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Backport 2131242 #44

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Backport 2131242 #44

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20 changes: 16 additions & 4 deletions llvm/lib/Transforms/Scalar/MemCpyOptimizer.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -1466,7 +1466,7 @@ bool MemCpyOptPass::performStackMoveOptzn(Instruction *Load, Instruction *Store,
// to remove them.

SmallVector<Instruction *, 4> LifetimeMarkers;
SmallSet<Instruction *, 4> NoAliasInstrs;
SmallSet<Instruction *, 4> AAMetadataInstrs;
bool SrcNotDom = false;

// Recursively track the user and check whether modified alias exist.
Expand Down Expand Up @@ -1521,8 +1521,7 @@ bool MemCpyOptPass::performStackMoveOptzn(Instruction *Load, Instruction *Store,
continue;
}
}
if (UI->hasMetadata(LLVMContext::MD_noalias))
NoAliasInstrs.insert(UI);
AAMetadataInstrs.insert(UI);
if (!ModRefCallback(UI))
return false;
}
Expand Down Expand Up @@ -1630,9 +1629,22 @@ bool MemCpyOptPass::performStackMoveOptzn(Instruction *Load, Instruction *Store,
// alias to begin to alias one another, we remove !noalias metadata from any
// uses of either alloca. This is conservative, but more precision doesn't
// seem worthwhile right now.
for (Instruction *I : NoAliasInstrs)
for (Instruction *I : AAMetadataInstrs) {


I->setMetadata(LLVMContext::MD_alias_scope, nullptr);

I->setMetadata(LLVMContext::MD_noalias, nullptr);


I->setMetadata(LLVMContext::MD_tbaa, nullptr);


I->setMetadata(LLVMContext::MD_tbaa_struct, nullptr);


}

LLVM_DEBUG(dbgs() << "Stack Move: Performed staack-move optimization\n");
NumStackMove++;
return true;
Expand Down