[llvm] [TaiDup] Allow large number of predecessors/successors without phis. (PR #116072)

[via llvm-commits]

https://github.com/DianQK approved this pull request.

> It would be great if we could get this resolved one way or another for the Clang 20 release, as this at the moment causes a 2-3% performance loss for Python workloads on ARM64 :) I rebased and tested #114990 and unfortunately it doesn't yield the same perf gain ( only in the noise/ < 0.5%)

LGTM. I believe these two PRs address different issues. I can verify that the PR doesn't resolve #106846 due to phis.

https://github.com/llvm/llvm-project/pull/116072