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[msan] Fix getOriginForNaryOp. 

The old version failed on a 3-arg instruction with (-1, 0, 0) shadows (it would
pick the 3rd operand origin irrespective of its shadow).
    
The new version always picks the origin of the rightmost poisoned operand.

llvm-svn: 168887
This commit is contained in:
Evgeniy Stepanov 2012-11-29 14:44:00 +00:00
parent 93aefa5f2c
commit f433cecf96
1 changed files with 3 additions and 2 deletions
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5
llvm/lib/Transforms/Instrumentation/MemorySanitizer.cpp
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@ -842,15 +842,16 @@ struct MemorySanitizerVisitor : public InstVisitor<MemorySanitizerVisitor> {
///
/// This is a general case of origin propagation. For an Nary operation,
/// is set to the origin of an argument that is not entirely initialized.
/// If there is more than one such arguments, the rightmost of them is picked.
/// It does not matter which one is picked if all arguments are initialized.
void setOriginForNaryOp(Instruction &I) {
if (!ClTrackOrigins) return;
IRBuilder<> IRB(&I);
Value *Origin = getOrigin(&I, 0);
for (unsigned Op = 1, n = I.getNumOperands(); Op < n; ++Op) {
Value *S = convertToShadowTyNoVec(getShadow(&I, Op - 1), IRB);
Value *S = convertToShadowTyNoVec(getShadow(&I, Op), IRB);
Origin = IRB.CreateSelect(IRB.CreateICmpNE(S, getCleanShadow(S)),
Origin, getOrigin(&I, Op));
getOrigin(&I, Op), Origin);
}
setOrigin(&I, Origin);
}