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[GlobalISel] Reorder code in CombinerHelper::buildUDivUsingMul. NFC #99565

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merged 2 commits into from
Jul 22, 2024
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[GlobalISel] Reorder code in CombinerHelper::buildUDivUsingMul. NFC #99565

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8a70d76
[GlobalISel] Reorder code in CombinerHelper::buildUDivUsingMul. NFC
topperc Jul 18, 2024
1f8f47d
fixup! Address review comment
topperc Jul 22, 2024
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54 changes: 27 additions & 27 deletions llvm/lib/CodeGen/GlobalISel/CombinerHelper.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -5179,13 +5179,9 @@ MachineInstr *CombinerHelper::buildUDivUsingMul(MachineInstr &MI) {
LLT ShiftAmtTy = getTargetLowering().getPreferredShiftAmountTy(Ty);
LLT ScalarShiftAmtTy = ShiftAmtTy.getScalarType();

unsigned KnownLeadingZeros =
KB ? KB->getKnownBits(LHS).countMinLeadingZeros() : 0;
auto &MIB = Builder;

bool UseSRL = false;
bool UseNPQ = false;
SmallVector<Register, 16> PreShifts, PostShifts, MagicFactors, NPQFactors;
SmallVector<Register, 16> Shifts, Factors;
auto *RHSDefInstr = cast<GenericMachineInstr>(getDefIgnoringCopies(RHS, MRI));
bool IsSplat = getIConstantSplatVal(*RHSDefInstr, MRI).has_value();
Expand Down Expand Up @@ -5213,6 +5209,33 @@ MachineInstr *CombinerHelper::buildUDivUsingMul(MachineInstr &MI) {
return true;
};

if (MI.getFlag(MachineInstr::MIFlag::IsExact)) {
// Collect all magic values from the build vector.
if (!matchUnaryPredicate(MRI, RHS, BuildExactUDIVPattern))
llvm_unreachable("Expected unary predicate match to succeed");

Register Shift, Factor;
if (Ty.isVector()) {
Shift = MIB.buildBuildVector(ShiftAmtTy, Shifts).getReg(0);
Factor = MIB.buildBuildVector(Ty, Factors).getReg(0);
} else {
Shift = Shifts[0];
Factor = Factors[0];
}

Register Res = LHS;

if (UseSRL)
Res = MIB.buildLShr(Ty, Res, Shift, MachineInstr::IsExact).getReg(0);

return MIB.buildMul(Ty, Res, Factor);
}

unsigned KnownLeadingZeros =
KB ? KB->getKnownBits(LHS).countMinLeadingZeros() : 0;

bool UseNPQ = false;
SmallVector<Register, 16> PreShifts, PostShifts, MagicFactors, NPQFactors;
auto BuildUDIVPattern = [&](const Constant *C) {
auto *CI = cast<ConstantInt>(C);
const APInt &Divisor = CI->getValue();
Expand Down Expand Up @@ -5258,29 +5281,6 @@ MachineInstr *CombinerHelper::buildUDivUsingMul(MachineInstr &MI) {
return true;
};

if (MI.getFlag(MachineInstr::MIFlag::IsExact)) {
// Collect all magic values from the build vector.
bool Matched = matchUnaryPredicate(MRI, RHS, BuildExactUDIVPattern);
(void)Matched;
assert(Matched && "Expected unary predicate match to succeed");

Register Shift, Factor;
if (Ty.isVector()) {
Shift = MIB.buildBuildVector(ShiftAmtTy, Shifts).getReg(0);
Factor = MIB.buildBuildVector(Ty, Factors).getReg(0);
} else {
Shift = Shifts[0];
Factor = Factors[0];
}

Register Res = LHS;

if (UseSRL)
Res = MIB.buildLShr(Ty, Res, Shift, MachineInstr::IsExact).getReg(0);

return MIB.buildMul(Ty, Res, Factor);
}

// Collect the shifts/magic values from each element.
bool Matched = matchUnaryPredicate(MRI, RHS, BuildUDIVPattern);
(void)Matched;
Expand Down
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