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[AMDGPU] Make sort ordering in AMDGPURewriteAGPRCopyMFMAImpl::eliminateSpillsOfReassignedVGPRs() strict weak. #162493

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Merged
merged 5 commits into from
Oct 8, 2025
Merged

[AMDGPU] Make sort ordering in AMDGPURewriteAGPRCopyMFMAImpl::eliminateSpillsOfReassignedVGPRs() strict weak. #162493

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56f9ded
Make sort ordering strictly weak.
weiweichen Oct 8, 2025
a364ce6
Actually make it strict weak ordering.
weiweichen Oct 8, 2025
e7e2598
Remove empty line.
weiweichen Oct 8, 2025
d6fc4ef
Address review comments.
weiweichen Oct 8, 2025
b17feb7
Merge branch 'main' of github.com:llvm/llvm-project into weiweic/issu…
weiweichen Oct 8, 2025
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11 changes: 6 additions & 5 deletions llvm/lib/Target/AMDGPU/AMDGPURewriteAGPRCopyMFMA.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -482,15 +482,16 @@ void AMDGPURewriteAGPRCopyMFMAImpl::eliminateSpillsOfReassignedVGPRs() const {
}

sort(StackIntervals, [](const LiveInterval *A, const LiveInterval *B) {
// The ordering have to be strictly weak.
/// Sort heaviest intervals first to prioritize their unspilling
if (A->weight() > B->weight())
return true;
if (A->weight() != B->weight())
return A->weight() > B->weight();

if (A->getSize() > B->getSize())
return true;
if (A->getSize() != B->getSize())
return A->getSize() > B->getSize();

// Tie breaker by number to avoid need for stable sort
return A->reg().stackSlotIndex() < B->reg().stackSlotIndex();
return (A->reg().stackSlotIndex() < B->reg().stackSlotIndex());
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Suggested change
return (A->reg().stackSlotIndex() < B->reg().stackSlotIndex());
return A->reg().stackSlotIndex() < B->reg().stackSlotIndex();

});

// FIXME: The APIs for dealing with the LiveInterval of a frame index are
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