[PATCH] D88569: [DAGCombiner] Call SimplifyDemandedBits to simplify EXTRACT_VECTOR_ELT

[Jay Foad via Phabricator via llvm-commits]

foad added inline comments.


================
Comment at: llvm/test/CodeGen/X86/vec_setcc.ll:223
+; SSE41-NEXT:    pmovsxwd %xmm1, %xmm0
+; SSE41-NEXT:    movd %xmm1, %eax
+; SSE41-NEXT:    pextrb $4, %xmm0, %edx
----------------
RKSimon wrote:
> foad wrote:
> > RKSimon wrote:
> > > why didn't this simplify?
> > What simplification are you expecting?
> The 0'th index should be able to extract from the source of the _EXTEND_VECTOR_INREG using SimplifyMultipleUseDemandedBits
Well %eax is extracted directly from the result of the pcmpeqw, which is the source of the sign_extend_vector_inreg.


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D88569/new/

https://reviews.llvm.org/D88569