C++ MachineBasicBlock::succ_end方法代码示例

void LazyLiveness::computeBackedgeChain(MachineFunction& mf, 
                                        MachineBasicBlock* MBB) {
  SparseBitVector<128> tmp = rv[MBB];
  tmp.set(preorder[MBB]);
  tmp &= backedge_source;
  calculated.set(preorder[MBB]);
  
  for (SparseBitVector<128>::iterator I = tmp.begin(); I != tmp.end(); ++I) {
    assert(rev_preorder.size() > *I && "Unknown block!");
    
    MachineBasicBlock* SrcMBB = rev_preorder[*I];
    
    for (MachineBasicBlock::succ_iterator SI = SrcMBB->succ_begin(),
         SE = SrcMBB->succ_end(); SI != SE; ++SI) {
      MachineBasicBlock* TgtMBB = *SI;
      
      if (backedges.count(std::make_pair(SrcMBB, TgtMBB)) &&
          !rv[MBB].test(preorder[TgtMBB])) {
        if (!calculated.test(preorder[TgtMBB]))
          computeBackedgeChain(mf, TgtMBB);
        
        tv[MBB].set(preorder[TgtMBB]);
        SparseBitVector<128> right = tv[TgtMBB];
        tv[MBB] |= right;
      }
    }
    
    tv[MBB].reset(preorder[MBB]);
  }
}

static bool checkEFLAGSLive(MachineInstr *MI) {
  if (MI->killsRegister(X86::EFLAGS))
    return false;

  // The EFLAGS operand of MI might be missing a kill marker.
  // Figure out whether EFLAGS operand should LIVE after MI instruction.
  MachineBasicBlock *BB = MI->getParent();
  MachineBasicBlock::iterator ItrMI = MI;

  // Scan forward through BB for a use/def of EFLAGS.
  for (auto I = std::next(ItrMI), E = BB->end(); I != E; ++I) {
    if (I->readsRegister(X86::EFLAGS))
      return true;
    if (I->definesRegister(X86::EFLAGS))
      return false;
  }

  // We hit the end of the block, check whether EFLAGS is live into a successor.
  for (auto I = BB->succ_begin(), E = BB->succ_end(); I != E; ++I) {
    if ((*I)->isLiveIn(X86::EFLAGS))
      return true;
  }

  return false;
}

void LiveIntervals::pruneValue(LiveRange &LR, SlotIndex Kill,
                               SmallVectorImpl<SlotIndex> *EndPoints) {
  LiveQueryResult LRQ = LR.Query(Kill);
  VNInfo *VNI = LRQ.valueOutOrDead();
  if (!VNI)
    return;

  MachineBasicBlock *KillMBB = Indexes->getMBBFromIndex(Kill);
  SlotIndex MBBEnd = Indexes->getMBBEndIdx(KillMBB);

  // If VNI isn't live out from KillMBB, the value is trivially pruned.
  if (LRQ.endPoint() < MBBEnd) {
    LR.removeSegment(Kill, LRQ.endPoint());
    if (EndPoints) EndPoints->push_back(LRQ.endPoint());
    return;
  }

  // VNI is live out of KillMBB.
  LR.removeSegment(Kill, MBBEnd);
  if (EndPoints) EndPoints->push_back(MBBEnd);

  // Find all blocks that are reachable from KillMBB without leaving VNI's live
  // range. It is possible that KillMBB itself is reachable, so start a DFS
  // from each successor.
  typedef SmallPtrSet<MachineBasicBlock*, 9> VisitedTy;
  VisitedTy Visited;
  for (MachineBasicBlock::succ_iterator
       SuccI = KillMBB->succ_begin(), SuccE = KillMBB->succ_end();
       SuccI != SuccE; ++SuccI) {
    for (df_ext_iterator<MachineBasicBlock*, VisitedTy>
         I = df_ext_begin(*SuccI, Visited), E = df_ext_end(*SuccI, Visited);
         I != E;) {
      MachineBasicBlock *MBB = *I;

