Program"" name=""GetNextInt"" parameterNames=""random"">
@@ -561,9 +549,6 @@ static async void Await(dynamic d)
           <slot kind=""28"" offset=""21"" ordinal=""1"" />
           <slot kind=""28"" offset=""21"" ordinal=""2"" />
         </encLocalSlotMap>
-        <encStateMachineStateMap>
-          <state number=""0"" offset=""21"" />
-        </encStateMachineStateMap>
       </customDebugInfo>
     </method>
     <method containingType=""TestCase+&lt;Await&gt;d__0"" name=""MoveNext"">
@@ -915,9 +900,6 @@ static async Task M(int b)
           <closure offset=""0"" />
           <lambda offset=""95"" closure=""0"" />
         </encLambdaMap>
-        <encStateMachineStateMap>
-          <state number=""0"" offset=""129"" />
-        </encStateMachineStateMap>
       </customDebugInfo>
     </method>
   </methods>
@@ -1108,9 +1090,6 @@ static async Task M(int b)
           <closure offset=""0"" />
           <lambda offset=""95"" closure=""0"" />
         </encLambdaMap>
-        <encStateMachineStateMap>
-          <state number=""0"" offset=""129"" />
-        </encStateMachineStateMap>
       </customDebugInfo>
     </method>
   </methods>
@@ -1432,9 +1411,6 @@ static async Task M()
         <encLocalSlotMap>
           <slot kind=""0"" offset=""19"" />
         </encLocalSlotMap>
-        <encStateMachineStateMap>
-          <state number=""0"" offset=""35"" />
-        </encStateMachineStateMap>
       </customDebugInfo>
     </method>
   </methods>
@@ -1614,9 +1590,6 @@ static async Task M()
         <encLocalSlotMap>
           <slot kind=""0"" offset=""19"" />
         </encLocalSlotMap>
-        <encStateMachineStateMap>
-          <state number=""0"" offset=""58"" />
-        </encStateMachineStateMap>
       </customDebugInfo>
     </method>
   </methods>
@@ -1720,9 +1693,6 @@ static async Task<int> G()
           <slot kind=""23"" offset=""34"" />
           <slot kind=""28"" offset=""105"" />
         </encLocalSlotMap>
-        <encStateMachineStateMap>
-          <state number=""0"" offset=""105"" />
-        </encStateMachineStateMap>
       </customDebugInfo>
     </method>
   </methods>
@@ -1994,10 +1964,6 @@ static async Task<int> G()
           <slot kind=""29"" offset=""150"" ordinal=""2"" />
           <slot kind=""29"" offset=""150"" ordinal=""3"" />
         </encLocalSlotMap>
-        <encStateMachineStateMap>
-          <state number=""0"" offset=""70"" />
-          <state number=""1"" offset=""150"" />
-        </encStateMachineStateMap>
       </customDebugInfo>
     </method>
   </methods>
diff --git a/src/Compilers/CSharp/Test/Emit/PDB/PDBIteratorTests.cs b/src/Compilers/CSharp/Test/Emit/PDB/PDBIteratorTests.cs
index e79f80483cb04..902c3fc002207 100644
--- a/src/Compilers/CSharp/Test/Emit/PDB/PDBIteratorTests.cs
+++ b/src/Compilers/CSharp/Test/Emit/PDB/PDBIteratorTests.cs
@@ -131,9 +131,6 @@ System.Collections.Generic.IEnumerable<int> Goo()
     <method containingType=""Program"" name=""Goo"">
       <customDebugInfo>
         <forwardIterator name=""&lt;Goo&gt;d__0"" />
-        <encStateMachineStateMap>
-          <state number=""1"" offset=""11"" />
-        </encStateMachineStateMap>
       </customDebugInfo>
     </method>
     <method containingType=""Program+&lt;Goo&gt;d__0"" name=""MoveNext"">
@@ -270,12 +267,6 @@ System.Collections.Generic.IEnumerable<int> IEI<T>(int i0, int i1)
           <slot kind=""0"" offset=""15"" />
           <slot kind=""0"" offset=""101"" />
         </encLocalSlotMap>
-        <encStateMachineStateMap>
-          <state number=""1"" offset=""32"" />
-          <state number=""2"" offset=""57"" />
-          <state number=""3"" offset=""122"" />
-          <state number=""4"" offset=""151"" />
-        </encStateMachineStateMap>
       </customDebugInfo>
     </method>
     <method containingType=""Program+&lt;IEI&gt;d__0`1"" name=""MoveNext"">
@@ -351,11 +342,6 @@ public static IEnumerator<T> M(IEnumerable<T> items)
           <slot kind=""5"" offset=""42"" />
           <slot kind=""0"" offset=""42"" />
         </encLocalSlotMap>
-        <encStateMachineStateMap>
-          <state number=""-3"" offset=""42"" />
-          <state number=""1"" offset=""117"" />
-          <state number=""2"" offset=""155"" />
-        </encStateMachineStateMap>
       </customDebugInfo>
     </method>
     <method containingType=""Test`1+&lt;M&gt;d__0"" name=""MoveNext"">
@@ -586,30 +572,16 @@ public static void Main()
           <slot kind=""5"" offset=""104"" />
           <slot kind=""0"" offset=""104"" />
         </encLocalSlotMap>
-        <encStateMachineStateMap>
-          <state number=""-3"" offset=""11"" />
-          <state number=""1"" offset=""68"" />
-          <state number=""-4"" offset=""104"" />
-          <state number=""2"" offset=""160"" />
-        </encStateMachineStateMap>
       </customDebugInfo>
     </method>
     <method containingType=""Test`1"" name=""get_IterProp"">
       <customDebugInfo>
         <forwardIterator name=""&lt;get_IterProp&gt;d__3"" />
-        <encStateMachineStateMap>
-          <state number=""1"" offset=""16"" />
-          <state number=""2"" offset=""48"" />
-        </encStateMachineStateMap>
       </customDebugInfo>
     </method>
     <method containingType=""Test`1"" name=""IterMethod"">
       <customDebugInfo>
         <forwardIterator name=""&lt;IterMethod&gt;d__4"" />
-        <encStateMachineStateMap>
-          <state number=""1"" offset=""11"" />
-          <state number=""2"" offset=""45"" />
-        </encStateMachineStateMap>
       </customDebugInfo>
     </method>
     <method containingType=""Test"" name=""Main"">
@@ -984,16 +956,6 @@ public IEnumerable<int> M(IDisposable disposable)
           <slot kind=""3"" offset=""367"" />
           <slot kind=""2"" offset=""367"" />
         </encLocalSlotMap>
-        <encStateMachineStateMap>
-          <state number=""-3"" offset=""53"" />
-          <state number=""1"" offset=""67"" />
-          <state number=""-4"" offset=""149"" />
-          <state number=""2"" offset=""163"" />
-          <state number=""-5"" offset=""216"" />
-          <state number=""3"" offset=""237"" />
-          <state number=""-6"" offset=""266"" />
-          <state number=""4"" offset=""280"" />
-        </encStateMachineStateMap>
       </customDebugInfo>
     </method>
   </methods>
@@ -1341,9 +1303,6 @@ .locals init (int V_0)
           <closure offset=""0"" />
           <lambda offset=""95"" closure=""0"" />
         </encLambdaMap>
-        <encStateMachineStateMap>
-          <state number=""1"" offset=""129"" />
-        </encStateMachineStateMap>
       </customDebugInfo>
     </method>
   </methods>
@@ -1426,9 +1385,6 @@ static IEnumerable<int> M()
         <encLocalSlotMap>
           <slot kind=""0"" offset=""19"" />
         </encLocalSlotMap>
-        <encStateMachineStateMap>
-          <state number=""1"" offset=""35"" />
-        </encStateMachineStateMap>
       </customDebugInfo>
     </method>
   </methods>
diff --git a/src/Compilers/CSharp/Test/Emit/PDB/PDBLambdaTests.cs b/src/Compilers/CSharp/Test/Emit/PDB/PDBLambdaTests.cs
index b5025702e0e8d..934f18bb41eb3 100644
--- a/src/Compilers/CSharp/Test/Emit/PDB/PDBLambdaTests.cs
+++ b/src/Compilers/CSharp/Test/Emit/PDB/PDBLambdaTests.cs
@@ -91,7 +91,7 @@ public static int Main()
     }
 
     static public int M(int p)
-    <M:0><C:0>{
+    <M><C:0>{
         Func<int, int> f1 = delegate(int x)
         <C:1><L:0.0>{
             int q = 2;
@@ -1833,7 +1833,7 @@ record R(int X);
 class Test
 {
     public static void M(int a)
-    <M:0><C:0>{
+    <M><C:0>{
         var x = new R(1);
         var y = x with
         {
@@ -1859,7 +1859,7 @@ record R(int X, int Y);
 class Test
 {
     public static void M(int a)
-    <M:0><C:0>{
+    <M><C:0>{
         var x = new R(1, 2);
         var b = 1;
         var y = x with
@@ -1888,7 +1888,7 @@ record Z(int A, R R);
 class Test
 {
     public static void M(int a)
-    <M:0><C:0>{
+    <M><C:0>{
         var r = new R(1, 2);
         var x = new Z(1, new R(2, 3));
         var b = 1;
diff --git a/src/Compilers/CSharp/Test/Emit/PDB/PDBTests.cs b/src/Compilers/CSharp/Test/Emit/PDB/PDBTests.cs
index a20ca98ab257f..d80e69b386486 100644
--- a/src/Compilers/CSharp/Test/Emit/PDB/PDBTests.cs
+++ b/src/Compilers/CSharp/Test/Emit/PDB/PDBTests.cs
@@ -7751,9 +7751,6 @@ public static IEnumerable<int> F()
           <slot kind=""0"" offset=""64"" />
           <slot kind=""0"" offset=""158"" />
         </encLocalSlotMap>
-        <encStateMachineStateMap>
-          <state number=""1"" offset=""222"" />
-        </encStateMachineStateMap>
       </customDebugInfo>
     </method>
     <method containingType=""C+&lt;F&gt;d__1"" name=""MoveNext"">
diff --git a/src/Compilers/Core/CodeAnalysisTest/Emit/CustomDebugInfoTests.cs b/src/Compilers/Core/CodeAnalysisTest/Emit/CustomDebugInfoTests.cs
index 43c4da4123e23..0eb0c108925a3 100644
--- a/src/Compilers/Core/CodeAnalysisTest/Emit/CustomDebugInfoTests.cs
+++ b/src/Compilers/Core/CodeAnalysisTest/Emit/CustomDebugInfoTests.cs
@@ -203,11 +203,10 @@ public void EditAndContinueLocalSlotMap_NegativeSyntaxOffsets()
 
             var closures = ImmutableArray<ClosureDebugInfo>.Empty;
             var lambdas = ImmutableArray<LambdaDebugInfo>.Empty;
-            var states = ImmutableArray<StateMachineStateDebugInfo>.Empty;
 
             var cmw = new BlobBuilder();
 
-            new EditAndContinueMethodDebugInformation(123, slots, closures, lambdas, states).SerializeLocalSlots(cmw);
+            new EditAndContinueMethodDebugInformation(123, slots, closures, lambdas).SerializeLocalSlots(cmw);
 
             var bytes = cmw.ToImmutableArray();
             AssertEx.Equal(new byte[] { 0xFF, 0xC0, 0x00, 0x4E, 0x20, 0x81, 0xC0, 0x00, 0x4E, 0x1F, 0x0A, 0x9A, 0x00, 0x0A }, bytes);
@@ -232,10 +231,9 @@ public void EditAndContinueLambdaAndClosureMap_NegativeSyntaxOffsets()
                 new LambdaDebugInfo(-50, new DebugId(1, 0), 0),
                 new LambdaDebugInfo(-180, new DebugId(2, 0), LambdaDebugInfo.StaticClosureOrdinal));
 
-            var states = ImmutableArray<StateMachineStateDebugInfo>.Empty;
             var cmw = new BlobBuilder();
 
-            new EditAndContinueMethodDebugInformation(0x7b, slots, closures, lambdas, states).SerializeLambdaMap(cmw);
+            new EditAndContinueMethodDebugInformation(0x7b, slots, closures, lambdas).SerializeLambdaMap(cmw);
 
             var bytes = cmw.ToImmutableArray();
 
@@ -254,11 +252,10 @@ public void EditAndContinueLambdaAndClosureMap_NoClosures()
 
             var closures = ImmutableArray<ClosureDebugInfo>.Empty;
             var lambdas = ImmutableArray.Create(new LambdaDebugInfo(20, new DebugId(0, 0), LambdaDebugInfo.StaticClosureOrdinal));
-            var states = ImmutableArray<StateMachineStateDebugInfo>.Empty;
 
             var cmw = new BlobBuilder();
 
-            new EditAndContinueMethodDebugInformation(-1, slots, closures, lambdas, states).SerializeLambdaMap(cmw);
+            new EditAndContinueMethodDebugInformation(-1, slots, closures, lambdas).SerializeLambdaMap(cmw);
 
             var bytes = cmw.ToImmutableArray();
 
@@ -278,11 +275,10 @@ public void EditAndContinueLambdaAndClosureMap_NoLambdas()
             var slots = ImmutableArray<LocalSlotDebugInfo>.Empty;
             var closures = ImmutableArray<ClosureDebugInfo>.Empty;
             var lambdas = ImmutableArray<LambdaDebugInfo>.Empty;
-            var states = ImmutableArray<StateMachineStateDebugInfo>.Empty;
 
             var cmw = new BlobBuilder();
 
-            new EditAndContinueMethodDebugInformation(10, slots, closures, lambdas, states).SerializeLambdaMap(cmw);
+            new EditAndContinueMethodDebugInformation(10, slots, closures, lambdas).SerializeLambdaMap(cmw);
 
             var bytes = cmw.ToImmutableArray();
 
@@ -311,9 +307,7 @@ public void EncCdiAlignment()
                 new LambdaDebugInfo(-50, new DebugId(1, 0), 0),
                 new LambdaDebugInfo(-180, new DebugId(2, 0), LambdaDebugInfo.StaticClosureOrdinal));
 
-            var states = ImmutableArray<StateMachineStateDebugInfo>.Empty;
-
-            var debugInfo = new EditAndContinueMethodDebugInformation(1, slots, closures, lambdas, states);
+            var debugInfo = new EditAndContinueMethodDebugInformation(1, slots, closures, lambdas);
 
             var builder = new BlobBuilder();
             var cdiEncoder = new CustomDebugInfoEncoder(builder);
diff --git a/src/Compilers/Core/Portable/CodeAnalysisResources.resx b/src/Compilers/Core/Portable/CodeAnalysisResources.resx
index c8c5d135b2883..c1281b0f0fcab 100644
--- a/src/Compilers/Core/Portable/CodeAnalysisResources.resx
+++ b/src/Compilers/Core/Portable/CodeAnalysisResources.resx
@@ -722,10 +722,4 @@
   <data name="ChangesMustBeWithinBoundsOfSourceText" xml:space="preserve">
     <value>Changes must be within bounds of SourceText</value>
   </data>
-  <data name="EncCannotResumeSuspendedAsyncMethod" xml:space="preserve">
-    <value>Edit and Continue can't resume suspended asynchronous method since the corresponding await expression has been deleted</value>
-  </data>
-  <data name="EncCannotResumeSuspendedIteratorMethod" xml:space="preserve">
-    <value>Edit and Continue can't resume suspended iterator since the corresponding yield return statement has been deleted</value>
-  </data>
 </root>
\ No newline at end of file
diff --git a/src/Compilers/Core/Portable/CodeGen/MethodBody.cs b/src/Compilers/Core/Portable/CodeGen/MethodBody.cs
index 9e5230a5b95e2..4f48c99e49b06 100644
--- a/src/Compilers/Core/Portable/CodeGen/MethodBody.cs
+++ b/src/Compilers/Core/Portable/CodeGen/MethodBody.cs
@@ -37,7 +37,6 @@ internal sealed class MethodBody : Cci.IMethodBody
         private readonly ImmutableArray<EncHoistedLocalInfo> _stateMachineHoistedLocalSlots;
         private readonly ImmutableArray<LambdaDebugInfo> _lambdaDebugInfo;
         private readonly ImmutableArray<ClosureDebugInfo> _closureDebugInfo;
-        private readonly StateMachineStatesDebugInfo _stateMachineStatesDebugInfo;
 
