[llvm] [TailDuplicator] Add maximum predecessors and successors to consider tail duplicating blocks (PR #78582)

[via llvm-commits]

alexfh wrote:

> We started seeing a ~36% regression in the https://github.com/llvm/llvm-test-suite/blob/main/SingleSource/Benchmarks/Misc/evalloop.c benchmark on AArch64. Is this expected?

@DianQK ^^

It's not blocking us in any way, but it would be nice to ensure nothing wrong is happening here.

https://github.com/llvm/llvm-project/pull/78582