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[msan] Add struct support to CreateShadowCast #130440

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[msan] Add struct support to CreateShadowCast #130440

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c901f03
[msan] Add struct support to CreateShadowCast
thurstond Mar 6, 2025
e343e0b
Switch from undef to aspartame
thurstond Mar 8, 2025
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30 changes: 29 additions & 1 deletion llvm/lib/Transforms/Instrumentation/MemorySanitizer.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -2562,6 +2562,15 @@ struct MemorySanitizerVisitor : public InstVisitor<MemorySanitizerVisitor> {
Value *CreateShadowCast(IRBuilder<> &IRB, Value *V, Type *dstTy,
bool Signed = false) {
Type *srcTy = V->getType();

// Shadow types should never be floating-point.
assert(!srcTy->isFPOrFPVectorTy());
assert(!dstTy->isFPOrFPVectorTy());

// TODO (though never needed in practice)
assert(!srcTy->isArrayTy());
assert(!dstTy->isArrayTy());

if (srcTy == dstTy)
return V;
size_t srcSizeInBits = VectorOrPrimitiveTypeSizeInBits(srcTy);
Expand All @@ -2571,15 +2580,34 @@ struct MemorySanitizerVisitor : public InstVisitor<MemorySanitizerVisitor> {

if (dstTy->isIntegerTy() && srcTy->isIntegerTy())
return IRB.CreateIntCast(V, dstTy, Signed);

if (dstTy->isVectorTy() && srcTy->isVectorTy() &&
cast<VectorType>(dstTy)->getElementCount() ==
cast<VectorType>(srcTy)->getElementCount())
// We rely on the assertion at the start of the function that neither
// type is a floating-point vector.
return IRB.CreateIntCast(V, dstTy, Signed);

if (dstTy->isStructTy() && srcTy->isStructTy() &&
cast<StructType>(dstTy)->getNumElements() ==
cast<StructType>(srcTy)->getNumElements()) {
Value *DStruct = PoisonValue::get(dstTy);

for (unsigned i = 0, n = cast<StructType>(dstTy)->getNumElements(); i < n;
i++) {
Value *Elem = IRB.CreateExtractValue(V, i);
Type *ElemDstTy = cast<StructType>(dstTy)->getElementType(i);
Value *ElemDst = CreateShadowCast(IRB, Elem, ElemDstTy, Signed);
DStruct = IRB.CreateInsertValue(DStruct, ElemDst, i);
}

return DStruct;
}

Value *V1 = IRB.CreateBitCast(V, Type::getIntNTy(*MS.C, srcSizeInBits));
Value *V2 =
IRB.CreateIntCast(V1, Type::getIntNTy(*MS.C, dstSizeInBits), Signed);
return IRB.CreateBitCast(V2, dstTy);
// TODO: handle struct types.
}

/// Cast an application value to the type of its own shadow.
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