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Eliminate dead branches around typeof comparisons #102248

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merged 4 commits into from
Jun 19, 2024
Merged

Eliminate dead branches around typeof comparisons #102248

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a2ccfc8
Eliminate dead branches around typeof comparisons
MichalStrehovsky May 15, 2024
6beca33
Update TrimmingDriver.cs
MichalStrehovsky May 15, 2024
31c52b0
Fixes
MichalStrehovsky May 20, 2024
ea42b25
Merge branch 'dotnet:main' into deadtypeofbranches
MichalStrehovsky Jun 19, 2024
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8 changes: 3 additions & 5 deletions src/coreclr/tools/aot/ILCompiler.Compiler/Compiler/Compilation.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -105,12 +105,12 @@ public bool CanInline(MethodDesc caller, MethodDesc callee)

public bool CanReferenceConstructedMethodTable(TypeDesc type)
{
return NodeFactory.DevirtualizationManager.CanReferenceConstructedMethodTable(type);
return NodeFactory.DevirtualizationManager.CanReferenceConstructedMethodTable(type.NormalizeInstantiation());
}

public bool CanReferenceConstructedTypeOrCanonicalFormOfType(TypeDesc type)
{
return NodeFactory.DevirtualizationManager.CanReferenceConstructedTypeOrCanonicalFormOfType(type);
return NodeFactory.DevirtualizationManager.CanReferenceConstructedTypeOrCanonicalFormOfType(type.NormalizeInstantiation());
}

public DelegateCreationInfo GetDelegateCtor(TypeDesc delegateType, MethodDesc target, TypeDesc constrainedType, bool followVirtualDispatch)
Expand Down Expand Up @@ -266,9 +266,7 @@ public bool NeedsRuntimeLookup(ReadyToRunHelperId lookupKind, object targetOfLoo

public ReadyToRunHelperId GetLdTokenHelperForType(TypeDesc type)
{
bool canConstructPerWholeProgramAnalysis = NodeFactory.DevirtualizationManager.CanReferenceConstructedMethodTable(type);
bool creationAllowed = ConstructedEETypeNode.CreationAllowed(type);
return (canConstructPerWholeProgramAnalysis && creationAllowed)
return (ConstructedEETypeNode.CreationAllowed(type) && NodeFactory.DevirtualizationManager.CanReferenceConstructedMethodTable(type.NormalizeInstantiation()))
? ReadyToRunHelperId.TypeHandle
: ReadyToRunHelperId.NecessaryTypeHandle;
}
Expand Down
12 changes: 10 additions & 2 deletions src/coreclr/tools/aot/ILCompiler.Compiler/Compiler/ILScanner.cs
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Expand Up @@ -703,10 +703,18 @@ protected override MethodDesc ResolveVirtualMethod(MethodDesc declMethod, DefTyp
}

public override bool CanReferenceConstructedMethodTable(TypeDesc type)
=> _constructedMethodTables.Contains(type);
{
Debug.Assert(type.NormalizeInstantiation() == type);
Debug.Assert(ConstructedEETypeNode.CreationAllowed(type));
return _constructedMethodTables.Contains(type);
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Should we also assert that we are only adding normalizations into _constructedMethodTables when it is populated?

}

public override bool CanReferenceConstructedTypeOrCanonicalFormOfType(TypeDesc type)
=> _constructedMethodTables.Contains(type) || _canonConstructedMethodTables.Contains(type);
{
Debug.Assert(type.NormalizeInstantiation() == type);
Debug.Assert(ConstructedEETypeNode.CreationAllowed(type));
return _constructedMethodTables.Contains(type) || _canonConstructedMethodTables.Contains(type);
}

public override TypeDesc[] GetImplementingClasses(TypeDesc type)
{
Expand Down
6 changes: 5 additions & 1 deletion src/coreclr/tools/aot/ILCompiler.Compiler/Compiler/SubstitutedILProvider.cs
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Expand Up @@ -1021,7 +1021,11 @@ private bool TryExpandTypeEquality_TokenOther(MethodIL methodIL, byte[] body, Op
if (knownType.IsCanonicalDefinitionType(CanonicalFormKind.Any))
return false;

