diff options
| -rw-r--r-- | lib/CodeGen/SelectionDAG/DAGCombiner.cpp | 3 |
1 files changed, 3 insertions, 0 deletions
diff --git a/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/lib/CodeGen/SelectionDAG/DAGCombiner.cpp index 186f4afc3d..a5b2d9594d 100644 --- a/lib/CodeGen/SelectionDAG/DAGCombiner.cpp +++ b/lib/CodeGen/SelectionDAG/DAGCombiner.cpp @@ -1542,6 +1542,9 @@ SDValue DAGCombiner::visitSUB(SDNode *N) { // Canonicalize (sub -1, x) -> ~x, i.e. (xor x, -1) if (N0C && N0C->isAllOnesValue()) return DAG.getNode(ISD::XOR, N->getDebugLoc(), VT, N1, N0); + // fold A-(A-B) -> B + if (N1.getOpcode() == ISD::SUB && N0 == N1.getOperand(0)) + return N1.getOperand(1); // fold (A+B)-A -> B if (N0.getOpcode() == ISD::ADD && N0.getOperand(0) == N1) return N0.getOperand(1); |