DAGCombine: fold (or (and X, M), (and X, N)) -> (and X, (or M, N))
It can help with argument juggling on some targets, and is generally a good
idea.
llvm-svn: 226740
diff --git a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
index 3bde9918..8495088 100644
--- a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
@@ -3527,6 +3527,17 @@
}
}
+ // (or (and X, M), (and X, N)) -> (and X, (or M, N))
+ if (N0.getOpcode() == ISD::AND &&
+ N1.getOpcode() == ISD::AND &&
+ N0.getOperand(0) == N1.getOperand(0) &&
+ // Don't increase # computations.
+ (N0.getNode()->hasOneUse() || N1.getNode()->hasOneUse())) {
+ SDValue X = DAG.getNode(ISD::OR, SDLoc(N0), VT,
+ N0.getOperand(1), N1.getOperand(1));
+ return DAG.getNode(ISD::AND, SDLoc(N), VT, N0.getOperand(0), X);
+ }
+
// See if this is some rotate idiom.
if (SDNode *Rot = MatchRotate(N0, N1, SDLoc(N)))
return SDValue(Rot, 0);