C++ PHINode::setIncomingBlock方法代码示例

// switchConvert - Convert the switch statement into a linear scan
// through all the case values
void LowerSwitchPass::switchConvert(CaseItr begin, CaseItr end,
                                    Value* value, BasicBlock* origBlock,
                                    BasicBlock* defaultBlock)
{
    BasicBlock *curHead = defaultBlock;
    Function *F = origBlock->getParent();

    // iterate through all the cases, creating a new BasicBlock for each
    for (CaseItr it = begin; it < end; ++it) {
        BasicBlock *newBlock = BasicBlock::Create(getGlobalContext(), "NodeBlock");
        Function::iterator FI = origBlock;
        F->getBasicBlockList().insert(++FI, newBlock);

        ICmpInst *cmpInst =
            new ICmpInst(*newBlock, ICmpInst::ICMP_EQ, value, it->value, "case.cmp");
        BranchInst::Create(it->block, curHead, cmpInst, newBlock);

        // If there were any PHI nodes in this successor, rewrite one entry
        // from origBlock to come from newBlock.
        for (BasicBlock::iterator bi = it->block->begin(); isa<PHINode>(bi); ++bi) {
            PHINode* PN = cast<PHINode>(bi);

            int blockIndex = PN->getBasicBlockIndex(origBlock);
            assert(blockIndex != -1 && "Switch didn't go to this successor??");
            PN->setIncomingBlock((unsigned)blockIndex, newBlock);
        }

        curHead = newBlock;
    }

    // Branch to our shiny new if-then stuff...
    BranchInst::Create(curHead, origBlock);
}

// \brief Update the first occurrence of the "switch statement" BB in the PHI
// node with the "new" BB. The other occurrences will:
//
// 1) Be updated by subsequent calls to this function.  Switch statements may
// have more than one outcoming edge into the same BB if they all have the same
// value. When the switch statement is converted these incoming edges are now
// coming from multiple BBs.
// 2) Removed if subsequent incoming values now share the same case, i.e.,
// multiple outcome edges are condensed into one. This is necessary to keep the
// number of phi values equal to the number of branches to SuccBB.
static void fixPhis(BasicBlock *SuccBB, BasicBlock *OrigBB, BasicBlock *NewBB,
                    unsigned NumMergedCases) {
  for (BasicBlock::iterator I = SuccBB->begin(), IE = SuccBB->getFirstNonPHI();
       I != IE; ++I) {
    PHINode *PN = cast<PHINode>(I);

    // Only update the first occurence.
    unsigned Idx = 0, E = PN->getNumIncomingValues();
    unsigned LocalNumMergedCases = NumMergedCases;
    for (; Idx != E; ++Idx) {
      if (PN->getIncomingBlock(Idx) == OrigBB) {
        PN->setIncomingBlock(Idx, NewBB);
        break;
      }
    }

    // Remove additional occurences coming from condensed cases and keep the
    // number of incoming values equal to the number of branches to SuccBB.
    SmallVector<unsigned, 8> Indices;
    for (++Idx; LocalNumMergedCases > 0 && Idx < E; ++Idx)
      if (PN->getIncomingBlock(Idx) == OrigBB) {
        Indices.push_back(Idx);
        LocalNumMergedCases--;
      }
    // Remove incoming values in the reverse order to prevent invalidating
    // *successive* index.
    for (auto III = Indices.rbegin(), IIE = Indices.rend(); III != IIE; ++III)
      PN->removeIncomingValue(*III);
  }
}

// newLeafBlock - Create a new leaf block for the binary lookup tree. It
// checks if the switch's value == the case's value. If not, then it
// jumps to the default branch. At this point in the tree, the value
// can't be another valid case value, so the jump to the "default" branch
// is warranted.
//
BasicBlock* LowerSwitch::newLeafBlock(CaseRange& Leaf, Value* Val,
                                      BasicBlock* OrigBlock,
                                      BasicBlock* Default)
{
  Function* F = OrigBlock->getParent();
  BasicBlock* NewLeaf = BasicBlock::Create(Val->getContext(), "LeafBlock");
  Function::iterator FI = OrigBlock;
  F->getBasicBlockList().insert(++FI, NewLeaf);

