[PATCH] D34904: [CGP] use subtract of cmps for result of memcmp expansion

[Sanjay Patel via Phabricator via llvm-commits]

spatel created this revision.
Herald added a subscriber: mcrosier.

There are some regressions for PPC here (even if we keep the 'subf', the 'extsw' is unnecessary, isn't it?). I'm hoping we can address that as a follow-up rather than make this change dependent on fixing that.

As noted in the code comment, transforming this in the other direction might require a separate transform here in CGP given the block-at-a-time DAG constraint.


https://reviews.llvm.org/D34904

Files:
  lib/CodeGen/CodeGenPrepare.cpp
  test/CodeGen/PowerPC/memcmp.ll
  test/CodeGen/PowerPC/memcmpIR.ll
  test/CodeGen/X86/memcmp.ll
  test/Transforms/CodeGenPrepare/X86/memcmp.ll

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