C++ iterator::hasDelaySlot方法代码示例

/// 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;

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

      if (!DisableDelaySlotFiller)
        D = findDelayInstr(MBB, I);

      ++FilledSlots;
      Changed = true;

      if (D == MBB.end())
        BuildMI(MBB, ++J, I->getDebugLoc(), TII->get(SP::NOP));
      else
        MBB.splice(++J, &MBB, D);
      unsigned structSize = 0;
      if (needsUnimp(I, structSize)) {
        MachineBasicBlock::iterator J = I;
        ++J; //skip the delay filler.
        BuildMI(MBB, ++J, I->getDebugLoc(),
                TII->get(SP::UNIMP)).addImm(structSize);
      }
    }
  return Changed;
}

MachineBasicBlock::iterator
Filler::findDelayInstr(MachineBasicBlock &MBB,
                       MachineBasicBlock::iterator slot)
{
  SmallSet<unsigned, 32> RegDefs;
  SmallSet<unsigned, 32> RegUses;
  bool sawLoad = false;
  bool sawStore = false;

  if (slot == MBB.begin())
    return MBB.end();

  if (slot->getOpcode() == SP::RET || slot->getOpcode() == SP::TLS_CALL)
    return MBB.end();

  if (slot->getOpcode() == SP::RETL) {
    MachineBasicBlock::iterator J = slot;
    --J;

    if (J->getOpcode() == SP::RESTORErr
        || J->getOpcode() == SP::RESTOREri) {
      // change retl to ret.
      slot->setDesc(TM.getInstrInfo()->get(SP::RET));
      return J;
    }
  }

  // Call's delay filler can def some of call's uses.
  if (slot->isCall())
    insertCallDefsUses(slot, RegDefs, RegUses);
  else
    insertDefsUses(slot, RegDefs, RegUses);

  bool done = false;

  MachineBasicBlock::iterator I = slot;

  while (!done) {
    done = (I == MBB.begin());

    if (!done)
      --I;

    // skip debug value
    if (I->isDebugValue())
      continue;

    if (I->hasUnmodeledSideEffects() || I->isInlineAsm() || I->isPosition() ||
        I->hasDelaySlot() || I->isBundledWithSucc())
      break;

    if (delayHasHazard(I, sawLoad, sawStore, RegDefs, RegUses)) {
      insertDefsUses(I, RegDefs, RegUses);
      continue;
    }

    return I;
  }
  return MBB.end();
}

/// 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;

}

/// 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;
  Subtarget = &MBB.getParent()->getSubtarget<SparcSubtarget>();
  const TargetInstrInfo *TII = Subtarget->getInstrInfo();

  for (MachineBasicBlock::iterator I = MBB.begin(); I != MBB.end(); ) {
    MachineBasicBlock::iterator MI = I;
    ++I;

    // If MI is restore, try combining it with previous inst.
    if (!DisableDelaySlotFiller &&
        (MI->getOpcode() == SP::RESTORErr
         || MI->getOpcode() == SP::RESTOREri)) {
      Changed |= tryCombineRestoreWithPrevInst(MBB, MI);
      continue;
    }

    // TODO: If we ever want to support v7, this needs to be extended
    // to cover all floating point operations.
    if (!Subtarget->isV9() &&
        (MI->getOpcode() == SP::FCMPS || MI->getOpcode() == SP::FCMPD
         || MI->getOpcode() == SP::FCMPQ)) {
      BuildMI(MBB, I, MI->getDebugLoc(), TII->get(SP::NOP));
      Changed = true;
      continue;
    }

    // If MI has no delay slot, skip.
    if (!MI->hasDelaySlot())
      continue;

    MachineBasicBlock::iterator D = MBB.end();

    if (!DisableDelaySlotFiller)
      D = findDelayInstr(MBB, MI);

