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[TargetLowering] Remove APInt divisor argument from BuildExactSDIV (NFCI). 

As requested in D50392, this is a minor refactor to BuildExactSDIV to stop taking the uniform constant APInt divisor and instead extract it locally.

I also cleanup the operands and valuetypes to better match BuildUDiv (and BuildSDIV in the near future).

llvm-svn: 339246
This commit is contained in:
Simon Pilgrim 2018-08-08 13:59:44 +00:00
parent 81f1fbdf5a
commit e4a4cf5a8b
1 changed files with 22 additions and 14 deletions
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36
llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp
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@ -3432,22 +3432,32 @@ void TargetLowering::ComputeConstraintToUse(AsmOperandInfo &OpInfo,
/// Given an exact SDIV by a constant, create a multiplication
/// with the multiplicative inverse of the constant.
static SDValue BuildExactSDIV(const TargetLowering &TLI, SDValue Op1, APInt d,
static SDValue BuildExactSDIV(const TargetLowering &TLI, SDNode *N,
const SDLoc &dl, SelectionDAG &DAG,
SmallVectorImpl<SDNode *> &Created) {
SDValue Op0 = N->getOperand(0);
SDValue Op1 = N->getOperand(1);
EVT VT = N->getValueType(0);
EVT ShVT = TLI.getShiftAmountTy(VT, DAG.getDataLayout());
ConstantSDNode *C = isConstOrConstSplat(Op1);
if (!C || C->isNullValue())
return SDValue();
APInt d = C->getAPIntValue();
assert(d != 0 && "Division by zero!");
SDValue Res = Op0;
// Shift the value upfront if it is even, so the LSB is one.
unsigned ShAmt = d.countTrailingZeros();
if (ShAmt) {
// TODO: For UDIV use SRL instead of SRA.
SDValue Amt =
DAG.getConstant(ShAmt, dl, TLI.getShiftAmountTy(Op1.getValueType(),
DAG.getDataLayout()));
SDValue Amt = DAG.getConstant(ShAmt, dl, ShVT);
SDNodeFlags Flags;
Flags.setExact(true);
Op1 = DAG.getNode(ISD::SRA, dl, Op1.getValueType(), Op1, Amt, Flags);
Created.push_back(Op1.getNode());
Res = DAG.getNode(ISD::SRA, dl, VT, Res, Amt, Flags);
Created.push_back(Res.getNode());
d.ashrInPlace(ShAmt);
}
@ -3456,10 +3466,8 @@ static SDValue BuildExactSDIV(const TargetLowering &TLI, SDValue Op1, APInt d,
while ((t = d*xn) != 1)
xn *= APInt(d.getBitWidth(), 2) - t;
SDValue Op2 = DAG.getConstant(xn, dl, Op1.getValueType());
SDValue Mul = DAG.getNode(ISD::MUL, dl, Op1.getValueType(), Op1, Op2);
Created.push_back(Mul.getNode());
return Mul;
SDValue Mul = DAG.getConstant(xn, dl, VT);
return DAG.getNode(ISD::MUL, dl, VT, Res, Mul);
}
SDValue TargetLowering::BuildSDIVPow2(SDNode *N, const APInt &Divisor,
@ -3487,16 +3495,16 @@ SDValue TargetLowering::BuildSDIV(SDNode *N, SelectionDAG &DAG,
if (!isTypeLegal(VT))
return SDValue();
// If the sdiv has an 'exact' bit we can use a simpler lowering.
if (N->getFlags().hasExact())
return BuildExactSDIV(*this, N, dl, DAG, Created);
// TODO: Add non-uniform constant support.
ConstantSDNode *C = isConstOrConstSplat(N->getOperand(1));
if (!C || C->isNullValue())
return SDValue();
const APInt &Divisor = C->getAPIntValue();
// If the sdiv has an 'exact' bit we can use a simpler lowering.
if (N->getFlags().hasExact())
return BuildExactSDIV(*this, N->getOperand(0), Divisor, dl, DAG, Created);
APInt::ms magics = Divisor.magic();
// Multiply the numerator (operand 0) by the magic value