diff options
| -rw-r--r-- | lib/CodeGen/SelectionDAG/DAGCombiner.cpp | 25 |
1 files changed, 14 insertions, 11 deletions
diff --git a/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/lib/CodeGen/SelectionDAG/DAGCombiner.cpp index cb7276e023..d69aede7d4 100644 --- a/lib/CodeGen/SelectionDAG/DAGCombiner.cpp +++ b/lib/CodeGen/SelectionDAG/DAGCombiner.cpp @@ -429,6 +429,11 @@ static SDOperand GetNegatedExpression(SDOperand Op, SelectionDAG &DAG, case ISD::FSUB: // We can't turn -(A-B) into B-A when we honor signed zeros. assert(UnsafeFPMath); + + // -(0-B) -> B + if (ConstantFPSDNode *N0CFP = dyn_cast<ConstantFPSDNode>(Op.getOperand(0))) + if (N0CFP->getValue() == 0.0) + return Op.getOperand(1); // -(A-B) -> B-A return DAG.getNode(ISD::FSUB, Op.getValueType(), Op.getOperand(1), @@ -3025,6 +3030,12 @@ SDOperand DAGCombiner::visitFSUB(SDNode *N) { // fold (fsub c1, c2) -> c1-c2 if (N0CFP && N1CFP) return DAG.getNode(ISD::FSUB, VT, N0, N1); + // fold (0-B) -> -B + if (UnsafeFPMath && N0CFP && N0CFP->getValue() == 0.0) { + if (isNegatibleForFree(N1)) + return GetNegatedExpression(N1, DAG); + return DAG.getNode(ISD::FNEG, VT, N1); + } // fold (A-(-B)) -> A+B if (isNegatibleForFree(N1)) return DAG.getNode(ISD::FADD, VT, N0, GetNegatedExpression(N1, DAG)); @@ -3297,18 +3308,10 @@ SDOperand DAGCombiner::visitFP_EXTEND(SDNode *N) { SDOperand DAGCombiner::visitFNEG(SDNode *N) { SDOperand N0 = N->getOperand(0); - ConstantFPSDNode *N0CFP = dyn_cast<ConstantFPSDNode>(N0); - MVT::ValueType VT = N->getValueType(0); - // fold (fneg c1) -> -c1 - if (N0CFP) - return DAG.getNode(ISD::FNEG, VT, N0); - // fold (fneg (sub x, y)) -> (sub y, x) - if (N0.getOpcode() == ISD::SUB) - return DAG.getNode(ISD::SUB, VT, N0.getOperand(1), N0.getOperand(0)); - // fold (fneg (fneg x)) -> x - if (N0.getOpcode() == ISD::FNEG) - return N0.getOperand(0); + if (isNegatibleForFree(N0)) + return GetNegatedExpression(N0, DAG); + return SDOperand(); } |