[PATCH] D122836: Fold more memchr calls

[Martin Sebor via Phabricator via llvm-commits]

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This patch extends the `LibCallSimplifier::optimizeMemChr` folder to perform two more simplifications:

1. folding the case where the size is equal to 1 to a byte comparison, analogously to other such cases already handled by other folders
2. simplifying to a size comparison the case where the sought character with constant value is known either to appear in the constant array or not to appear, regardless of the size argument

I have tested the patch by bootstrapping LLVM + Clang on x86_64-linux and running `check-all`.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D122836

Files:
  llvm/lib/Transforms/Utils/SimplifyLibCalls.cpp
  llvm/test/Transforms/InstCombine/memchr-2.ll
  llvm/test/Transforms/InstCombine/memchr-3.ll

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