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Use early return/continue in TailDuplicator::duplicateInstruction [nfc]

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This commit is contained in:
Philip Reames
2025-05-16 13:23:23 -07:00
committed by Philip Reames
parent ba93685ea2
commit 3def9976eb
1 changed files with 74 additions and 74 deletions
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148
llvm/lib/CodeGen/TailDuplicator.cpp
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@@ -399,81 +399,81 @@ void TailDuplicator::duplicateInstruction(
return;
}
MachineInstr &NewMI = TII->duplicate(*PredBB, PredBB->end(), *MI);
if (PreRegAlloc) {
for (unsigned i = 0, e = NewMI.getNumOperands(); i != e; ++i) {
MachineOperand &MO = NewMI.getOperand(i);
if (!MO.isReg())
continue;
Register Reg = MO.getReg();
if (!Reg.isVirtual())
continue;
if (MO.isDef()) {
const TargetRegisterClass *RC = MRI->getRegClass(Reg);
Register NewReg = MRI->createVirtualRegister(RC);
MO.setReg(NewReg);
LocalVRMap.insert(std::make_pair(Reg, RegSubRegPair(NewReg, 0)));
if (isDefLiveOut(Reg, TailBB, MRI) || UsedByPhi.count(Reg))
addSSAUpdateEntry(Reg, NewReg, PredBB);
} else {
auto VI = LocalVRMap.find(Reg);
if (VI != LocalVRMap.end()) {
// Need to make sure that the register class of the mapped register
// will satisfy the constraints of the class of the register being
// replaced.
auto *OrigRC = MRI->getRegClass(Reg);
auto *MappedRC = MRI->getRegClass(VI->second.Reg);
const TargetRegisterClass *ConstrRC;
if (VI->second.SubReg != 0) {
ConstrRC = TRI->getMatchingSuperRegClass(MappedRC, OrigRC,
VI->second.SubReg);
if (ConstrRC) {
// The actual constraining (as in "find appropriate new class")
// is done by getMatchingSuperRegClass, so now we only need to
// change the class of the mapped register.
MRI->setRegClass(VI->second.Reg, ConstrRC);
}
} else {
// For mapped registers that do not have sub-registers, simply
// restrict their class to match the original one.
// We don't want debug instructions affecting the resulting code so
// if we're cloning a debug instruction then just use MappedRC
// rather than constraining the register class further.
ConstrRC = NewMI.isDebugInstr()
? MappedRC
: MRI->constrainRegClass(VI->second.Reg, OrigRC);
}
if (ConstrRC) {
// If the class constraining succeeded, we can simply replace
// the old register with the mapped one.
MO.setReg(VI->second.Reg);
// We have Reg -> VI.Reg:VI.SubReg, so if Reg is used with a
// sub-register, we need to compose the sub-register indices.
MO.setSubReg(
TRI->composeSubRegIndices(VI->second.SubReg, MO.getSubReg()));
} else {
// The direct replacement is not possible, due to failing register
// class constraints. An explicit COPY is necessary. Create one
// that can be reused.
Register NewReg = MRI->createVirtualRegister(OrigRC);
BuildMI(*PredBB, NewMI, NewMI.getDebugLoc(),
TII->get(TargetOpcode::COPY), NewReg)
.addReg(VI->second.Reg, 0, VI->second.SubReg);
LocalVRMap.erase(VI);
LocalVRMap.insert(std::make_pair(Reg, RegSubRegPair(NewReg, 0)));
MO.setReg(NewReg);
// The composed VI.Reg:VI.SubReg is replaced with NewReg, which
// is equivalent to the whole register Reg. Hence, Reg:subreg
// is same as NewReg:subreg, so keep the sub-register index
// unchanged.
}
// Clear any kill flags from this operand. The new register could
// have uses after this one, so kills are not valid here.
MO.setIsKill(false);
}
}
if (!PreRegAlloc)
return;
for (unsigned i = 0, e = NewMI.getNumOperands(); i != e; ++i) {
MachineOperand &MO = NewMI.getOperand(i);
if (!MO.isReg())
continue;
Register Reg = MO.getReg();
if (!Reg.isVirtual())
continue;
if (MO.isDef()) {
const TargetRegisterClass *RC = MRI->getRegClass(Reg);
Register NewReg = MRI->createVirtualRegister(RC);
MO.setReg(NewReg);
LocalVRMap.insert(std::make_pair(Reg, RegSubRegPair(NewReg, 0)));
if (isDefLiveOut(Reg, TailBB, MRI) || UsedByPhi.count(Reg))
addSSAUpdateEntry(Reg, NewReg, PredBB);
continue;
}
auto VI = LocalVRMap.find(Reg);
if (VI == LocalVRMap.end())
continue;
// Need to make sure that the register class of the mapped register
// will satisfy the constraints of the class of the register being
// replaced.
auto *OrigRC = MRI->getRegClass(Reg);
auto *MappedRC = MRI->getRegClass(VI->second.Reg);
const TargetRegisterClass *ConstrRC;
if (VI->second.SubReg != 0) {
ConstrRC =
TRI->getMatchingSuperRegClass(MappedRC, OrigRC, VI->second.SubReg);
if (ConstrRC) {
// The actual constraining (as in "find appropriate new class")
// is done by getMatchingSuperRegClass, so now we only need to
// change the class of the mapped register.
MRI->setRegClass(VI->second.Reg, ConstrRC);
}
} else {
// For mapped registers that do not have sub-registers, simply
// restrict their class to match the original one.
// We don't want debug instructions affecting the resulting code so
// if we're cloning a debug instruction then just use MappedRC
// rather than constraining the register class further.
ConstrRC = NewMI.isDebugInstr()
? MappedRC
: MRI->constrainRegClass(VI->second.Reg, OrigRC);
}
if (ConstrRC) {
// If the class constraining succeeded, we can simply replace
// the old register with the mapped one.
MO.setReg(VI->second.Reg);
// We have Reg -> VI.Reg:VI.SubReg, so if Reg is used with a
// sub-register, we need to compose the sub-register indices.
MO.setSubReg(
TRI->composeSubRegIndices(VI->second.SubReg, MO.getSubReg()));
} else {
// The direct replacement is not possible, due to failing register
// class constraints. An explicit COPY is necessary. Create one
// that can be reused.
Register NewReg = MRI->createVirtualRegister(OrigRC);
BuildMI(*PredBB, NewMI, NewMI.getDebugLoc(), TII->get(TargetOpcode::COPY),
NewReg)
.addReg(VI->second.Reg, 0, VI->second.SubReg);
LocalVRMap.erase(VI);
LocalVRMap.insert(std::make_pair(Reg, RegSubRegPair(NewReg, 0)));
MO.setReg(NewReg);
// The composed VI.Reg:VI.SubReg is replaced with NewReg, which
// is equivalent to the whole register Reg. Hence, Reg:subreg
// is same as NewReg:subreg, so keep the sub-register index
// unchanged.
}
// Clear any kill flags from this operand. The new register could
// have uses after this one, so kills are not valid here.
MO.setIsKill(false);
}
}