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[msan] Optimize getOriginPtr.

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Rewrite getOriginPtr in a way that lets subsequent optimizations factor out
the common part of Shadow and Origin address calculation. Improves perf by
up to 5%.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@168879 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Evgeniy Stepanov 2012-11-29 13:43:05 +00:00
parent 2ea25f2f1c
commit af4451b37e
1 changed files with 4 additions and 3 deletions
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7
lib/Transforms/Instrumentation/MemorySanitizer.cpp
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@ -503,15 +503,16 @@ struct MemorySanitizerVisitor : public InstVisitor<MemorySanitizerVisitor> {
/// address.
///
/// OriginAddr = (ShadowAddr + OriginOffset) & ~3ULL
/// = Addr & (~ShadowMask & ~3ULL) + OriginOffset
Value *getOriginPtr(Value *Addr, IRBuilder<> &IRB) {
Value *ShadowLong =
IRB.CreateAnd(IRB.CreatePointerCast(Addr, MS.IntptrTy),
ConstantInt::get(MS.IntptrTy, ~MS.ShadowMask & ~3ULL));
ConstantInt::get(MS.IntptrTy, ~MS.ShadowMask));
Value *Add =
IRB.CreateAdd(ShadowLong,
ConstantInt::get(MS.IntptrTy, MS.OriginOffset));
return IRB.CreateIntToPtr(Add, PointerType::get(IRB.getInt32Ty(), 0));
Value *SecondAnd =
IRB.CreateAnd(Add, ConstantInt::get(MS.IntptrTy, ~3ULL));
return IRB.CreateIntToPtr(SecondAnd, PointerType::get(IRB.getInt32Ty(), 0));
}
/// \brief Compute the shadow address for a given function argument.