[PATCH] D22726: [DAGCombine] Match shift amount by value rather than relying on common sub-expressions.

[bryant via llvm-commits]

bryant added a comment.

The InstCombine patch is here: https://reviews.llvm.org/D25913

With that patch:

  $ opt -O3 cmp-zext-combine.ll | llc -march=x86-64
  nonzero16:                              # @nonzero16
          xorl    %eax, %eax
          testw   %di, %di
          setne   %al
          retq
  
  nonzero32:                              # @nonzero32
          xorl    %eax, %eax
          testl   %edi, %edi
          setne   %al
          retq
  
  nonzero64:                              # @nonzero64
          xorl    %eax, %eax
          testq   %rdi, %rdi
          setne   %al
          retq

which are the results that we want.


Repository:
  rL LLVM

https://reviews.llvm.org/D22726