diff options
Diffstat (limited to 'llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp')
| -rw-r--r-- | llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp | 18 |
1 files changed, 18 insertions, 0 deletions
diff --git a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp index 03698ac862a..c2be9f3f058 100644 --- a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp +++ b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp @@ -9469,6 +9469,14 @@ SDValue DAGCombiner::visitFMULForFMADistributiveCombine(SDNode *N) { return SDValue(); } +static bool isFMulNegTwo(SDValue &N) { + if (N.getOpcode() != ISD::FMUL) + return false; + if (ConstantFPSDNode *CFP = isConstOrConstSplatFP(N.getOperand(1))) + return CFP->isExactlyValue(-2.0); + return false; +} + SDValue DAGCombiner::visitFADD(SDNode *N) { SDValue N0 = N->getOperand(0); SDValue N1 = N->getOperand(1); @@ -9507,6 +9515,16 @@ SDValue DAGCombiner::visitFADD(SDNode *N) { return DAG.getNode(ISD::FSUB, DL, VT, N1, GetNegatedExpression(N0, DAG, LegalOperations), Flags); + // fold (fadd A, (fmul B, -2.0)) -> (fsub A, (fadd B, B)) + // fold (fadd (fmul B, -2.0), A) -> (fsub A, (fadd B, B)) + if ((isFMulNegTwo(N0) && N0.hasOneUse()) || + (isFMulNegTwo(N1) && N1.hasOneUse())) { + bool N1IsFMul = isFMulNegTwo(N1); + SDValue AddOp = N1IsFMul ? N1.getOperand(0) : N0.getOperand(0); + SDValue Add = DAG.getNode(ISD::FADD, DL, VT, AddOp, AddOp, Flags); + return DAG.getNode(ISD::FSUB, DL, VT, N1IsFMul ? N0 : N1, Add, Flags); + } + // FIXME: Auto-upgrade the target/function-level option. if (Options.NoSignedZerosFPMath || N->getFlags().hasNoSignedZeros()) { // fold (fadd A, 0) -> A |
