- // If allowed, fold (fadd (fadd x, c1), c2) -> (fadd x, (fadd c1, c2))
- if (Options.UnsafeFPMath && N1CFP &&
- N0.getOpcode() == ISD::FADD && N0.getNode()->hasOneUse() &&
- isa<ConstantFPSDNode>(N0.getOperand(1)))
- return DAG.getNode(ISD::FADD, SDLoc(N), VT, N0.getOperand(0),
- DAG.getNode(ISD::FADD, SDLoc(N), VT,
- N0.getOperand(1), N1));
-
- // No FP constant should be created after legalization as Instruction
- // Selection pass has hard time in dealing with FP constant.
- //
- // We don't need test this condition for transformation like following, as
- // the DAG being transformed implies it is legal to take FP constant as
- // operand.
- //
- // (fadd (fmul c, x), x) -> (fmul c+1, x)
- //
- bool AllowNewFpConst = (Level < AfterLegalizeDAG);
-
- // If allow, fold (fadd (fneg x), x) -> 0.0
- if (AllowNewFpConst && Options.UnsafeFPMath &&
- N0.getOpcode() == ISD::FNEG && N0.getOperand(0) == N1)
- return DAG.getConstantFP(0.0, VT);
-
- // If allow, fold (fadd x, (fneg x)) -> 0.0
- if (AllowNewFpConst && Options.UnsafeFPMath &&
- N1.getOpcode() == ISD::FNEG && N1.getOperand(0) == N0)
- return DAG.getConstantFP(0.0, VT);
-
- // In unsafe math mode, we can fold chains of FADD's of the same value
- // into multiplications. This transform is not safe in general because
- // we are reducing the number of rounding steps.
- if (Options.UnsafeFPMath && TLI.isOperationLegalOrCustom(ISD::FMUL, VT) &&
- !N0CFP && !N1CFP) {
- if (N0.getOpcode() == ISD::FMUL) {
- ConstantFPSDNode *CFP00 = dyn_cast<ConstantFPSDNode>(N0.getOperand(0));
- ConstantFPSDNode *CFP01 = dyn_cast<ConstantFPSDNode>(N0.getOperand(1));
-
- // (fadd (fmul c, x), x) -> (fmul x, c+1)
- if (CFP00 && !CFP01 && N0.getOperand(1) == N1) {
- SDValue NewCFP = DAG.getNode(ISD::FADD, SDLoc(N), VT,
- SDValue(CFP00, 0),
- DAG.getConstantFP(1.0, VT));
- return DAG.getNode(ISD::FMUL, SDLoc(N), VT,
- N1, NewCFP);
- }
-
- // (fadd (fmul x, c), x) -> (fmul x, c+1)
- if (CFP01 && !CFP00 && N0.getOperand(0) == N1) {
- SDValue NewCFP = DAG.getNode(ISD::FADD, SDLoc(N), VT,
- SDValue(CFP01, 0),
- DAG.getConstantFP(1.0, VT));
- return DAG.getNode(ISD::FMUL, SDLoc(N), VT,
- N1, NewCFP);
- }
-
- // (fadd (fmul c, x), (fadd x, x)) -> (fmul x, c+2)
- if (CFP00 && !CFP01 && N1.getOpcode() == ISD::FADD &&
- N1.getOperand(0) == N1.getOperand(1) &&
- N0.getOperand(1) == N1.getOperand(0)) {
- SDValue NewCFP = DAG.getNode(ISD::FADD, SDLoc(N), VT,
- SDValue(CFP00, 0),
- DAG.getConstantFP(2.0, VT));
- return DAG.getNode(ISD::FMUL, SDLoc(N), VT,
- N0.getOperand(1), NewCFP);
- }