         // Data used when emitting EnC delta:
         private readonly ImmutableArray<Cci.ITypeReference?> _stateMachineAwaiterSlots;
@@ -65,7 +64,6 @@ public MethodBody(
             ImmutableArray<StateMachineHoistedLocalScope> stateMachineHoistedLocalScopes,
             ImmutableArray<EncHoistedLocalInfo> stateMachineHoistedLocalSlots,
             ImmutableArray<Cci.ITypeReference?> stateMachineAwaiterSlots,
-            StateMachineStatesDebugInfo stateMachineStatesDebugInfo,
             StateMachineMoveNextBodyDebugInfo stateMachineMoveNextDebugInfoOpt,
             DynamicAnalysisMethodBodyData dynamicAnalysisDataOpt)
         {
@@ -90,7 +88,6 @@ public MethodBody(
             _stateMachineHoistedLocalScopes = stateMachineHoistedLocalScopes;
             _stateMachineHoistedLocalSlots = stateMachineHoistedLocalSlots;
             _stateMachineAwaiterSlots = stateMachineAwaiterSlots;
-            _stateMachineStatesDebugInfo = stateMachineStatesDebugInfo;
             _stateMachineMoveNextDebugInfoOpt = stateMachineMoveNextDebugInfoOpt;
             _dynamicAnalysisDataOpt = dynamicAnalysisDataOpt;
             _sequencePoints = GetSequencePoints(sequencePoints, debugDocumentProvider);
@@ -152,8 +149,6 @@ ImmutableArray<EncHoistedLocalInfo> Cci.IMethodBody.StateMachineHoistedLocalSlot
 
         public ImmutableArray<ClosureDebugInfo> ClosureDebugInfo => _closureDebugInfo;
 
-        public StateMachineStatesDebugInfo StateMachineStatesDebugInfo => _stateMachineStatesDebugInfo;
-
         /// <summary>
         /// True if there's a stackalloc somewhere in the method.
         /// </summary>
diff --git a/src/Compilers/Core/Portable/CodeGen/StateMachineStateDebugInfo.cs b/src/Compilers/Core/Portable/CodeGen/StateMachineStateDebugInfo.cs
deleted file mode 100644
index e772df5aab45e..0000000000000
--- a/src/Compilers/Core/Portable/CodeGen/StateMachineStateDebugInfo.cs
+++ /dev/null
@@ -1,68 +0,0 @@
-// Licensed to the .NET Foundation under one or more agreements.
-// The .NET Foundation licenses this file to you under the MIT license.
-// See the LICENSE file in the project root for more information.
-
-using System;
-using System.Collections.Immutable;
-using System.Linq;
-
-namespace Microsoft.CodeAnalysis.CodeGen;
-
-internal readonly struct StateMachineStateDebugInfo
-{
-    public readonly int SyntaxOffset;
-    public readonly int StateNumber;
-
-    public StateMachineStateDebugInfo(int syntaxOffset, int stateNumber)
-    {
-        SyntaxOffset = syntaxOffset;
-        StateNumber = stateNumber;
-    }
-}
-
-internal readonly struct StateMachineStatesDebugInfo
-{
-    public readonly ImmutableArray<StateMachineStateDebugInfo> States;
-    public readonly int? FirstUnusedIncreasingStateMachineState;
-    public readonly int? FirstUnusedDecreasingStateMachineState;
-
-    public StateMachineStatesDebugInfo(ImmutableArray<StateMachineStateDebugInfo> states, int? firstUnusedIncreasingStateMachineState, int? firstUnusedDecreasingStateMachineState)
-    {
-        States = states;
-        FirstUnusedIncreasingStateMachineState = firstUnusedIncreasingStateMachineState;
-        FirstUnusedDecreasingStateMachineState = firstUnusedDecreasingStateMachineState;
-    }
-
-    public static StateMachineStatesDebugInfo Create(VariableSlotAllocator? variableSlotAllocator, ImmutableArray<StateMachineStateDebugInfo> stateInfos)
-    {
-        int? firstUnusedIncreasingStateMachineState = null, firstUnusedDecreasingStateMachineState = null;
-
-        if (variableSlotAllocator != null)
-        {
-            // We start with first unused state numbers from the previous generation and update them based on states generated in the current one.
-            firstUnusedIncreasingStateMachineState = variableSlotAllocator.GetFirstUnusedStateMachineState(increasing: true);
-            firstUnusedDecreasingStateMachineState = variableSlotAllocator.GetFirstUnusedStateMachineState(increasing: false);
-
-            if (!stateInfos.IsDefaultOrEmpty)
-            {
-                // The current method is a state machine and has some resumable/finalization states.
-                // Update the first unused states based on the highest resumable (positive numbers) and lowest finalization (negative numbers) of this method.
-
-                var maxState = stateInfos.Max(info => info.StateNumber) + 1;
-                var minState = stateInfos.Min(info => info.StateNumber) - 1;
-
-                firstUnusedIncreasingStateMachineState = (firstUnusedIncreasingStateMachineState != null) ? Math.Max(firstUnusedIncreasingStateMachineState.Value, maxState) : maxState;
-
-                if (minState < 0)
-                {
-                    firstUnusedDecreasingStateMachineState = (firstUnusedDecreasingStateMachineState != null) ? Math.Min(firstUnusedDecreasingStateMachineState.Value, minState) : minState;
-                }
-            }
-        }
-
-        return new StateMachineStatesDebugInfo(
-            stateInfos,
-            firstUnusedIncreasingStateMachineState,
-            firstUnusedDecreasingStateMachineState);
-    }
-}
diff --git a/src/Compilers/Core/Portable/CodeGen/VariableSlotAllocator.cs b/src/Compilers/Core/Portable/CodeGen/VariableSlotAllocator.cs
index d0bac38235b1f..084af4f1ba93f 100644
--- a/src/Compilers/Core/Portable/CodeGen/VariableSlotAllocator.cs
+++ b/src/Compilers/Core/Portable/CodeGen/VariableSlotAllocator.cs
@@ -2,7 +2,6 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 // See the LICENSE file in the project root for more information.
 
-using System.Collections.Generic;
 using System.Collections.Immutable;
 using System.Reflection.Metadata;
 using Microsoft.CodeAnalysis.PooledObjects;
@@ -80,24 +79,5 @@ public abstract bool TryGetPreviousHoistedLocalSlotIndex(
         /// or lambda body syntax (<paramref name="isLambdaBody"/> is true).
         /// </summary>
         public abstract bool TryGetPreviousLambda(SyntaxNode lambdaOrLambdaBodySyntax, bool isLambdaBody, out DebugId lambdaId);
-
-        /// <summary>
-        /// State number to be used for next state of the state machine,
-        /// or <see langword="null"/> if none of the previous versions of the method was a state machine with a increasing state
-        /// </summary>
-        /// <param name="increasing">True if the state number increases with progress, false if it decreases.</param>
-        public abstract int? GetFirstUnusedStateMachineState(bool increasing);
-
-        /// <summary>
-        /// For a given node associated with entering a state of a state machine in the new compilation,
-        /// returns the ordinal of the corresponding state in the previous version of the state machine.
-        /// </summary>
-        /// <returns>
-        /// True if there is a corresponding node in the previous code version that matches the given <paramref name="syntax"/>.
-        /// </returns>
-        /// <remarks>
-        /// <paramref name="syntax"/> is an await expression, yield return statement, or try block syntax node.
-        /// </remarks>
-        public abstract bool TryGetPreviousStateMachineState(SyntaxNode syntax, out int stateOrdinal);
     }
 }
diff --git a/src/Compilers/Core/Portable/Emit/EditAndContinue/AddedOrChangedMethodInfo.cs b/src/Compilers/Core/Portable/Emit/EditAndContinue/AddedOrChangedMethodInfo.cs
index 98080deeaa1c7..2f98ba9d78668 100644
--- a/src/Compilers/Core/Portable/Emit/EditAndContinue/AddedOrChangedMethodInfo.cs
+++ b/src/Compilers/Core/Portable/Emit/EditAndContinue/AddedOrChangedMethodInfo.cs
@@ -24,7 +24,6 @@ internal readonly struct AddedOrChangedMethodInfo
         public readonly string? StateMachineTypeName;
         public readonly ImmutableArray<EncHoistedLocalInfo> StateMachineHoistedLocalSlotsOpt;
         public readonly ImmutableArray<Cci.ITypeReference?> StateMachineAwaiterSlotsOpt;
-        public readonly StateMachineStatesDebugInfo StateMachineStates;
 
         public AddedOrChangedMethodInfo(
             DebugId methodId,
@@ -33,18 +32,17 @@ public AddedOrChangedMethodInfo(
             ImmutableArray<ClosureDebugInfo> closureDebugInfo,
             string? stateMachineTypeName,
             ImmutableArray<EncHoistedLocalInfo> stateMachineHoistedLocalSlotsOpt,
-            ImmutableArray<Cci.ITypeReference?> stateMachineAwaiterSlotsOpt,
-            StateMachineStatesDebugInfo stateMachineStates)
+            ImmutableArray<Cci.ITypeReference?> stateMachineAwaiterSlotsOpt)
         {
             // An updated method will carry its id over,
             // an added method id has generation set to the current generation ordinal.
             Debug.Assert(methodId.Generation >= 0);
 
             // each state machine has to have awaiters:
-            Debug.Assert(stateMachineAwaiterSlotsOpt.IsDefault == stateMachineTypeName is null);
+            Debug.Assert(stateMachineAwaiterSlotsOpt.IsDefault == (stateMachineTypeName == null));
 
             // a state machine might not have hoisted variables:
-            Debug.Assert(stateMachineHoistedLocalSlotsOpt.IsDefault || stateMachineTypeName is not null);
+            Debug.Assert(stateMachineHoistedLocalSlotsOpt.IsDefault || (stateMachineTypeName != null));
 
             MethodId = methodId;
             Locals = locals;
@@ -53,7 +51,6 @@ public AddedOrChangedMethodInfo(
             StateMachineTypeName = stateMachineTypeName;
             StateMachineHoistedLocalSlotsOpt = stateMachineHoistedLocalSlotsOpt;
             StateMachineAwaiterSlotsOpt = stateMachineAwaiterSlotsOpt;
-            StateMachineStates = stateMachineStates;
         }
 
         public AddedOrChangedMethodInfo MapTypes(SymbolMatcher map)
@@ -66,7 +63,7 @@ public AddedOrChangedMethodInfo MapTypes(SymbolMatcher map)
             var mappedAwaiterSlots = StateMachineAwaiterSlotsOpt.IsDefault ? default :
                 ImmutableArray.CreateRange(StateMachineAwaiterSlotsOpt, static (typeRef, map) => (typeRef is null) ? null : map.MapReference(typeRef), map);
 
-            return new AddedOrChangedMethodInfo(MethodId, mappedLocals, LambdaDebugInfo, ClosureDebugInfo, StateMachineTypeName, mappedHoistedLocalSlots, mappedAwaiterSlots, StateMachineStates);
+            return new AddedOrChangedMethodInfo(MethodId, mappedLocals, LambdaDebugInfo, ClosureDebugInfo, StateMachineTypeName, mappedHoistedLocalSlots, mappedAwaiterSlots);
         }
 
         private static EncLocalInfo MapLocalInfo(EncLocalInfo info, SymbolMatcher map)
diff --git a/src/Compilers/Core/Portable/Emit/EditAndContinue/DefinitionMap.cs b/src/Compilers/Core/Portable/Emit/EditAndContinue/DefinitionMap.cs
index 5eb02ef5dfe3c..d5dca8be2c661 100644
--- a/src/Compilers/Core/Portable/Emit/EditAndContinue/DefinitionMap.cs
+++ b/src/Compilers/Core/Portable/Emit/EditAndContinue/DefinitionMap.cs
@@ -143,7 +143,7 @@ protected abstract void GetStateMachineFieldMapFromMetadata(
             out int awaiterSlotCount);
 
         protected abstract ImmutableArray<EncLocalInfo> GetLocalSlotMapFromMetadata(StandaloneSignatureHandle handle, EditAndContinueMethodDebugInformation debugInfo);
-        protected abstract ITypeSymbolInternal? TryGetStateMachineType(MethodDefinitionHandle methodHandle);
+        protected abstract ITypeSymbolInternal? TryGetStateMachineType(EntityHandle methodHandle);
 
         internal VariableSlotAllocator? TryCreateVariableSlotAllocator(EmitBaseline baseline, Compilation compilation, IMethodSymbolInternal method, IMethodSymbolInternal topLevelMethod, DiagnosticBag diagnostics)
         {
@@ -167,9 +167,6 @@ protected abstract void GetStateMachineFieldMapFromMetadata(
             IReadOnlyDictionary<Cci.ITypeReference, int>? awaiterMap = null;
             IReadOnlyDictionary<int, KeyValuePair<DebugId, int>>? lambdaMap = null;
             IReadOnlyDictionary<int, DebugId>? closureMap = null;
-            IReadOnlyDictionary<int, int>? stateMachineStateMap = null;
-            int? firstUnusedIncreasingStateMachineState = null;
-            int? firstUnusedDecreasingStateMachineState = null;
 
             int hoistedLocalSlotCount = 0;
             int awaiterSlotCount = 0;
@@ -185,10 +182,6 @@ protected abstract void GetStateMachineFieldMapFromMetadata(
                 methodId = addedOrChangedMethod.MethodId;
 
                 MakeLambdaAndClosureMaps(addedOrChangedMethod.LambdaDebugInfo, addedOrChangedMethod.ClosureDebugInfo, out lambdaMap, out closureMap);
-                MakeStateMachineStateMap(addedOrChangedMethod.StateMachineStates.States, out stateMachineStateMap);
-
-                firstUnusedIncreasingStateMachineState = addedOrChangedMethod.StateMachineStates.FirstUnusedIncreasingStateMachineState;
-                firstUnusedDecreasingStateMachineState = addedOrChangedMethod.StateMachineStates.FirstUnusedDecreasingStateMachineState;
 
                 if (addedOrChangedMethod.StateMachineTypeName != null)
                 {
@@ -248,14 +241,6 @@ protected abstract void GetStateMachineFieldMapFromMetadata(
                     MakeLambdaAndClosureMaps(debugInfo.Lambdas, debugInfo.Closures, out lambdaMap, out closureMap);
                 }
 
-                MakeStateMachineStateMap(debugInfo.StateMachineStates, out stateMachineStateMap);
-
-                if (!debugInfo.StateMachineStates.IsDefaultOrEmpty)
-                {
-                    firstUnusedIncreasingStateMachineState = debugInfo.StateMachineStates.Max(s => s.StateNumber) + 1;
-                    firstUnusedDecreasingStateMachineState = debugInfo.StateMachineStates.Min(s => s.StateNumber) - 1;
-                }
-
                 ITypeSymbolInternal? stateMachineType = TryGetStateMachineType(previousHandle);
                 if (stateMachineType != null)
                 {
@@ -332,9 +317,6 @@ protected abstract void GetStateMachineFieldMapFromMetadata(
                 hoistedLocalMap,
                 awaiterSlotCount,
                 awaiterMap,
-                stateMachineStateMap,
-                firstUnusedIncreasingStateMachineState,
-                firstUnusedDecreasingStateMachineState,
                 GetLambdaSyntaxFacts());
         }
 
