[PATCH] D66456: [DAGCombiner][X86] Teach visitCONCAT_VECTORS to combine (concat_vectors (concat_vectors X, Y), undef)) -> (concat_vectors X, Y, undef, undef)

[Craig Topper via Phabricator via llvm-commits]

craig.topper updated this revision to Diff 216193.
craig.topper added a comment.

Replace the combineInsertSubVector change with a new combine in combineExtractSubvector. This just narrows an insert into zero if we are extracting a smaller portion of it and the extract is only the only user. This should be a more straightforward change. The combine I edited in combineInsertSubvector has no one use checks so doing an index other than zero may not be the best choice.


CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D66456/new/

https://reviews.llvm.org/D66456

Files:
  llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
  llvm/lib/Target/X86/X86ISelLowering.cpp
  llvm/test/CodeGen/X86/avx512vl-vec-masked-cmp.ll
  llvm/test/CodeGen/X86/oddshuffles.ll
  llvm/test/CodeGen/X86/vec_saddo.ll
  llvm/test/CodeGen/X86/vec_smulo.ll
  llvm/test/CodeGen/X86/vec_ssubo.ll
  llvm/test/CodeGen/X86/vec_uaddo.ll
  llvm/test/CodeGen/X86/vec_umulo.ll
  llvm/test/CodeGen/X86/vec_usubo.ll

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