[llvm] r325429 - [DAGCombiner] Remove simplifyShuffleMask - now handled more generally by SimplifyDemandedVectorElts.

[Simon Pilgrim via llvm-commits]

Author: rksimon
Date: Sat Feb 17 04:36:56 2018
New Revision: 325429

URL: http://llvm.org/viewvc/llvm-project?rev=325429&view=rev
Log:
[DAGCombiner] Remove simplifyShuffleMask - now handled more generally by SimplifyDemandedVectorElts.

Modified:
    llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp

Modified: llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp?rev=325429&r1=325428&r2=325429&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp (original)
+++ llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp Sat Feb 17 04:36:56 2018
@@ -15591,37 +15591,6 @@ SDValue DAGCombiner::visitEXTRACT_SUBVEC
   return SDValue();
 }
 
-static SDValue simplifyShuffleMask(ShuffleVectorSDNode *SVN, SDValue N0,
-                                   SDValue N1, SelectionDAG &DAG) {
-  auto isUndefElt = [](SDValue V, int Idx) {
-    // TODO - handle more cases as required.
-    if (V.getOpcode() == ISD::BUILD_VECTOR)
-      return V.getOperand(Idx).isUndef();
-    if (V.getOpcode() == ISD::SCALAR_TO_VECTOR)
-      return (Idx != 0) || V.getOperand(0).isUndef();
-    return false;
-  };
-
-  EVT VT = SVN->getValueType(0);
-  unsigned NumElts = VT.getVectorNumElements();
-
-  bool Changed = false;
-  SmallVector<int, 8> NewMask;
-  for (unsigned i = 0; i != NumElts; ++i) {
-    int Idx = SVN->getMaskElt(i);
-    if ((0 <= Idx && Idx < (int)NumElts && isUndefElt(N0, Idx)) ||
-        ((int)NumElts < Idx && isUndefElt(N1, Idx - NumElts))) {
-      Changed = true;
-      Idx = -1;
-    }
-    NewMask.push_back(Idx);
-  }
-  if (Changed)
-    return DAG.getVectorShuffle(VT, SDLoc(SVN), N0, N1, NewMask);
-
-  return SDValue();
-}
-
 // Tries to turn a shuffle of two CONCAT_VECTORS into a single concat,
 // or turn a shuffle of a single concat into simpler shuffle then concat.
 static SDValue partitionShuffleOfConcats(SDNode *N, SelectionDAG &DAG) {
@@ -16064,10 +16033,6 @@ SDValue DAGCombiner::visitVECTOR_SHUFFLE
       return DAG.getVectorShuffle(VT, SDLoc(N), N0, N1, NewMask);
   }
 
-  // Simplify shuffle mask if a referenced element is UNDEF.
-  if (SDValue V = simplifyShuffleMask(SVN, N0, N1, DAG))
-    return V;
-
   if (SDValue InsElt = replaceShuffleOfInsert(SVN, DAG))
     return InsElt;