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[msan] Use zero-extension in shadow cast by default. 

Switch to sign-extension in r192575 caused 7% perf loss on 482.sphinx3.

llvm-svn: 192882
This commit is contained in:
Evgeniy Stepanov 2013-10-17 10:53:50 +00:00
parent 39f5d7d5f0
commit 21a9c93a4d
1 changed files with 8 additions and 7 deletions
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15
llvm/lib/Transforms/Instrumentation/MemorySanitizer.cpp
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@ -1244,18 +1244,19 @@ struct MemorySanitizerVisitor : public InstVisitor<MemorySanitizerVisitor> {
/// \brief Cast between two shadow types, extending or truncating as
/// necessary.
Value *CreateShadowCast(IRBuilder<> &IRB, Value *V, Type *dstTy) {
Value *CreateShadowCast(IRBuilder<> &IRB, Value *V, Type *dstTy,
bool Signed = false) {
Type *srcTy = V->getType();
if (dstTy->isIntegerTy() && srcTy->isIntegerTy())
return IRB.CreateIntCast(V, dstTy, true);
return IRB.CreateIntCast(V, dstTy, Signed);
if (dstTy->isVectorTy() && srcTy->isVectorTy() &&
dstTy->getVectorNumElements() == srcTy->getVectorNumElements())
return IRB.CreateIntCast(V, dstTy, true);
return IRB.CreateIntCast(V, dstTy, Signed);
size_t srcSizeInBits = VectorOrPrimitiveTypeSizeInBits(srcTy);
size_t dstSizeInBits = VectorOrPrimitiveTypeSizeInBits(dstTy);
Value *V1 = IRB.CreateBitCast(V, Type::getIntNTy(*MS.C, srcSizeInBits));
Value *V2 =
IRB.CreateIntCast(V1, Type::getIntNTy(*MS.C, dstSizeInBits), true);
IRB.CreateIntCast(V1, Type::getIntNTy(*MS.C, dstSizeInBits), Signed);
return IRB.CreateBitCast(V2, dstTy);
// TODO: handle struct types.
}
@ -2019,9 +2020,9 @@ struct MemorySanitizerVisitor : public InstVisitor<MemorySanitizerVisitor> {
"_msprop_select_agg");
} else {
// Sa = (sext Sb) | (select b, Sc, Sd)
S = IRB.CreateOr(
S, CreateShadowCast(IRB, getShadow(I.getCondition()), S->getType()),
"_msprop_select");
S = IRB.CreateOr(S, CreateShadowCast(IRB, getShadow(I.getCondition()),
S->getType(), true),
"_msprop_select");
}
setShadow(&I, S);
if (MS.TrackOrigins) {