    ++FilledSlots;
    Changed = true;

    if (D == MBB.end())
      BuildMI(MBB, I, MI->getDebugLoc(), TII->get(SP::NOP));
    else
      MBB.splice(I, &MBB, D);

    unsigned structSize = 0;
    if (needsUnimp(MI, structSize)) {
      MachineBasicBlock::iterator J = MI;
      ++J; // skip the delay filler.
      assert (J != MBB.end() && "MI needs a delay instruction.");
      BuildMI(MBB, ++J, MI->getDebugLoc(),
              TII->get(SP::UNIMP)).addImm(structSize);
      // Bundle the delay filler and unimp with the instruction.
      MIBundleBuilder(MBB, MachineBasicBlock::iterator(MI), J);
    } else {
      MIBundleBuilder(MBB, MachineBasicBlock::iterator(MI), I);
    }
  }
  return Changed;
}

MachineBasicBlock::iterator
Filler::findDelayInstr(MachineBasicBlock &MBB,
                       MachineBasicBlock::iterator slot)
{
  SmallSet<unsigned, 32> RegDefs;
  SmallSet<unsigned, 32> RegUses;
  bool sawLoad = false;
  bool sawStore = false;

  MachineBasicBlock::iterator I = slot;

  if (slot->getOpcode() == SP::RET)
    return MBB.end();

  if (slot->getOpcode() == SP::RETL) {
    --I;
    if (I->getOpcode() != SP::RESTORErr)
      return MBB.end();
    //change retl to ret
    slot->setDesc(TII->get(SP::RET));
    return I;
  }

  //Call's delay filler can def some of call's uses.
  if (slot->isCall())
    insertCallUses(slot, RegUses);
  else
    insertDefsUses(slot, RegDefs, RegUses);

  bool done = false;

  while (!done) {
    done = (I == MBB.begin());

    if (!done)
      --I;

    // skip debug value
    if (I->isDebugValue())
      continue;


    if (I->hasUnmodeledSideEffects()
        || I->isInlineAsm()
        || I->isLabel()
        || I->hasDelaySlot()
        || isDelayFiller(MBB, I))
      break;

    if (delayHasHazard(I, sawLoad, sawStore, RegDefs, RegUses)) {
      insertDefsUses(I, RegDefs, RegUses);
      continue;
    }

    return I;
  }
  return MBB.end();
}

// return true if the candidate is a delay filler.
bool Filler::isDelayFiller(MachineBasicBlock &MBB,
                           MachineBasicBlock::iterator candidate)
{
  if (candidate == MBB.begin())
    return false;
  if (candidate->getOpcode() == SP::UNIMP)
    return true;
  --candidate;
  return candidate->hasDelaySlot();
}

/// 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;

  for (MachineBasicBlock::iterator I = MBB.begin(); I != MBB.end(); ) {
    MachineBasicBlock::iterator MI = I;
    ++I;

    // If MI is restore, try combining it with previous inst.
    if (!DisableDelaySlotFiller &&
        (MI->getOpcode() == SP::RESTORErr
         || MI->getOpcode() == SP::RESTOREri)) {
      Changed |= tryCombineRestoreWithPrevInst(MBB, MI);
      continue;
    }

    // If MI has no delay slot, skip.
    if (!MI->hasDelaySlot())
      continue;

    MachineBasicBlock::iterator D = MBB.end();

    if (!DisableDelaySlotFiller)
      D = findDelayInstr(MBB, MI);

    ++FilledSlots;
    Changed = true;

    const TargetInstrInfo *TII = TM.getInstrInfo();
    if (D == MBB.end())
      BuildMI(MBB, I, MI->getDebugLoc(), TII->get(SP::NOP));
    else
      MBB.splice(I, &MBB, D);

    unsigned structSize = 0;
    if (needsUnimp(MI, structSize)) {
      MachineBasicBlock::iterator J = MI;
      ++J; // skip the delay filler.
      assert (J != MBB.end() && "MI needs a delay instruction.");
      BuildMI(MBB, ++J, I->getDebugLoc(),
              TII->get(SP::UNIMP)).addImm(structSize);
    }
  }
  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;
}