[PATCH] D145866: [DAG] visitAND - fold (and (any_ext V), c) -> (zero_ext (and (trunc V), c)) if profitable.

[Phoebe Wang via Phabricator via llvm-commits]

pengfei accepted this revision.
pengfei added a comment.
This revision is now accepted and ready to land.

X86 tests change looks good.



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Comment at: llvm/test/CodeGen/X86/switch-phi-const.ll:95
+; CHECK-NEXT:    movzbl %dil, %eax
+; CHECK-NEXT:    leal -1(%rax), %ecx
 ; CHECK-NEXT:    cmpl $54, %ecx
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RKSimon wrote:
> pengfei wrote:
> > This doesn't look efficient than `decl %ecx`.
> I agree but we always fold mov+dec to lea: https://simd.godbolt.org/z/vvzfe14oc
Thanks! I see, just notice we also saved a `movzbl %dil, %eax`. So it's indeed a win.


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