[PATCH] D58872: [InstCombine] Start canonicalizing to uadd.sat and usub.sat

[Sanjay Patel via Phabricator via llvm-commits]

spatel added a subscriber: dmgreen.
spatel added a comment.

There are 2 concerns here:

1. Is the IR-level analysis for the intrinsics as good/better than the raw IR? The description says yes, so I assume we've filled all the known analysis, value tracking, vectorization, and combining gaps.
2. Is codegen as good/better than the raw IR? Ie, for all known targets/types, are we DAG combining/lowering the intrinsics optimally?

I want to make sure about #2 because there was some potential fallout from aggressively forming the similar usub overflow intrinsic in CGP in D57789 <https://reviews.llvm.org/D57789>, so we ended up adding a target hook (cc @dmgreen).


CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D58872/new/

https://reviews.llvm.org/D58872