llvm-project

2007dcfe - Reapply [Metadata] Preserve MD_prof when merging instructions when one is missing. (#135418)

Reapply [Metadata] Preserve MD_prof when merging instructions when one is missing. (#135418) Preserve branch weight metadata when merging instructions if one of the instructions is missing metadata. This is similar in behaviour to what we do today for other types of metadata such as mmra, memprof and callsite metadata. Also add a legality check when merging prof metadata based on instruction type. Without this check GVN PRE optimizations result in prof metadata on phi nodes which break the module verifier. Build failure caught by https://lab.llvm.org/buildbot/#/builders/113/builds/6621 ``` !9185 = !{!"branch_weights", i32 3912, i32 802} Wrong number of operands !9185 = !{!"branch_weights", i32 3912, i32 802} fatal error: error in backend: Broken module found, compilation aborted! ``` Reverts #134200 with additional changes.