+void LiveRangeCalc::createDeadDefs(LiveRange &LR, unsigned Reg) {
+ assert(MRI && Indexes && "call reset() first");
+
+ // Visit all def operands. If the same instruction has multiple defs of Reg,
+ // LR.createDeadDef() will deduplicate.
+ for (MachineOperand &MO : MRI->def_operands(Reg)) {
+ const MachineInstr *MI = MO.getParent();
+ // Find the corresponding slot index.
+ SlotIndex Idx;
+ if (MI->isPHI())
+ // PHI defs begin at the basic block start index.
+ Idx = Indexes->getMBBStartIdx(MI->getParent());
+ else
+ // Instructions are either normal 'r', or early clobber 'e'.
+ Idx = Indexes->getInstructionIndex(MI)
+ .getRegSlot(MO.isEarlyClobber());
+
+ // Create the def in LR. This may find an existing def.
+ LR.createDeadDef(Idx, *Alloc);
+ }
+}
+
+
+void LiveRangeCalc::extendToUses(LiveRange &LR, unsigned Reg) {
+ assert(MRI && Indexes && "call reset() first");
+
+ // Visit all operands that read Reg. This may include partial defs.
+ for (MachineOperand &MO : MRI->reg_nodbg_operands(Reg)) {
+ // Clear all kill flags. They will be reinserted after register allocation
+ // by LiveIntervalAnalysis::addKillFlags().
+ if (MO.isUse())
+ MO.setIsKill(false);
+ if (!MO.readsReg())
+ continue;
+ // MI is reading Reg. We may have visited MI before if it happens to be
+ // reading Reg multiple times. That is OK, extend() is idempotent.
+ const MachineInstr *MI = MO.getParent();
+ unsigned OpNo = (&MO - &MI->getOperand(0));
+
+ // Find the SlotIndex being read.
+ SlotIndex Idx;
+ if (MI->isPHI()) {
+ assert(!MO.isDef() && "Cannot handle PHI def of partial register.");
+ // PHI operands are paired: (Reg, PredMBB).
+ // Extend the live range to be live-out from PredMBB.
+ Idx = Indexes->getMBBEndIdx(MI->getOperand(OpNo+1).getMBB());
+ } else {
+ // This is a normal instruction.
+ Idx = Indexes->getInstructionIndex(MI).getRegSlot();
+ // Check for early-clobber redefs.
+ unsigned DefIdx;
+ if (MO.isDef()) {
+ if (MO.isEarlyClobber())
+ Idx = Idx.getRegSlot(true);
+ } else if (MI->isRegTiedToDefOperand(OpNo, &DefIdx)) {
+ // FIXME: This would be a lot easier if tied early-clobber uses also
+ // had an early-clobber flag.
+ if (MI->getOperand(DefIdx).isEarlyClobber())
+ Idx = Idx.getRegSlot(true);
+ }
+ }
+ extend(LR, Idx, Reg);
+ }
+}
+
+