[PATCH] D131306: [llvm][misexpect] Track provenance of branch weights

[Teresa Johnson via Phabricator via llvm-commits]

tejohnson added subscribers: xur, davidxl.
tejohnson added a comment.

@davidxl @xur for review and thoughts.

I'm a little wary of requiring that both pieces of metadata be carried together, as that seems very brittle to maintain in the compiler. What would happen if the MD_expected didn't get propagated by some pass along with the MD_prof? I think you would get a false negative, which I suppose is better than a false positive. An alternative, that I guess would require more extensive changes, is to add an additional item to the "branch_weights" list (would need to be obviously distinguishable by type from the list of weights since that can be variable though).

Patch needs tests showing uses of the new metadata, and some documentation in LangRef (i.e. near https://llvm.org/docs/LangRef.html#prof-metadata).


Repository:
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https://reviews.llvm.org/D131306