[llvm] [GVN] MemorySSA for GVN: add optional `AllowMemorySSA` (PR #120982)

[Nikita Popov via llvm-commits]

https://github.com/nikic commented:

Something here isn't right. There is some compile-time impact and codegen changes: https://llvm-compile-time-tracker.com/compare.php?from=66e41a1a20f2190a800669028a0e80bd86e735ce&to=eb63cd62a4a1907dbd58f12660efd8244e7d81e9&stat=instructions:u

https://github.com/llvm/llvm-project/pull/120982