diff options
Diffstat (limited to 'llvm/lib/CodeGen')
| -rw-r--r-- | llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp | 6 |
1 files changed, 6 insertions, 0 deletions
diff --git a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp index 7a99687757f..963081c2e95 100644 --- a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp +++ b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp @@ -2671,6 +2671,12 @@ SDValue DAGCombiner::visitSUB(SDNode *N) { return DAG.getNode(ISD::SUB, DL, VT, N0.getOperand(0), N0.getOperand(1).getOperand(0)); + // fold (A-(B-C)) -> A+(C-B) + if (N1.getOpcode() == ISD::SUB && N1.hasOneUse()) + return DAG.getNode(ISD::ADD, DL, VT, N0, + DAG.getNode(ISD::SUB, DL, VT, N1.getOperand(1), + N1.getOperand(0))); + // fold (X - (-Y * Z)) -> (X + (Y * Z)) if (N1.getOpcode() == ISD::MUL && N1.hasOneUse()) { if (N1.getOperand(0).getOpcode() == ISD::SUB && |