  // Emit comparison
  ICmpInst* Comp = NULL;
  if (Leaf.Low == Leaf.High) {
    // Make the seteq instruction...
    Comp = new ICmpInst(*NewLeaf, ICmpInst::ICMP_EQ, Val,
                        Leaf.Low, "SwitchLeaf");
  } else {
    // Make range comparison
    if (cast<ConstantInt>(Leaf.Low)->isMinValue(true /*isSigned*/)) {
      // Val >= Min && Val <= Hi --> Val <= Hi
      Comp = new ICmpInst(*NewLeaf, ICmpInst::ICMP_SLE, Val, Leaf.High,
                          "SwitchLeaf");
    } else if (cast<ConstantInt>(Leaf.Low)->isZero()) {
      // Val >= 0 && Val <= Hi --> Val <=u Hi
      Comp = new ICmpInst(*NewLeaf, ICmpInst::ICMP_ULE, Val, Leaf.High,
                          "SwitchLeaf");      
    } else {
      // Emit V-Lo <=u Hi-Lo
      Constant* NegLo = ConstantExpr::getNeg(Leaf.Low);
      Instruction* Add = BinaryOperator::CreateAdd(Val, NegLo,
                                                   Val->getName()+".off",
                                                   NewLeaf);
      Constant *UpperBound = ConstantExpr::getAdd(NegLo, Leaf.High);
      Comp = new ICmpInst(*NewLeaf, ICmpInst::ICMP_ULE, Add, UpperBound,
                          "SwitchLeaf");
    }
  }

  // Make the conditional branch...
  BasicBlock* Succ = Leaf.BB;
  BranchInst::Create(Succ, Default, Comp, NewLeaf);

  // If there were any PHI nodes in this successor, rewrite one entry
  // from OrigBlock to come from NewLeaf.
  for (BasicBlock::iterator I = Succ->begin(); isa<PHINode>(I); ++I) {
    PHINode* PN = cast<PHINode>(I);
    // Remove all but one incoming entries from the cluster
    uint64_t Range = cast<ConstantInt>(Leaf.High)->getSExtValue() -
                     cast<ConstantInt>(Leaf.Low)->getSExtValue();    
    for (uint64_t j = 0; j < Range; ++j) {
      PN->removeIncomingValue(OrigBlock);
    }
    
    int BlockIdx = PN->getBasicBlockIndex(OrigBlock);
    assert(BlockIdx != -1 && "Switch didn't go to this successor??");
    PN->setIncomingBlock((unsigned)BlockIdx, NewLeaf);
  }

  return NewLeaf;
}

void CheckInserter::insertCycleChecks(Function &F) {
  IdentifyBackEdges &IBE = getAnalysis<IdentifyBackEdges>();

  for (Function::iterator B1 = F.begin(); B1 != F.end(); ++B1) {
    TerminatorInst *TI = B1->getTerminator();
    for (unsigned j = 0; j < TI->getNumSuccessors(); ++j) {
      BasicBlock *B2 = TI->getSuccessor(j);
      unsigned BackEdgeID = IBE.getID(B1, B2);
      if (BackEdgeID != (unsigned)-1) {
        assert(BackEdgeID < MaxNumBackEdges);
        BasicBlock *BackEdgeBlock = BasicBlock::Create(
            F.getContext(),
            "backedge_" + B1->getName() + "_" + B2->getName(),
            &F);
        CallInst::Create(CycleCheck,
                         ConstantInt::get(IntType, BackEdgeID),
                         "",
                         BackEdgeBlock);
        // BackEdgeBlock -> B2
        // Fix the PHINodes in B2.
        BranchInst::Create(B2, BackEdgeBlock);
        for (BasicBlock::iterator I = B2->begin();
             B2->getFirstNonPHI() != I;
             ++I) {
          PHINode *PHI = cast<PHINode>(I);
          // Note: If B2 has multiple incoming edges from B1 (e.g. B1 terminates
          // with a SelectInst), its PHINodes must also have multiple incoming
          // edges from B1. However, after adding BackEdgeBlock and essentially
          // merging the multiple incoming edges from B1, there will be only one
          // edge from BackEdgeBlock to B2. Therefore, we need to remove the
          // redundant incoming edges from B2's PHINodes.
          bool FirstIncomingFromB1 = true;
          for (unsigned k = 0; k < PHI->getNumIncomingValues(); ++k) {
            if (PHI->getIncomingBlock(k) == B1) {
              if (FirstIncomingFromB1) {
                FirstIncomingFromB1 = false;
                PHI->setIncomingBlock(k, BackEdgeBlock);
              } else {
                PHI->removeIncomingValue(k, false);
                --k;
              }
            }
          }
        }
        // B1 -> BackEdgeBlock
        // There might be multiple back edges from B1 to B2. Need to replace
        // them all.
        for (unsigned j2 = j; j2 < TI->getNumSuccessors(); ++j2) {
          if (TI->getSuccessor(j2) == B2) {
            TI->setSuccessor(j2, BackEdgeBlock);
          }
        }
      }
    }
  }
}

