[PATCH] D141240: [SVE][Builtins] Add metadata to intrinsic calls for builtins that don't define the result of inactive lanes.

[Sander de Smalen via Phabricator via cfe-commits]

sdesmalen added a comment.

Using metadata seems sensible, but did you also identify any downsides? I could imagine that we'd need to manually propagate metadata to any nodes after we do a combine (which can't be blindly copied?), e.g. add + mul -> mla, this new intrinsic would also need the metadata.

For intrinsics that don't have a directly corresponding (unpredicated) LLVM IR instruction, is there still a way to use this information in SelectionDAG?

> the select instruction itself has strict rules relating to poison that hampered the intent of this change

For my understanding, can you elaborate what these strict rules regarding poison are that hamper such a change, and what it was that you tried?


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D141240/new/

https://reviews.llvm.org/D141240