      // Check if VNI is live in to MBB.
      SlotIndex MBBStart, MBBEnd;
      std::tie(MBBStart, MBBEnd) = Indexes->getMBBRange(MBB);
      LiveQueryResult LRQ = LR.Query(MBBStart);
      if (LRQ.valueIn() != VNI) {
        // This block isn't part of the VNI segment. Prune the search.
        I.skipChildren();
        continue;
      }

      // Prune the search if VNI is killed in MBB.
      if (LRQ.endPoint() < MBBEnd) {
        LR.removeSegment(MBBStart, LRQ.endPoint());
        if (EndPoints) EndPoints->push_back(LRQ.endPoint());
        I.skipChildren();
        continue;
      }

      // VNI is live through MBB.
      LR.removeSegment(MBBStart, MBBEnd);
      if (EndPoints) EndPoints->push_back(MBBEnd);
      ++I;
    }
  }
}

void RegDefsUses::addLiveOut(const MachineBasicBlock &MBB,
                             const MachineBasicBlock &SuccBB) {
  for (MachineBasicBlock::const_succ_iterator SI = MBB.succ_begin(),
       SE = MBB.succ_end(); SI != SE; ++SI)
    if (*SI != &SuccBB)
      for (const auto &LI : (*SI)->liveins())
        Uses.set(LI.PhysReg);
}

bool PTXInstrInfo::
IsAnySuccessorAlsoLayoutSuccessor(const MachineBasicBlock& MBB) {
  for (MachineBasicBlock::const_succ_iterator
      i = MBB.succ_begin(), e = MBB.succ_end(); i != e; ++i)
    if (MBB.isLayoutSuccessor((const MachineBasicBlock*) &*i))
      return true;
  return false;
}

static bool isCPSRLiveout(MachineBasicBlock &MBB) {
  for (MachineBasicBlock::succ_iterator I = MBB.succ_begin(),
         E = MBB.succ_end(); I != E; ++I) {
    if ((*I)->isLiveIn(ARM::CPSR))
      return true;
  }
  return false;
}

void RegDefsUses::addLiveOut(const MachineBasicBlock &MBB,
                             const MachineBasicBlock &SuccBB) {
  for (MachineBasicBlock::const_succ_iterator SI = MBB.succ_begin(),
       SE = MBB.succ_end(); SI != SE; ++SI)
    if (*SI != &SuccBB)
      for (MachineBasicBlock::livein_iterator LI = (*SI)->livein_begin(),
           LE = (*SI)->livein_end(); LI != LE; ++LI)
        Uses.set(*LI);
}

static bool
bothUsedInPHI(const MachineBasicBlock &A,
              SmallPtrSet<MachineBasicBlock*, 8> SuccsB) {
  for (MachineBasicBlock::const_succ_iterator SI = A.succ_begin(),
         SE = A.succ_end(); SI != SE; ++SI) {
    MachineBasicBlock *BB = *SI;
    if (SuccsB.count(BB) && !BB->empty() && BB->begin()->isPHI())
      return true;
  }

