// There is no native floating point division, but we can convert this to a
// reciprocal/multiply operation. If the first parameter is constant 1.0, then
// just a reciprocal will suffice.
SDValue
VectorProcTargetLowering::LowerFDIV(SDValue Op, SelectionDAG &DAG) const
{
DebugLoc dl = Op.getDebugLoc();
EVT type = Op.getOperand(1).getValueType();
SDValue two = DAG.getConstantFP(2.0, type);
SDValue denom = Op.getOperand(1);
SDValue estimate = DAG.getNode(VectorProcISD::RECIPROCAL_EST, dl, type, denom);
// Perform a series of newton/raphson refinements. Each iteration doubles
// the precision. The initial estimate has 6 bits of precision, so two iteration
// results in 24 bits, which is larger than the significand.
for (int i = 0; i < 2; i++)
{
// trial = x * estimate (ideally, x * 1/x should be 1.0)
// error = 2.0 - trial
// estimate = estimate * error
SDValue trial = DAG.getNode(ISD::FMUL, dl, type, estimate, denom);
SDValue error = DAG.getNode(ISD::FSUB, dl, type, two, trial);
estimate = DAG.getNode(ISD::FMUL, dl, type, estimate, error);
}
// Check if the first parameter is constant 1.0. If so, we don't need
// to multiply.
bool isOne = false;
if (type.isVector())
{
if (isSplatVector(Op.getOperand(0).getNode()))
{
ConstantFPSDNode *C = dyn_cast<ConstantFPSDNode>(Op.getOperand(0).getOperand(0));
isOne = C && C->isExactlyValue(1.0);
}
}
else
{
ConstantFPSDNode *C = dyn_cast<ConstantFPSDNode>(Op.getOperand(0));
isOne = C && C->isExactlyValue(1.0);
}
if (!isOne)
estimate = DAG.getNode(ISD::FMUL, dl, type, Op.getOperand(0), estimate);
return estimate;
}
SDValue R600TargetLowering::LowerSELECT_CC(SDValue Op, SelectionDAG &DAG) const
{
DebugLoc DL = Op.getDebugLoc();
EVT VT = Op.getValueType();
SDValue LHS = Op.getOperand(0);
SDValue RHS = Op.getOperand(1);
SDValue True = Op.getOperand(2);
SDValue False = Op.getOperand(3);
SDValue CC = Op.getOperand(4);
ISD::CondCode CCOpcode = cast<CondCodeSDNode>(CC)->get();
SDValue Temp;
// LHS and RHS are guaranteed to be the same value type
EVT CompareVT = LHS.getValueType();
// We need all the operands of SELECT_CC to have the same value type, so if
// necessary we need to convert LHS and RHS to be the same type True and
// False. True and False are guaranteed to have the same type as this
// SELECT_CC node.
if (CompareVT != VT) {
ISD::NodeType ConversionOp = ISD::DELETED_NODE;
if (VT == MVT::f32 && CompareVT == MVT::i32) {
if (isUnsignedIntSetCC(CCOpcode)) {
ConversionOp = ISD::UINT_TO_FP;
} else {
ConversionOp = ISD::SINT_TO_FP;
}
} else if (VT == MVT::i32 && CompareVT == MVT::f32) {
ConversionOp = ISD::FP_TO_SINT;
} else {
// I don't think there will be any other type pairings.
assert(!"Unhandled operand type parings in SELECT_CC");
}
// XXX Check the value of LHS and RHS and avoid creating sequences like
// (FTOI (ITOF))
LHS = DAG.getNode(ConversionOp, DL, VT, LHS);
RHS = DAG.getNode(ConversionOp, DL, VT, RHS);
}
// If True is a hardware TRUE value and False is a hardware FALSE value or
// vice-versa we can handle this with a native instruction (SET* instructions).
if ((isHWTrueValue(True) && isHWFalseValue(False))) {
return DAG.getNode(ISD::SELECT_CC, DL, VT, LHS, RHS, True, False, CC);
}
// XXX If True is a hardware TRUE value and False is a hardware FALSE value,
// we can handle this with a native instruction, but we need to swap true
// and false and change the conditional.
if (isHWTrueValue(False) && isHWFalseValue(True)) {
}
// XXX Check if we can lower this to a SELECT or if it is supported by a native
// operation. (The code below does this but we don't have the Instruction
// selection patterns to do this yet.
#if 0
if (isZero(LHS) || isZero(RHS)) {
SDValue Cond = (isZero(LHS) ? RHS : LHS);
bool SwapTF = false;
switch (CCOpcode) {
case ISD::SETOEQ:
case ISD::SETUEQ:
case ISD::SETEQ:
SwapTF = true;
// Fall through
case ISD::SETONE:
case ISD::SETUNE:
case ISD::SETNE:
// We can lower to select
if (SwapTF) {
Temp = True;
True = False;
False = Temp;
}
// CNDE
return DAG.getNode(ISD::SELECT, DL, VT, Cond, True, False);
default:
// Supported by a native operation (CNDGE, CNDGT)
return DAG.getNode(ISD::SELECT_CC, DL, VT, LHS, RHS, True, False, CC);
}
}
#endif
// If we make it this for it means we have no native instructions to handle
// this SELECT_CC, so we must lower it.
SDValue HWTrue, HWFalse;
if (VT == MVT::f32) {
HWTrue = DAG.getConstantFP(1.0f, VT);
HWFalse = DAG.getConstantFP(0.0f, VT);
} else if (VT == MVT::i32) {
HWTrue = DAG.getConstant(-1, VT);
HWFalse = DAG.getConstant(0, VT);
}
else {
assert(!"Unhandled value type in LowerSELECT_CC");
}
// Lower this unsupported SELECT_CC into a combination of two supported
// SELECT_CC operations.
SDValue Cond = DAG.getNode(ISD::SELECT_CC, DL, VT, LHS, RHS, HWTrue, HWFalse, CC);
// Convert floating point condition to i1
if (VT == MVT::f32) {
Cond = DAG.getNode(ISD::FP_TO_SINT, DL, MVT::i32,
DAG.getNode(ISD::FNEG, DL, VT, Cond));
}
return DAG.getNode(ISD::SELECT, DL, VT, Cond, True, False);
}