+ if (LastRefOrPartRef == PhysRegDef[Reg] && LastRefOrPartRef != MI) {
+ if (LastPartDef)
+ // The last partial def kills the register.
+ LastPartDef->addOperand(MachineOperand::CreateReg(Reg, false/*IsDef*/,
+ true/*IsImp*/, true/*IsKill*/));
+ else {
+ MachineOperand *MO =
+ LastRefOrPartRef->findRegisterDefOperand(Reg, false, TRI);
+ bool NeedEC = MO->isEarlyClobber() && MO->getReg() != Reg;
+ // If the last reference is the last def, then it's not used at all.
+ // That is, unless we are currently processing the last reference itself.
+ LastRefOrPartRef->addRegisterDead(Reg, TRI, true);
+ if (NeedEC) {
+ // If we are adding a subreg def and the superreg def is marked early
+ // clobber, add an early clobber marker to the subreg def.
+ MO = LastRefOrPartRef->findRegisterDefOperand(Reg);
+ if (MO)
+ MO->setIsEarlyClobber();
+ }
+ }
+ } else if (!PhysRegUse[Reg]) {
+ // Partial uses. Mark register def dead and add implicit def of
+ // sub-registers which are used.
+ // EAX<dead> = op AL<imp-def>
+ // That is, EAX def is dead but AL def extends pass it.
+ PhysRegDef[Reg]->addRegisterDead(Reg, TRI, true);
+ for (const unsigned *SubRegs = TRI->getSubRegisters(Reg);
+ unsigned SubReg = *SubRegs; ++SubRegs) {
+ if (!PartUses.count(SubReg))
+ continue;
+ bool NeedDef = true;
+ if (PhysRegDef[Reg] == PhysRegDef[SubReg]) {
+ MachineOperand *MO = PhysRegDef[Reg]->findRegisterDefOperand(SubReg);
+ if (MO) {
+ NeedDef = false;
+ assert(!MO->isDead());
+ }
+ }
+ if (NeedDef)
+ PhysRegDef[Reg]->addOperand(MachineOperand::CreateReg(SubReg,
+ true/*IsDef*/, true/*IsImp*/));
+ LastRefOrPartRef->addRegisterKilled(SubReg, TRI, true);
+ for (const unsigned *SS = TRI->getSubRegisters(SubReg); *SS; ++SS)
+ PartUses.erase(*SS);
+ }
+ } else
+ LastRefOrPartRef->addRegisterKilled(Reg, TRI, true);
+ return true;
+}
+
+void LiveVariables::HandlePhysRegDef(unsigned Reg, MachineInstr *MI,
+ SmallVector<unsigned, 4> &Defs) {
+ // What parts of the register are previously defined?
+ SmallSet<unsigned, 32> Live;
+ if (PhysRegDef[Reg] || PhysRegUse[Reg]) {
+ Live.insert(Reg);
+ for (const unsigned *SS = TRI->getSubRegisters(Reg); *SS; ++SS)
+ Live.insert(*SS);
+ } else {
+ for (const unsigned *SubRegs = TRI->getSubRegisters(Reg);
+ unsigned SubReg = *SubRegs; ++SubRegs) {
+ // If a register isn't itself defined, but all parts that make up of it
+ // are defined, then consider it also defined.
+ // e.g.
+ // AL =
+ // AH =
+ // = AX
+ if (Live.count(SubReg))
+ continue;
+ if (PhysRegDef[SubReg] || PhysRegUse[SubReg]) {
+ Live.insert(SubReg);
+ for (const unsigned *SS = TRI->getSubRegisters(SubReg); *SS; ++SS)
+ Live.insert(*SS);
+ }
+ }
+ }
+
+ // Start from the largest piece, find the last time any part of the register
+ // is referenced.
+ HandlePhysRegKill(Reg, MI);
+ // Only some of the sub-registers are used.
+ for (const unsigned *SubRegs = TRI->getSubRegisters(Reg);
+ unsigned SubReg = *SubRegs; ++SubRegs) {
+ if (!Live.count(SubReg))
+ // Skip if this sub-register isn't defined.
+ continue;
+ HandlePhysRegKill(SubReg, MI);
+ }