void LoopInterchangeTransform::updateIncomingBlock(BasicBlock *CurrBlock,
                                                   BasicBlock *OldPred,
                                                   BasicBlock *NewPred) {
  for (auto I = CurrBlock->begin(); isa<PHINode>(I); ++I) {
    PHINode *PHI = cast<PHINode>(I);
    unsigned Num = PHI->getNumIncomingValues();
    for (unsigned i = 0; i < Num; ++i) {
      if (PHI->getIncomingBlock(i) == OldPred)
        PHI->setIncomingBlock(i, NewPred);
    }
  }
}

// processSwitchInst - Replace the specified switch instruction with a sequence
// of chained if-then instructions.
//
void LowerSwitchPass::processSwitchInst(SwitchInst *SI) {
  BasicBlock *origBlock = SI->getParent();
  BasicBlock *defaultBlock = SI->getDefaultDest();
  Function *F = origBlock->getParent();
  Value *switchValue = SI->getCondition();

  // Create a new, empty default block so that the new hierarchy of
  // if-then statements go to this and the PHI nodes are happy.
  BasicBlock* newDefault = BasicBlock::Create(getGlobalContext(), "newDefault");

#if LLVM_VERSION_CODE >= LLVM_VERSION(3, 8)
  F->getBasicBlockList().insert(defaultBlock->getIterator(), newDefault);
#else
  F->getBasicBlockList().insert(defaultBlock, newDefault);
#endif
  BranchInst::Create(defaultBlock, newDefault);

  // If there is an entry in any PHI nodes for the default edge, make sure
  // to update them as well.
  for (BasicBlock::iterator I = defaultBlock->begin(); isa<PHINode>(I); ++I) {
    PHINode *PN = cast<PHINode>(I);
    int BlockIdx = PN->getBasicBlockIndex(origBlock);
    assert(BlockIdx != -1 && "Switch didn't go to this successor??");
    PN->setIncomingBlock((unsigned)BlockIdx, newDefault);
  }
  
  CaseVector cases;
  
#if LLVM_VERSION_CODE >= LLVM_VERSION(3, 1)
  for (SwitchInst::CaseIt i = SI->case_begin(), e = SI->case_end(); i != e; ++i)
    cases.push_back(SwitchCase(i.getCaseValue(),
                               i.getCaseSuccessor()));
#else
  for (unsigned i = 1; i < SI->getNumSuccessors(); ++i)  
    cases.push_back(SwitchCase(SI->getSuccessorValue(i),
                               SI->getSuccessor(i)));
#endif
  
  // reverse cases, as switchConvert constructs a chain of
  //   basic blocks by appending to the front. if we reverse,
  //   the if comparisons will happen in the same order
  //   as the cases appear in the switch
  std::reverse(cases.begin(), cases.end());
  
  switchConvert(cases.begin(), cases.end(), switchValue, origBlock, newDefault);

  // We are now done with the switch instruction, so delete it
  origBlock->getInstList().erase(SI);
}

// processSwitchInst - Replace the specified switch instruction with a sequence
// of chained if-then insts in a balanced binary search.
//
void LowerSwitch::processSwitchInst(SwitchInst *SI) {
  BasicBlock *CurBlock = SI->getParent();
  BasicBlock *OrigBlock = CurBlock;
  Function *F = CurBlock->getParent();
  Value *Val = SI->getOperand(0);  // The value we are switching on...
  BasicBlock* Default = SI->getDefaultDest();

  // If there is only the default destination, don't bother with the code below.
  if (SI->getNumOperands() == 2) {
    BranchInst::Create(SI->getDefaultDest(), CurBlock);
    CurBlock->getInstList().erase(SI);
    return;
  }

  // Create a new, empty default block so that the new hierarchy of
  // if-then statements go to this and the PHI nodes are happy.
  BasicBlock* NewDefault = BasicBlock::Create(SI->getContext(), "NewDefault");
  F->getBasicBlockList().insert(Default, NewDefault);

  BranchInst::Create(Default, NewDefault);

