1 files changed, 23 insertions, 16 deletions

diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
index d667988..90e4b5d 100644
--- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
@@ -4684,26 +4684,33 @@ bool SelectionDAG::isEqualTo(SDValue A, SDValue B) const {
   return false;
 }
 
+static bool haveNoCommonBitsSetCommutative(SDValue A, SDValue B) {
+  // Match masked merge pattern (X & ~M) op (Y & M)
+  // Including degenerate case (X & ~M) op M
+  auto MatchNoCommonBitsPattern = [&](SDValue NotM, SDValue Other) {
+    if (isBitwiseNot(NotM, true)) {
+      SDValue NotOperand = NotM->getOperand(0);
+      if (Other == NotOperand)
+        return true;
+      if (Other->getOpcode() == ISD::AND)
+        return NotOperand == Other->getOperand(0) ||
+               NotOperand == Other->getOperand(1);
+    }
+    return false;
+  };
+  if (A->getOpcode() == ISD::AND)
+    return MatchNoCommonBitsPattern(A->getOperand(0), B) ||
+           MatchNoCommonBitsPattern(A->getOperand(1), B);
+  return false;
+}
+
 // FIXME: unify with llvm::haveNoCommonBitsSet.
 bool SelectionDAG::haveNoCommonBitsSet(SDValue A, SDValue B) const {
   assert(A.getValueType() == B.getValueType() &&
          "Values must have the same type");
-  // Match masked merge pattern (X & ~M) op (Y & M)
-  if (A->getOpcode() == ISD::AND && B->getOpcode() == ISD::AND) {
-    auto MatchNoCommonBitsPattern = [&](SDValue NotM, SDValue And) {
-      if (isBitwiseNot(NotM, true)) {
-        SDValue NotOperand = NotM->getOperand(0);
-        return NotOperand == And->getOperand(0) ||
-               NotOperand == And->getOperand(1);
-      }
-      return false;
-    };
-    if (MatchNoCommonBitsPattern(A->getOperand(0), B) ||
-        MatchNoCommonBitsPattern(A->getOperand(1), B) ||
-        MatchNoCommonBitsPattern(B->getOperand(0), A) ||
-        MatchNoCommonBitsPattern(B->getOperand(1), A))
-      return true;
-  }
+  if (haveNoCommonBitsSetCommutative(A, B) ||
+      haveNoCommonBitsSetCommutative(B, A))
+    return true;
   return KnownBits::haveNoCommonBitsSet(computeKnownBits(A),
                                         computeKnownBits(B));
 }