- for (df_ext_iterator<MachineBasicBlock*, SmallPtrSet<MachineBasicBlock*,16> >
- DFI = df_ext_begin(Entry, Visited), E = df_ext_end(Entry, Visited);
- DFI != E; ++DFI) {
- MachineBasicBlock *MBB = *DFI;
-
- // Mark live-in registers as live-in.
- SmallVector<unsigned, 4> Defs;
- for (MachineBasicBlock::livein_iterator II = MBB->livein_begin(),
- EE = MBB->livein_end(); II != EE; ++II) {
- assert(TargetRegisterInfo::isPhysicalRegister(*II) &&
- "Cannot have a live-in virtual register!");
- HandlePhysRegDef(*II, 0, Defs);
- }
-
- // Loop over all of the instructions, processing them.
- DistanceMap.clear();
- unsigned Dist = 0;
- for (MachineBasicBlock::iterator I = MBB->begin(), E = MBB->end();
- I != E; ++I) {
- MachineInstr *MI = I;
- if (MI->isDebugValue())
- continue;
- DistanceMap.insert(std::make_pair(MI, Dist++));
-
- // Process all of the operands of the instruction...
- unsigned NumOperandsToProcess = MI->getNumOperands();
-
- // Unless it is a PHI node. In this case, ONLY process the DEF, not any
- // of the uses. They will be handled in other basic blocks.
- if (MI->isPHI())
- NumOperandsToProcess = 1;
-
- // Clear kill and dead markers. LV will recompute them.
- SmallVector<unsigned, 4> UseRegs;
- SmallVector<unsigned, 4> DefRegs;
- SmallVector<unsigned, 1> RegMasks;
- for (unsigned i = 0; i != NumOperandsToProcess; ++i) {
- MachineOperand &MO = MI->getOperand(i);
- if (MO.isRegMask()) {
- RegMasks.push_back(i);
- continue;
- }
- if (!MO.isReg() || MO.getReg() == 0)
- continue;
- unsigned MOReg = MO.getReg();
- if (MO.isUse()) {
- MO.setIsKill(false);
- if (MO.readsReg())
- UseRegs.push_back(MOReg);
- } else /*MO.isDef()*/ {
- MO.setIsDead(false);
- DefRegs.push_back(MOReg);
- }
- }
-
- // Process all uses.
- for (unsigned i = 0, e = UseRegs.size(); i != e; ++i) {
- unsigned MOReg = UseRegs[i];
- if (TargetRegisterInfo::isVirtualRegister(MOReg))
- HandleVirtRegUse(MOReg, MBB, MI);
- else if (!ReservedRegisters[MOReg])
- HandlePhysRegUse(MOReg, MI);
- }
-
- // Process all masked registers. (Call clobbers).
- for (unsigned i = 0, e = RegMasks.size(); i != e; ++i)
- HandleRegMask(MI->getOperand(RegMasks[i]));
-
- // Process all defs.
- for (unsigned i = 0, e = DefRegs.size(); i != e; ++i) {
- unsigned MOReg = DefRegs[i];
- if (TargetRegisterInfo::isVirtualRegister(MOReg))
- HandleVirtRegDef(MOReg, MI);
- else if (!ReservedRegisters[MOReg])
- HandlePhysRegDef(MOReg, MI, Defs);
- }
- UpdatePhysRegDefs(MI, Defs);
- }
-
- // Handle any virtual assignments from PHI nodes which might be at the
- // bottom of this basic block. We check all of our successor blocks to see
- // if they have PHI nodes, and if so, we simulate an assignment at the end
- // of the current block.
- if (!PHIVarInfo[MBB->getNumber()].empty()) {
- SmallVector<unsigned, 4>& VarInfoVec = PHIVarInfo[MBB->getNumber()];
-
- for (SmallVector<unsigned, 4>::iterator I = VarInfoVec.begin(),
- E = VarInfoVec.end(); I != E; ++I)
- // Mark it alive only in the block we are representing.
- MarkVirtRegAliveInBlock(getVarInfo(*I),MRI->getVRegDef(*I)->getParent(),
- MBB);
- }
-
- // Finally, if the last instruction in the block is a return, make sure to
- // mark it as using all of the live-out values in the function.
- // Things marked both call and return are tail calls; do not do this for
- // them. The tail callee need not take the same registers as input
- // that it produces as output, and there are dependencies for its input
- // registers elsewhere.
- if (!MBB->empty() && MBB->back().isReturn()
- && !MBB->back().isCall()) {
- MachineInstr *Ret = &MBB->back();
-
- for (MachineRegisterInfo::liveout_iterator
- I = MF->getRegInfo().liveout_begin(),
- E = MF->getRegInfo().liveout_end(); I != E; ++I) {
- assert(TargetRegisterInfo::isPhysicalRegister(*I) &&
- "Cannot have a live-out virtual register!");
- HandlePhysRegUse(*I, Ret);
-
- // Add live-out registers as implicit uses.
- if (!Ret->readsRegister(*I))
- Ret->addOperand(MachineOperand::CreateReg(*I, false, true));
- }
- }
-
- // MachineCSE may CSE instructions which write to non-allocatable physical
- // registers across MBBs. Remember if any reserved register is liveout.
- SmallSet<unsigned, 4> LiveOuts;
- for (MachineBasicBlock::const_succ_iterator SI = MBB->succ_begin(),
- SE = MBB->succ_end(); SI != SE; ++SI) {
- MachineBasicBlock *SuccMBB = *SI;
- if (SuccMBB->isLandingPad())
- continue;
- for (MachineBasicBlock::livein_iterator LI = SuccMBB->livein_begin(),
- LE = SuccMBB->livein_end(); LI != LE; ++LI) {
- unsigned LReg = *LI;
- if (!TRI->isInAllocatableClass(LReg))
- // Ignore other live-ins, e.g. those that are live into landing pads.
- LiveOuts.insert(LReg);
- }
- }
-
- // Loop over PhysRegDef / PhysRegUse, killing any registers that are
- // available at the end of the basic block.
- for (unsigned i = 0; i != NumRegs; ++i)
- if ((PhysRegDef[i] || PhysRegUse[i]) && !LiveOuts.count(i))
- HandlePhysRegDef(i, 0, Defs);