  // If there is an entry in any PHI nodes for the default edge, make sure
  // to update them as well.
  for (BasicBlock::iterator I = Default->begin(); isa<PHINode>(I); ++I) {
    PHINode *PN = cast<PHINode>(I);
    int BlockIdx = PN->getBasicBlockIndex(OrigBlock);
    assert(BlockIdx != -1 && "Switch didn't go to this successor??");
    PN->setIncomingBlock((unsigned)BlockIdx, NewDefault);
  }

  // Prepare cases vector.
  CaseVector Cases;
  unsigned numCmps = Clusterify(Cases, SI);

  DEBUG(dbgs() << "Clusterify finished. Total clusters: " << Cases.size()
               << ". Total compares: " << numCmps << "\n");
  DEBUG(dbgs() << "Cases: " << Cases << "\n");
  (void)numCmps;
  
  BasicBlock* SwitchBlock = switchConvert(Cases.begin(), Cases.end(), Val,
                                          OrigBlock, NewDefault);

  // Branch to our shiny new if-then stuff...
  BranchInst::Create(SwitchBlock, OrigBlock);

  // We are now done with the switch instruction, delete it.
  CurBlock->getInstList().erase(SI);
}

void BasicBlock::replaceSuccessorsPhiUsesWith(BasicBlock *New) {
  TerminatorInst *TI = getTerminator();
  if (!TI)
    // Cope with being called on a BasicBlock that doesn't have a terminator
    // yet. Clang's CodeGenFunction::EmitReturnBlock() likes to do this.
    return;
  for (BasicBlock *Succ : TI->successors()) {
    // N.B. Succ might not be a complete BasicBlock, so don't assume
    // that it ends with a non-phi instruction.
    for (iterator II = Succ->begin(), IE = Succ->end(); II != IE; ++II) {
      PHINode *PN = dyn_cast<PHINode>(II);
      if (!PN)
        break;
      int i;
      while ((i = PN->getBasicBlockIndex(this)) >= 0)
        PN->setIncomingBlock(i, New);
    }
  }
}

void MemoryInstrumenter::instrumentPointerInstruction(Instruction *I) {
    BasicBlock::iterator Loc;
    if (isa<PHINode>(I)) {
        // Cannot insert hooks right after a PHI, because PHINodes have to be
        // grouped together.
        Loc = I->getParent()->getFirstNonPHI();
    } else if (!I->isTerminator()) {
        Loc = I;
        ++Loc;
    } else {
        assert(isa<InvokeInst>(I));
        InvokeInst *II = cast<InvokeInst>(I);
        BasicBlock *NormalDest = II->getNormalDest();
        // It's not always OK to insert HookTopLevel simply at the beginning of the
        // normal destination, because the normal destionation may be shared by
        // multiple InvokeInsts. In that case, we will create a critical edge block,
        // and add the HookTopLevel over there.
        if (NormalDest->getUniquePredecessor()) {
            Loc = NormalDest->getFirstNonPHI();
        } else {
            BasicBlock *CritEdge = BasicBlock::Create(I->getContext(),
                                   "crit_edge",
                                   I->getParent()->getParent());
            Loc = BranchInst::Create(NormalDest, CritEdge);
            // Now that CritEdge becomes the new predecessor of NormalDest, replace
            // all phi uses of I->getParent() with CritEdge.
            for (auto J = NormalDest->begin();
                    NormalDest->getFirstNonPHI() != J;
                    ++J) {
                PHINode *Phi = cast<PHINode>(J);
                int i;
                while ((i = Phi->getBasicBlockIndex(I->getParent())) >= 0)
                    Phi->setIncomingBlock(i, CritEdge);
            }
            II->setNormalDest(CritEdge);
        }
    }
    if (LoadInst *LI = dyn_cast<LoadInst>(I))
        instrumentPointer(I, LI->getPointerOperand(), Loc);
    else
        instrumentPointer(I, NULL, Loc);
}

/// This splits a basic block into two at the specified
/// instruction.  Note that all instructions BEFORE the specified iterator stay
/// as part of the original basic block, an unconditional branch is added to
/// the new BB, and the rest of the instructions in the BB are moved to the new
/// BB, including the old terminator.  This invalidates the iterator.
///
/// Note that this only works on well formed basic blocks (must have a
/// terminator), and 'I' must not be the end of instruction list (which would
/// cause a degenerate basic block to be formed, having a terminator inside of
/// the basic block).
///
BasicBlock *BasicBlock::splitBasicBlock(iterator I, const Twine &BBName) {
  assert(getTerminator() && "Can't use splitBasicBlock on degenerate BB!");
  assert(I != InstList.end() &&
         "Trying to get me to create degenerate basic block!");