@@ -374,15 +356,6 @@ private static void MakeLambdaAndClosureMaps(
             closureMap = closures;
         }
 
-        private static void MakeStateMachineStateMap(
-            ImmutableArray<StateMachineStateDebugInfo> debugInfos,
-            out IReadOnlyDictionary<int, int>? map)
-        {
-            map = debugInfos.IsDefault ?
-                null :
-                debugInfos.ToDictionary(entry => entry.SyntaxOffset, entry => entry.StateNumber);
-        }
-
         private static void GetStateMachineFieldMapFromPreviousCompilation(
             ImmutableArray<EncHoistedLocalInfo> hoistedLocalSlots,
             ImmutableArray<Cci.ITypeReference?> hoistedAwaiters,
diff --git a/src/Compilers/Core/Portable/Emit/EditAndContinue/DeltaMetadataWriter.cs b/src/Compilers/Core/Portable/Emit/EditAndContinue/DeltaMetadataWriter.cs
index 42c215222b11f..4412a2bbbe4bf 100644
--- a/src/Compilers/Core/Portable/Emit/EditAndContinue/DeltaMetadataWriter.cs
+++ b/src/Compilers/Core/Portable/Emit/EditAndContinue/DeltaMetadataWriter.cs
@@ -759,8 +759,7 @@ protected override StandaloneSignatureHandle SerializeLocalVariablesSignature(IM
                 body.ClosureDebugInfo,
                 body.StateMachineTypeName,
                 body.StateMachineHoistedLocalSlots,
-                body.StateMachineAwaiterSlots,
-                body.StateMachineStatesDebugInfo);
+                body.StateMachineAwaiterSlots);
 
             _addedOrChangedMethods.Add(body.MethodDefinition, info);
 
diff --git a/src/Compilers/Core/Portable/Emit/EditAndContinue/EncVariableSlotAllocator.cs b/src/Compilers/Core/Portable/Emit/EditAndContinue/EncVariableSlotAllocator.cs
index 841bd83956ca3..6bc4ceff225b0 100644
--- a/src/Compilers/Core/Portable/Emit/EditAndContinue/EncVariableSlotAllocator.cs
+++ b/src/Compilers/Core/Portable/Emit/EditAndContinue/EncVariableSlotAllocator.cs
@@ -35,9 +35,6 @@ internal sealed class EncVariableSlotAllocator : VariableSlotAllocator
         private readonly IReadOnlyDictionary<EncHoistedLocalInfo, int>? _hoistedLocalSlots;
         private readonly int _awaiterCount;
         private readonly IReadOnlyDictionary<Cci.ITypeReference, int>? _awaiterMap;
-        private readonly IReadOnlyDictionary<int, int>? _stateMachineStateMap; // SyntaxOffset -> State Ordinal
-        private readonly int? _firstUnusedDecreasingStateMachineState;
-        private readonly int? _firstUnusedIncreasingStateMachineState;
 
         // closures:
         private readonly IReadOnlyDictionary<int, KeyValuePair<DebugId, int>>? _lambdaMap; // SyntaxOffset -> (Lambda Id, Closure Ordinal)
@@ -58,9 +55,6 @@ public EncVariableSlotAllocator(
             IReadOnlyDictionary<EncHoistedLocalInfo, int>? hoistedLocalSlots,
             int awaiterCount,
             IReadOnlyDictionary<Cci.ITypeReference, int>? awaiterMap,
-            IReadOnlyDictionary<int, int>? stateMachineStateMap,
-            int? firstUnusedIncreasingStateMachineState,
-            int? firstUnusedDecreasingStateMachineState,
             LambdaSyntaxFacts lambdaSyntaxFacts)
         {
             Debug.Assert(!previousLocals.IsDefault);
@@ -75,12 +69,9 @@ public EncVariableSlotAllocator(
             _stateMachineTypeName = stateMachineTypeName;
             _awaiterCount = awaiterCount;
             _awaiterMap = awaiterMap;
-            _stateMachineStateMap = stateMachineStateMap;
             _lambdaMap = lambdaMap;
             _closureMap = closureMap;
             _lambdaSyntaxFacts = lambdaSyntaxFacts;
-            _firstUnusedIncreasingStateMachineState = firstUnusedIncreasingStateMachineState;
-            _firstUnusedDecreasingStateMachineState = firstUnusedDecreasingStateMachineState;
 
             // Create a map from local info to slot.
             var previousLocalInfoToSlot = new Dictionary<EncLocalInfo, int>();
@@ -328,21 +319,5 @@ public override bool TryGetPreviousLambda(SyntaxNode lambdaOrLambdaBodySyntax, b
             lambdaId = default;
             return false;
         }
-
-        public override int? GetFirstUnusedStateMachineState(bool increasing)
-            => increasing ? _firstUnusedIncreasingStateMachineState : _firstUnusedDecreasingStateMachineState;
-
-        public override bool TryGetPreviousStateMachineState(SyntaxNode syntax, out int stateOrdinal)
-        {
-            if (_stateMachineStateMap != null &&
-                TryGetPreviousSyntaxOffset(syntax, out int syntaxOffset) &&
-                _stateMachineStateMap.TryGetValue(syntaxOffset, out stateOrdinal))
-            {
-                return true;
-            }
-
-            stateOrdinal = -1;
-            return false;
-        }
     }
 }
diff --git a/src/Compilers/Core/Portable/Emit/EditAndContinueMethodDebugInformation.cs b/src/Compilers/Core/Portable/Emit/EditAndContinueMethodDebugInformation.cs
index 4cc95b0b8b427..c15f3a874c9b2 100644
--- a/src/Compilers/Core/Portable/Emit/EditAndContinueMethodDebugInformation.cs
+++ b/src/Compilers/Core/Portable/Emit/EditAndContinueMethodDebugInformation.cs
@@ -22,14 +22,8 @@ public readonly struct EditAndContinueMethodDebugInformation
         internal readonly ImmutableArray<LocalSlotDebugInfo> LocalSlots;
         internal readonly ImmutableArray<LambdaDebugInfo> Lambdas;
         internal readonly ImmutableArray<ClosureDebugInfo> Closures;
-        internal readonly ImmutableArray<StateMachineStateDebugInfo> StateMachineStates;
-
-        internal EditAndContinueMethodDebugInformation(
-            int methodOrdinal,
-            ImmutableArray<LocalSlotDebugInfo> localSlots,
-            ImmutableArray<ClosureDebugInfo> closures,
-            ImmutableArray<LambdaDebugInfo> lambdas,
-            ImmutableArray<StateMachineStateDebugInfo> stateMachineStates)
+
+        internal EditAndContinueMethodDebugInformation(int methodOrdinal, ImmutableArray<LocalSlotDebugInfo> localSlots, ImmutableArray<ClosureDebugInfo> closures, ImmutableArray<LambdaDebugInfo> lambdas)
         {
             Debug.Assert(methodOrdinal >= -1);
 
@@ -37,7 +31,6 @@ internal EditAndContinueMethodDebugInformation(
             LocalSlots = localSlots;
             Lambdas = lambdas;
             Closures = closures;
-            StateMachineStates = stateMachineStates;
         }
 
         /// <summary>
@@ -47,25 +40,9 @@ internal EditAndContinueMethodDebugInformation(
         /// <param name="compressedLambdaMap">Lambda and closure map.</param>
         /// <exception cref="InvalidDataException">Invalid data.</exception>
         public static EditAndContinueMethodDebugInformation Create(ImmutableArray<byte> compressedSlotMap, ImmutableArray<byte> compressedLambdaMap)
-            => Create(compressedSlotMap, compressedLambdaMap, compressedStateMachineStateMap: default);
-
-
-        /// <summary>
-        /// Deserializes Edit and Continue method debug information from specified blobs.
-        /// </summary>
-        /// <param name="compressedSlotMap">Local variable slot map.</param>
-        /// <param name="compressedLambdaMap">Lambda and closure map.</param>
-        /// <param name="compressedStateMachineStateMap">State machine suspension points, if the method is the MoveNext method of the state machine.</param>
-        /// <exception cref="InvalidDataException">Invalid data.</exception>
-        public static EditAndContinueMethodDebugInformation Create(ImmutableArray<byte> compressedSlotMap, ImmutableArray<byte> compressedLambdaMap, ImmutableArray<byte> compressedStateMachineStateMap)
         {
             UncompressLambdaMap(compressedLambdaMap, out var methodOrdinal, out var closures, out var lambdas);
-            return new EditAndContinueMethodDebugInformation(
-                methodOrdinal,
-                UncompressSlotMap(compressedSlotMap),
-                closures,
-                lambdas,
-                UncompressStateMachineStates(compressedStateMachineStateMap));
+            return new EditAndContinueMethodDebugInformation(methodOrdinal, UncompressSlotMap(compressedSlotMap), closures, lambdas);
         }
 
         private static InvalidDataException CreateInvalidDataException(ImmutableArray<byte> data, int offset)
@@ -300,56 +277,5 @@ internal void SerializeLambdaMap(BlobBuilder writer)
         }
 
         #endregion
-
-        #region State Machine States
-
-        /// <exception cref="InvalidDataException">Invalid data.</exception>
-        private static unsafe ImmutableArray<StateMachineStateDebugInfo> UncompressStateMachineStates(ImmutableArray<byte> compressedStateMachineStates)
-        {
-            if (compressedStateMachineStates.IsDefaultOrEmpty)
-            {
-                return default;
-            }
-
-            var mapBuilder = ArrayBuilder<StateMachineStateDebugInfo>.GetInstance();
-
-            fixed (byte* ptr = &compressedStateMachineStates.ToArray()[0])
-            {
-                var blobReader = new BlobReader(ptr, compressedStateMachineStates.Length);
-
-                try
-                {
-                    int count = blobReader.ReadCompressedInteger();
-
-                    while (count > 0)
-                    {
-                        int stateNumber = blobReader.ReadCompressedSignedInteger();
-                        int syntaxOffset = blobReader.ReadCompressedInteger();
-
-                        mapBuilder.Add(new StateMachineStateDebugInfo(syntaxOffset, stateNumber));
-                        count--;
-                    }
-                }
-                catch (BadImageFormatException)
-                {
-                    throw CreateInvalidDataException(compressedStateMachineStates, blobReader.Offset);
-                }
-            }
-
-            return mapBuilder.ToImmutableAndFree();
-        }
-
-        internal void SerializeStateMachineStates(BlobBuilder writer)
-        {
-            writer.WriteCompressedInteger(StateMachineStates.Length);
-
-            foreach (StateMachineStateDebugInfo state in StateMachineStates)
-            {
-                writer.WriteCompressedSignedInteger(state.StateNumber);
-                writer.WriteCompressedInteger(state.SyntaxOffset);
-            }
-        }
-
-        #endregion
     }
 }
diff --git a/src/Compilers/Core/Portable/Emit/NoPia/CommonEmbeddedMethod.cs b/src/Compilers/Core/Portable/Emit/NoPia/CommonEmbeddedMethod.cs
index 6d8771f789e6f..66692ffdf4ed3 100644
--- a/src/Compilers/Core/Portable/Emit/NoPia/CommonEmbeddedMethod.cs
+++ b/src/Compilers/Core/Portable/Emit/NoPia/CommonEmbeddedMethod.cs
@@ -161,9 +161,6 @@ public EmptyBody(CommonEmbeddedMethod method)
                 ImmutableArray<LambdaDebugInfo> Cci.IMethodBody.LambdaDebugInfo =>
                     default(ImmutableArray<LambdaDebugInfo>);
 
-                public StateMachineStatesDebugInfo StateMachineStatesDebugInfo
-                    => default;
-
                 public DebugId MethodId => default(DebugId);
             }
 
diff --git a/src/Compilers/Core/Portable/MetadataReader/PEModule.cs b/src/Compilers/Core/Portable/MetadataReader/PEModule.cs
index 077e195f7fdd8..16c3a5db53233 100644
--- a/src/Compilers/Core/Portable/MetadataReader/PEModule.cs
+++ b/src/Compilers/Core/Portable/MetadataReader/PEModule.cs
@@ -1780,11 +1780,6 @@ private bool TryExtractValueFromAttribute<T>(CustomAttributeHandle handle, out T
         }
 #nullable disable
 
-        internal bool HasStateMachineAttribute(MethodDefinitionHandle handle, out string stateMachineTypeName)
-            => HasStringValuedAttribute(handle, AttributeDescription.AsyncStateMachineAttribute, out stateMachineTypeName) ||
-               HasStringValuedAttribute(handle, AttributeDescription.IteratorStateMachineAttribute, out stateMachineTypeName) ||
-               HasStringValuedAttribute(handle, AttributeDescription.AsyncIteratorStateMachineAttribute, out stateMachineTypeName);
-
         internal bool HasStringValuedAttribute(EntityHandle token, AttributeDescription description, out string value)
         {
             AttributeInfo info = FindTargetAttribute(token, description);
diff --git a/src/Compilers/Core/Portable/PEWriter/CustomDebugInfoWriter.cs b/src/Compilers/Core/Portable/PEWriter/CustomDebugInfoWriter.cs
index 72fc9d41e1336..2371acc5d48a8 100644
--- a/src/Compilers/Core/Portable/PEWriter/CustomDebugInfoWriter.cs
+++ b/src/Compilers/Core/Portable/PEWriter/CustomDebugInfoWriter.cs
@@ -147,14 +147,6 @@ internal static void SerializeCustomDebugInformation(ref CustomDebugInfoEncoder
                     debugInfo,
                     (info, builder) => info.SerializeLambdaMap(builder));
             }
-
-            if (!debugInfo.StateMachineStates.IsDefaultOrEmpty)
-            {
-                encoder.AddRecord(
-                    CustomDebugInfoKind.EditAndContinueStateMachineStateMap,
-                    debugInfo,
-                    (info, builder) => info.SerializeStateMachineStates(builder));
-            }
         }
 
         private static ArrayBuilder<T> GetLocalInfoToSerialize<T>(
diff --git a/src/Compilers/Core/Portable/PEWriter/Members.cs b/src/Compilers/Core/Portable/PEWriter/Members.cs
index 0625117b7b837..fcb78a61af057 100644
--- a/src/Compilers/Core/Portable/PEWriter/Members.cs
+++ b/src/Compilers/Core/Portable/PEWriter/Members.cs
@@ -475,7 +475,6 @@ ImmutableArray<ExceptionHandlerRegion> ExceptionRegions
 
         ImmutableArray<ClosureDebugInfo> ClosureDebugInfo { get; }
         ImmutableArray<LambdaDebugInfo> LambdaDebugInfo { get; }
-        StateMachineStatesDebugInfo StateMachineStatesDebugInfo { get; }
 
         DynamicAnalysisMethodBodyData DynamicAnalysisData { get; }
     }
diff --git a/src/Compilers/Core/Portable/PEWriter/MetadataWriter.PortablePdb.cs b/src/Compilers/Core/Portable/PEWriter/MetadataWriter.PortablePdb.cs
index 74b080264b787..bfd660f5e4b1f 100644
--- a/src/Compilers/Core/Portable/PEWriter/MetadataWriter.PortablePdb.cs
+++ b/src/Compilers/Core/Portable/PEWriter/MetadataWriter.PortablePdb.cs
@@ -817,18 +817,6 @@ private void SerializeEncMethodDebugInformation(IMethodBody methodBody, MethodDe
                     kind: _debugMetadataOpt.GetOrAddGuid(PortableCustomDebugInfoKinds.EncLambdaAndClosureMap),
                     value: _debugMetadataOpt.GetOrAddBlob(writer));
             }
-
-            if (!encInfo.StateMachineStates.IsDefaultOrEmpty)
-            {
-                var writer = new BlobBuilder();
-
-                encInfo.SerializeStateMachineStates(writer);
-
-                _debugMetadataOpt.AddCustomDebugInformation(
-                    parent: method,
-                    kind: _debugMetadataOpt.GetOrAddGuid(PortableCustomDebugInfoKinds.EncStateMachineStateMap),
-                    value: _debugMetadataOpt.GetOrAddBlob(writer));
-            }
         }
 
