/// runOnMachineBasicBlock - Fill in delay slots for the given basic block.
/// We assume there is only one delay slot per delayed instruction.
bool Filler::
runOnMachineBasicBlock(MachineBasicBlock &MBB) {
  bool Changed = false;
  LastFiller = MBB.end();

  for (MachineBasicBlock::iterator I = MBB.begin(); I != MBB.end(); ++I)
    if (I->hasDelaySlot()) {
      ++FilledSlots;
      Changed = true;

      MachineBasicBlock::iterator D;

      if (EnableDelaySlotFiller && findDelayInstr(MBB, I, D)) {
        MBB.splice(llvm::next(I), &MBB, D);
        ++UsefulSlots;
      } else
        BuildMI(MBB, llvm::next(I), I->getDebugLoc(), TII->get(Mips::NOP));

      // Record the filler instruction that filled the delay slot.
      // The instruction after it will be visited in the next iteration.
      LastFiller = ++I;
     }
  return Changed;

}
bool PatmosDelaySlotKiller::killDelaySlots(MachineBasicBlock &MBB) {
  bool Changed = false;

  DEBUG( dbgs() << "Killing slots in BB#" << MBB.getNumber()
                << " (" << MBB.getFullName() << ")\n" );

  // consider the basic block from top to bottom
  for (MachineBasicBlock::iterator I = MBB.begin(); I != MBB.end(); ++I) {
    // Control-flow instructions ("proper" delay slots)
    if (I->hasDelaySlot()) {
      assert( ( I->isCall() || I->isReturn() || I->isBranch() )
              && "Unexpected instruction with delay slot.");

      MachineBasicBlock::instr_iterator MI = *I;
      if (I->isBundle()) { ++MI; }

      unsigned Opcode = MI->getOpcode();

      if (Opcode == Patmos::BR ||
          Opcode == Patmos::BRu ||
          Opcode == Patmos::BRR ||
          Opcode == Patmos::BRRu ||
          Opcode == Patmos::BRT ||
          Opcode == Patmos::BRTu ||
          Opcode == Patmos::BRCF ||
          Opcode == Patmos::BRCFu ||
          Opcode == Patmos::BRCFR ||
          Opcode == Patmos::BRCFRu ||
          Opcode == Patmos::BRCFT ||
          Opcode == Patmos::BRCFTu ||
          Opcode == Patmos::CALL ||
          Opcode == Patmos::CALLR ||
          Opcode == Patmos::RET ||
          Opcode == Patmos::XRET) {

        bool onlyNops = true;
        unsigned maxCount = TM.getSubtargetImpl()->getDelaySlotCycles(&*I);
        unsigned count = 0;
        for (MachineBasicBlock::iterator K = llvm::next(I), E = MBB.end();
             K != E && count < maxCount; ++K, ++count) {
          TII->skipPseudos(MBB, K);
          if (K->getOpcode() != Patmos::NOP) {
            onlyNops = false;
          }
        }
        if (onlyNops) {
          unsigned NewOpcode = 0;
          switch(Opcode) {
          case Patmos::BR:     NewOpcode = Patmos::BRND; break;
          case Patmos::BRu:    NewOpcode = Patmos::BRNDu; break;
          case Patmos::BRR:    NewOpcode = Patmos::BRRND; break;
          case Patmos::BRRu:   NewOpcode = Patmos::BRRNDu; break;
          case Patmos::BRT:    NewOpcode = Patmos::BRTND; break;
          case Patmos::BRTu:   NewOpcode = Patmos::BRTNDu; break;
          case Patmos::BRCF:   NewOpcode = Patmos::BRCFND; break;
          case Patmos::BRCFu:  NewOpcode = Patmos::BRCFNDu; break;
          case Patmos::BRCFR:  NewOpcode = Patmos::BRCFRND; break;
          case Patmos::BRCFRu: NewOpcode = Patmos::BRCFRNDu; break;
          case Patmos::BRCFT:  NewOpcode = Patmos::BRCFTND; break;
          case Patmos::BRCFTu: NewOpcode = Patmos::BRCFTNDu; break;
          case Patmos::CALL:   NewOpcode = Patmos::CALLND; break;
          case Patmos::CALLR:  NewOpcode = Patmos::CALLRND; break;
          case Patmos::RET:    NewOpcode = Patmos::RETND; break;
          case Patmos::XRET:   NewOpcode = Patmos::XRETND; break;
          }
          const MCInstrDesc &nonDelayed = TII->get(NewOpcode);
          MI->setDesc(nonDelayed);

          unsigned killCount = 0;
          MachineBasicBlock::iterator K = llvm::next(I);
          for (MachineBasicBlock::iterator E = MBB.end();
               K != E && killCount < count; ++K, ++killCount) {
            TII->skipPseudos(MBB, K);
            KilledSlots++;
          }
          MBB.erase(llvm::next(I), K);
        }
      }
      Changed = true; // pass result
    }
  }
  return Changed;
}