if (_devirtualizationManager.CanReferenceConstructedTypeOrCanonicalFormOfType(knownType))
// We don't track types without a constructed MethodTable very well.
if (!ConstructedEETypeNode.CreationAllowed(knownType))
return false;

if (_devirtualizationManager.CanReferenceConstructedTypeOrCanonicalFormOfType(knownType.NormalizeInstantiation()))
return false;

constant = 0;
Expand Down
6 changes: 4 additions & 2 deletions src/coreclr/tools/aot/ILCompiler.RyuJit/Compiler/RyuJitCompilation.cs
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Expand Up @@ -72,7 +72,8 @@ public override IEETypeNode NecessaryTypeSymbolIfPossible(TypeDesc type)
// information proving that it isn't, give RyuJIT the constructed symbol even
// though we just need the unconstructed one.
// https://github.com/dotnet/runtimelab/issues/1128
bool canPotentiallyConstruct = NodeFactory.DevirtualizationManager.CanReferenceConstructedMethodTable(type);
bool canPotentiallyConstruct = ConstructedEETypeNode.CreationAllowed(type)
&& NodeFactory.DevirtualizationManager.CanReferenceConstructedMethodTable(type);
if (canPotentiallyConstruct)
return _nodeFactory.MaximallyConstructableType(type);

Expand All @@ -81,7 +82,8 @@ public override IEETypeNode NecessaryTypeSymbolIfPossible(TypeDesc type)

public FrozenRuntimeTypeNode NecessaryRuntimeTypeIfPossible(TypeDesc type)
{
bool canPotentiallyConstruct = NodeFactory.DevirtualizationManager.CanReferenceConstructedMethodTable(type);
bool canPotentiallyConstruct = ConstructedEETypeNode.CreationAllowed(type)
&& NodeFactory.DevirtualizationManager.CanReferenceConstructedMethodTable(type);
if (canPotentiallyConstruct)
return _nodeFactory.SerializedMaximallyConstructableRuntimeTypeObject(type);

Expand Down
63 changes: 55 additions & 8 deletions src/tests/nativeaot/SmokeTests/TrimmingBehaviors/DeadCodeElimination.cs
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Expand Up @@ -351,9 +351,14 @@ class Canary2 { }
class Never3 { }
class Canary3 { }

class Maybe1<T, U> { }

[MethodImpl(MethodImplOptions.NoInlining)]
static Type GetTheType() => null;

[MethodImpl(MethodImplOptions.NoInlining)]
static Type GetThePointerType() => typeof(void*);

[MethodImpl(MethodImplOptions.NoInlining)]
static object GetTheObject() => new object();

Expand All @@ -371,19 +376,61 @@ public static void Run()
#if !DEBUG
ThrowIfPresent(typeof(TestTypeEquals), nameof(Never));

Type someType = GetTheType();
if (someType == typeof(Never2))
{
s_sink = new Canary2();
RunCheck(GetTheType());

static void RunCheck(Type t)
{
if (t == typeof(Never2))
{
s_sink = new Canary2();
}
}

ThrowIfPresentWithUsableMethodTable(typeof(TestTypeEquals), nameof(Canary2));
}

{

RunCheck(GetTheObject());

static void RunCheck(object o)
{
if (o.GetType() == typeof(Never3))
{
s_sink = new Canary3();
}
}

ThrowIfPresentWithUsableMethodTable(typeof(TestTypeEquals), nameof(Canary3));
}

{
RunCheck(GetThePointerType());

static void RunCheck(Type t)
{
if (t == typeof(void*))
{
return;
}
throw new Exception();
}
}
ThrowIfPresentWithUsableMethodTable(typeof(TestTypeEquals), nameof(Canary2));

object someObject = GetTheObject();
if (someObject.GetType() == typeof(Never3))
{
s_sink = new Canary3();
RunCheck<object>(typeof(Maybe1<object, string>));

[MethodImpl(MethodImplOptions.NoInlining)]
static void RunCheck<T>(Type t)
{
if (t == typeof(Maybe1<T, string>))
{
return;
}
throw new Exception();
}
}
ThrowIfPresentWithUsableMethodTable(typeof(TestTypeEquals), nameof(Canary3));
#endif
}
}
Expand Down
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