         #endregion
diff --git a/src/Compilers/Core/Portable/PEWriter/MetadataWriter.cs b/src/Compilers/Core/Portable/PEWriter/MetadataWriter.cs
index e8fd04f5faace..17defcf93881b 100644
--- a/src/Compilers/Core/Portable/PEWriter/MetadataWriter.cs
+++ b/src/Compilers/Core/Portable/PEWriter/MetadataWriter.cs
@@ -4054,12 +4054,7 @@ internal static EditAndContinueMethodDebugInformation GetEncMethodDebugInfo(IMet
                 encLocalSlots = GetLocalSlotDebugInfos(encSlotInfo);
             }
 
-            return new EditAndContinueMethodDebugInformation(
-                methodBody.MethodId.Ordinal,
-                encLocalSlots,
-                methodBody.ClosureDebugInfo,
-                methodBody.LambdaDebugInfo,
-                methodBody.StateMachineStatesDebugInfo.States);
+            return new EditAndContinueMethodDebugInformation(methodBody.MethodId.Ordinal, encLocalSlots, methodBody.ClosureDebugInfo, methodBody.LambdaDebugInfo);
         }
 
         internal static ImmutableArray<LocalSlotDebugInfo> GetLocalSlotDebugInfos(ImmutableArray<ILocalDefinition> locals)
diff --git a/src/Compilers/Core/Portable/PEWriter/RootModuleStaticConstructor.cs b/src/Compilers/Core/Portable/PEWriter/RootModuleStaticConstructor.cs
index b6001e1a37a07..b397eb48370b9 100644
--- a/src/Compilers/Core/Portable/PEWriter/RootModuleStaticConstructor.cs
+++ b/src/Compilers/Core/Portable/PEWriter/RootModuleStaticConstructor.cs
@@ -161,11 +161,8 @@ public RootModuleStaticConstructor(ITypeDefinition containingTypeDefinition, Imm
 
         public ImmutableArray<LambdaDebugInfo> LambdaDebugInfo => ImmutableArray<LambdaDebugInfo>.Empty;
 
-        public StateMachineStatesDebugInfo StateMachineStatesDebugInfo => default;
-
         public DynamicAnalysisMethodBodyData DynamicAnalysisData => null;
 
-
         public sealed override bool Equals(object obj)
         {
             // It is not supported to rely on default equality of these Cci objects, an explicit way to compare and hash them should be used.
diff --git a/src/Compilers/Core/Portable/PublicAPI.Unshipped.txt b/src/Compilers/Core/Portable/PublicAPI.Unshipped.txt
index a28db91aaa246..1d622432a2be9 100644
--- a/src/Compilers/Core/Portable/PublicAPI.Unshipped.txt
+++ b/src/Compilers/Core/Portable/PublicAPI.Unshipped.txt
@@ -56,7 +56,6 @@ Microsoft.CodeAnalysis.SymbolVisitor<TArgument, TResult>
 Microsoft.CodeAnalysis.SymbolVisitor<TArgument, TResult>.SymbolVisitor() -> void
 override sealed Microsoft.CodeAnalysis.Diagnostic.Equals(object? obj) -> bool
 *REMOVED*static Microsoft.CodeAnalysis.SyntaxNodeExtensions.ReplaceSyntax<TRoot>(this TRoot! root, System.Collections.Generic.IEnumerable<Microsoft.CodeAnalysis.SyntaxNode!>! nodes, System.Func<Microsoft.CodeAnalysis.SyntaxNode!, Microsoft.CodeAnalysis.SyntaxNode!, Microsoft.CodeAnalysis.SyntaxNode!>! computeReplacementNode, System.Collections.Generic.IEnumerable<Microsoft.CodeAnalysis.SyntaxToken>! tokens, System.Func<Microsoft.CodeAnalysis.SyntaxToken, Microsoft.CodeAnalysis.SyntaxToken, Microsoft.CodeAnalysis.SyntaxToken>! computeReplacementToken, System.Collections.Generic.IEnumerable<Microsoft.CodeAnalysis.SyntaxTrivia>! trivia, System.Func<Microsoft.CodeAnalysis.SyntaxTrivia, Microsoft.CodeAnalysis.SyntaxTrivia, Microsoft.CodeAnalysis.SyntaxTrivia>! computeReplacementTrivia) -> TRoot!
-static Microsoft.CodeAnalysis.Emit.EditAndContinueMethodDebugInformation.Create(System.Collections.Immutable.ImmutableArray<byte> compressedSlotMap, System.Collections.Immutable.ImmutableArray<byte> compressedLambdaMap, System.Collections.Immutable.ImmutableArray<byte> compressedStateMachineStateMap) -> Microsoft.CodeAnalysis.Emit.EditAndContinueMethodDebugInformation
 static Microsoft.CodeAnalysis.SyntaxNodeExtensions.ReplaceSyntax<TRoot>(this TRoot! root, System.Collections.Generic.IEnumerable<Microsoft.CodeAnalysis.SyntaxNode!>? nodes, System.Func<Microsoft.CodeAnalysis.SyntaxNode!, Microsoft.CodeAnalysis.SyntaxNode!, Microsoft.CodeAnalysis.SyntaxNode!>? computeReplacementNode, System.Collections.Generic.IEnumerable<Microsoft.CodeAnalysis.SyntaxToken>? tokens, System.Func<Microsoft.CodeAnalysis.SyntaxToken, Microsoft.CodeAnalysis.SyntaxToken, Microsoft.CodeAnalysis.SyntaxToken>? computeReplacementToken, System.Collections.Generic.IEnumerable<Microsoft.CodeAnalysis.SyntaxTrivia>? trivia, System.Func<Microsoft.CodeAnalysis.SyntaxTrivia, Microsoft.CodeAnalysis.SyntaxTrivia, Microsoft.CodeAnalysis.SyntaxTrivia>? computeReplacementTrivia) -> TRoot!
 const Microsoft.CodeAnalysis.WellKnownMemberNames.CheckedDecrementOperatorName = "op_CheckedDecrement" -> string!
 const Microsoft.CodeAnalysis.WellKnownMemberNames.CheckedIncrementOperatorName = "op_CheckedIncrement" -> string!
diff --git a/src/Compilers/Core/Portable/WellKnownMember.cs b/src/Compilers/Core/Portable/WellKnownMember.cs
index fe2b3e646e0f7..8eef3970f4ebb 100644
--- a/src/Compilers/Core/Portable/WellKnownMember.cs
+++ b/src/Compilers/Core/Portable/WellKnownMember.cs
@@ -500,7 +500,6 @@ internal enum WellKnownMember
         System_Runtime_CompilerServices_ITuple__get_Length,
 
         System_InvalidOperationException__ctor,
-        System_InvalidOperationException__ctorString,
         System_Runtime_CompilerServices_SwitchExpressionException__ctor,
         System_Runtime_CompilerServices_SwitchExpressionException__ctorObject,
 
diff --git a/src/Compilers/Core/Portable/WellKnownMembers.cs b/src/Compilers/Core/Portable/WellKnownMembers.cs
index 1f8f98524758f..d43618ec1631b 100644
--- a/src/Compilers/Core/Portable/WellKnownMembers.cs
+++ b/src/Compilers/Core/Portable/WellKnownMembers.cs
@@ -3454,14 +3454,6 @@ static WellKnownMembers()
                     0,                                                                                                                        // Method Signature
                     (byte)SignatureTypeCode.TypeHandle, (byte)SpecialType.System_Void,
 
