[PATCH] D78582: [InstCombine] substitute equivalent constant to reduce logic-of-icmps

[Sanjay Patel via Phabricator via llvm-commits]

spatel updated this revision to Diff 259291.
spatel marked 2 inline comments as done.
spatel added a comment.

Patch updated:

1. Call SimplifyICmpInst() to determine if the transform truly requires a new instruction; if not, we do not need a hasOneUse() restriction.
2. Remove unlikely TODO comment.

The internal use of Simplify* here should make it possible to delete existing code in InstSimplify as discussed in D78430 <https://reviews.llvm.org/D78430> (and definitely makes the new code in that patch unnecessary unless I've missed some loophole).

Also with this patch applied, I did an audit of the existing AndOrOfICmps* logic by commenting out chunks of code and seeing if tests fail. Everything else is apparently still necessary; this patch does not provide a complete superset for anything else we do in InstCombine. So we can't delete anything from InstCombine in this patch.


CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D78582/new/

https://reviews.llvm.org/D78582

Files:
  llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
  llvm/test/Transforms/InstCombine/and-or-icmp-min-max.ll
  llvm/test/Transforms/InstCombine/and-or-icmp-nullptr.ll
  llvm/test/Transforms/InstCombine/and-or-icmps.ll

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