public:
static char ID; // Pass identification, replacement for typeid
- DeadMachineInstructionElim() : MachineFunctionPass(&ID) {}
+ DeadMachineInstructionElim() : MachineFunctionPass(ID) {}
private:
bool isDead(const MachineInstr *MI) const;
}
char DeadMachineInstructionElim::ID = 0;
-static RegisterPass<DeadMachineInstructionElim>
-Y("dead-mi-elimination",
- "Remove dead machine instructions");
+INITIALIZE_PASS(DeadMachineInstructionElim, "dead-mi-elimination",
+ "Remove dead machine instructions", false, false);
FunctionPass *llvm::createDeadMachineInstructionElimPass() {
return new DeadMachineInstructionElim();
bool DeadMachineInstructionElim::isDead(const MachineInstr *MI) const {
// Don't delete instructions with side effects.
bool SawStore = false;
- if (!MI->isSafeToMove(TII, SawStore, 0))
+ if (!MI->isSafeToMove(TII, 0, SawStore) && !MI->isPHI())
return false;
// Examine each operand.
if (MO.isReg() && MO.isDef()) {
unsigned Reg = MO.getReg();
if (TargetRegisterInfo::isPhysicalRegister(Reg) ?
- LivePhysRegs[Reg] : !MRI->use_empty(Reg)) {
- // This def has a use. Don't delete the instruction!
+ LivePhysRegs[Reg] : !MRI->use_nodbg_empty(Reg)) {
+ // This def has a non-debug use. Don't delete the instruction!
return false;
}
}
MIE = MBB->rend(); MII != MIE; ) {
MachineInstr *MI = &*MII;
- if (MI->getOpcode()==TargetInstrInfo::DEBUG_VALUE) {
- // Don't delete the DEBUG_VALUE itself, but if its Value operand is
- // a vreg and this is the only use, substitute an undef operand;
- // the former operand will then be deleted normally.
- if (MI->getNumOperands()==3 && MI->getOperand(0).isReg()) {
- unsigned Reg = MI->getOperand(0).getReg();
- MachineRegisterInfo::use_iterator I = MRI->use_begin(Reg);
- assert(I != MRI->use_end());
- if (++I == MRI->use_end())
- // only one use, which must be this DEBUG_VALUE.
- MI->getOperand(0).setReg(0U);
- }
- }
-
// If the instruction is dead, delete it!
if (isDead(MI)) {
DEBUG(dbgs() << "DeadMachineInstructionElim: DELETING: " << *MI);
+ // It is possible that some DBG_VALUE instructions refer to this
+ // instruction. Examine each def operand for such references;
+ // if found, mark the DBG_VALUE as undef (but don't delete it).
+ for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) {
+ const MachineOperand &MO = MI->getOperand(i);
+ if (!MO.isReg() || !MO.isDef())
+ continue;
+ unsigned Reg = MO.getReg();
+ if (!TargetRegisterInfo::isVirtualRegister(Reg))
+ continue;
+ MachineRegisterInfo::use_iterator nextI;
+ for (MachineRegisterInfo::use_iterator I = MRI->use_begin(Reg),
+ E = MRI->use_end(); I!=E; I=nextI) {
+ nextI = llvm::next(I); // I is invalidated by the setReg
+ MachineOperand& Use = I.getOperand();
+ MachineInstr *UseMI = Use.getParent();
+ if (UseMI==MI)
+ continue;
+ assert(Use.isDebug());
+ UseMI->getOperand(0).setReg(0U);
+ }
+ }
AnyChanges = true;
MI->eraseFromParent();
++NumDeletes;