diff options
Diffstat (limited to 'lib/CodeGen/DeadMachineInstructionElim.cpp')
-rw-r--r-- | lib/CodeGen/DeadMachineInstructionElim.cpp | 42 |
1 files changed, 25 insertions, 17 deletions
diff --git a/lib/CodeGen/DeadMachineInstructionElim.cpp b/lib/CodeGen/DeadMachineInstructionElim.cpp index b0cb24d..d69c995 100644 --- a/lib/CodeGen/DeadMachineInstructionElim.cpp +++ b/lib/CodeGen/DeadMachineInstructionElim.cpp @@ -55,7 +55,7 @@ FunctionPass *llvm::createDeadMachineInstructionElimPass() { 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. @@ -64,8 +64,8 @@ bool DeadMachineInstructionElim::isDead(const MachineInstr *MI) const { 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; } } @@ -111,23 +111,31 @@ bool DeadMachineInstructionElim::runOnMachineFunction(MachineFunction &MF) { MIE = MBB->rend(); MII != MIE; ) { MachineInstr *MI = &*MII; - if (MI->isDebugValue()) { - // Don't delete the DBG_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 DBG_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; |