  BasicBlock *InsertBefore = std::next(Function::iterator(this))
                               .getNodePtrUnchecked();
  BasicBlock *New = BasicBlock::Create(getContext(), BBName,
                                       getParent(), InsertBefore);

  // Save DebugLoc of split point before invalidating iterator.
  DebugLoc Loc = I->getDebugLoc();
  // Move all of the specified instructions from the original basic block into
  // the new basic block.
  New->getInstList().splice(New->end(), this->getInstList(), I, end());

  // Add a branch instruction to the newly formed basic block.
  BranchInst *BI = BranchInst::Create(New, this);
  BI->setDebugLoc(Loc);

  // Now we must loop through all of the successors of the New block (which
  // _were_ the successors of the 'this' block), and update any PHI nodes in
  // successors.  If there were PHI nodes in the successors, then they need to
  // know that incoming branches will be from New, not from Old.
  //
  for (succ_iterator I = succ_begin(New), E = succ_end(New); I != E; ++I) {
    // Loop over any phi nodes in the basic block, updating the BB field of
    // incoming values...
    BasicBlock *Successor = *I;
    PHINode *PN;
    for (BasicBlock::iterator II = Successor->begin();
         (PN = dyn_cast<PHINode>(II)); ++II) {
      int IDX = PN->getBasicBlockIndex(this);
      while (IDX != -1) {
        PN->setIncomingBlock((unsigned)IDX, New);
        IDX = PN->getBasicBlockIndex(this);
      }
    }
  }
  return New;
}

// This is basically the split basic block function but it does not create
// a new basic block.
void Decompiler::splitBasicBlockIntoBlock(Function::iterator Src,
  BasicBlock::iterator FirstInst, BasicBlock *Tgt) {
  assert(Src->getTerminator() && "Can't use splitBasicBlock on degenerate BB!");
  assert(FirstInst != Src->end() &&
         "Trying to get me to create degenerate basic block!");

  Tgt->moveAfter(Src);

  // Move all of the specified instructions from the original basic block into
  // the new basic block.
  Tgt->getInstList().splice(Tgt->end(), Src->getInstList(),
    FirstInst, Src->end());

  // Add a branch instruction to the newly formed basic block.
  BranchInst *BI = BranchInst::Create(Tgt, Src);
  // Set debugLoc to the instruction before the terminator's DebugLoc.
  // Note the pre-inc which can confuse folks.
  BI->setDebugLoc((++Src->rbegin())->getDebugLoc());

  // Now we must loop through all of the successors of the New block (which
  // _were_ the successors of the 'this' block), and update any PHI nodes in
  // successors.  If there were PHI nodes in the successors, then they need to
  // know that incoming branches will be from New, not from Old.
  //
  for (succ_iterator I = succ_begin(Tgt), E = succ_end(Tgt); I != E; ++I) {
    // Loop over any phi nodes in the basic block, updating the BB field of
    // incoming values...
    BasicBlock *Successor = *I;
    PHINode *PN;
    for (BasicBlock::iterator II = Successor->begin();
         (PN = dyn_cast<PHINode>(II)); ++II) {
      int IDX = PN->getBasicBlockIndex(Src);
      while (IDX != -1) {
        PN->setIncomingBlock((unsigned)IDX, Tgt);
        IDX = PN->getBasicBlockIndex(Src);
      }
    }
  }
}

/// SplitCriticalEdge - If this edge is a critical edge, insert a new node to
/// split the critical edge.  This will update DominatorTree information if it
/// is available, thus calling this pass will not invalidate either of them.
/// This returns the new block if the edge was split, null otherwise.
///
/// If MergeIdenticalEdges is true (not the default), *all* edges from TI to the
/// specified successor will be merged into the same critical edge block.
/// This is most commonly interesting with switch instructions, which may
/// have many edges to any one destination.  This ensures that all edges to that
/// dest go to one block instead of each going to a different block, but isn't
/// the standard definition of a "critical edge".
///
/// It is invalid to call this function on a critical edge that starts at an
/// IndirectBrInst.  Splitting these edges will almost always create an invalid
/// program because the address of the new block won't be the one that is jumped
/// to.
///
BasicBlock *llvm::SplitCriticalEdge(TerminatorInst *TI, unsigned SuccNum,
                                    Pass *P, bool MergeIdenticalEdges,
                                    bool DontDeleteUselessPhis,
                                    bool SplitLandingPads) {
  if (!isCriticalEdge(TI, SuccNum, MergeIdenticalEdges)) return 0;

  assert(!isa<IndirectBrInst>(TI) &&
         "Cannot split critical edge from IndirectBrInst");

