[PATCH] D66718: [DAGCombiner] (insert_vector_elt (vector_shuffle X, Y), (extract_vector_elt X, N), IdxC) -> (vector_shuffle X, Y)

[Amaury SECHET via Phabricator via llvm-commits]

deadalnix marked an inline comment as done.
deadalnix added inline comments.


================
Comment at: lib/CodeGen/SelectionDAG/DAGCombiner.cpp:16456
+
+      return DAG.getVectorShuffle(Vec.getValueType(), SDLoc(N),
+                                  Vec.getOperand(0), Vec.getOperand(1),
----------------
RKSimon wrote:
> You need to check NewMask is legal: if (!TLI.isShuffleMaskLegal(NewMask, Vec.getValueType()))
There are a few places where isShuffleMaskLegal is used. Some try to flip operands inc ase it isn't legal. Should that be an idiom?


Repository:
  rL LLVM

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  https://reviews.llvm.org/D66718/new/

https://reviews.llvm.org/D66718