diff options
Diffstat (limited to 'lib/CodeGen/SelectionDAG/DAGCombiner.cpp')
| -rw-r--r-- | lib/CodeGen/SelectionDAG/DAGCombiner.cpp | 23 |
1 files changed, 23 insertions, 0 deletions
diff --git a/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/lib/CodeGen/SelectionDAG/DAGCombiner.cpp index 549527c..8883064 100644 --- a/lib/CodeGen/SelectionDAG/DAGCombiner.cpp +++ b/lib/CodeGen/SelectionDAG/DAGCombiner.cpp @@ -1088,6 +1088,26 @@ SDValue DAGCombiner::visitADD(SDNode *N) { if (Result.getNode()) return Result; } + // fold (add x, shl(0 - y, n)) -> sub(x, shl(y, n)) + if (N1.getOpcode() == ISD::SHL && + N1.getOperand(0).getOpcode() == ISD::SUB) + if (ConstantSDNode *C = + dyn_cast<ConstantSDNode>(N1.getOperand(0).getOperand(0))) + if (C->getAPIntValue() == 0) + return DAG.getNode(ISD::SUB, N->getDebugLoc(), VT, N0, + DAG.getNode(ISD::SHL, N->getDebugLoc(), VT, + N1.getOperand(0).getOperand(1), + N1.getOperand(1))); + if (N0.getOpcode() == ISD::SHL && + N0.getOperand(0).getOpcode() == ISD::SUB) + if (ConstantSDNode *C = + dyn_cast<ConstantSDNode>(N0.getOperand(0).getOperand(0))) + if (C->getAPIntValue() == 0) + return DAG.getNode(ISD::SUB, N->getDebugLoc(), VT, N1, + DAG.getNode(ISD::SHL, N->getDebugLoc(), VT, + N0.getOperand(0).getOperand(1), + N0.getOperand(1))); + return SDValue(); } @@ -1176,6 +1196,9 @@ 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); |
