[all-commits] [llvm/llvm-project] 78f7ca: [InstCombine] Use KnownBits predicate helpers (#11...

[Nikita Popov via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 78f7ca0980f3369da19e3cbb01890fe718307ac2
      https://github.com/llvm/llvm-project/commit/78f7ca0980f3369da19e3cbb01890fe718307ac2
  Author: Nikita Popov <npopov at redhat.com>
  Date:   2024-11-14 (Thu, 14 Nov 2024)

  Changed paths:
    M llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
    M llvm/test/Transforms/InstCombine/icmp-gep.ll
    M llvm/test/Transforms/InstCombine/mul-inseltpoison.ll
    M llvm/test/Transforms/InstCombine/mul.ll
    M llvm/test/Transforms/InstCombine/shift-amount-reassociation-in-bittest.ll

  Log Message:
  -----------
  [InstCombine] Use KnownBits predicate helpers (#115874)

Inside foldICmpUsingKnownBits(), instead of rolling our own logic based
on min/max values, make use of ICmpInst::compare() working on KnownBits.
This gives better results for the equality predicates. In practice, the
improvement is only for pointers, because isKnownNonEqual() handles the
non-pointer case.

I've adjusted some tests to prevent the new fold from triggering, to
retain their original intent of testing constant expressions.



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