[DAGCombiner] Teach DAG combiner to fold (vselect (N0 xor AllOnes), N1, N2) -> (vselect N0, N2, N1). Only do this if the target indicates its vector boolean type is ZeroOrNegativeOneBooleanContent.

llvm-svn: 291645

1 files changed, 9 insertions, 0 deletions

diff --git a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
index 680f62fa91b..2f603628916 100644
--- a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
@@ -5966,6 +5966,15 @@ SDValue DAGCombiner::visitVSELECT(SDNode *N) {
       return CV;
   }
 
+  // Fold (vselect (N0 xor AllOnes), N1, N2) -> (vselect N0, N2, N1)
+  if (N0.getOpcode() == ISD::XOR &&
+      ISD::isBuildVectorAllOnes(N0.getOperand(1).getNode()) &&
+      TLI.getBooleanContents(N0.getValueType()) ==
+            TargetLowering::ZeroOrNegativeOneBooleanContent) {
+    EVT VT = N->getValueType(0);
+    return DAG.getNode(ISD::VSELECT, DL, VT, N0.getOperand(0), N2, N1);
+  }
+
   return SDValue();
 }