-                 // System_InvalidOperationException__ctorString
-                 (byte)MemberFlags.Constructor,                                                                                               // Flags
-                  (byte)WellKnownType.ExtSentinel, (byte)(WellKnownType.System_InvalidOperationException - WellKnownType.ExtSentinel),        // DeclaringTypeId
-                 0,                                                                                                                           // Arity
-                    1,                                                                                                                        // Method Signature
-                    (byte)SignatureTypeCode.TypeHandle, (byte)SpecialType.System_Void,
-                    (byte)SignatureTypeCode.TypeHandle, (byte)SpecialType.System_String,
-
                  // System_Runtime_CompilerServices_SwitchExpressionException__ctor
                  (byte)MemberFlags.Constructor,                                                                                               // Flags
                  (byte)WellKnownType.ExtSentinel, (byte)(WellKnownType.System_Runtime_CompilerServices_SwitchExpressionException - WellKnownType.ExtSentinel),// DeclaringTypeId
@@ -4065,7 +4057,6 @@ static WellKnownMembers()
                 "get_Item",                                 // System_Runtime_CompilerServices_ITuple__get_Item
                 "get_Length",                               // System_Runtime_CompilerServices_ITuple__get_Length
                 ".ctor",                                    // System_InvalidOperationException__ctor
-                ".ctor",                                    // System_InvalidOperationException__ctorString
                 ".ctor",                                    // System_Runtime_CompilerServices_SwitchExpressionException__ctor
                 ".ctor",                                    // System_Runtime_CompilerServices_SwitchExpressionException__ctorObject
                 "Equals",                                   // System_Threading_CancellationToken__Equals
diff --git a/src/Compilers/Core/Portable/xlf/CodeAnalysisResources.cs.xlf b/src/Compilers/Core/Portable/xlf/CodeAnalysisResources.cs.xlf
index 2fa852c159d6c..4aa76eeed541c 100644
--- a/src/Compilers/Core/Portable/xlf/CodeAnalysisResources.cs.xlf
+++ b/src/Compilers/Core/Portable/xlf/CodeAnalysisResources.cs.xlf
@@ -39,16 +39,6 @@
         <target state="translated">Pokud chcete tento analyzátor zakázat, potlačte následující diagnostiku: {0}</target>
         <note>{0}: Comma-separated list of diagnostic IDs</note>
       </trans-unit>
-      <trans-unit id="EncCannotResumeSuspendedAsyncMethod">
-        <source>Edit and Continue can't resume suspended asynchronous method since the corresponding await expression has been deleted</source>
-        <target state="new">Edit and Continue can't resume suspended asynchronous method since the corresponding await expression has been deleted</target>
-        <note />
-      </trans-unit>
-      <trans-unit id="EncCannotResumeSuspendedIteratorMethod">
-        <source>Edit and Continue can't resume suspended iterator since the corresponding yield return statement has been deleted</source>
-        <target state="new">Edit and Continue can't resume suspended iterator since the corresponding yield return statement has been deleted</target>
-        <note />
-      </trans-unit>
       <trans-unit id="HintNameInvalidChar">
         <source>The hintName '{0}' contains an invalid character '{1}' at position {2}.</source>
         <target state="translated">{0} hintName obsahuje neplatný znak {1} na pozici {2}.</target>
diff --git a/src/Compilers/Core/Portable/xlf/CodeAnalysisResources.de.xlf b/src/Compilers/Core/Portable/xlf/CodeAnalysisResources.de.xlf
index 364047feec649..00ea4369d37cd 100644
--- a/src/Compilers/Core/Portable/xlf/CodeAnalysisResources.de.xlf
+++ b/src/Compilers/Core/Portable/xlf/CodeAnalysisResources.de.xlf
@@ -39,16 +39,6 @@
         <target state="translated">Unterdrücken Sie die folgende Diagnose, um dieses Analysetool zu deaktivieren: {0}</target>
         <note>{0}: Comma-separated list of diagnostic IDs</note>
       </trans-unit>
-      <trans-unit id="EncCannotResumeSuspendedAsyncMethod">
-        <source>Edit and Continue can't resume suspended asynchronous method since the corresponding await expression has been deleted</source>
-        <target state="new">Edit and Continue can't resume suspended asynchronous method since the corresponding await expression has been deleted</target>
-        <note />
-      </trans-unit>
-      <trans-unit id="EncCannotResumeSuspendedIteratorMethod">
-        <source>Edit and Continue can't resume suspended iterator since the corresponding yield return statement has been deleted</source>
-        <target state="new">Edit and Continue can't resume suspended iterator since the corresponding yield return statement has been deleted</target>
-        <note />
-      </trans-unit>
       <trans-unit id="HintNameInvalidChar">
         <source>The hintName '{0}' contains an invalid character '{1}' at position {2}.</source>
         <target state="translated">Der hintName "{0}" enthält ein ungültiges Zeichen "{1}" an Position {2}.</target>
diff --git a/src/Compilers/Core/Portable/xlf/CodeAnalysisResources.es.xlf b/src/Compilers/Core/Portable/xlf/CodeAnalysisResources.es.xlf
index 1253ec5496d77..f7b6c0d69253b 100644
--- a/src/Compilers/Core/Portable/xlf/CodeAnalysisResources.es.xlf
+++ b/src/Compilers/Core/Portable/xlf/CodeAnalysisResources.es.xlf
@@ -39,16 +39,6 @@
         <target state="translated">Suprima el diagnóstico siguiente para deshabilitar este analizador: {0}</target>
         <note>{0}: Comma-separated list of diagnostic IDs</note>
       </trans-unit>
-      <trans-unit id="EncCannotResumeSuspendedAsyncMethod">
-        <source>Edit and Continue can't resume suspended asynchronous method since the corresponding await expression has been deleted</source>
-        <target state="new">Edit and Continue can't resume suspended asynchronous method since the corresponding await expression has been deleted</target>
-        <note />
-      </trans-unit>
-      <trans-unit id="EncCannotResumeSuspendedIteratorMethod">
-        <source>Edit and Continue can't resume suspended iterator since the corresponding yield return statement has been deleted</source>
-        <target state="new">Edit and Continue can't resume suspended iterator since the corresponding yield return statement has been deleted</target>
-        <note />
-      </trans-unit>
       <trans-unit id="HintNameInvalidChar">
         <source>The hintName '{0}' contains an invalid character '{1}' at position {2}.</source>
         <target state="translated">El elemento hintName "{0}" contiene un carácter no válido "{1}" en la posición {2}.</target>
diff --git a/src/Compilers/Core/Portable/xlf/CodeAnalysisResources.fr.xlf b/src/Compilers/Core/Portable/xlf/CodeAnalysisResources.fr.xlf
index 967be7424cccc..5240ce918f8c4 100644
--- a/src/Compilers/Core/Portable/xlf/CodeAnalysisResources.fr.xlf
+++ b/src/Compilers/Core/Portable/xlf/CodeAnalysisResources.fr.xlf
@@ -39,16 +39,6 @@
         <target state="translated">Supprimez les diagnostics suivants pour désactiver cet analyseur : {0}</target>
         <note>{0}: Comma-separated list of diagnostic IDs</note>
       </trans-unit>
-      <trans-unit id="EncCannotResumeSuspendedAsyncMethod">
-        <source>Edit and Continue can't resume suspended asynchronous method since the corresponding await expression has been deleted</source>
-        <target state="new">Edit and Continue can't resume suspended asynchronous method since the corresponding await expression has been deleted</target>
-        <note />
-      </trans-unit>
-      <trans-unit id="EncCannotResumeSuspendedIteratorMethod">
-        <source>Edit and Continue can't resume suspended iterator since the corresponding yield return statement has been deleted</source>
-        <target state="new">Edit and Continue can't resume suspended iterator since the corresponding yield return statement has been deleted</target>
-        <note />
-      </trans-unit>
       <trans-unit id="HintNameInvalidChar">
         <source>The hintName '{0}' contains an invalid character '{1}' at position {2}.</source>
         <target state="translated">Le hintName « {0} » contient un caractère non valide « {1} » à la position {2}.</target>
diff --git a/src/Compilers/Core/Portable/xlf/CodeAnalysisResources.it.xlf b/src/Compilers/Core/Portable/xlf/CodeAnalysisResources.it.xlf
index e968e21f33ce0..bc850fd6a3102 100644
--- a/src/Compilers/Core/Portable/xlf/CodeAnalysisResources.it.xlf
+++ b/src/Compilers/Core/Portable/xlf/CodeAnalysisResources.it.xlf
@@ -39,16 +39,6 @@
         <target state="translated">Per disabilitare questo analizzatore, eliminare la diagnostica seguente: {0}</target>
         <note>{0}: Comma-separated list of diagnostic IDs</note>
       </trans-unit>
-      <trans-unit id="EncCannotResumeSuspendedAsyncMethod">
-        <source>Edit and Continue can't resume suspended asynchronous method since the corresponding await expression has been deleted</source>
-        <target state="new">Edit and Continue can't resume suspended asynchronous method since the corresponding await expression has been deleted</target>
-        <note />
-      </trans-unit>
-      <trans-unit id="EncCannotResumeSuspendedIteratorMethod">
-        <source>Edit and Continue can't resume suspended iterator since the corresponding yield return statement has been deleted</source>
-        <target state="new">Edit and Continue can't resume suspended iterator since the corresponding yield return statement has been deleted</target>
-        <note />
-      </trans-unit>
       <trans-unit id="HintNameInvalidChar">
         <source>The hintName '{0}' contains an invalid character '{1}' at position {2}.</source>
         <target state="translated">L'elemento hintName '{0}' contiene un carattere non valido '{1}' alla posizione {2}.</target>
diff --git a/src/Compilers/Core/Portable/xlf/CodeAnalysisResources.ja.xlf b/src/Compilers/Core/Portable/xlf/CodeAnalysisResources.ja.xlf
index ada7f1dafc681..75847de1ed2f6 100644
--- a/src/Compilers/Core/Portable/xlf/CodeAnalysisResources.ja.xlf
+++ b/src/Compilers/Core/Portable/xlf/CodeAnalysisResources.ja.xlf
@@ -39,16 +39,6 @@
         <target state="translated">次の診断を抑制して、このアナライザーを無効にします: {0}</target>
         <note>{0}: Comma-separated list of diagnostic IDs</note>
       </trans-unit>
-      <trans-unit id="EncCannotResumeSuspendedAsyncMethod">
-        <source>Edit and Continue can't resume suspended asynchronous method since the corresponding await expression has been deleted</source>
-        <target state="new">Edit and Continue can't resume suspended asynchronous method since the corresponding await expression has been deleted</target>
-        <note />
-      </trans-unit>
-      <trans-unit id="EncCannotResumeSuspendedIteratorMethod">
-        <source>Edit and Continue can't resume suspended iterator since the corresponding yield return statement has been deleted</source>
-        <target state="new">Edit and Continue can't resume suspended iterator since the corresponding yield return statement has been deleted</target>
-        <note />
-      </trans-unit>
       <trans-unit id="HintNameInvalidChar">
         <source>The hintName '{0}' contains an invalid character '{1}' at position {2}.</source>
         <target state="translated">hintName {0} の位置 {2} に無効な文字 '{1}' が含まれています。</target>
diff --git a/src/Compilers/Core/Portable/xlf/CodeAnalysisResources.ko.xlf b/src/Compilers/Core/Portable/xlf/CodeAnalysisResources.ko.xlf
index 03be4626a83c9..097be4f235c04 100644
--- a/src/Compilers/Core/Portable/xlf/CodeAnalysisResources.ko.xlf
+++ b/src/Compilers/Core/Portable/xlf/CodeAnalysisResources.ko.xlf
@@ -39,16 +39,6 @@
         <target state="translated">이 분석기를 사용하지 않도록 설정하려면 다음 진단이 표시되지 않도록 설정하세요. {0}</target>
         <note>{0}: Comma-separated list of diagnostic IDs</note>
       </trans-unit>
-      <trans-unit id="EncCannotResumeSuspendedAsyncMethod">
-        <source>Edit and Continue can't resume suspended asynchronous method since the corresponding await expression has been deleted</source>
-        <target state="new">Edit and Continue can't resume suspended asynchronous method since the corresponding await expression has been deleted</target>
-        <note />
-      </trans-unit>
-      <trans-unit id="EncCannotResumeSuspendedIteratorMethod">
-        <source>Edit and Continue can't resume suspended iterator since the corresponding yield return statement has been deleted</source>
-        <target state="new">Edit and Continue can't resume suspended iterator since the corresponding yield return statement has been deleted</target>
-        <note />
-      </trans-unit>
       <trans-unit id="HintNameInvalidChar">
         <source>The hintName '{0}' contains an invalid character '{1}' at position {2}.</source>
         <target state="translated">hintName의 {0} 위치 {2}에 잘못된 문자 '{1}'이(가) 있습니다.</target>
diff --git a/src/Compilers/Core/Portable/xlf/CodeAnalysisResources.pl.xlf b/src/Compilers/Core/Portable/xlf/CodeAnalysisResources.pl.xlf
index bb38bea3940f1..aed49848d2d89 100644
--- a/src/Compilers/Core/Portable/xlf/CodeAnalysisResources.pl.xlf
+++ b/src/Compilers/Core/Portable/xlf/CodeAnalysisResources.pl.xlf
@@ -39,16 +39,6 @@
         <target state="translated">Pomiń następującą diagnostykę, aby wyłączyć ten analizator: {0}</target>
         <note>{0}: Comma-separated list of diagnostic IDs</note>
       </trans-unit>
-      <trans-unit id="EncCannotResumeSuspendedAsyncMethod">
-        <source>Edit and Continue can't resume suspended asynchronous method since the corresponding await expression has been deleted</source>
-        <target state="new">Edit and Continue can't resume suspended asynchronous method since the corresponding await expression has been deleted</target>
-        <note />
-      </trans-unit>
-      <trans-unit id="EncCannotResumeSuspendedIteratorMethod">
-        <source>Edit and Continue can't resume suspended iterator since the corresponding yield return statement has been deleted</source>
-        <target state="new">Edit and Continue can't resume suspended iterator since the corresponding yield return statement has been deleted</target>
-        <note />
-      </trans-unit>
       <trans-unit id="HintNameInvalidChar">
         <source>The hintName '{0}' contains an invalid character '{1}' at position {2}.</source>
         <target state="translated">Element hintName „{0}” zawiera nieprawidłowy znak „{1}” na pozycji {2}.</target>
diff --git a/src/Compilers/Core/Portable/xlf/CodeAnalysisResources.pt-BR.xlf b/src/Compilers/Core/Portable/xlf/CodeAnalysisResources.pt-BR.xlf
index 1c522fba6c113..aa6850941c6ee 100644
--- a/src/Compilers/Core/Portable/xlf/CodeAnalysisResources.pt-BR.xlf
+++ b/src/Compilers/Core/Portable/xlf/CodeAnalysisResources.pt-BR.xlf
@@ -39,16 +39,6 @@
         <target state="translated">Suprimir os seguintes diagnósticos para desabilitar este analisador: {0}</target>
         <note>{0}: Comma-separated list of diagnostic IDs</note>
       </trans-unit>
-      <trans-unit id="EncCannotResumeSuspendedAsyncMethod">
-        <source>Edit and Continue can't resume suspended asynchronous method since the corresponding await expression has been deleted</source>
-        <target state="new">Edit and Continue can't resume suspended asynchronous method since the corresponding await expression has been deleted</target>
-        <note />
-      </trans-unit>
-      <trans-unit id="EncCannotResumeSuspendedIteratorMethod">
-        <source>Edit and Continue can't resume suspended iterator since the corresponding yield return statement has been deleted</source>
-        <target state="new">Edit and Continue can't resume suspended iterator since the corresponding yield return statement has been deleted</target>
-        <note />
-      </trans-unit>
       <trans-unit id="HintNameInvalidChar">
         <source>The hintName '{0}' contains an invalid character '{1}' at position {2}.</source>
         <target state="translated">O hintName '{0}' contém um caractere inválido '{1}' na posição {2}.</target>
diff --git a/src/Compilers/Core/Portable/xlf/CodeAnalysisResources.ru.xlf b/src/Compilers/Core/Portable/xlf/CodeAnalysisResources.ru.xlf
index 480ee2cc98470..625cd0fd53384 100644
--- a/src/Compilers/Core/Portable/xlf/CodeAnalysisResources.ru.xlf
+++ b/src/Compilers/Core/Portable/xlf/CodeAnalysisResources.ru.xlf
@@ -39,16 +39,6 @@
         <target state="translated">Отключите следующую диагностику, чтобы отключить этот анализатор: {0}</target>
         <note>{0}: Comma-separated list of diagnostic IDs</note>
       </trans-unit>
-      <trans-unit id="EncCannotResumeSuspendedAsyncMethod">
-        <source>Edit and Continue can't resume suspended asynchronous method since the corresponding await expression has been deleted</source>
-        <target state="new">Edit and Continue can't resume suspended asynchronous method since the corresponding await expression has been deleted</target>
-        <note />
-      </trans-unit>
-      <trans-unit id="EncCannotResumeSuspendedIteratorMethod">
-        <source>Edit and Continue can't resume suspended iterator since the corresponding yield return statement has been deleted</source>
-        <target state="new">Edit and Continue can't resume suspended iterator since the corresponding yield return statement has been deleted</target>
-        <note />
-      </trans-unit>
       <trans-unit id="HintNameInvalidChar">
         <source>The hintName '{0}' contains an invalid character '{1}' at position {2}.</source>
         <target state="translated">hintName "{0}" содержит недопустимый символ "{1}" в позиции {2}.</target>
diff --git a/src/Compilers/Core/Portable/xlf/CodeAnalysisResources.tr.xlf b/src/Compilers/Core/Portable/xlf/CodeAnalysisResources.tr.xlf
index 5186af765f636..0fb46e1e726b6 100644
--- a/src/Compilers/Core/Portable/xlf/CodeAnalysisResources.tr.xlf
+++ b/src/Compilers/Core/Portable/xlf/CodeAnalysisResources.tr.xlf
@@ -39,16 +39,6 @@
         <target state="translated">Bu çözümleyiciyi devre dışı bırakmak için şu tanılamaları gizleyin: {0}</target>
         <note>{0}: Comma-separated list of diagnostic IDs</note>
       </trans-unit>
-      <trans-unit id="EncCannotResumeSuspendedAsyncMethod">
-        <source>Edit and Continue can't resume suspended asynchronous method since the corresponding await expression has been deleted</source>
-        <target state="new">Edit and Continue can't resume suspended asynchronous method since the corresponding await expression has been deleted</target>
-        <note />
-      </trans-unit>
-      <trans-unit id="EncCannotResumeSuspendedIteratorMethod">
-        <source>Edit and Continue can't resume suspended iterator since the corresponding yield return statement has been deleted</source>
-        <target state="new">Edit and Continue can't resume suspended iterator since the corresponding yield return statement has been deleted</target>
-        <note />
-      </trans-unit>
       <trans-unit id="HintNameInvalidChar">
         <source>The hintName '{0}' contains an invalid character '{1}' at position {2}.</source>
         <target state="translated">hintName '{0}', {2} konumunda geçersiz bir '{1}' karakteri içeriyor.</target>
diff --git a/src/Compilers/Core/Portable/xlf/CodeAnalysisResources.zh-Hans.xlf b/src/Compilers/Core/Portable/xlf/CodeAnalysisResources.zh-Hans.xlf
index 9714b0083f904..b22f62b9662fc 100644
--- a/src/Compilers/Core/Portable/xlf/CodeAnalysisResources.zh-Hans.xlf
+++ b/src/Compilers/Core/Portable/xlf/CodeAnalysisResources.zh-Hans.xlf
@@ -39,16 +39,6 @@
         <target state="translated">取消以下诊断以禁用此分析器: {0}</target>
         <note>{0}: Comma-separated list of diagnostic IDs</note>
       </trans-unit>
-      <trans-unit id="EncCannotResumeSuspendedAsyncMethod">
-        <source>Edit and Continue can't resume suspended asynchronous method since the corresponding await expression has been deleted</source>
-        <target state="new">Edit and Continue can't resume suspended asynchronous method since the corresponding await expression has been deleted</target>
-        <note />
-      </trans-unit>
-      <trans-unit id="EncCannotResumeSuspendedIteratorMethod">
-        <source>Edit and Continue can't resume suspended iterator since the corresponding yield return statement has been deleted</source>
-        <target state="new">Edit and Continue can't resume suspended iterator since the corresponding yield return statement has been deleted</target>
-        <note />
-      </trans-unit>
       <trans-unit id="HintNameInvalidChar">
         <source>The hintName '{0}' contains an invalid character '{1}' at position {2}.</source>
         <target state="translated">hintName“{0}”在位置 {2} 处包含无效字符“{1}”。</target>
diff --git a/src/Compilers/Core/Portable/xlf/CodeAnalysisResources.zh-Hant.xlf b/src/Compilers/Core/Portable/xlf/CodeAnalysisResources.zh-Hant.xlf
index d7100f2db3ca8..fec16f40c1ab8 100644
--- a/src/Compilers/Core/Portable/xlf/CodeAnalysisResources.zh-Hant.xlf
+++ b/src/Compilers/Core/Portable/xlf/CodeAnalysisResources.zh-Hant.xlf
@@ -39,16 +39,6 @@
         <target state="translated">請隱藏下列診斷以停用此分析器: {0}</target>
         <note>{0}: Comma-separated list of diagnostic IDs</note>
       </trans-unit>
-      <trans-unit id="EncCannotResumeSuspendedAsyncMethod">
-        <source>Edit and Continue can't resume suspended asynchronous method since the corresponding await expression has been deleted</source>
-        <target state="new">Edit and Continue can't resume suspended asynchronous method since the corresponding await expression has been deleted</target>
-        <note />
-      </trans-unit>
-      <trans-unit id="EncCannotResumeSuspendedIteratorMethod">
-        <source>Edit and Continue can't resume suspended iterator since the corresponding yield return statement has been deleted</source>
-        <target state="new">Edit and Continue can't resume suspended iterator since the corresponding yield return statement has been deleted</target>
-        <note />
-      </trans-unit>
       <trans-unit id="HintNameInvalidChar">
         <source>The hintName '{0}' contains an invalid character '{1}' at position {2}.</source>
         <target state="translated">位置 {2} 的 hintName {0} 包含無效的字元 '{1}'。</target>
diff --git a/src/Compilers/Test/Core/Compilation/CompilationTestDataExtensions.cs b/src/Compilers/Test/Core/Compilation/CompilationTestDataExtensions.cs
index 0a7d4b5916ba8..11e63278c95ab 100644
--- a/src/Compilers/Test/Core/Compilation/CompilationTestDataExtensions.cs
+++ b/src/Compilers/Test/Core/Compilation/CompilationTestDataExtensions.cs
@@ -108,8 +108,7 @@ internal static EditAndContinueMethodDebugInformation GetEncDebugInfo(this Compi
                 0,
                 Cci.MetadataWriter.GetLocalSlotDebugInfos(methodData.ILBuilder.LocalSlotManager.LocalsInOrder()),
                 closures: ImmutableArray<ClosureDebugInfo>.Empty,
-                lambdas: ImmutableArray<LambdaDebugInfo>.Empty,
-                stateMachineStates: ImmutableArray<StateMachineStateDebugInfo>.Empty);
+                lambdas: ImmutableArray<LambdaDebugInfo>.Empty);
         }
 
         internal static Func<MethodDefinitionHandle, EditAndContinueMethodDebugInformation> EncDebugInfoProvider(this CompilationTestData.MethodData methodData)
diff --git a/src/Compilers/Test/Core/MarkedSource/SourceWithMarkedNodes.cs b/src/Compilers/Test/Core/MarkedSource/SourceWithMarkedNodes.cs
index 24bab1d23ddc3..9b30cb6c8da06 100644
--- a/src/Compilers/Test/Core/MarkedSource/SourceWithMarkedNodes.cs
+++ b/src/Compilers/Test/Core/MarkedSource/SourceWithMarkedNodes.cs
@@ -81,7 +81,7 @@ internal static string ClearTags(string source)
         }
 
         private static readonly Regex s_tags = new Regex(
-            @"[<][/]?[NMCL][:][:\.A-Za-z0-9]*[>]",
+            @"[<][/]?[NMCL][:]?[:\.A-Za-z0-9]*[>]",
             RegexOptions.IgnorePatternWhitespace | RegexOptions.Singleline);
 
         private static readonly Regex s_markerPattern = new Regex(
@@ -93,7 +93,7 @@ internal static string ClearTags(string source)
                 (?<Id>[0-9]+)                    # The first number after the colon is the Id
                 ([.](?<ParentId>[0-9]+))?        # Digits after a decimal point are the parent Id
                 ([:](?<SyntaxKind>[A-Za-z]+))?   # A second colon separates the syntax kind
-              )                                  # Close the group for the things after the tag name
+              )?                                 # Close the group for the things after the tag name
               [>]                                # Close tag
 
