+/// FindUnusedRegisters - Gather a list of allocatable registers that
+/// have not been allocated to any virtual register.
+bool VirtRegMap::FindUnusedRegisters(LiveIntervals* LIs) {
+ unsigned NumRegs = TRI->getNumRegs();
+ UnusedRegs.reset();
+ UnusedRegs.resize(NumRegs);
+
+ BitVector Used(NumRegs);
+ for (unsigned i = 0, e = MRI->getNumVirtRegs(); i != e; ++i) {
+ unsigned Reg = TargetRegisterInfo::index2VirtReg(i);
+ if (Virt2PhysMap[Reg] != (unsigned)VirtRegMap::NO_PHYS_REG)
+ Used.set(Virt2PhysMap[Reg]);
+ }
+
+ BitVector Allocatable = TRI->getAllocatableSet(*MF);
+ bool AnyUnused = false;
+ for (unsigned Reg = 1; Reg < NumRegs; ++Reg) {
+ if (Allocatable[Reg] && !Used[Reg] && !LIs->hasInterval(Reg)) {
+ bool ReallyUnused = true;
+ for (const unsigned *AS = TRI->getAliasSet(Reg); *AS; ++AS) {
+ if (Used[*AS] || LIs->hasInterval(*AS)) {
+ ReallyUnused = false;
+ break;
+ }
+ }
+ if (ReallyUnused) {
+ AnyUnused = true;
+ UnusedRegs.set(Reg);
+ }
+ }
+ }
+
+ return AnyUnused;
+}
+
+void VirtRegMap::rewrite(SlotIndexes *Indexes) {
+ DEBUG(dbgs() << "********** REWRITE VIRTUAL REGISTERS **********\n"
+ << "********** Function: "
+ << MF->getFunction()->getName() << '\n');
+ DEBUG(dump());
+ SmallVector<unsigned, 8> SuperKills;
+
+ for (MachineFunction::iterator MBBI = MF->begin(), MBBE = MF->end();
+ MBBI != MBBE; ++MBBI) {
+ DEBUG(MBBI->print(dbgs(), Indexes));
+ for (MachineBasicBlock::iterator MII = MBBI->begin(), MIE = MBBI->end();
+ MII != MIE;) {
+ MachineInstr *MI = MII;
+ ++MII;
+
+ for (MachineInstr::mop_iterator MOI = MI->operands_begin(),
+ MOE = MI->operands_end(); MOI != MOE; ++MOI) {
+ MachineOperand &MO = *MOI;
+ if (!MO.isReg() || !TargetRegisterInfo::isVirtualRegister(MO.getReg()))
+ continue;
+ unsigned VirtReg = MO.getReg();
+ unsigned PhysReg = getPhys(VirtReg);
+ assert(PhysReg != NO_PHYS_REG && "Instruction uses unmapped VirtReg");
+
+ // Preserve semantics of sub-register operands.
+ if (MO.getSubReg()) {
+ // A virtual register kill refers to the whole register, so we may
+ // have to add <imp-use,kill> operands for the super-register.
+ if (MO.isUse() && MO.isKill() && !MO.isUndef())
+ SuperKills.push_back(PhysReg);
+
+ // We don't have to deal with sub-register defs because
+ // LiveIntervalAnalysis already added the necessary <imp-def>
+ // operands.
+
+ // PhysReg operands cannot have subregister indexes.
+ PhysReg = TRI->getSubReg(PhysReg, MO.getSubReg());
+ assert(PhysReg && "Invalid SubReg for physical register");
+ MO.setSubReg(0);
+ }
+ // Rewrite. Note we could have used MachineOperand::substPhysReg(), but
+ // we need the inlining here.
+ MO.setReg(PhysReg);
+ }
+
+ // Add any missing super-register kills after rewriting the whole
+ // instruction.
+ while (!SuperKills.empty())
+ MI->addRegisterKilled(SuperKills.pop_back_val(), TRI, true);
+
+ DEBUG(dbgs() << "> " << *MI);
+
+ // Finally, remove any identity copies.
+ if (MI->isIdentityCopy()) {
+ if (MI->getNumOperands() == 2) {
+ DEBUG(dbgs() << "Deleting identity copy.\n");
+ RemoveMachineInstrFromMaps(MI);
+ if (Indexes)
+ Indexes->removeMachineInstrFromMaps(MI);
+ // It's safe to erase MI because MII has already been incremented.
+ MI->eraseFromParent();
+ } else {
+ // Transform identity copy to a KILL to deal with subregisters.
+ MI->setDesc(TII->get(TargetOpcode::KILL));
+ DEBUG(dbgs() << "Identity copy: " << *MI);
+ }
+ }
+ }
+ }
+
+ // Tell MRI about physical registers in use.
+ for (unsigned Reg = 1, RegE = TRI->getNumRegs(); Reg != RegE; ++Reg)
+ if (!MRI->reg_nodbg_empty(Reg))
+ MRI->setPhysRegUsed(Reg);
+}
+
+void VirtRegMap::print(raw_ostream &OS, const Module* M) const {