- DEBUG(dbgs() << "Deleting dead def " << Idx << '\t' << *MI);
-
- // 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))
- continue;
- LiveInterval &LI = LIS.getInterval(Reg);
-
- // Shrink read registers.
- if (MI->readsVirtualRegister(Reg))
- ToShrink.insert(&LI);
-
- // Remove defined value.
- if (MOI->isDef()) {
- if (VNInfo *VNI = LI.getVNInfoAt(Idx)) {
- if (delegate_)
- delegate_->LRE_WillShrinkVirtReg(LI.reg);
- LI.removeValNo(VNI);
- if (LI.empty()) {
- ToShrink.remove(&LI);
- eraseVirtReg(Reg, LIS);
- }
+ 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);