[DAG] Refactor some logic. No functional change.

This patch removes function 'CommuteVectorShuffle' from X86ISelLowering.cpp
and moves its logic into SelectionDAG.cpp as method 'getCommutedVectorShuffles'.
This refactoring is in preperation of an upcoming change to the DAGCombiner.

llvm-svn: 213503

1 files changed, 21 insertions, 0 deletions

diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
index 34f5014d1b0..22379de801e 100644
--- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
@@ -1598,6 +1598,27 @@ SDValue SelectionDAG::getVectorShuffle(EVT VT, SDLoc dl, SDValue N1,
   return SDValue(N, 0);
 }
 
+SDValue SelectionDAG::getCommutedVectorShuffle(const ShuffleVectorSDNode &SV) {
+  MVT VT = SV.getSimpleValueType(0);
+  unsigned NumElems = VT.getVectorNumElements();
+  SmallVector<int, 8> MaskVec;
+
+  for (unsigned i = 0; i != NumElems; ++i) {
+    int Idx = SV.getMaskElt(i);
+    if (Idx >= 0) {
+      if (Idx < (int)NumElems)
+        Idx += NumElems;
+      else
+        Idx -= NumElems;
+    }
+    MaskVec.push_back(Idx);
+  }
+
+  SDValue Op0 = SV.getOperand(0);
+  SDValue Op1 = SV.getOperand(1);
+  return getVectorShuffle(VT, SDLoc(&SV), Op1, Op0, &MaskVec[0]);
+}
+
 SDValue SelectionDAG::getConvertRndSat(EVT VT, SDLoc dl,
                                        SDValue Val, SDValue DTy,
                                        SDValue STy, SDValue Rnd, SDValue Sat,