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[AMDGPU][NPM] Preserve analyses in AMDGPURewriteAGPRCopyMFMA for NPM #170130

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Merged
merged 3 commits into from
Dec 1, 2025
+7 −2
Merged

[AMDGPU][NPM] Preserve analyses in AMDGPURewriteAGPRCopyMFMA for NPM #170130

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2dced06
Fixes to be upstreamed - 8
vikramRH Sep 8, 2025
be7f800
Fixes to be upstreamed - Preserve SlotIndexes in AMDGPURewriteAGPRCop…
PrasoonMishra Nov 5, 2025
8998881
Apply clang-format.
PrasoonMishra Dec 1, 2025
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9 changes: 7 additions & 2 deletions llvm/lib/Target/AMDGPU/AMDGPURewriteAGPRCopyMFMA.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -32,6 +32,7 @@
#include "llvm/CodeGen/LiveStacks.h"
#include "llvm/CodeGen/MachineFrameInfo.h"
#include "llvm/CodeGen/MachineFunctionPass.h"
#include "llvm/CodeGen/SlotIndexes.h"
#include "llvm/CodeGen/VirtRegMap.h"
#include "llvm/InitializePasses.h"

Expand Down Expand Up @@ -659,7 +660,11 @@ AMDGPURewriteAGPRCopyMFMAPass::run(MachineFunction &MF,
if (!Impl.run(MF))
return PreservedAnalyses::all();
auto PA = getMachineFunctionPassPreservedAnalyses();
PA.preserveSet<CFGAnalyses>();
PA.preserve<LiveStacksAnalysis>();
PA.preserveSet<CFGAnalyses>()
.preserve<LiveStacksAnalysis>()
.preserve<VirtRegMapAnalysis>()
.preserve<SlotIndexesAnalysis>()
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@cdevadas cdevadas Dec 1, 2025

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I guess SlotIndex is not directly used here, but invoked inside LiveIntervals?
It doesn't seem good to me to explicitly preserve the analyses that aren't explicitly used in a pass. Rather, the pass manager should have some way to preserve them. In this case LiveIntervals analysis is preserved here. The pass-manager infrastructure should preserve the SlitIndex too. Anyway, it doesn't work that way at the moment.

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@PrasoonMishra PrasoonMishra Dec 1, 2025

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Thanks for pointing that out. I agree the current approach isn’t ideal, but given the limitations of the pass manager right now, I’ll leave it as is.

.preserve<LiveIntervalsAnalysis>()
.preserve<LiveRegMatrixAnalysis>();
return PA;
}