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[MSan] Don't create zero offsets in getShadowPtrForArgument(). NFC 

For MSan instrumentation with MS.ParamTLS and MS.ParamOriginTLS being
TLS variables, the CreateAdd() with ArgOffset==0 is a no-op, because
the compiler is able to fold the addition of 0.

But for KMSAN, which receives ParamTLS and ParamOriginTLS from a call
to the runtime library, this introduces a stray instruction which
complicates reading/testing the IR.

Differential revision: https://reviews.llvm.org/D44514

llvm-svn: 327829
This commit is contained in:
Alexander Potapenko 2018-03-19 10:03:47 +00:00
parent e0bafb4359
commit 014ff63f24
1 changed files with 4 additions and 2 deletions
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6
llvm/lib/Transforms/Instrumentation/MemorySanitizer.cpp
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@ -1094,7 +1094,8 @@ struct MemorySanitizerVisitor : public InstVisitor<MemorySanitizerVisitor> {
Value *getShadowPtrForArgument(Value *A, IRBuilder<> &IRB,
int ArgOffset) {
Value *Base = IRB.CreatePointerCast(MS.ParamTLS, MS.IntptrTy);
Base = IRB.CreateAdd(Base, ConstantInt::get(MS.IntptrTy, ArgOffset));
if (ArgOffset)
Base = IRB.CreateAdd(Base, ConstantInt::get(MS.IntptrTy, ArgOffset));
return IRB.CreateIntToPtr(Base, PointerType::get(getShadowTy(A), 0),
"_msarg");
}
@ -1104,7 +1105,8 @@ struct MemorySanitizerVisitor : public InstVisitor<MemorySanitizerVisitor> {
int ArgOffset) {
if (!MS.TrackOrigins) return nullptr;
Value *Base = IRB.CreatePointerCast(MS.ParamOriginTLS, MS.IntptrTy);
Base = IRB.CreateAdd(Base, ConstantInt::get(MS.IntptrTy, ArgOffset));
if (ArgOffset)
Base = IRB.CreateAdd(Base, ConstantInt::get(MS.IntptrTy, ArgOffset));
return IRB.CreateIntToPtr(Base, PointerType::get(MS.OriginTy, 0),
"_msarg_o");
}