// Target Optimization Hooks
//===----------------------------------------------------------------------===//
-SDValue PPCTargetLowering::DAGCombineFastRecip(SDValue Op,
- DAGCombinerInfo &DCI) const {
- if (DCI.isAfterLegalizeVectorOps())
- return SDValue();
-
- EVT VT = Op.getValueType();
-
- if ((VT == MVT::f32 && Subtarget.hasFRES()) ||
- (VT == MVT::f64 && Subtarget.hasFRE()) ||
- (VT == MVT::v4f32 && Subtarget.hasAltivec()) ||
- (VT == MVT::v2f64 && Subtarget.hasVSX())) {
-
- // Newton iteration for a function: F(X) is X_{i+1} = X_i - F(X_i)/F'(X_i)
- // For the reciprocal, we need to find the zero of the function:
- // F(X) = A X - 1 [which has a zero at X = 1/A]
- // =>
- // X_{i+1} = X_i (2 - A X_i) = X_i + X_i (1 - A X_i) [this second form
- // does not require additional intermediate precision]
-
+SDValue PPCTargetLowering::getEstimate(unsigned Opcode, SDValue Operand,
+ DAGCombinerInfo &DCI,
+ unsigned &RefinementSteps) const {
+ EVT VT = Operand.getValueType();
+ SDValue RV;
+ if (Opcode == ISD::FSQRT) {
+ if ((VT == MVT::f32 && Subtarget.hasFRSQRTES()) ||
+ (VT == MVT::f64 && Subtarget.hasFRSQRTE()) ||
+ (VT == MVT::v4f32 && Subtarget.hasAltivec()) ||
+ (VT == MVT::v2f64 && Subtarget.hasVSX()))
+ RV = DCI.DAG.getNode(PPCISD::FRSQRTE, SDLoc(Operand), VT, Operand);
+ } else if (Opcode == ISD::FDIV) {
+ if ((VT == MVT::f32 && Subtarget.hasFRES()) ||
+ (VT == MVT::f64 && Subtarget.hasFRE()) ||
+ (VT == MVT::v4f32 && Subtarget.hasAltivec()) ||
+ (VT == MVT::v2f64 && Subtarget.hasVSX()))
+ RV = DCI.DAG.getNode(PPCISD::FRE, SDLoc(Operand), VT, Operand);
+ }
+ if (RV.getNode()) {
// Convergence is quadratic, so we essentially double the number of digits
- // correct after every iteration. The minimum architected relative
- // accuracy is 2^-5. When hasRecipPrec(), this is 2^-14. IEEE float has
- // 23 digits and double has 52 digits.
- int Iterations = Subtarget.hasRecipPrec() ? 1 : 3;
+ // correct after every iteration. For both FRE and FRSQRTE, the minimum
+ // architected relative accuracy is 2^-5. When hasRecipPrec(), this is
+ // 2^-14. IEEE float has 23 digits and double has 52 digits.
+ RefinementSteps = Subtarget.hasRecipPrec() ? 1 : 3;
if (VT.getScalarType() == MVT::f64)
- ++Iterations;
-
- SelectionDAG &DAG = DCI.DAG;
- SDLoc dl(Op);
-
- SDValue FPOne =
- DAG.getConstantFP(1.0, VT.getScalarType());
- if (VT.isVector()) {
- assert(VT.getVectorNumElements() == 4 &&
- "Unknown vector type");
- FPOne = DAG.getNode(ISD::BUILD_VECTOR, dl, VT,
- FPOne, FPOne, FPOne, FPOne);
- }
-
- SDValue Est = DAG.getNode(PPCISD::FRE, dl, VT, Op);
- DCI.AddToWorklist(Est.getNode());
-
- // Newton iterations: Est = Est + Est (1 - Arg * Est)
- for (int i = 0; i < Iterations; ++i) {
- SDValue NewEst = DAG.getNode(ISD::FMUL, dl, VT, Op, Est);
- DCI.AddToWorklist(NewEst.getNode());
-
- NewEst = DAG.getNode(ISD::FSUB, dl, VT, FPOne, NewEst);
- DCI.AddToWorklist(NewEst.getNode());
-
- NewEst = DAG.getNode(ISD::FMUL, dl, VT, Est, NewEst);
- DCI.AddToWorklist(NewEst.getNode());
-
- Est = DAG.getNode(ISD::FADD, dl, VT, Est, NewEst);
- DCI.AddToWorklist(Est.getNode());
- }
-
- return Est;
+ ++RefinementSteps;
}
-
- return SDValue();
-}
-
-SDValue PPCTargetLowering::BuildRSQRTE(SDValue Op, DAGCombinerInfo &DCI) const {
- if (DCI.isAfterLegalizeVectorOps())
- return SDValue();
-
- EVT VT = Op.getValueType();
-
- if ((VT == MVT::f32 && Subtarget.hasFRSQRTES()) ||
- (VT == MVT::f64 && Subtarget.hasFRSQRTE()) ||
- (VT == MVT::v4f32 && Subtarget.hasAltivec()) ||
- (VT == MVT::v2f64 && Subtarget.hasVSX())) {
-
- // Newton iteration for a function: F(X) is X_{i+1} = X_i - F(X_i)/F'(X_i)
- // For the reciprocal sqrt, we need to find the zero of the function:
- // F(X) = 1/X^2 - A [which has a zero at X = 1/sqrt(A)]
- // =>
- // X_{i+1} = X_i (1.5 - A X_i^2 / 2)
- // As a result, we precompute A/2 prior to the iteration loop.