               (                                  # Start a group so that the closing tag is optional
diff --git a/src/Compilers/VisualBasic/Portable/Compilation/MethodCompiler.vb b/src/Compilers/VisualBasic/Portable/Compilation/MethodCompiler.vb
index b3ade194c24dd..8a926154dfff4 100644
--- a/src/Compilers/VisualBasic/Portable/Compilation/MethodCompiler.vb
+++ b/src/Compilers/VisualBasic/Portable/Compilation/MethodCompiler.vb
@@ -315,7 +315,6 @@ Namespace Microsoft.CodeAnalysis.VisualBasic
                                              block:=body,
                                              lambdaDebugInfo:=ImmutableArray(Of LambdaDebugInfo).Empty,
                                              closureDebugInfo:=ImmutableArray(Of ClosureDebugInfo).Empty,
-                                             stateMachineStateDebugInfos:=ImmutableArray(Of StateMachineStateDebugInfo).Empty,
                                              stateMachineTypeOpt:=Nothing,
                                              variableSlotAllocatorOpt:=Nothing,
                                              debugDocumentProvider:=Nothing,
@@ -887,7 +886,6 @@ Namespace Microsoft.CodeAnalysis.VisualBasic
                                                          block:=boundBody,
                                                          lambdaDebugInfo:=ImmutableArray(Of LambdaDebugInfo).Empty,
                                                          closureDebugInfo:=ImmutableArray(Of ClosureDebugInfo).Empty,
-                                                         stateMachineStateDebugInfos:=ImmutableArray(Of StateMachineStateDebugInfo).Empty,
                                                          stateMachineTypeOpt:=Nothing,
                                                          variableSlotAllocatorOpt:=Nothing,
                                                          debugDocumentProvider:=If(_emitTestCoverageData, _debugDocumentProvider, Nothing),
@@ -918,11 +916,7 @@ Namespace Microsoft.CodeAnalysis.VisualBasic
         Private Sub CompileSynthesizedMethods(additionalTypes As ImmutableArray(Of NamedTypeSymbol))
             Debug.Assert(_moduleBeingBuiltOpt IsNot Nothing)
 
-            Dim lambdaDebugInfoBuilder = ArrayBuilder(Of LambdaDebugInfo).GetInstance()
-            Dim closureDebugInfoBuilder = ArrayBuilder(Of ClosureDebugInfo).GetInstance()
-            Dim stateMachineStateDebugInfoBuilder = ArrayBuilder(Of StateMachineStateDebugInfo).GetInstance()
             Dim compilationState As New TypeCompilationState(_compilation, _moduleBeingBuiltOpt, initializeComponentOpt:=Nothing)
-
             For Each additionalType In additionalTypes
                 Dim methodOrdinal As Integer = 0
 
@@ -937,6 +931,8 @@ Namespace Microsoft.CodeAnalysis.VisualBasic
                         Dim lazyVariableSlotAllocator As VariableSlotAllocator = Nothing
                         Dim statemachineTypeOpt As StateMachineTypeSymbol = Nothing
 
+                        Dim lambdaDebugInfoBuilder = ArrayBuilder(Of LambdaDebugInfo).GetInstance()
+                        Dim closureDebugInfoBuilder = ArrayBuilder(Of ClosureDebugInfo).GetInstance()
                         Dim delegateRelaxationIdDispenser = 0
                         Dim dynamicAnalysisSpans As ImmutableArray(Of SourceSpan) = ImmutableArray(Of SourceSpan).Empty
 
@@ -953,7 +949,6 @@ Namespace Microsoft.CodeAnalysis.VisualBasic
                             lazyVariableSlotAllocator:=lazyVariableSlotAllocator,
                             lambdaDebugInfoBuilder:=lambdaDebugInfoBuilder,
                             closureDebugInfoBuilder:=closureDebugInfoBuilder,
-                            stateMachineStateDebugInfoBuilder:=stateMachineStateDebugInfoBuilder,
                             delegateRelaxationIdDispenser:=delegateRelaxationIdDispenser,
                             stateMachineTypeOpt:=statemachineTypeOpt,
                             allowOmissionOfConditionalCalls:=_moduleBeingBuiltOpt.AllowOmissionOfConditionalCalls,
@@ -968,7 +963,6 @@ Namespace Microsoft.CodeAnalysis.VisualBasic
                                                              rewrittenBody,
                                                              lambdaDebugInfoBuilder.ToImmutable(),
                                                              closureDebugInfoBuilder.ToImmutable(),
-                                                             stateMachineStateDebugInfoBuilder.ToImmutable(),
                                                              statemachineTypeOpt,
                                                              lazyVariableSlotAllocator,
                                                              debugDocumentProvider:=Nothing,
@@ -977,6 +971,9 @@ Namespace Microsoft.CodeAnalysis.VisualBasic
                                                              emitTestCoverageData:=False,
                                                              dynamicAnalysisSpans:=dynamicAnalysisSpans)
                         End If
+
+                        lambdaDebugInfoBuilder.Free()
+                        closureDebugInfoBuilder.Free()
                     End If
 
                     _diagnostics.AddRange(diagnosticsThisMethod)
@@ -991,10 +988,6 @@ Namespace Microsoft.CodeAnalysis.VisualBasic
                         _moduleBeingBuiltOpt.SetMethodBody(method, emittedBody)
                     End If
 
-                    lambdaDebugInfoBuilder.Clear()
-                    closureDebugInfoBuilder.Clear()
-                    stateMachineStateDebugInfoBuilder.Clear()
-
                     methodOrdinal += 1
                 Next
             Next
@@ -1004,9 +997,6 @@ Namespace Microsoft.CodeAnalysis.VisualBasic
             End If
 
             compilationState.Free()
-            lambdaDebugInfoBuilder.Free()
-            closureDebugInfoBuilder.Free()
-            stateMachineStateDebugInfoBuilder.Free()
         End Sub
 
         Private Sub CompileSynthesizedMethods(compilationState As TypeCompilationState)
@@ -1027,7 +1017,6 @@ Namespace Microsoft.CodeAnalysis.VisualBasic
                                                          block:=methodWithBody.Body,
                                                          lambdaDebugInfo:=ImmutableArray(Of LambdaDebugInfo).Empty,
                                                          closureDebugInfo:=ImmutableArray(Of ClosureDebugInfo).Empty,
-                                                         stateMachineStateDebugInfos:=ImmutableArray(Of StateMachineStateDebugInfo).Empty,
                                                          stateMachineTypeOpt:=Nothing,
                                                          variableSlotAllocatorOpt:=Nothing,
                                                          debugDocumentProvider:=_debugDocumentProvider,
@@ -1362,7 +1351,6 @@ Namespace Microsoft.CodeAnalysis.VisualBasic
 
                 Dim lambdaDebugInfoBuilder = ArrayBuilder(Of LambdaDebugInfo).GetInstance()
                 Dim closureDebugInfoBuilder = ArrayBuilder(Of ClosureDebugInfo).GetInstance()
-                Dim stateMachineStateDebugInfoBuilder = ArrayBuilder(Of StateMachineStateDebugInfo).GetInstance()
 
                 setterBody = Rewriter.LowerBodyOrInitializer(setter,
                                                              withEventPropertyIdDispenser,
@@ -1376,20 +1364,17 @@ Namespace Microsoft.CodeAnalysis.VisualBasic
                                                              lazyVariableSlotAllocator:=Nothing,
                                                              lambdaDebugInfoBuilder:=lambdaDebugInfoBuilder,
                                                              closureDebugInfoBuilder:=closureDebugInfoBuilder,
-                                                             stateMachineStateDebugInfoBuilder:=stateMachineStateDebugInfoBuilder,
                                                              delegateRelaxationIdDispenser:=delegateRelaxationIdDispenser,
                                                              stateMachineTypeOpt:=Nothing,
                                                              allowOmissionOfConditionalCalls:=True,
                                                              isBodySynthesized:=True)
 
-                ' There shall be no lambdas and no awaits/yields in the synthesized accessor but delegate relaxation conversions:
-                Debug.Assert(lambdaDebugInfoBuilder.IsEmpty())
-                Debug.Assert(closureDebugInfoBuilder.IsEmpty())
-                Debug.Assert(stateMachineStateDebugInfoBuilder.IsEmpty())
+                ' There shall be no lambdas in the synthesized accessor but delegate relaxation conversions:
+                Debug.Assert(Not lambdaDebugInfoBuilder.Any())
+                Debug.Assert(Not closureDebugInfoBuilder.Any())
 
                 lambdaDebugInfoBuilder.Free()
                 closureDebugInfoBuilder.Free()
-                stateMachineStateDebugInfoBuilder.Free()
 
                 compilationState.AddMethodWrapper(setter, setter, setterBody)
                 _moduleBeingBuiltOpt.AddSynthesizedDefinition(containingType, setter.GetCciAdapter())
@@ -1474,7 +1459,6 @@ Namespace Microsoft.CodeAnalysis.VisualBasic
             Dim allowOmissionOfConditionalCalls = _moduleBeingBuiltOpt Is Nothing OrElse _moduleBeingBuiltOpt.AllowOmissionOfConditionalCalls
             Dim lambdaDebugInfoBuilder = ArrayBuilder(Of LambdaDebugInfo).GetInstance()
             Dim closureDebugInfoBuilder = ArrayBuilder(Of ClosureDebugInfo).GetInstance()
-            Dim stateMachineStateDebugInfoBuilder = ArrayBuilder(Of StateMachineStateDebugInfo).GetInstance()
             Dim dynamicAnalysisSpans As ImmutableArray(Of SourceSpan) = ImmutableArray(Of SourceSpan).Empty
 
             body = Rewriter.LowerBodyOrInitializer(method,
@@ -1489,7 +1473,6 @@ Namespace Microsoft.CodeAnalysis.VisualBasic
                                                    lazyVariableSlotAllocator,
                                                    lambdaDebugInfoBuilder,
                                                    closureDebugInfoBuilder,
-                                                   stateMachineStateDebugInfoBuilder,
                                                    delegateRelaxationIdDispenser,
                                                    stateMachineTypeOpt,
                                                    allowOmissionOfConditionalCalls,
@@ -1530,7 +1513,6 @@ Namespace Microsoft.CodeAnalysis.VisualBasic
                                                               body,
                                                               lambdaDebugInfoBuilder.ToImmutable(),
                                                               closureDebugInfoBuilder.ToImmutable(),
-                                                              stateMachineStateDebugInfoBuilder.ToImmutable(),
                                                               stateMachineTypeOpt,
                                                               lazyVariableSlotAllocator,
                                                               _debugDocumentProvider,
@@ -1558,7 +1540,6 @@ Namespace Microsoft.CodeAnalysis.VisualBasic
                                                   block As BoundStatement,
                                                   lambdaDebugInfo As ImmutableArray(Of LambdaDebugInfo),
                                                   closureDebugInfo As ImmutableArray(Of ClosureDebugInfo),
-                                                  stateMachineStateDebugInfos As ImmutableArray(Of StateMachineStateDebugInfo),
                                                   stateMachineTypeOpt As StateMachineTypeSymbol,
                                                   variableSlotAllocatorOpt As VariableSlotAllocator,
                                                   debugDocumentProvider As DebugDocumentProvider,
@@ -1690,7 +1671,6 @@ Namespace Microsoft.CodeAnalysis.VisualBasic
                                       stateMachineHoistedLocalScopes:=stateMachineHoistedLocalScopes,
                                       stateMachineHoistedLocalSlots:=stateMachineHoistedLocalSlots,
                                       stateMachineAwaiterSlots:=stateMachineAwaiterSlots,
-                                      stateMachineStatesDebugInfo:=StateMachineStatesDebugInfo.Create(variableSlotAllocatorOpt, stateMachineStateDebugInfos),
                                       stateMachineMoveNextDebugInfoOpt:=moveNextBodyDebugInfoOpt,
                                       dynamicAnalysisDataOpt:=dynamicAnalysisDataOpt)
             Finally
diff --git a/src/Compilers/VisualBasic/Portable/Emit/EditAndContinue/VisualBasicDefinitionMap.vb b/src/Compilers/VisualBasic/Portable/Emit/EditAndContinue/VisualBasicDefinitionMap.vb
index 98b2a823c3454..1e0f115eadb06 100644
--- a/src/Compilers/VisualBasic/Portable/Emit/EditAndContinue/VisualBasicDefinitionMap.vb
+++ b/src/Compilers/VisualBasic/Portable/Emit/EditAndContinue/VisualBasicDefinitionMap.vb
@@ -124,9 +124,11 @@ Namespace Microsoft.CodeAnalysis.VisualBasic.Emit
             End If
         End Function
 
-        Protected Overrides Function TryGetStateMachineType(methodHandle As MethodDefinitionHandle) As ITypeSymbolInternal
+        Protected Overrides Function TryGetStateMachineType(methodHandle As EntityHandle) As ITypeSymbolInternal
             Dim typeName As String = Nothing
-            If _metadataDecoder.Module.HasStateMachineAttribute(methodHandle, typeName) Then
+            If _metadataDecoder.Module.HasStringValuedAttribute(methodHandle, AttributeDescription.AsyncStateMachineAttribute, typeName) OrElse
+               _metadataDecoder.Module.HasStringValuedAttribute(methodHandle, AttributeDescription.IteratorStateMachineAttribute, typeName) Then
+
                 Return _metadataDecoder.GetTypeSymbolForSerializedType(typeName)
             End If
 
diff --git a/src/Compilers/VisualBasic/Portable/Lowering/AsyncRewriter/AsyncRewriter.AsyncMethodToClassRewriter.vb b/src/Compilers/VisualBasic/Portable/Lowering/AsyncRewriter/AsyncRewriter.AsyncMethodToClassRewriter.vb
index 8f15aa7075c26..d67f29bc420c9 100644
--- a/src/Compilers/VisualBasic/Portable/Lowering/AsyncRewriter/AsyncRewriter.AsyncMethodToClassRewriter.vb
+++ b/src/Compilers/VisualBasic/Portable/Lowering/AsyncRewriter/AsyncRewriter.AsyncMethodToClassRewriter.vb
@@ -66,12 +66,11 @@ Namespace Microsoft.CodeAnalysis.VisualBasic
                            builder As FieldSymbol,
                            hoistedVariables As IReadOnlySet(Of Symbol),
                            nonReusableLocalProxies As Dictionary(Of Symbol, CapturedSymbolOrExpression),
-                           stateMachineStateDebugInfoBuilder As ArrayBuilder(Of StateMachineStateDebugInfo),
                            slotAllocatorOpt As VariableSlotAllocator,
                            owner As AsyncRewriter,
                            diagnostics As BindingDiagnosticBag)
 
