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Fix Endianess issue #162881

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Fix Endianess issue #162881

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552bdae
Resolve Endianess issue with getting shadow 4 bytes corresponding to …
Oct 10, 2025
ec10bb5
Merge branch 'llvm:main' into dfsan_Endian
anoopkg6 Oct 10, 2025
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10 changes: 8 additions & 2 deletions llvm/lib/Transforms/Instrumentation/DataFlowSanitizer.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -2187,8 +2187,14 @@ std::pair<Value *, Value *> DFSanFunction::loadShadowFast(
// and then the entire shadow for the second origin pointer (which will be
// chosen by combineOrigins() iff the least-significant half of the wide
// shadow was empty but the other half was not).
Value *WideShadowLo = IRB.CreateShl(
WideShadow, ConstantInt::get(WideShadowTy, WideShadowBitWidth / 2));
Value *WideShadowLo =
F->getParent()->getDataLayout().isLittleEndian()
? IRB.CreateShl(
WideShadow,
ConstantInt::get(WideShadowTy, WideShadowBitWidth / 2))
: IRB.CreateAnd(
WideShadow,
ConstantInt::get(WideShadowTy, 0xFFFFFFFF00000000ULL));
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Can this be rewritten in terms of WideShadowBitWidth?

(I think it's something like (1 - (1 << (WideShadowBitWidth / 2))) << (WideShadowBitWidth / 2))

Shadows.push_back(WideShadow);
Origins.push_back(DFS.loadNextOrigin(Pos, OriginAlign, &OriginAddr));

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