-
- // Convergence is quadratic, so we essentially double the number of digits
- // correct after every iteration. The minimum architected relative
- // accuracy is 2^-5. When hasRecipPrec(), this is 2^-14. IEEE float has
- // 23 digits and double has 52 digits.
- int Iterations = Subtarget.hasRecipPrec() ? 1 : 3;
- if (VT.getScalarType() == MVT::f64)
- ++Iterations;
-
- SelectionDAG &DAG = DCI.DAG;
- SDLoc dl(Op);
-
- SDValue FPThreeHalves =
- DAG.getConstantFP(1.5, VT.getScalarType());
- if (VT.isVector()) {
- assert(VT.getVectorNumElements() == 4 &&
- "Unknown vector type");
- FPThreeHalves = DAG.getNode(ISD::BUILD_VECTOR, dl, VT,
- FPThreeHalves, FPThreeHalves,
- FPThreeHalves, FPThreeHalves);
- }
-
- SDValue Est = DAG.getNode(PPCISD::FRSQRTE, dl, VT, Op);
- DCI.AddToWorklist(Est.getNode());
-
- // We now need 0.5*Arg which we can write as (1.5*Arg - Arg) so that
- // this entire sequence requires only one FP constant.
- SDValue HalfArg = DAG.getNode(ISD::FMUL, dl, VT, FPThreeHalves, Op);
- DCI.AddToWorklist(HalfArg.getNode());
-
- HalfArg = DAG.getNode(ISD::FSUB, dl, VT, HalfArg, Op);
- DCI.AddToWorklist(HalfArg.getNode());
-
- // Newton iterations: Est = Est * (1.5 - HalfArg * Est * Est)
- for (int i = 0; i < Iterations; ++i) {
- SDValue NewEst = DAG.getNode(ISD::FMUL, dl, VT, Est, Est);
- DCI.AddToWorklist(NewEst.getNode());
-
- NewEst = DAG.getNode(ISD::FMUL, dl, VT, HalfArg, NewEst);
- DCI.AddToWorklist(NewEst.getNode());
-
- NewEst = DAG.getNode(ISD::FSUB, dl, VT, FPThreeHalves, NewEst);
- DCI.AddToWorklist(NewEst.getNode());
-
- Est = DAG.getNode(ISD::FMUL, dl, VT, Est, NewEst);
- DCI.AddToWorklist(Est.getNode());
- }
-
- return Est;
- }
-
- return SDValue();
+ return RV;
}
static bool isConsecutiveLSLoc(SDValue Loc, EVT VT, LSBaseSDNode *Base,
case ISD::SETCC:
case ISD::SELECT_CC:
return DAGCombineTruncBoolExt(N, DCI);
- case ISD::FDIV: {
- assert(TM.Options.UnsafeFPMath &&
- "Reciprocal estimates require UnsafeFPMath");
-
- SDValue RV = DAGCombineFastRecip(N->getOperand(1), DCI);
- if (RV.getNode()) {
- DCI.AddToWorklist(RV.getNode());
- return DAG.getNode(ISD::FMUL, dl, N->getValueType(0),
- N->getOperand(0), RV);
- }
-
- }
- break;
- case ISD::FSQRT: {
- assert(TM.Options.UnsafeFPMath &&
- "Reciprocal estimates require UnsafeFPMath");
-
- // Compute this as 1/(1/sqrt(X)), which is the reciprocal of the
- // reciprocal sqrt.
- SDValue RV = BuildRSQRTE(N->getOperand(0), DCI);
- if (RV.getNode()) {
- DCI.AddToWorklist(RV.getNode());
- RV = DAGCombineFastRecip(RV, DCI);
- if (RV.getNode()) {
- // Unfortunately, RV is now NaN if the input was exactly 0. Select out
- // this case and force the answer to 0.
-
- EVT VT = RV.getValueType();
-
- SDValue Zero = DAG.getConstantFP(0.0, VT.getScalarType());
- if (VT.isVector()) {
- assert(VT.getVectorNumElements() == 4 && "Unknown vector type");
- Zero = DAG.getNode(ISD::BUILD_VECTOR, dl, VT, Zero, Zero, Zero, Zero);
- }
-
- SDValue ZeroCmp =
- DAG.getSetCC(dl, getSetCCResultType(*DAG.getContext(), VT),
- N->getOperand(0), Zero, ISD::SETEQ);
- DCI.AddToWorklist(ZeroCmp.getNode());
- DCI.AddToWorklist(RV.getNode());
-
- RV = DAG.getNode(VT.isVector() ? ISD::VSELECT : ISD::SELECT, dl, VT,
- ZeroCmp, Zero, RV);
- return RV;
- }
- }
-
- }
- break;
case ISD::SINT_TO_FP:
if (TM.getSubtarget<PPCSubtarget>().has64BitSupport()) {
if (N->getOperand(0).getOpcode() == ISD::FP_TO_SINT) {
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