  return false;
}

void MIRPrinter::convert(ModuleSlotTracker &MST,
                         yaml::MachineBasicBlock &YamlMBB,
                         const MachineBasicBlock &MBB) {
  assert(MBB.getNumber() >= 0 && "Invalid MBB number");
  YamlMBB.ID = (unsigned)MBB.getNumber();
  if (const auto *BB = MBB.getBasicBlock()) {
    if (BB->hasName()) {
      YamlMBB.Name.Value = BB->getName();
    } else {
      int Slot = MST.getLocalSlot(BB);
      if (Slot == -1)
        YamlMBB.IRBlock.Value = "<badref>";
      else
        YamlMBB.IRBlock.Value = (Twine("%ir-block.") + Twine(Slot)).str();
    }
  }
  YamlMBB.Alignment = MBB.getAlignment();
  YamlMBB.AddressTaken = MBB.hasAddressTaken();
  YamlMBB.IsLandingPad = MBB.isLandingPad();
  for (const auto *SuccMBB : MBB.successors()) {
    std::string Str;
    raw_string_ostream StrOS(Str);
    MIPrinter(StrOS, MST, RegisterMaskIds, StackObjectOperandMapping)
        .printMBBReference(*SuccMBB);
    YamlMBB.Successors.push_back(StrOS.str());
  }
  if (MBB.hasSuccessorWeights()) {
    for (auto I = MBB.succ_begin(), E = MBB.succ_end(); I != E; ++I)
      YamlMBB.SuccessorWeights.push_back(
          yaml::UnsignedValue(MBB.getSuccWeight(I)));
  }
  // Print the live in registers.
  const auto *TRI = MBB.getParent()->getSubtarget().getRegisterInfo();
  assert(TRI && "Expected target register info");
  for (auto I = MBB.livein_begin(), E = MBB.livein_end(); I != E; ++I) {
    std::string Str;
    raw_string_ostream StrOS(Str);
    printReg(*I, StrOS, TRI);
    YamlMBB.LiveIns.push_back(StrOS.str());
  }
  // Print the machine instructions.
  YamlMBB.Instructions.reserve(MBB.size());
  std::string Str;
  for (const auto &MI : MBB) {
    raw_string_ostream StrOS(Str);
    MIPrinter(StrOS, MST, RegisterMaskIds, StackObjectOperandMapping).print(MI);
    YamlMBB.Instructions.push_back(StrOS.str());
    Str.clear();
  }
}

void SPScope::buildfcfg(void) {
    std::set<const MachineBasicBlock *> body(++Blocks.begin(), Blocks.end());
    std::vector<Edge> outedges;

    for (unsigned i=0; i<Blocks.size(); i++) {
        MachineBasicBlock *MBB = Blocks[i];

        if (HeaderMap.count(MBB)) {
            const SPScope *subloop = HeaderMap[MBB];
            // successors of the loop
            outedges.insert(outedges.end(),
                            subloop->ExitEdges.begin(),
                            subloop->ExitEdges.end());
        } else {
            // simple block
            for (MachineBasicBlock::succ_iterator si = MBB->succ_begin(),
                    se = MBB->succ_end(); si != se; ++si) {
                outedges.push_back(std::make_pair(MBB, *si));
            }
        }

        Node &n = FCFG.getNodeFor(MBB);
        for (unsigned i=0; i<outedges.size(); i++) {
            const MachineBasicBlock *succ = outedges[i].second;
            if (body.count(succ)) {
                Node &ns = FCFG.getNodeFor(succ);
                n.connect(ns, outedges[i]);
            } else {
                if (succ != getHeader()) {
                    // record exit edges
                    FCFG.toexit(n, outedges[i]);
                } else {
                    // we don't need back edges recorded
                    FCFG.toexit(n);
                }
            }
        }

        // special case: top-level loop has no exit/backedge
        if (outedges.empty()) {
            assert(isTopLevel());
            FCFG.toexit(n);
        }
        outedges.clear();
    }
}

bool MIPrinter::canPredictSuccessors(const MachineBasicBlock &MBB) const {
  SmallVector<MachineBasicBlock*,8> GuessedSuccs;
  bool GuessedFallthrough;
  guessSuccessors(MBB, GuessedSuccs, GuessedFallthrough);
  if (GuessedFallthrough) {
    const MachineFunction &MF = *MBB.getParent();
    MachineFunction::const_iterator NextI = std::next(MBB.getIterator());
    if (NextI != MF.end()) {
      MachineBasicBlock *Next = const_cast<MachineBasicBlock*>(&*NextI);
      if (!is_contained(GuessedSuccs, Next))
        GuessedSuccs.push_back(Next);
    }
  }
  if (GuessedSuccs.size() != MBB.succ_size())
    return false;
  return std::equal(MBB.succ_begin(), MBB.succ_end(), GuessedSuccs.begin());
}

bool LiveVariables::isLiveOut(unsigned Reg, const MachineBasicBlock &MBB) {
  LiveVariables::VarInfo &VI = getVarInfo(Reg);

