llvm-6502/include/llvm/Analysis/LoopInfo.h

//===- llvm/Analysis/LoopInfo.h - Natural Loop Calculator -------*- C++ -*-===//
//
//                     The LLVM Compiler Infrastructure
//
// This file was developed by the LLVM research group and is distributed under
// the University of Illinois Open Source License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file defines the LoopInfo class that is used to identify natural loops
// and determine the loop depth of various nodes of the CFG.  Note that natural
// loops may actually be several loops that share the same header node.
//
// This analysis calculates the nesting structure of loops in a function.  For
// each natural loop identified, this analysis identifies natural loops
// contained entirely within the loop and the basic blocks the make up the loop.
//
// It can calculate on the fly various bits of information, for example:
//
//  * whether there is a preheader for the loop
//  * the number of back edges to the header
//  * whether or not a particular block branches out of the loop
//  * the successor blocks of the loop
//  * the loop depth
//  * the trip count
//  * etc...
//
//===----------------------------------------------------------------------===//

#ifndef LLVM_ANALYSIS_LOOP_INFO_H
#define LLVM_ANALYSIS_LOOP_INFO_H

#include "llvm/Pass.h"
#include "llvm/Constants.h"
#include "llvm/Instructions.h"
#include "llvm/ADT/GraphTraits.h"
#include "llvm/ADT/SmallPtrSet.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/Support/CFG.h"
#include "llvm/Support/Streams.h"
#include <algorithm>
#include <ostream>

template<typename T>
static void RemoveFromVector(std::vector<T*> &V, T *N) {
  typename std::vector<T*>::iterator I = std::find(V.begin(), V.end(), N);
  assert(I != V.end() && "N is not in this list!");
  V.erase(I);
}

namespace llvm {

class DominatorTree;
class LoopInfo;
class PHINode;
class Instruction;

//===----------------------------------------------------------------------===//
/// LoopBase class - Instances of this class are used to represent loops that are
/// detected in the flow graph
///
template<class BlockT>
class LoopBase {
  LoopBase<BlockT> *ParentLoop;
  std::vector<LoopBase<BlockT>*> SubLoops;       // Loops contained entirely within this one
  std::vector<BlockT*> Blocks;   // First entry is the header node

  LoopBase(const LoopBase<BlockT> &);                  // DO NOT IMPLEMENT
  const LoopBase<BlockT> &operator=(const LoopBase<BlockT> &); // DO NOT IMPLEMENT
public:
  /// Loop ctor - This creates an empty loop.
  LoopBase() : ParentLoop(0) {}
  ~LoopBase() {
    for (unsigned i = 0, e = SubLoops.size(); i != e; ++i)
      delete SubLoops[i];
  }

  unsigned getLoopDepth() const {
    unsigned D = 0;
    for (const LoopBase<BlockT> *CurLoop = this; CurLoop;
         CurLoop = CurLoop->ParentLoop)
      ++D;
    return D;
  }
  BlockT *getHeader() const { return Blocks.front(); }
  LoopBase<BlockT> *getParentLoop() const { return ParentLoop; }

  /// contains - Return true of the specified basic block is in this loop
  ///
  bool contains(const BlockT *BB) const {
    return std::find(Blocks.begin(), Blocks.end(), BB) != Blocks.end();
  }

  /// iterator/begin/end - Return the loops contained entirely within this loop.
  ///
  const std::vector<LoopBase<BlockT>*> &getSubLoops() const { return SubLoops; }
  typedef typename std::vector<LoopBase<BlockT>*>::const_iterator iterator;
  iterator begin() const { return SubLoops.begin(); }
  iterator end() const { return SubLoops.end(); }
  bool empty() const { return SubLoops.empty(); }

  /// getBlocks - Get a list of the basic blocks which make up this loop.
  ///
  const std::vector<BlockT*> &getBlocks() const { return Blocks; }
  typedef typename std::vector<BlockT*>::const_iterator block_iterator;
  block_iterator block_begin() const { return Blocks.begin(); }
  block_iterator block_end() const { return Blocks.end(); }

  /// isLoopExit - True if terminator in the block can branch to another block
  /// that is outside of the current loop.
  ///
  bool isLoopExit(const BlockT *BB) const {
    for (succ_const_iterator SI = succ_begin(BB), SE = succ_end(BB);
         SI != SE; ++SI) {
      if (!contains(*SI))
        return true;
    }
    return false;
  }

