diff options
Diffstat (limited to 'lib/CodeGen/SelectionDAG/DAGCombiner.cpp')
| -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 549527c1a3..7fe908c730 100644 --- a/lib/CodeGen/SelectionDAG/DAGCombiner.cpp +++ b/lib/CodeGen/SelectionDAG/DAGCombiner.cpp @@ -1176,6 +1176,9 @@ SDValue DAGCombiner::visitSUB(SDNode *N) { if (N1C) return DAG.getNode(ISD::ADD, N->getDebugLoc(), VT, N0, DAG.getConstant(-N1C->getAPIntValue(), VT)); + // 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+B)-A -> B if (N0.getOpcode() == ISD::ADD && N0.getOperand(0) == N1) return N0.getOperand(1); |