-                MyBase.New(F, state, hoistedVariables, nonReusableLocalProxies, stateMachineStateDebugInfoBuilder, slotAllocatorOpt, diagnostics)
+                MyBase.New(F, state, hoistedVariables, nonReusableLocalProxies, slotAllocatorOpt, diagnostics)
 
                 Me._method = method
                 Me._builder = builder
diff --git a/src/Compilers/VisualBasic/Portable/Lowering/AsyncRewriter/AsyncRewriter.vb b/src/Compilers/VisualBasic/Portable/Lowering/AsyncRewriter/AsyncRewriter.vb
index d1032d750de75..80eccb8a90524 100644
--- a/src/Compilers/VisualBasic/Portable/Lowering/AsyncRewriter/AsyncRewriter.vb
+++ b/src/Compilers/VisualBasic/Portable/Lowering/AsyncRewriter/AsyncRewriter.vb
@@ -28,13 +28,12 @@ Namespace Microsoft.CodeAnalysis.VisualBasic
         Public Sub New(body As BoundStatement,
                        method As MethodSymbol,
                        stateMachineType As AsyncStateMachine,
-                       stateMachineStateDebugInfoBuilder As ArrayBuilder(Of StateMachineStateDebugInfo),
                        slotAllocatorOpt As VariableSlotAllocator,
                        asyncKind As AsyncMethodKind,
                        compilationState As TypeCompilationState,
                        diagnostics As BindingDiagnosticBag)
 
-            MyBase.New(body, method, stateMachineType, stateMachineStateDebugInfoBuilder, slotAllocatorOpt, compilationState, diagnostics)
+            MyBase.New(body, method, stateMachineType, slotAllocatorOpt, compilationState, diagnostics)
 
             Me._binder = CreateMethodBinder(method)
             Me._lookupOptions = LookupOptions.AllMethodsOfAnyArity Or LookupOptions.IgnoreExtensionMethods Or LookupOptions.NoBaseClassLookup
@@ -72,7 +71,6 @@ Namespace Microsoft.CodeAnalysis.VisualBasic
         Friend Overloads Shared Function Rewrite(body As BoundBlock,
                                                  method As MethodSymbol,
                                                  methodOrdinal As Integer,
-                                                 stateMachineStateDebugInfoBuilder As ArrayBuilder(Of StateMachineStateDebugInfo),
                                                  slotAllocatorOpt As VariableSlotAllocator,
                                                  compilationState As TypeCompilationState,
                                                  diagnostics As BindingDiagnosticBag,
@@ -94,7 +92,7 @@ Namespace Microsoft.CodeAnalysis.VisualBasic
 
             compilationState.ModuleBuilderOpt.CompilationState.SetStateMachineType(method, stateMachineType)
 
-            Dim rewriter As New AsyncRewriter(body, method, stateMachineType, stateMachineStateDebugInfoBuilder, slotAllocatorOpt, asyncMethodKind, compilationState, diagnostics)
+            Dim rewriter As New AsyncRewriter(body, method, stateMachineType, slotAllocatorOpt, asyncMethodKind, compilationState, diagnostics)
 
             ' check if we have all the types we need
             If rewriter.EnsureAllSymbolsAndSignature() Then
@@ -259,7 +257,6 @@ Namespace Microsoft.CodeAnalysis.VisualBasic
                 builder:=_builderField,
                 hoistedVariables:=hoistedVariables,
                 nonReusableLocalProxies:=nonReusableLocalProxies,
-                StateDebugInfoBuilder,
                 slotAllocatorOpt:=SlotAllocatorOpt,
                 owner:=Me,
                 diagnostics:=Diagnostics)
diff --git a/src/Compilers/VisualBasic/Portable/Lowering/IteratorRewriter/IteratorRewriter.IteratorMethodToClassRewriter.vb b/src/Compilers/VisualBasic/Portable/Lowering/IteratorRewriter/IteratorRewriter.IteratorMethodToClassRewriter.vb
index 2eae48b96e447..ce00cd5b7bf72 100644
--- a/src/Compilers/VisualBasic/Portable/Lowering/IteratorRewriter/IteratorRewriter.IteratorMethodToClassRewriter.vb
+++ b/src/Compilers/VisualBasic/Portable/Lowering/IteratorRewriter/IteratorRewriter.IteratorMethodToClassRewriter.vb
@@ -29,11 +29,10 @@ Namespace Microsoft.CodeAnalysis.VisualBasic
                            current As FieldSymbol,
                            hoistedVariables As IReadOnlySet(Of Symbol),
                            localProxies As Dictionary(Of Symbol, FieldSymbol),
-                           stateMachineStateDebugInfoBuilder As ArrayBuilder(Of StateMachineStateDebugInfo),
                            slotAllocatorOpt As VariableSlotAllocator,
                            diagnostics As BindingDiagnosticBag)
 
-                MyBase.New(F, state, hoistedVariables, localProxies, stateMachineStateDebugInfoBuilder, slotAllocatorOpt, diagnostics)
+                MyBase.New(F, state, hoistedVariables, localProxies, slotAllocatorOpt, diagnostics)
 
                 _current = current
             End Sub
diff --git a/src/Compilers/VisualBasic/Portable/Lowering/IteratorRewriter/IteratorRewriter.vb b/src/Compilers/VisualBasic/Portable/Lowering/IteratorRewriter/IteratorRewriter.vb
index 125c80376913d..e5d4b2b0bc25f 100644
--- a/src/Compilers/VisualBasic/Portable/Lowering/IteratorRewriter/IteratorRewriter.vb
+++ b/src/Compilers/VisualBasic/Portable/Lowering/IteratorRewriter/IteratorRewriter.vb
@@ -23,12 +23,11 @@ Namespace Microsoft.CodeAnalysis.VisualBasic
                        method As MethodSymbol,
                        isEnumerable As Boolean,
                        stateMachineType As IteratorStateMachine,
-                       stateMachineStateDebugInfoBuilder As ArrayBuilder(Of StateMachineStateDebugInfo),
                        slotAllocatorOpt As VariableSlotAllocator,
                        compilationState As TypeCompilationState,
                        diagnostics As BindingDiagnosticBag)
 
-            MyBase.New(body, method, stateMachineType, stateMachineStateDebugInfoBuilder, slotAllocatorOpt, compilationState, diagnostics)
+            MyBase.New(body, method, stateMachineType, slotAllocatorOpt, compilationState, diagnostics)
 
             Me._isEnumerable = isEnumerable
 
@@ -47,7 +46,6 @@ Namespace Microsoft.CodeAnalysis.VisualBasic
         Friend Overloads Shared Function Rewrite(body As BoundBlock,
                                                  method As MethodSymbol,
                                                  methodOrdinal As Integer,
-                                                 stateMachineStateDebugInfoBuilder As ArrayBuilder(Of StateMachineStateDebugInfo),
                                                  slotAllocatorOpt As VariableSlotAllocator,
                                                  compilationState As TypeCompilationState,
                                                  diagnostics As BindingDiagnosticBag,
@@ -74,7 +72,7 @@ Namespace Microsoft.CodeAnalysis.VisualBasic
 
             compilationState.ModuleBuilderOpt.CompilationState.SetStateMachineType(method, stateMachineType)
 
-            Dim rewriter As New IteratorRewriter(body, method, isEnumerable, stateMachineType, stateMachineStateDebugInfoBuilder, slotAllocatorOpt, compilationState, diagnostics)
+            Dim rewriter As New IteratorRewriter(body, method, isEnumerable, stateMachineType, slotAllocatorOpt, compilationState, diagnostics)
 
             ' check if we have all the types we need
             If rewriter.EnsureAllSymbolsAndSignature() Then
@@ -349,7 +347,6 @@ Namespace Microsoft.CodeAnalysis.VisualBasic
                 current:=_currentField,
                 hoistedVariables:=hoistedVariables,
                 localProxies:=nonReusableLocalProxies,
-                StateDebugInfoBuilder,
                 slotAllocatorOpt:=SlotAllocatorOpt,
                 diagnostics:=Diagnostics)
 
diff --git a/src/Compilers/VisualBasic/Portable/Lowering/LambdaRewriter/LambdaRewriter.vb b/src/Compilers/VisualBasic/Portable/Lowering/LambdaRewriter/LambdaRewriter.vb
index 28fb21526a96d..7a60d299baec6 100644
--- a/src/Compilers/VisualBasic/Portable/Lowering/LambdaRewriter/LambdaRewriter.vb
+++ b/src/Compilers/VisualBasic/Portable/Lowering/LambdaRewriter/LambdaRewriter.vb
@@ -901,11 +901,8 @@ Namespace Microsoft.CodeAnalysis.VisualBasic
             ' produce a unique method ordinal for the corresponding state machine type, whose name includes the (unique) method name.
             Const methodOrdinal As Integer = -1
 
-            Dim stateMachineStateDebugInfosBuilder = ArrayBuilder(Of StateMachineStateDebugInfo).GetInstance()
             Dim slotAllocatorOpt = CompilationState.ModuleBuilderOpt.TryCreateVariableSlotAllocator(method, method.TopLevelMethod, Diagnostics.DiagnosticBag)
-            Dim result = Rewriter.RewriteIteratorAndAsync(loweredBody, method, methodOrdinal, CompilationState, Diagnostics, stateMachineStateDebugInfosBuilder, slotAllocatorOpt, stateMachineTypeOpt)
-            stateMachineStateDebugInfosBuilder.Free()
-            Return result
+            Return Rewriter.RewriteIteratorAndAsync(loweredBody, method, methodOrdinal, CompilationState, Diagnostics, slotAllocatorOpt, stateMachineTypeOpt)
         End Function
 
         Public Overrides Function VisitTryCast(node As BoundTryCast) As BoundNode
diff --git a/src/Compilers/VisualBasic/Portable/Lowering/Rewriter.vb b/src/Compilers/VisualBasic/Portable/Lowering/Rewriter.vb
index 9c2f8e72bbf6a..91c2bdff8f81a 100644
--- a/src/Compilers/VisualBasic/Portable/Lowering/Rewriter.vb
+++ b/src/Compilers/VisualBasic/Portable/Lowering/Rewriter.vb
@@ -26,7 +26,6 @@ Namespace Microsoft.CodeAnalysis.VisualBasic
             ByRef lazyVariableSlotAllocator As VariableSlotAllocator,
             lambdaDebugInfoBuilder As ArrayBuilder(Of LambdaDebugInfo),
             closureDebugInfoBuilder As ArrayBuilder(Of ClosureDebugInfo),
-            stateMachineStateDebugInfoBuilder As ArrayBuilder(Of StateMachineStateDebugInfo),
             ByRef delegateRelaxationIdDispenser As Integer,
             <Out> ByRef stateMachineTypeOpt As StateMachineTypeSymbol,
             allowOmissionOfConditionalCalls As Boolean,
@@ -109,7 +108,7 @@ Namespace Microsoft.CodeAnalysis.VisualBasic
                     Return bodyWithoutLambdas
                 End If
 
-                Dim bodyWithoutIteratorAndAsync = RewriteIteratorAndAsync(bodyWithoutLambdas, method, methodOrdinal, compilationState, localDiagnostics, stateMachineStateDebugInfoBuilder, lazyVariableSlotAllocator, stateMachineTypeOpt)
+                Dim bodyWithoutIteratorAndAsync = RewriteIteratorAndAsync(bodyWithoutLambdas, method, methodOrdinal, compilationState, localDiagnostics, lazyVariableSlotAllocator, stateMachineTypeOpt)
 
                 diagnostics.AddRangeAndFree(localDiagnostics)
 
@@ -128,7 +127,6 @@ Namespace Microsoft.CodeAnalysis.VisualBasic
                                                        methodOrdinal As Integer,
                                                        compilationState As TypeCompilationState,
                                                        diagnostics As BindingDiagnosticBag,
-                                                       stateMachineStateDebugInfoBuilder As ArrayBuilder(Of StateMachineStateDebugInfo),
                                                        slotAllocatorOpt As VariableSlotAllocator,
                                                        <Out> ByRef stateMachineTypeOpt As StateMachineTypeSymbol) As BoundBlock
 
@@ -138,7 +136,6 @@ Namespace Microsoft.CodeAnalysis.VisualBasic
             Dim bodyWithoutIterators = IteratorRewriter.Rewrite(bodyWithoutLambdas,
                                                                 method,
                                                                 methodOrdinal,
-                                                                stateMachineStateDebugInfoBuilder,
                                                                 slotAllocatorOpt,
                                                                 compilationState,
                                                                 diagnostics,
@@ -152,7 +149,6 @@ Namespace Microsoft.CodeAnalysis.VisualBasic
             Dim bodyWithoutAsync = AsyncRewriter.Rewrite(bodyWithoutIterators,
                                                          method,
                                                          methodOrdinal,
-                                                         stateMachineStateDebugInfoBuilder,
                                                          slotAllocatorOpt,
                                                          compilationState,
                                                          diagnostics,
diff --git a/src/Compilers/VisualBasic/Portable/Lowering/StateMachineRewriter/StateMachineRewriter.StateMachineMethodToClassRewriter.vb b/src/Compilers/VisualBasic/Portable/Lowering/StateMachineRewriter/StateMachineRewriter.StateMachineMethodToClassRewriter.vb
index 786aa909d716a..7003970ca9c60 100644
--- a/src/Compilers/VisualBasic/Portable/Lowering/StateMachineRewriter/StateMachineRewriter.StateMachineMethodToClassRewriter.vb
+++ b/src/Compilers/VisualBasic/Portable/Lowering/StateMachineRewriter/StateMachineRewriter.StateMachineMethodToClassRewriter.vb
@@ -65,13 +65,10 @@ Namespace Microsoft.CodeAnalysis.VisualBasic
             ''' </summary>
             Private ReadOnly _hoistedVariables As IReadOnlySet(Of Symbol) = Nothing
 
-            Private ReadOnly _stateDebugInfoBuilder As ArrayBuilder(Of StateMachineStateDebugInfo)
-
             Public Sub New(F As SyntheticBoundNodeFactory,
                            stateField As FieldSymbol,
                            hoistedVariables As IReadOnlySet(Of Symbol),
                            initialProxies As Dictionary(Of Symbol, TProxy),
-                           stateMachineStateDebugInfoBuilder As ArrayBuilder(Of StateMachineStateDebugInfo),
                            slotAllocatorOpt As VariableSlotAllocator,
                            diagnostics As BindingDiagnosticBag)
 
@@ -87,7 +84,6 @@ Namespace Microsoft.CodeAnalysis.VisualBasic
                 Me.StateField = stateField
                 Me.CachedState = F.SynthesizedLocal(F.SpecialType(SpecialType.System_Int32), SynthesizedLocalKind.StateMachineCachedState, F.Syntax)
                 Me._hoistedVariables = hoistedVariables
-                Me._stateDebugInfoBuilder = stateMachineStateDebugInfoBuilder
 
                 For Each p In initialProxies
                     Me.Proxies.Add(p.Key, p.Value)
diff --git a/src/Compilers/VisualBasic/Portable/Lowering/StateMachineRewriter/StateMachineRewriter.vb b/src/Compilers/VisualBasic/Portable/Lowering/StateMachineRewriter/StateMachineRewriter.vb
index 008be8c2623d7..a36f12afb3185 100644
--- a/src/Compilers/VisualBasic/Portable/Lowering/StateMachineRewriter/StateMachineRewriter.vb
+++ b/src/Compilers/VisualBasic/Portable/Lowering/StateMachineRewriter/StateMachineRewriter.vb
@@ -28,7 +28,6 @@ Namespace Microsoft.CodeAnalysis.VisualBasic
         Protected ReadOnly StateMachineType As SynthesizedContainer
         Protected ReadOnly SlotAllocatorOpt As VariableSlotAllocator
         Protected ReadOnly SynthesizedLocalOrdinals As SynthesizedLocalOrdinalsDispenser
-        Protected ReadOnly StateDebugInfoBuilder As ArrayBuilder(Of StateMachineStateDebugInfo)
 
