[llvm] [MemCpyOpt] Merge memset and skip unrelated clobber in one scan (PR #90350)

[Nikita Popov via llvm-commits]

nikic wrote:

Hrm, looks like this currently has higher overhead than the other patch: https://llvm-compile-time-tracker.com/compare.php?from=e1622e189e8c0ef457bfac528f90a7a930d9aad2&to=2be43b19a8b584a44fd03967aa1f02fb890a2753&stat=instructions:u (Haven't looked in detail yet, maybe this is fixable...)

https://github.com/llvm/llvm-project/pull/90350