[PATCH] D104156: [DAGCombine][X86][ARM] EXTRACT_SUBVECTOR(VECTOR_SHUFFLE(?,?,Mask)) -> VECTOR_SHUFFLE(EXTRACT_SUBVECTOR(?, ?), EXTRACT_SUBVECTOR(?, ?), Mask')

Mon Dec 6 13:15:35 PST 2021

RKSimon added inline comments.

================
Comment at: llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp:20833
+    // Profitability check: only deal with extractions from the first subvector.
+    if (OpSubvecIdx != 0)
+      return SDValue();
----------------
lebedev.ri wrote:
> RKSimon wrote:
> > Why do we need this and isExtractSubvectorCheap ?
> Because the test changes were somewhat less controversial with that check.
OK, let's keep it for now

Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D104156/new/

https://reviews.llvm.org/D104156