================
@@ -4552,16 +4552,22 @@ struct MemorySanitizerVisitor : public
InstVisitor<MemorySanitizerVisitor> {
}
if (!ElemTy->isSized())
return;
- Value *SizeVal =
- IRB.CreateTypeSize(MS.IntptrTy, DL.getTypeStoreSize(ElemTy));
+ auto Size = DL.getTypeStoreSize(ElemTy);
+ Value *SizeVal = IRB.CreateTypeSize(MS.IntptrTy, Size);
if (MS.CompileKernel) {
IRB.CreateCall(MS.MsanInstrumentAsmStoreFn, {Operand, SizeVal});
} else {
// ElemTy, derived from elementtype(), does not encode the alignment of
// the pointer. Conservatively assume that the shadow memory is
unaligned.
+ // When Size is large, avoid StoreInst as it would expand to many
+ // instructions.
auto [ShadowPtr, _] =
getShadowOriginPtrUserspace(Operand, IRB, IRB.getInt8Ty(), Align(1));
- IRB.CreateAlignedStore(getCleanShadow(ElemTy), ShadowPtr, Align(1));
+ if (Size <= 32)
----------------
MaskRay wrote:
This is a bit arbitrary. Perhaps
`// The size threshold matches shouldUseBZeroPlusStoresToInitialize for
-ftrivial-auto-var-init=zero`?
https://github.com/llvm/llvm-project/pull/79924
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