         Protected StateField As FieldSymbol
         Protected nonReusableLocalProxies As Dictionary(Of Symbol, TProxy)
@@ -39,7 +38,6 @@ Namespace Microsoft.CodeAnalysis.VisualBasic
         Protected Sub New(body As BoundStatement,
                           method As MethodSymbol,
                           stateMachineType As StateMachineTypeSymbol,
-                          stateMachineStateDebugInfoBuilder As ArrayBuilder(Of StateMachineStateDebugInfo),
                           slotAllocatorOpt As VariableSlotAllocator,
                           compilationState As TypeCompilationState,
                           diagnostics As BindingDiagnosticBag)
@@ -57,7 +55,6 @@ Namespace Microsoft.CodeAnalysis.VisualBasic
             Me.SlotAllocatorOpt = slotAllocatorOpt
             Me.Diagnostics = diagnostics
             Me.SynthesizedLocalOrdinals = New SynthesizedLocalOrdinalsDispenser()
-            Me.StateDebugInfoBuilder = stateMachineStateDebugInfoBuilder
             Me.nonReusableLocalProxies = New Dictionary(Of Symbol, TProxy)()
 
             Me.F = New SyntheticBoundNodeFactory(method, method, method.ContainingType, body.Syntax, compilationState, diagnostics)
diff --git a/src/Dependencies/CodeAnalysis.Debugging/CustomDebugInfoKind.cs b/src/Dependencies/CodeAnalysis.Debugging/CustomDebugInfoKind.cs
index 9be8932163b09..afaf08923233f 100644
--- a/src/Dependencies/CodeAnalysis.Debugging/CustomDebugInfoKind.cs
+++ b/src/Dependencies/CodeAnalysis.Debugging/CustomDebugInfoKind.cs
@@ -62,10 +62,5 @@ internal enum CustomDebugInfoKind : byte
         /// C# and VB. Tuple element names for local variables and constants.
         /// </summary>
         TupleElementNames = 8,
-
-        /// <summary>
-        /// C# and VB. Syntax offsets of nodes associated with state machine states in an async/iterator method and their corresponding state numbers.
-        /// </summary>
-        EditAndContinueStateMachineStateMap = 9,
     }
 }
diff --git a/src/Dependencies/CodeAnalysis.Debugging/PortableCustomDebugInfoKinds.cs b/src/Dependencies/CodeAnalysis.Debugging/PortableCustomDebugInfoKinds.cs
index 4e0e325055ab0..d05cb8526a91b 100644
--- a/src/Dependencies/CodeAnalysis.Debugging/PortableCustomDebugInfoKinds.cs
+++ b/src/Dependencies/CodeAnalysis.Debugging/PortableCustomDebugInfoKinds.cs
@@ -17,7 +17,6 @@ internal static class PortableCustomDebugInfoKinds
         public static readonly Guid DefaultNamespace = new("58b2eab6-209f-4e4e-a22c-b2d0f910c782");
         public static readonly Guid EncLocalSlotMap = new("755F52A8-91C5-45BE-B4B8-209571E552BD");
         public static readonly Guid EncLambdaAndClosureMap = new("A643004C-0240-496F-A783-30D64F4979DE");
-        public static readonly Guid EncStateMachineStateMap = new("8B78CD68-2EDE-420B-980B-E15884B8AAA3");
         public static readonly Guid SourceLink = new("CC110556-A091-4D38-9FEC-25AB9A351A6A");
         public static readonly Guid EmbeddedSource = new("0E8A571B-6926-466E-B4AD-8AB04611F5FE");
         public static readonly Guid CompilationMetadataReferences = new("7E4D4708-096E-4C5C-AEDA-CB10BA6A740D");
diff --git a/src/ExpressionEvaluator/CSharp/Source/ExpressionCompiler/CompilationExtensions.cs b/src/ExpressionEvaluator/CSharp/Source/ExpressionCompiler/CompilationExtensions.cs
index 932effdfbd4e9..4401a643f5afd 100644
--- a/src/ExpressionEvaluator/CSharp/Source/ExpressionCompiler/CompilationExtensions.cs
+++ b/src/ExpressionEvaluator/CSharp/Source/ExpressionCompiler/CompilationExtensions.cs
@@ -38,11 +38,20 @@ internal static PEMethodSymbol GetSourceMethod(this CSharpCompilation compilatio
             {
                 foreach (var member in containingType.ContainingType.GetMembers(sourceMethodName))
                 {
-                    if (member is PEMethodSymbol candidateMethod &&
-                        metadataDecoder.Module.HasStateMachineAttribute(candidateMethod.Handle, out var stateMachineTypeName) &&
-                        metadataDecoder.GetTypeSymbolForSerializedType(stateMachineTypeName).OriginalDefinition.Equals(containingType))
+                    if (member is PEMethodSymbol candidateMethod)
                     {
-                        return candidateMethod;
+                        var module = metadataDecoder.Module;
+                        methodHandle = candidateMethod.Handle;
+                        string stateMachineTypeName;
+                        if (module.HasStringValuedAttribute(methodHandle, AttributeDescription.AsyncStateMachineAttribute, out stateMachineTypeName) ||
+                            module.HasStringValuedAttribute(methodHandle, AttributeDescription.IteratorStateMachineAttribute, out stateMachineTypeName) ||
+                            module.HasStringValuedAttribute(methodHandle, AttributeDescription.AsyncIteratorStateMachineAttribute, out stateMachineTypeName))
+                        {
+                            if (metadataDecoder.GetTypeSymbolForSerializedType(stateMachineTypeName).OriginalDefinition.Equals(containingType))
+                            {
+                                return candidateMethod;
+                            }
+                        }
                     }
                 }
             }
diff --git a/src/ExpressionEvaluator/CSharp/Source/ExpressionCompiler/EEAssemblyBuilder.cs b/src/ExpressionEvaluator/CSharp/Source/ExpressionCompiler/EEAssemblyBuilder.cs
index bb174945a96de..5b1cb9fe323c1 100644
--- a/src/ExpressionEvaluator/CSharp/Source/ExpressionCompiler/EEAssemblyBuilder.cs
+++ b/src/ExpressionEvaluator/CSharp/Source/ExpressionCompiler/EEAssemblyBuilder.cs
@@ -12,7 +12,6 @@
 using Microsoft.CodeAnalysis.Symbols;
 using Roslyn.Utilities;
 using System;
-using System.Collections.Generic;
 using System.Collections.Immutable;
 using System.Diagnostics;
 using System.Reflection.Metadata;
@@ -174,13 +173,6 @@ public override bool TryGetPreviousLambda(SyntaxNode lambdaOrLambdaBodySyntax, b
                 return false;
             }
 
-            public override bool TryGetPreviousStateMachineState(SyntaxNode awaitOrYieldSyntax, out int stateOrdinal)
-            {
-                stateOrdinal = 0;
-                return false;
-            }
-
-            public override int? GetFirstUnusedStateMachineState(bool increasing) => null;
             public override string? PreviousStateMachineTypeName => null;
             public override int PreviousHoistedLocalSlotCount => 0;
             public override int PreviousAwaiterSlotCount => 0;
diff --git a/src/ExpressionEvaluator/VisualBasic/Source/ExpressionCompiler/CompilationExtensions.vb b/src/ExpressionEvaluator/VisualBasic/Source/ExpressionCompiler/CompilationExtensions.vb
index 78ac4b0404922..90096eaf0d461 100644
--- a/src/ExpressionEvaluator/VisualBasic/Source/ExpressionCompiler/CompilationExtensions.vb
+++ b/src/ExpressionEvaluator/VisualBasic/Source/ExpressionCompiler/CompilationExtensions.vb
@@ -35,10 +35,16 @@ Namespace Microsoft.CodeAnalysis.VisualBasic.ExpressionEvaluator
                 For Each member In containingType.ContainingType.GetMembers(sourceMethodName)
                     Dim candidateMethod = TryCast(member, PEMethodSymbol)
                     If candidateMethod IsNot Nothing Then
+                        Dim [module] = metadataDecoder.Module
+                        methodHandle = candidateMethod.Handle
                         Dim stateMachineTypeName As String = Nothing
-                        If metadataDecoder.Module.HasStateMachineAttribute(candidateMethod.Handle, stateMachineTypeName) AndAlso
-                            metadataDecoder.GetTypeSymbolForSerializedType(stateMachineTypeName).OriginalDefinition.Equals(containingType) Then
-                            Return candidateMethod
+                        If [module].HasStringValuedAttribute(methodHandle, AttributeDescription.AsyncStateMachineAttribute, stateMachineTypeName) OrElse
+                            [module].HasStringValuedAttribute(methodHandle, AttributeDescription.IteratorStateMachineAttribute, stateMachineTypeName) OrElse
+                            [module].HasStringValuedAttribute(methodHandle, AttributeDescription.AsyncIteratorStateMachineAttribute, stateMachineTypeName) _
+                        Then
+                            If metadataDecoder.GetTypeSymbolForSerializedType(stateMachineTypeName).OriginalDefinition.Equals(containingType) Then
+                                Return candidateMethod
+                            End If
                         End If
                     End If
                 Next
diff --git a/src/ExpressionEvaluator/VisualBasic/Source/ExpressionCompiler/EEAssemblyBuilder.vb b/src/ExpressionEvaluator/VisualBasic/Source/ExpressionCompiler/EEAssemblyBuilder.vb
index aad85d9ce0e75..4e2cb1a42a5b5 100644
--- a/src/ExpressionEvaluator/VisualBasic/Source/ExpressionCompiler/EEAssemblyBuilder.vb
+++ b/src/ExpressionEvaluator/VisualBasic/Source/ExpressionCompiler/EEAssemblyBuilder.vb
@@ -191,15 +191,6 @@ Namespace Microsoft.CodeAnalysis.VisualBasic.ExpressionEvaluator
                 Return False
             End Function
 
-            Public Overrides Function TryGetPreviousStateMachineState(awaitOrYieldSyntax As SyntaxNode, ByRef stateOrdinal As Integer) As Boolean
-                stateOrdinal = 0
-                Return False
-            End Function
-
-            Public Overrides Function GetFirstUnusedStateMachineState(increasing As Boolean) As Integer?
-                Return Nothing
-            End Function
-
             Public Overrides ReadOnly Property PreviousStateMachineTypeName As String
                 Get
                     Return Nothing
diff --git a/src/Features/Core/Portable/EditAndContinue/EditAndContinueMethodDebugInfoReader.cs b/src/Features/Core/Portable/EditAndContinue/EditAndContinueMethodDebugInfoReader.cs
index cbc870e77d4dc..98917b86fbc76 100644
--- a/src/Features/Core/Portable/EditAndContinue/EditAndContinueMethodDebugInfoReader.cs
+++ b/src/Features/Core/Portable/EditAndContinue/EditAndContinueMethodDebugInfoReader.cs
@@ -81,19 +81,18 @@ public override EditAndContinueMethodDebugInformation GetDebugInfo(MethodDefinit
 
                 try
                 {
-                    ImmutableArray<byte> localSlots, lambdaMap, stateMachineSuspensionPoints;
+                    ImmutableArray<byte> localSlots, lambdaMap;
                     if (debugInfo != null)
                     {
                         localSlots = CustomDebugInfoReader.TryGetCustomDebugInfoRecord(debugInfo, CustomDebugInfoKind.EditAndContinueLocalSlotMap);
                         lambdaMap = CustomDebugInfoReader.TryGetCustomDebugInfoRecord(debugInfo, CustomDebugInfoKind.EditAndContinueLambdaMap);
-                        stateMachineSuspensionPoints = CustomDebugInfoReader.TryGetCustomDebugInfoRecord(debugInfo, CustomDebugInfoKind.EditAndContinueStateMachineStateMap);
                     }
                     else
                     {
-                        localSlots = lambdaMap = stateMachineSuspensionPoints = default;
+                        localSlots = lambdaMap = default;
                     }
 
-                    return EditAndContinueMethodDebugInformation.Create(localSlots, lambdaMap, stateMachineSuspensionPoints);
+                    return EditAndContinueMethodDebugInformation.Create(localSlots, lambdaMap);
                 }
                 catch (InvalidOperationException e) when (FatalError.ReportAndCatch(e)) // likely a bug in the compiler/debugger
                 {
@@ -121,8 +120,7 @@ public override StandaloneSignatureHandle GetLocalSignature(MethodDefinitionHand
             public override EditAndContinueMethodDebugInformation GetDebugInfo(MethodDefinitionHandle methodHandle)
                 => EditAndContinueMethodDebugInformation.Create(
                     compressedSlotMap: GetCdiBytes(methodHandle, PortableCustomDebugInfoKinds.EncLocalSlotMap),
-                    compressedLambdaMap: GetCdiBytes(methodHandle, PortableCustomDebugInfoKinds.EncLambdaAndClosureMap),
-                    compressedStateMachineStateMap: GetCdiBytes(methodHandle, PortableCustomDebugInfoKinds.EncStateMachineStateMap));
+                    compressedLambdaMap: GetCdiBytes(methodHandle, PortableCustomDebugInfoKinds.EncLambdaAndClosureMap));
 
             private ImmutableArray<byte> GetCdiBytes(MethodDefinitionHandle methodHandle, Guid kind)
                 => TryGetCustomDebugInformation(_pdbReader, methodHandle, kind, out var cdi) ?
diff --git a/src/Test/PdbUtilities/Reader/PdbTestUtilities.cs b/src/Test/PdbUtilities/Reader/PdbTestUtilities.cs
index eeb34443188e0..0845b48e57a42 100644
--- a/src/Test/PdbUtilities/Reader/PdbTestUtilities.cs
+++ b/src/Test/PdbUtilities/Reader/PdbTestUtilities.cs
@@ -47,8 +47,7 @@ ImmutableArray<byte> GetCdiBytes(Guid kind) =>
 
                     return EditAndContinueMethodDebugInformation.Create(
                         compressedSlotMap: GetCdiBytes(PortableCustomDebugInfoKinds.EncLocalSlotMap),
-                        compressedLambdaMap: GetCdiBytes(PortableCustomDebugInfoKinds.EncLambdaAndClosureMap),
-                        compressedStateMachineStateMap: GetCdiBytes(PortableCustomDebugInfoKinds.EncStateMachineStateMap));
+                        compressedLambdaMap: GetCdiBytes(PortableCustomDebugInfoKinds.EncLambdaAndClosureMap));
                 }
             }
 
diff --git a/src/Test/PdbUtilities/Reader/PdbValidation.cs b/src/Test/PdbUtilities/Reader/PdbValidation.cs
index 4d86ef5f9ec7c..37fc37f00f6e1 100644
--- a/src/Test/PdbUtilities/Reader/PdbValidation.cs
+++ b/src/Test/PdbUtilities/Reader/PdbValidation.cs
@@ -642,7 +642,7 @@ internal static void VerifyPdbLambdasAndClosures(this Compilation compilation, S
             expectedTags.Sort((x, y) => x.StartIndex.CompareTo(y.StartIndex));
 
             // Ensure the tag for the method start is the first element
-            expectedTags.Insert(0, new { Tag = "<M:0>", StartIndex = methodStart });
+            expectedTags.Insert(0, new { Tag = "<M>", StartIndex = methodStart });
 
             // Now reverse the list so we can insert without worrying about offsets
             expectedTags.Reverse();