  // Loop over all of the successors of the basic block, checking to see if
  // the value is either live in the block, or if it is killed in the block.
  SmallVector<MachineBasicBlock*, 8> OpSuccBlocks;
  for (MachineBasicBlock::const_succ_iterator SI = MBB.succ_begin(),
         E = MBB.succ_end(); SI != E; ++SI) {
    MachineBasicBlock *SuccMBB = *SI;

    // Is it alive in this successor?
    unsigned SuccIdx = SuccMBB->getNumber();
    if (VI.AliveBlocks.test(SuccIdx))
      return true;
    OpSuccBlocks.push_back(SuccMBB);
  }

  // Check to see if this value is live because there is a use in a successor
  // that kills it.
  switch (OpSuccBlocks.size()) {
  case 1: {
    MachineBasicBlock *SuccMBB = OpSuccBlocks[0];
    for (unsigned i = 0, e = VI.Kills.size(); i != e; ++i)
      if (VI.Kills[i]->getParent() == SuccMBB)
        return true;
    break;
  }
  case 2: {
    MachineBasicBlock *SuccMBB1 = OpSuccBlocks[0], *SuccMBB2 = OpSuccBlocks[1];
    for (unsigned i = 0, e = VI.Kills.size(); i != e; ++i)
      if (VI.Kills[i]->getParent() == SuccMBB1 ||
          VI.Kills[i]->getParent() == SuccMBB2)
        return true;
    break;
  }
  default:
    std::sort(OpSuccBlocks.begin(), OpSuccBlocks.end());
    for (unsigned i = 0, e = VI.Kills.size(); i != e; ++i)
      if (std::binary_search(OpSuccBlocks.begin(), OpSuccBlocks.end(),
                             VI.Kills[i]->getParent()))
        return true;
  }
  return false;
}

bool
TailDuplicatePass::canCompletelyDuplicateBB(MachineBasicBlock &BB) {
    SmallPtrSet<MachineBasicBlock*, 8> Succs(BB.succ_begin(), BB.succ_end());

    for (MachineBasicBlock::pred_iterator PI = BB.pred_begin(),
            PE = BB.pred_end(); PI != PE; ++PI) {
        MachineBasicBlock *PredBB = *PI;

        if (PredBB->succ_size() > 1)
            return false;

        MachineBasicBlock *PredTBB = NULL, *PredFBB = NULL;
        SmallVector<MachineOperand, 4> PredCond;
        if (TII->AnalyzeBranch(*PredBB, PredTBB, PredFBB, PredCond, true))
            return false;

        if (!PredCond.empty())
            return false;
    }
    return true;
}

 void LoopSplitter::dumpOddTerminators() {
   for (MachineFunction::iterator bbItr = mf->begin(), bbEnd = mf->end();
        bbItr != bbEnd; ++bbItr) {
     MachineBasicBlock *mbb = &*bbItr;
     MachineBasicBlock *a = 0, *b = 0;
     SmallVector<MachineOperand, 4> c;
     if (tii->AnalyzeBranch(*mbb, a, b, c)) {
       dbgs() << "MBB#" << mbb->getNumber() << " has multiway terminator.\n";
       dbgs() << "  Terminators:\n";
       for (MachineBasicBlock::iterator iItr = mbb->begin(), iEnd = mbb->end();
            iItr != iEnd; ++iItr) {
         MachineInstr *instr= &*iItr;
         dbgs() << "    " << *instr << "";
       }
       dbgs() << "\n  Listed successors: [ ";
       for (MachineBasicBlock::succ_iterator sItr = mbb->succ_begin(), sEnd = mbb->succ_end();
            sItr != sEnd; ++sItr) {
         MachineBasicBlock *succMBB = *sItr;
         dbgs() << succMBB->getNumber() << " ";
       }
       dbgs() << "]\n\n";
     }
   }
 }

