[PATCH] D65047: [DAGCombine] matchBinOpReduction - add partial reduction matching

[Simon Pilgrim via Phabricator via llvm-commits]

RKSimon added inline comments.


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Comment at: test/CodeGen/X86/phaddsub-extract.ll:2128
 ; SSE3-NEXT:    movd %xmm1, %eax
 ; SSE3-NEXT:    retq
 ;
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We don't optimize the SSE case because the isExtractSubvectorCheap check returns false (SSE has no EXTRACT_SUBVECTOR ops) - we could tweak this to always permit the extraction pre-legalops, or we tweak X86TargetLowering::isExtractSubvectorCheap to handle the case where we know extract_subvector will just end up splitting into legal types.


Repository:
  rL LLVM

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D65047/new/

https://reviews.llvm.org/D65047