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JIT: generalize escape analysis delegate invoke expansion slightly #116099

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Merged
merged 3 commits into from
May 30, 2025
Merged

JIT: generalize escape analysis delegate invoke expansion slightly #116099

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7d80ec8
JIT: generalize escape analysis delegate invoke expansion slightly
AndyAyersMS May 29, 2025
9c78a3c
fix test
AndyAyersMS May 29, 2025
550f660
Merge branch 'main' into EscapeDelegateImprovements
AndyAyersMS May 30, 2025
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11 changes: 7 additions & 4 deletions src/coreclr/jit/objectalloc.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -2456,25 +2456,28 @@ void ObjectAllocator::RewriteUses()
CallArg* const thisArg = call->gtArgs.GetThisArg();
GenTree* const delegateThis = thisArg->GetNode();

if (delegateThis->OperIs(GT_LCL_VAR))
if (delegateThis->OperIs(GT_LCL_VAR, GT_LCL_ADDR))
{
GenTreeLclVarCommon* const lcl = delegateThis->AsLclVarCommon();
bool const isStackAllocatedDelegate =
delegateThis->OperIs(GT_LCL_ADDR) || m_allocator->DoesLclVarPointToStack(lcl->GetLclNum());

if (m_allocator->DoesLclVarPointToStack(lcl->GetLclNum()))
if (isStackAllocatedDelegate)
{
JITDUMP("Expanding delegate invoke [%06u]\n", m_compiler->dspTreeID(call));

// Expand the delgate invoke early, so that physical promotion has
// a chance to promote the delegate fields.
//
// Note the instance field may also be stack allocatable (someday)
//
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Copilot AI May 29, 2025

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Passing the 'complexOk' flag as true ensures proper cloning of address nodes; consider adding a brief inline comment to detail the necessity of this flag in handling GT_LCL_ADDR nodes.

Suggested change
//
//
// The 'complexOk' flag is set to true to ensure proper cloning of address nodes,
// particularly for GT_LCL_ADDR nodes, which are crucial for delegate invocation expansion.

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GenTree* const cloneThis = m_compiler->gtClone(lcl);
GenTree* const cloneThis = m_compiler->gtClone(lcl, /* complexOk */ true);
unsigned const instanceOffset = m_compiler->eeGetEEInfo()->offsetOfDelegateInstance;
GenTree* const newThisAddr =
m_compiler->gtNewOperNode(GT_ADD, TYP_I_IMPL, cloneThis,
m_compiler->gtNewIconNode(instanceOffset, TYP_I_IMPL));

// For now assume the instance is heap...
// For now assume the instance field is on the heap...
//
GenTree* const newThis = m_compiler->gtNewIndir(TYP_REF, newThisAddr);
thisArg->SetEarlyNode(newThis);
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28 changes: 28 additions & 0 deletions src/tests/JIT/opt/ObjectStackAllocation/Delegates.cs
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Expand Up @@ -34,6 +34,17 @@ static AllocationKind StackAllocation()
return expectedAllocationKind;
}

static AllocationKind HeapAllocation()
{
AllocationKind expectedAllocationKind = AllocationKind.Heap;
if (GCStressEnabled())
{
Console.WriteLine("GCStress is enabled");
expectedAllocationKind = AllocationKind.Undefined;
}
return expectedAllocationKind;
}

static int CallTestAndVerifyAllocation(Test test, int expectedResult, AllocationKind expectedAllocationsKind, bool throws = false)
{
string methodName = test.Method.Name;
Expand Down Expand Up @@ -122,4 +133,21 @@ public static int Test1()
RunTest1();
return CallTestAndVerifyAllocation(RunTest1, 100, StackAllocation());
}

// Here the delegate gets stack allocated, but not the closure.
// With PGO the delegate is also inlined.
//
[MethodImpl(MethodImplOptions.NoInlining)]
static int RunTest2Inner(int a) => InvokeFunc(x => x + a);

static int InvokeFunc(Func<int, int> func) => func(101);

[MethodImpl(MethodImplOptions.NoInlining)]
static int RunTest2() => RunTest2Inner(-1);

[Fact]
public static int Test2()
{
return CallTestAndVerifyAllocation(RunTest2, 100, HeapAllocation());
}
}
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