  BasicBlock *TIBB = TI->getParent();
  BasicBlock *DestBB = TI->getSuccessor(SuccNum);

  // Splitting the critical edge to a landing pad block is non-trivial. Don't do
  // it in this generic function.
  if (DestBB->isLandingPad()) return 0;

  // Create a new basic block, linking it into the CFG.
  BasicBlock *NewBB = BasicBlock::Create(TI->getContext(),
                      TIBB->getName() + "." + DestBB->getName() + "_crit_edge");
  // Create our unconditional branch.
  BranchInst *NewBI = BranchInst::Create(DestBB, NewBB);
  NewBI->setDebugLoc(TI->getDebugLoc());

  // Branch to the new block, breaking the edge.
  TI->setSuccessor(SuccNum, NewBB);

  // Insert the block into the function... right after the block TI lives in.
  Function &F = *TIBB->getParent();
  Function::iterator FBBI = TIBB;
  F.getBasicBlockList().insert(++FBBI, NewBB);

  // If there are any PHI nodes in DestBB, we need to update them so that they
  // merge incoming values from NewBB instead of from TIBB.
  {
    unsigned BBIdx = 0;
    for (BasicBlock::iterator I = DestBB->begin(); isa<PHINode>(I); ++I) {
      // We no longer enter through TIBB, now we come in through NewBB.
      // Revector exactly one entry in the PHI node that used to come from
      // TIBB to come from NewBB.
      PHINode *PN = cast<PHINode>(I);

      // Reuse the previous value of BBIdx if it lines up.  In cases where we
      // have multiple phi nodes with *lots* of predecessors, this is a speed
      // win because we don't have to scan the PHI looking for TIBB.  This
      // happens because the BB list of PHI nodes are usually in the same
      // order.
      if (PN->getIncomingBlock(BBIdx) != TIBB)
        BBIdx = PN->getBasicBlockIndex(TIBB);
      PN->setIncomingBlock(BBIdx, NewBB);
    }
  }

  // If there are any other edges from TIBB to DestBB, update those to go
  // through the split block, making those edges non-critical as well (and
  // reducing the number of phi entries in the DestBB if relevant).
  if (MergeIdenticalEdges) {
    for (unsigned i = SuccNum+1, e = TI->getNumSuccessors(); i != e; ++i) {
      if (TI->getSuccessor(i) != DestBB) continue;

      // Remove an entry for TIBB from DestBB phi nodes.
      DestBB->removePredecessor(TIBB, DontDeleteUselessPhis);

      // We found another edge to DestBB, go to NewBB instead.
      TI->setSuccessor(i, NewBB);
    }
  }



  // If we don't have a pass object, we can't update anything...
  if (P == 0) return NewBB;

  DominatorTree *DT = P->getAnalysisIfAvailable<DominatorTree>();
  LoopInfo *LI = P->getAnalysisIfAvailable<LoopInfo>();

  // If we have nothing to update, just return.
  if (DT == 0 && LI == 0)
    return NewBB;

  // Now update analysis information.  Since the only predecessor of NewBB is
  // the TIBB, TIBB clearly dominates NewBB.  TIBB usually doesn't dominate
  // anything, as there are other successors of DestBB.  However, if all other
  // predecessors of DestBB are already dominated by DestBB (e.g. DestBB is a
//.........这里部分代码省略.........

//.........这里部分代码省略.........
        break;
      }
    }

    // Finally, remap the terminator instructions, as those can't be remapped
    // until all BBs are mapped.
    RemapInstruction(NewBB->getTerminator(), VMap,
                     ModuleLevelChanges ? RF_None : RF_NoModuleLevelChanges,
                     TypeMapper, Materializer);
  }
  
  // Defer PHI resolution until rest of function is resolved, PHI resolution
  // requires the CFG to be up-to-date.
  for (unsigned phino = 0, e = PHIToResolve.size(); phino != e; ) {
    const PHINode *OPN = PHIToResolve[phino];
    unsigned NumPreds = OPN->getNumIncomingValues();
    const BasicBlock *OldBB = OPN->getParent();
    BasicBlock *NewBB = cast<BasicBlock>(VMap[OldBB]);

