[vm/aot/tfa] Signature shaking for both static and instance methods

The existing signature shaker transforms optional and named parameters
of static and top-level methods and constructors into required
parameters whenever they are always passed.

This change improves signature shaking in a number of areas:
- Extend signature shaking to cover instance methods.
- Remove parameters which are never passed.
- Remove parameters which are not used.
- Transform signatures before unboxing, enabling transformed parameters
  to be unboxed.

TFA summaries for transformed functions are updated to stay in sync with
the program for later transformations.

Reduces instructions size of Flutter Gallery on ARM64 by 2.2%.

Issue: #40488

Change-Id: I39e364bc23b01e4502864d7369a745a9278cfb92
Cq-Do-Not-Cancel-Tryjobs: true
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/161175
Commit-Queue: Aske Simon Christensen <askesc@google.com>
Reviewed-by: Martin Kustermann <kustermann@google.com>
Reviewed-by: Alexander Markov <alexmarkov@google.com>

pkg/vm/lib/transformations/type_flow/analysis.dart

@@ -1535,14 +1535,13 @@ class TypeFlowAnalysis implements EntryPointsListener, CallHandler {
 
   Args<Type> argumentTypes(Member member) => _summaries[member]?.argumentTypes;
 
+  Type argumentType(Member member, VariableDeclaration memberParam) {
+    return _summaries[member]?.argumentType(member, memberParam);
+  }
+
   List<VariableDeclaration> uncheckedParameters(Member member) =>
       _summaries[member]?.uncheckedParameters;
 
-  // The set of optional and named parameters to this procedure which
-  // are passed at all call-sites.
-  Set<String> alwaysPassedOptionalParameters(Member member) =>
-      _summaries[member]?.alwaysPassedOptionalParameters() ?? const {};
-
   bool isTearOffTaken(Member member) => _tearOffTaken.contains(member);
 
   /// Returns true if this member is called on a receiver with static type
@@ -1565,6 +1564,12 @@ class TypeFlowAnalysis implements EntryPointsListener, CallHandler {
       _methodsAndSettersCalledDynamically.contains(member) ||
       _calledViaInterfaceSelector.contains(member);
 
+  /// Update the summary parameters to reflect a signature change with moved
+  /// and/or removed parameters.
+  void adjustFunctionParameters(Member member) {
+    _summaries[member]?.adjustFunctionParameters(member);
+  }
+
   /// ---- Implementation of [CallHandler] interface. ----
 
   @override
@@ -1648,4 +1653,9 @@ class TypeFlowAnalysis implements EntryPointsListener, CallHandler {
   void recordMemberCalledViaThis(Member target) {
     _calledViaThis.add(target);
   }
+
+  @override
+  void recordTearOff(Procedure target) {
+    _tearOffTaken.add(target);
+  }
 }

pkg/vm/lib/transformations/type_flow/calls.dart

@@ -187,20 +187,15 @@ class Args<T extends TypeExpr> {
   final List<T> values;
   final List<String> names;
 
-  // Whether it is not known which optional arguments are passed or not.
-  final bool unknownArity;
-
   int _hashCode;
 
-  Args(this.values,
-      {this.names = const <String>[], this.unknownArity = false}) {
+  Args(this.values, {this.names = const <String>[]}) {
     assert(isSorted(names));
   }
 
   Args.withReceiver(Args<T> args, T receiver)
       : values = new List.from(args.values),
-        names = args.names,
-        unknownArity = args.unknownArity {
+        names = args.names {
     values[0] = receiver;
   }
 
@@ -220,7 +215,6 @@ class Args<T extends TypeExpr> {
     for (var n in names) {
       hash = (((hash * 31) & kHashMask) + n.hashCode) & kHashMask;
     }
-    if (unknownArity) hash ^= -1;
     return hash;
   }
 
@@ -240,7 +234,7 @@ class Args<T extends TypeExpr> {
           return false;
         }
       }
-      return unknownArity == other.unknownArity;
+      return true;
     }
     return false;
   }
@@ -263,11 +257,7 @@ class Args<T extends TypeExpr> {
       buf.write(': ');
       buf.write(values[positionalCount + i]);
     }
-    if (unknownArity) {
-      buf.write(", <unknown arity>)");
-    } else {
-      buf.write(")");
-    }
+    buf.write(")");
     return buf.toString();
   }
 }

pkg/vm/lib/transformations/type_flow/native_code.dart

@@ -32,6 +32,9 @@ abstract class EntryPointsListener {
 
   /// Record the fact that given member is called from this.
   void recordMemberCalledViaThis(Member target);
+
+  /// Record the fact that given method is torn off.
+  void recordTearOff(Procedure target) {}
 }
 
 class PragmaEntryPointsVisitor extends RecursiveVisitor {