Thurston Dang 0d15d46362 [ubsan] Change ubsan-unique-traps to use nomerge instead of counter (#117651) ...

https://github.com/llvm/llvm-project/pull/65972 (continuation of
https://reviews.llvm.org/D148654) had considered adding nomerge to
ubsantrap, but did not proceed with that because of
https://github.com/llvm/llvm-project/issues/53011. Instead, it added a
counter (based on TrapBB->getParent()->size()) to each ubsantrap call.
However, this counter is not guaranteed to be unique after inlining, as
shown by https://github.com/llvm/llvm-project/pull/83470, which can
result in ubsantraps being merged by the backend.

https://github.com/llvm/llvm-project/pull/101549 has since fixed the
nomerge limitation ("It sets nomerge flag for the node if the
instruction has nomerge arrtibute."). This patch therefore takes
advantage of nomerge instead of using the counter, guaranteeing that the
ubsantraps are not merged.

This patch is equivalent to
https://github.com/llvm/llvm-project/pull/83470 but also adds nomerge
and updates tests (https://github.com/llvm/llvm-project/pull/117649:
ubsan-trap-merge.c; https://github.com/llvm/llvm-project/pull/117657:
ubsan-trap-merge.ll, ubsan-trap-nomerge.ll; catch-undef-behavior.c).

2024-11-26 21:13:00 -08:00

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