Skip the balanced switch dispatch optimization for patterns on floati…

…ng-point inputs (#62322)
dotnet · Jul 6, 2022 · 04a4764 · 04a4764
1 parent af92deb
commit 04a4764
Show file tree

Hide file tree

Showing 4 changed files with 807 additions and 305 deletions.
diff --git a/src/Compilers/CSharp/Portable/Lowering/LocalRewriter/LocalRewriter.DecisionDagRewriter.cs b/src/Compilers/CSharp/Portable/Lowering/LocalRewriter/LocalRewriter.DecisionDagRewriter.cs
@@ -535,6 +535,13 @@ bool canDispatch(BoundTestDecisionDagNode test1, BoundTestDecisionDagNode test2)
  return false;
  if (!t1.Input.Equals(t2.Input))
  return false;
+
+ if (t1.Input.Type.SpecialType is SpecialType.System_Double or SpecialType.System_Single)
+ {
+ // The optimization (using balanced switch dispatch) breaks the semantics of NaN
+ return false;
+ }
+
  return true;
  }
  }

diff --git a/src/Compilers/CSharp/Test/Emit/CodeGen/PatternTests.cs b/src/Compilers/CSharp/Test/Emit/CodeGen/PatternTests.cs
@@ -558,11 +558,11 @@ .locals init (object V_0,
  IL_000e: unbox.any ""double""
  IL_0013: stloc.1
  IL_0014: ldloc.1
- IL_0015: ldc.r8 3.14
- IL_001e: beq.s  IL_0055
- IL_0020: ldloc.1
- IL_0021: call  ""bool double.IsNaN(double)""
- IL_0026: brtrue.s IL_004b
+ IL_0015: call  ""bool double.IsNaN(double)""
+ IL_001a: brtrue.s IL_004b
+ IL_001c: ldloc.1
+ IL_001d: ldc.r8 3.14
+ IL_0026: beq.s  IL_0055
  IL_0028: br.s IL_005f
  IL_002a: ldloc.0
  IL_002b: isinst ""float""
@@ -571,11 +571,11 @@ .locals init (object V_0,
  IL_0033: unbox.any ""float""
  IL_0038: stloc.2
  IL_0039: ldloc.2
- IL_003a: ldc.r4 3.14
- IL_003f: beq.s  IL_005a
+ IL_003a: call  ""bool float.IsNaN(float)""
+ IL_003f: brtrue.s IL_0050
  IL_0041: ldloc.2
- IL_0042: call  ""bool float.IsNaN(float)""
- IL_0047: brtrue.s IL_0050
+ IL_0042: ldc.r4 3.14
+ IL_0047: beq.s  IL_005a
  IL_0049: br.s IL_005f
  IL_004b: ldc.i4.1
  IL_004c: stloc.s V_4