[clang] [llvm] [IR] Optimize PHINode::removeIncomingValue() by swapping removed incoming value with the last incoming value. (PR #171963)

[Nikita Popov via llvm-commits]

nikic wrote:

FYI the non-determinism is also visible on llvm-opt-benchmark. Maybe repeatedly running test cases from https://github.com/dtcxzyw/llvm-opt-benchmark/commit/299446d99f04024d5f569ce1f7e9338c9bcf55fe could reproduce the issue...

https://github.com/llvm/llvm-project/pull/171963