[PATCH] D146149: [InstCombine] Canonicalize icmp eq pow2 more thoroughly

[Nikita Popov via Phabricator via llvm-commits]

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We currently already canonicalize `icmp eq (%x & Pow2), Pow2` to `icmp ne (%x & Pow2), 0`. This patch generalizes the fold based on known bits.

In particular, this allows us to handle comparisons against `!range !{i64 0, i64 2}` loads, which addresses an optimization regression in Rust caused by https://github.com/llvm/llvm-project/commit/8df376db7282b955e7990cb8887ee9dcd3565040.


https://reviews.llvm.org/D146149

Files:
  llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
  llvm/test/Transforms/InstCombine/div.ll
  llvm/test/Transforms/InstCombine/icmp-range.ll
  llvm/test/Transforms/InstCombine/icmp-shl-nsw.ll
  llvm/test/Transforms/InstCombine/icmp-shr-lt-gt.ll
  llvm/test/Transforms/InstCombine/zext.ll

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