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[IR] Fix string overlap issue in Value::setNameImpl #158288

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[IR] Fix string overlap issue in Value::setNameImpl #158288

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f3ea129
[IR] Fix string overlap issue in Value::setNameImpl
w-gc Sep 12, 2025
18d4154
Merge branch 'main' into bugfix
w-gc Sep 12, 2025
cd30e8e
Merge branch 'main' into bugfix
w-gc Sep 15, 2025
36bfc12
[IR] Fix string overlap issue in Value::setNameImpl
w-gc Sep 15, 2025
ea051e2
Merge branch 'main' into bugfix
w-gc Sep 15, 2025
f3521a3
Merge branch 'main' into bugfix
w-gc Sep 15, 2025
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10 changes: 10 additions & 0 deletions llvm/lib/IR/Value.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -356,6 +356,16 @@ void Value::setNameImpl(const Twine &NewName) {
if (getSymTab(this, ST))
return; // Cannot set a name on this value (e.g. constant).

// Copy NewName forcely if the memory overlaps.
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Suggested change
// Copy NewName forcely if the memory overlaps.
// Copy NewName if the memory overlaps.

or "forcefully", but I think you can just omit it.

if (!NameRef.empty()) {
StringRef OldNameRef = getName();
if ((OldNameRef.bytes_begin() < NameRef.bytes_end()) &&
(NameRef.bytes_begin() < OldNameRef.bytes_end())) {
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I believe this is technically UB in the case where it doesn't overlap. One has to use std::less in this case.

NewName.toVector(NameData);
NameRef = StringRef(NameData.data(), NameData.size());
}
}

if (!ST) { // No symbol table to update? Just do the change.
// NOTE: Could optimize for the case the name is shrinking to not deallocate
// then reallocated.
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