[llvm] [ARM] Avoid reference into modified vector (PR #93965)

[Nikita Popov via llvm-commits]

nikic wrote:

@rgwott I'd love to have a reproducer for this -- it actually sounds like exactly the case I was concerned about here: RepeatedSequenceLocs gets reassigned to CandidatesWithoutStackFixups, while FirstCand still points into the old vector memory. If you run your test case under valgrind (or address sanitizer), do you maybe get a use-after-free report? I'd expect that to happen, if I'm not misunderstanding the code.

In any case, I'd be happy to revert this change in the meantime if it's causing issues for you.

https://github.com/llvm/llvm-project/pull/93965