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

[Walter Lee via cfe-commits]

googlewalt wrote:

Thanks for the info.  If there is already a reproducer upstream, can we consider a revert?

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