    // Map operands for blocks that are live and remove operands for blocks
    // that are dead.
    for (; phino != PHIToResolve.size() &&
         PHIToResolve[phino]->getParent() == OldBB; ++phino) {
      OPN = PHIToResolve[phino];
      PHINode *PN = cast<PHINode>(VMap[OPN]);
      for (unsigned pred = 0, e = NumPreds; pred != e; ++pred) {
        Value *V = VMap[PN->getIncomingBlock(pred)];
        if (BasicBlock *MappedBlock = cast_or_null<BasicBlock>(V)) {
          Value *InVal = MapValue(PN->getIncomingValue(pred),
                                  VMap, 
                        ModuleLevelChanges ? RF_None : RF_NoModuleLevelChanges);
          assert(InVal && "Unknown input value?");
          PN->setIncomingValue(pred, InVal);
          PN->setIncomingBlock(pred, MappedBlock);
        } else {
          PN->removeIncomingValue(pred, false);
          --pred, --e;  // Revisit the next entry.
        }
      } 
    }
    
    // The loop above has removed PHI entries for those blocks that are dead
    // and has updated others.  However, if a block is live (i.e. copied over)
    // but its terminator has been changed to not go to this block, then our
    // phi nodes will have invalid entries.  Update the PHI nodes in this
    // case.
    PHINode *PN = cast<PHINode>(NewBB->begin());
    NumPreds = std::distance(pred_begin(NewBB), pred_end(NewBB));
    if (NumPreds != PN->getNumIncomingValues()) {
      assert(NumPreds < PN->getNumIncomingValues());
      // Count how many times each predecessor comes to this block.
      std::map<BasicBlock*, unsigned> PredCount;
      for (pred_iterator PI = pred_begin(NewBB), E = pred_end(NewBB);
           PI != E; ++PI)
        --PredCount[*PI];
      
      // Figure out how many entries to remove from each PHI.
      for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i)
        ++PredCount[PN->getIncomingBlock(i)];
      
      // At this point, the excess predecessor entries are positive in the
      // map.  Loop over all of the PHIs and remove excess predecessor
      // entries.
      BasicBlock::iterator I = NewBB->begin();
      for (; (PN = dyn_cast<PHINode>(I)); ++I) {
        for (std::map<BasicBlock*, unsigned>::iterator PCI =PredCount.begin(),

bool klee::PhiCleanerPass::runOnFunction(Function &f) {
    bool changed = false;

    for (Function::iterator b = f.begin(), be = f.end(); b != be; ++b) {
        BasicBlock::iterator it = b->begin();

        if (it->getOpcode() == Instruction::PHI) {
            PHINode *reference = cast<PHINode>(it);

            std::set<Value*> phis;
            phis.insert(reference);

            unsigned numBlocks = reference->getNumIncomingValues();
            for (++it; isa<PHINode>(*it); ++it) {
                PHINode *pi = cast<PHINode>(it);

                assert(numBlocks == pi->getNumIncomingValues());

                // see if it is out of order
                unsigned i;
                for (i=0; i<numBlocks; i++)
                    if (pi->getIncomingBlock(i) != reference->getIncomingBlock(i))
                        break;

                if (i!=numBlocks) {
                    std::vector<Value*> values;
                    values.reserve(numBlocks);
                    for (unsigned i=0; i<numBlocks; i++)
                        values[i] = pi->getIncomingValueForBlock(reference->getIncomingBlock(i));
                    for (unsigned i=0; i<numBlocks; i++) {
                        pi->setIncomingBlock(i, reference->getIncomingBlock(i));
                        pi->setIncomingValue(i, values[i]);
                    }
                    changed = true;
                }

                // see if it uses any previously defined phi nodes
                for (i=0; i<numBlocks; i++) {
                    Value *value = pi->getIncomingValue(i);

                    if (phis.find(value) != phis.end()) {
                        // fix by making a "move" at the end of the incoming block
                        // to a new temporary, which is thus known not to be a phi
                        // result. we could be somewhat more efficient about this
                        // by sharing temps and by reordering phi instructions so
                        // this isn't completely necessary, but in the end this is
                        // just a pathological case which does not occur very
                        // often.
                        Instruction *tmp =
                            new BitCastInst(value,
                                            value->getType(),
                                            value->getName() + ".phiclean",
                                            pi->getIncomingBlock(i)->getTerminator());
                        pi->setIncomingValue(i, tmp);
                    }

                    changed = true;
                }

                phis.insert(pi);
            }
        }
    }

    return changed;
}

// CreateOneLoop should take the current Loop 
Loop * SplitPass2::CreateOneLoop(Loop *L, std::map<Instruction*, Instruction*>  &instMap) {
    DEBUG(dbgs() << "Running CreateOneLoop\n");
    // TODO check if only one exit block.
    // TODO check if save to clone.

