diff options
Diffstat (limited to 'lib/CodeGen')
| -rw-r--r-- | lib/CodeGen/SelectionDAG/DAGCombiner.cpp | 6 |
1 files changed, 6 insertions, 0 deletions
diff --git a/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/lib/CodeGen/SelectionDAG/DAGCombiner.cpp index 783bfce9cc..e3525df181 100644 --- a/lib/CodeGen/SelectionDAG/DAGCombiner.cpp +++ b/lib/CodeGen/SelectionDAG/DAGCombiner.cpp @@ -1184,6 +1184,12 @@ SDValue DAGCombiner::visitSUB(SDNode *N) { N0.getOperand(1).getOperand(0) == N1) return DAG.getNode(ISD::SUB, VT, N0.getOperand(0), N0.getOperand(1).getOperand(1)); + // fold ((A-(B-C))-C) -> A-B + if (N0.getOpcode() == ISD::SUB && + N0.getOperand(1).getOpcode() == ISD::SUB && + N0.getOperand(1).getOperand(1) == N1) + return DAG.getNode(ISD::SUB, VT, N0.getOperand(0), + N0.getOperand(1).getOperand(0)); // fold (sub x, (select cc, 0, c)) -> (select cc, x, (sub, x, c)) if (N1.getOpcode() == ISD::SELECT && N1.getNode()->hasOneUse()) { SDValue Result = combineSelectAndUse(N, N1, N0, DAG, TLI, LegalOperations); |