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Assertion failure in operator delete of llvm::User #129900

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marcauberer opened this issue Mar 5, 2025 · 0 comments · Fixed by #129914
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Assertion failure in operator delete of llvm::User #129900

marcauberer opened this issue Mar 5, 2025 · 0 comments · Fixed by #129914
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llvm:ir

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marcauberer commented Mar 5, 2025 •
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Commit e3f936e introduces a functional regression. If the constructor after operator new fails, and then operator delete is called, we run into the following assertion. This was caught by malfunction tests:

https://github.com/llvm/llvm-project/blob/main/llvm/lib/IR/User.cpp#L190

Reverting the removal of:

Obj->NumUserOperands = Us;
Obj->HasHungOffUses = false;
Obj->HasDescriptor = DescBytes != 0;

respecively

Obj->NumUserOperands = 0;
Obj->HasHungOffUses = true;
Obj->HasDescriptor = false;

helps.

I will prepare a patch for that.
@marcauberer marcauberer self-assigned this Mar 5, 2025
@marcauberer marcauberer mentioned this issue Mar 5, 2025
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@shiltian shiltian mentioned this issue Mar 10, 2025
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swift-ci pushed a commit to swiftlang/llvm-project that referenced this issue Apr 11, 2025
@marcauberer @tstellar
[IR] Fix assertion error in User new/delete edge case (llvm#129914)
e0db588 
Fixes llvm#129900

If `operator delete` was called after an unsuccessful constructor call
after `operator new`, we ran into undefined behaviour.
This was discovered by our malfunction tests while preparing an upgrade
to LLVM 20, that explicitly check for such kind of bugs.

(cherry picked from commit 8d38906)
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[IR] Fix assertion error in User new/delete edge case marcauberer/llvm-project
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