    BasicBlock *Header = L->getHeader();
    std::vector< BasicBlock * > body = L->getBlocks();
    BasicBlock *PreHeader = L->getLoopPredecessor(); 

    BasicBlock *Exit = L->getExitBlock(); 
    ValueToValueMapTy LastValueMap;
    std::vector<BasicBlock *> new_body;

    for(std::vector<BasicBlock * >::iterator it = body.begin(); it != body.end(); ++it) {
        ValueToValueMapTy VMap;
        BasicBlock *New = CloneBasicBlock(*it, VMap, ".copied");
        Header->getParent()->getBasicBlockList().push_back(New);
        new_body.push_back(New);

        // add to instMap
        std::vector<Instruction *> new_insts;
        for (BasicBlock::iterator I = New->begin(); I != New->end(); ++I) {
            new_insts.push_back(I);
        }
        std::vector<Instruction *> old_insts;
        for (BasicBlock::iterator I = (*it)->begin(); I != (*it)->end(); ++I) {
            old_insts.push_back(I);
        }

        for (unsigned i=0; i< new_insts.size(); ++i) {
            instMap[new_insts[i]] = old_insts[i];
        }

        // Update our running map of newest clones
        LastValueMap[*it] = New;
        for (ValueToValueMapTy::iterator VI = VMap.begin(), VE = VMap.end(); VI != VE; ++VI) {
            LastValueMap[VI->first] = VI->second;
        }
    }
    // new_body[0] is Header new_body(new_body.size()-1) is Latch
    
    // change vars
    for(unsigned i=0; i<new_body.size(); ++i) {
        for (BasicBlock::iterator I = new_body[i]->begin(); I != new_body[i]->end(); ++I) {
            remapInstruction(I, LastValueMap);
        }
    }
    DEBUG(dbgs() << "Cloned loop's register name changed ok\n");

    // fix the phi node in cloned Loops Header  
    for (BasicBlock::iterator I = new_body[0]->begin(); isa<PHINode>(I); ++I) {
        PHINode *NewPHI = cast<PHINode>(I); 

        for (unsigned i=0; i<NewPHI->getNumIncomingValues(); ++i) {
            if (NewPHI->getIncomingBlock(i) == PreHeader) {
                NewPHI->setIncomingBlock(i, Header);
            }
        }
    }
    DEBUG(dbgs() << "Start working on exit block \n");
    // fix the phi node in original Loop's exit BB. Because the cloned loop points to it.
    for (BasicBlock::iterator I = Exit->begin(); isa<PHINode>(I); ++I) {
        PHINode *NewPHI = cast<PHINode>(I);

        for (unsigned i=0; i<NewPHI->getNumIncomingValues(); ++i) {
            if (NewPHI->getIncomingBlock(i) == Header) {
                NewPHI->setIncomingBlock(i, new_body[0]); // cloned loop's Header
            }
        }
        DEBUG(dbgs() << "Exit block, Done phi node: "<<  NewPHI << "\n");
    }

    DEBUG(dbgs() << "All Phi Node done \n");



    BranchInst *new_back_edge = cast<BranchInst>(new_body[new_body.size()-1]->getTerminator());   // Latch's last inst is branch
    new_back_edge->setSuccessor(0, new_body[0]); // Set to branch to new Cond (Header) 1st BB

    // link new loop body together
    for(unsigned i=0; i<new_body.size()-1; i++) {
        BranchInst *next = cast<BranchInst>(new_body[i]->getTerminator());   
        next->setSuccessor(0, new_body[i+1]);
    }

    // first cond exit points to second cond block
    BranchInst *first_loop_to_next_loop = cast<BranchInst>(Header->getTerminator());
    for(unsigned i=0; i< first_loop_to_next_loop->getNumSuccessors(); ++i) { 
        if (first_loop_to_next_loop->getSuccessor(i) == Exit) {
            first_loop_to_next_loop->setSuccessor(i, new_body[0]);
        }
    }

    Loop *new_loop = new Loop();

    for (unsigned i=0; i<new_body.size();i++) {
        new_loop->addBlockEntry(new_body[i]);
    }
    new_loop->moveToHeader(new_body[0]); // set Header for new loop 
//.........这里部分代码省略.........