+ TII.reMaterialize(MBB, MI, DestReg, 0, RM.OrigMI, tri);
+ Rematted.insert(RM.ParentVNI);
+ return LIS.getSlotIndexes()->insertMachineInstrInMaps(--MI, Late)
+ .getRegSlot();
+}
+
+void LiveRangeEdit::eraseVirtReg(unsigned Reg) {
+ if (TheDelegate && TheDelegate->LRE_CanEraseVirtReg(Reg))
+ LIS.removeInterval(Reg);
+}
+
+bool LiveRangeEdit::foldAsLoad(LiveInterval *LI,
+ SmallVectorImpl<MachineInstr*> &Dead) {
+ MachineInstr *DefMI = nullptr, *UseMI = nullptr;
+
+ // Check that there is a single def and a single use.
+ for (MachineOperand &MO : MRI.reg_nodbg_operands(LI->reg)) {
+ MachineInstr *MI = MO.getParent();
+ if (MO.isDef()) {
+ if (DefMI && DefMI != MI)
+ return false;
+ if (!MI->canFoldAsLoad())
+ return false;
+ DefMI = MI;
+ } else if (!MO.isUndef()) {
+ if (UseMI && UseMI != MI)
+ return false;
+ // FIXME: Targets don't know how to fold subreg uses.
+ if (MO.getSubReg())
+ return false;
+ UseMI = MI;
+ }
+ }
+ if (!DefMI || !UseMI)
+ return false;
+
+ // Since we're moving the DefMI load, make sure we're not extending any live
+ // ranges.
+ if (!allUsesAvailableAt(DefMI,
+ LIS.getInstructionIndex(DefMI),
+ LIS.getInstructionIndex(UseMI)))
+ return false;
+
+ // We also need to make sure it is safe to move the load.
+ // Assume there are stores between DefMI and UseMI.
+ bool SawStore = true;
+ if (!DefMI->isSafeToMove(&TII, nullptr, SawStore))
+ return false;
+
+ DEBUG(dbgs() << "Try to fold single def: " << *DefMI
+ << " into single use: " << *UseMI);
+
+ SmallVector<unsigned, 8> Ops;
+ if (UseMI->readsWritesVirtualRegister(LI->reg, &Ops).second)
+ return false;
+
+ MachineInstr *FoldMI = TII.foldMemoryOperand(UseMI, Ops, DefMI);
+ if (!FoldMI)
+ return false;
+ DEBUG(dbgs() << " folded: " << *FoldMI);
+ LIS.ReplaceMachineInstrInMaps(UseMI, FoldMI);
+ UseMI->eraseFromParent();
+ DefMI->addRegisterDead(LI->reg, nullptr);
+ Dead.push_back(DefMI);
+ ++NumDCEFoldedLoads;
+ return true;
+}
+
+/// Find all live intervals that need to shrink, then remove the instruction.
+void LiveRangeEdit::eliminateDeadDef(MachineInstr *MI, ToShrinkSet &ToShrink) {
+ assert(MI->allDefsAreDead() && "Def isn't really dead");
+ SlotIndex Idx = LIS.getInstructionIndex(MI).getRegSlot();
+
+ // Never delete a bundled instruction.
+ if (MI->isBundled()) {
+ return;
+ }
+ // Never delete inline asm.
+ if (MI->isInlineAsm()) {
+ DEBUG(dbgs() << "Won't delete: " << Idx << '\t' << *MI);
+ return;
+ }
+
+ // Use the same criteria as DeadMachineInstructionElim.
+ bool SawStore = false;
+ if (!MI->isSafeToMove(&TII, nullptr, SawStore)) {
+ DEBUG(dbgs() << "Can't delete: " << Idx << '\t' << *MI);
+ return;
+ }
+
+ DEBUG(dbgs() << "Deleting dead def " << Idx << '\t' << *MI);
+
+ // Collect virtual registers to be erased after MI is gone.
+ SmallVector<unsigned, 8> RegsToErase;
+ bool ReadsPhysRegs = false;
+
+ // Check for live intervals that may shrink
+ for (MachineInstr::mop_iterator MOI = MI->operands_begin(),
+ MOE = MI->operands_end(); MOI != MOE; ++MOI) {
+ if (!MOI->isReg())
+ continue;
+ unsigned Reg = MOI->getReg();
+ if (!TargetRegisterInfo::isVirtualRegister(Reg)) {
+ // Check if MI reads any unreserved physregs.
+ if (Reg && MOI->readsReg() && !MRI.isReserved(Reg))
+ ReadsPhysRegs = true;
+ else if (MOI->isDef()) {
+ for (MCRegUnitIterator Units(Reg, MRI.getTargetRegisterInfo());
+ Units.isValid(); ++Units) {
+ if (LiveRange *LR = LIS.getCachedRegUnit(*Units)) {
+ if (VNInfo *VNI = LR->getVNInfoAt(Idx))
+ LR->removeValNo(VNI);
+ }
+ }
+ }
+ continue;
+ }
+ LiveInterval &LI = LIS.getInterval(Reg);
+
+ // Shrink read registers, unless it is likely to be expensive and
+ // unlikely to change anything. We typically don't want to shrink the
+ // PIC base register that has lots of uses everywhere.
+ // Always shrink COPY uses that probably come from live range splitting.
+ if (MI->readsVirtualRegister(Reg) &&
+ (MI->isCopy() || MOI->isDef() || MRI.hasOneNonDBGUse(Reg) ||
+ LI.Query(Idx).isKill()))
+ ToShrink.insert(&LI);
+
+ // Remove defined value.
+ if (MOI->isDef()) {
+ if (VNInfo *VNI = LI.getVNInfoAt(Idx)) {
+ if (TheDelegate)
+ TheDelegate->LRE_WillShrinkVirtReg(LI.reg);
+ LI.removeValNo(VNI);
+ if (LI.empty())
+ RegsToErase.push_back(Reg);
+ }
+ }
+ }
+
+ // Currently, we don't support DCE of physreg live ranges. If MI reads
+ // any unreserved physregs, don't erase the instruction, but turn it into
+ // a KILL instead. This way, the physreg live ranges don't end up
+ // dangling.
+ // FIXME: It would be better to have something like shrinkToUses() for
+ // physregs. That could potentially enable more DCE and it would free up
+ // the physreg. It would not happen often, though.
+ if (ReadsPhysRegs) {
+ MI->setDesc(TII.get(TargetOpcode::KILL));
+ // Remove all operands that aren't physregs.
+ for (unsigned i = MI->getNumOperands(); i; --i) {
+ const MachineOperand &MO = MI->getOperand(i-1);
+ if (MO.isReg() && TargetRegisterInfo::isPhysicalRegister(MO.getReg()))
+ continue;
+ MI->RemoveOperand(i-1);
+ }
+ DEBUG(dbgs() << "Converted physregs to:\t" << *MI);
+ } else {
+ if (TheDelegate)
+ TheDelegate->LRE_WillEraseInstruction(MI);
+ LIS.RemoveMachineInstrFromMaps(MI);
+ MI->eraseFromParent();
+ ++NumDCEDeleted;
+ }
+
+ // Erase any virtregs that are now empty and unused. There may be <undef>
+ // uses around. Keep the empty live range in that case.
+ for (unsigned i = 0, e = RegsToErase.size(); i != e; ++i) {
+ unsigned Reg = RegsToErase[i];
+ if (LIS.hasInterval(Reg) && MRI.reg_nodbg_empty(Reg)) {
+ ToShrink.remove(&LIS.getInterval(Reg));
+ eraseVirtReg(Reg);
+ }
+ }