void StackColoring::calculateLocalLiveness() {
  // Perform a standard reverse dataflow computation to solve for
  // global liveness.  The BEGIN set here is equivalent to KILL in the standard
  // formulation, and END is equivalent to GEN.  The result of this computation
  // is a map from blocks to bitvectors where the bitvectors represent which
  // allocas are live in/out of that block.
  SmallPtrSet<MachineBasicBlock*, 8> BBSet(BasicBlockNumbering.begin(),
                                           BasicBlockNumbering.end());
  unsigned NumSSMIters = 0;
  bool changed = true;
  while (changed) {
    changed = false;
    ++NumSSMIters;

    SmallPtrSet<MachineBasicBlock*, 8> NextBBSet;

    for (SmallVector<MachineBasicBlock*, 8>::iterator
         PI = BasicBlockNumbering.begin(), PE = BasicBlockNumbering.end();
         PI != PE; ++PI) {

      MachineBasicBlock *BB = *PI;
      if (!BBSet.count(BB)) continue;

      BitVector LocalLiveIn;
      BitVector LocalLiveOut;

      // Forward propagation from begins to ends.
      for (MachineBasicBlock::pred_iterator PI = BB->pred_begin(),
           PE = BB->pred_end(); PI != PE; ++PI)
        LocalLiveIn |= BlockLiveness[*PI].LiveOut;
      LocalLiveIn |= BlockLiveness[BB].End;
      LocalLiveIn.reset(BlockLiveness[BB].Begin);

      // Reverse propagation from ends to begins.
      for (MachineBasicBlock::succ_iterator SI = BB->succ_begin(),
           SE = BB->succ_end(); SI != SE; ++SI)
        LocalLiveOut |= BlockLiveness[*SI].LiveIn;
      LocalLiveOut |= BlockLiveness[BB].Begin;
      LocalLiveOut.reset(BlockLiveness[BB].End);

      LocalLiveIn |= LocalLiveOut;
      LocalLiveOut |= LocalLiveIn;

      // After adopting the live bits, we need to turn-off the bits which
      // are de-activated in this block.
      LocalLiveOut.reset(BlockLiveness[BB].End);
      LocalLiveIn.reset(BlockLiveness[BB].Begin);

      // If we have both BEGIN and END markers in the same basic block then
      // we know that the BEGIN marker comes after the END, because we already
      // handle the case where the BEGIN comes before the END when collecting
      // the markers (and building the BEGIN/END vectore).
      // Want to enable the LIVE_IN and LIVE_OUT of slots that have both
      // BEGIN and END because it means that the value lives before and after
      // this basic block.
      BitVector LocalEndBegin = BlockLiveness[BB].End;
      LocalEndBegin &= BlockLiveness[BB].Begin;
      LocalLiveIn |= LocalEndBegin;
      LocalLiveOut |= LocalEndBegin;

      if (LocalLiveIn.test(BlockLiveness[BB].LiveIn)) {
        changed = true;
        BlockLiveness[BB].LiveIn |= LocalLiveIn;

        for (MachineBasicBlock::pred_iterator PI = BB->pred_begin(),
             PE = BB->pred_end(); PI != PE; ++PI)
          NextBBSet.insert(*PI);
      }

      if (LocalLiveOut.test(BlockLiveness[BB].LiveOut)) {
        changed = true;
        BlockLiveness[BB].LiveOut |= LocalLiveOut;

        for (MachineBasicBlock::succ_iterator SI = BB->succ_begin(),
             SE = BB->succ_end(); SI != SE; ++SI)
          NextBBSet.insert(*SI);
      }
    }

    BBSet = NextBBSet;
  }// while changed.
}