  /// getNumBackEdges - Calculate the number of back edges to the loop header
  ///
  unsigned getNumBackEdges() const {
    unsigned NumBackEdges = 0;
    BlockT *H = getHeader();

    for (pred_iterator I = pred_begin(H), E = pred_end(H); I != E; ++I)
      if (contains(*I))
        ++NumBackEdges;

    return NumBackEdges;
  }

  /// isLoopInvariant - Return true if the specified value is loop invariant
  ///
  bool isLoopInvariant(Value *V) const {
    if (Instruction *I = dyn_cast<Instruction>(V))
      return !contains(I->getParent());
    return true;  // All non-instructions are loop invariant
  }

  //===--------------------------------------------------------------------===//
  // APIs for simple analysis of the loop.
  //
  // Note that all of these methods can fail on general loops (ie, there may not
  // be a preheader, etc).  For best success, the loop simplification and
  // induction variable canonicalization pass should be used to normalize loops
  // for easy analysis.  These methods assume canonical loops.

  /// getExitingBlocks - Return all blocks inside the loop that have successors
  /// outside of the loop.  These are the blocks _inside of the current loop_
  /// which branch out.  The returned list is always unique.
  ///
  void getExitingBlocks(SmallVectorImpl<BlockT *> &ExitingBlocks) const {
    // Sort the blocks vector so that we can use binary search to do quick
    // lookups.
    SmallVector<BlockT*, 128> LoopBBs(block_begin(), block_end());
    std::sort(LoopBBs.begin(), LoopBBs.end());

    for (typename std::vector<BlockT*>::const_iterator BI = Blocks.begin(),
         BE = Blocks.end(); BI != BE; ++BI)
      for (succ_iterator I = succ_begin(*BI), E = succ_end(*BI); I != E; ++I)
        if (!std::binary_search(LoopBBs.begin(), LoopBBs.end(), *I)) {
          // Not in current loop? It must be an exit block.
          ExitingBlocks.push_back(*BI);
          break;
        }
  }

  /// getExitBlocks - Return all of the successor blocks of this loop.  These
  /// are the blocks _outside of the current loop_ which are branched to.
  ///
  void getExitBlocks(SmallVectorImpl<BlockT*> &ExitBlocks) const {
    // Sort the blocks vector so that we can use binary search to do quick
    // lookups.
    SmallVector<BlockT*, 128> LoopBBs(block_begin(), block_end());
    std::sort(LoopBBs.begin(), LoopBBs.end());

    for (typename std::vector<BlockT*>::const_iterator BI = Blocks.begin(),
         BE = Blocks.end(); BI != BE; ++BI)
      for (succ_iterator I = succ_begin(*BI), E = succ_end(*BI); I != E; ++I)
        if (!std::binary_search(LoopBBs.begin(), LoopBBs.end(), *I))
          // Not in current loop? It must be an exit block.
          ExitBlocks.push_back(*I);
  }

  /// getUniqueExitBlocks - Return all unique successor blocks of this loop. 
  /// These are the blocks _outside of the current loop_ which are branched to.
  /// This assumes that loop is in canonical form.
  ///
  void getUniqueExitBlocks(SmallVectorImpl<BlockT*> &ExitBlocks) const {
    // Sort the blocks vector so that we can use binary search to do quick
    // lookups.
    SmallVector<BlockT*, 128> LoopBBs(block_begin(), block_end());
    std::sort(LoopBBs.begin(), LoopBBs.end());

    std::vector<BlockT*> switchExitBlocks;  

    for (typename std::vector<BlockT*>::const_iterator BI = Blocks.begin(),
         BE = Blocks.end(); BI != BE; ++BI) {

      BlockT *current = *BI;
      switchExitBlocks.clear();

      for (succ_iterator I = succ_begin(*BI), E = succ_end(*BI); I != E; ++I) {
        if (std::binary_search(LoopBBs.begin(), LoopBBs.end(), *I))
      // If block is inside the loop then it is not a exit block.
          continue;

        pred_iterator PI = pred_begin(*I);
        BlockT *firstPred = *PI;

        // If current basic block is this exit block's first predecessor
        // then only insert exit block in to the output ExitBlocks vector.
        // This ensures that same exit block is not inserted twice into
        // ExitBlocks vector.
        if (current != firstPred) 
          continue;

        // If a terminator has more then two successors, for example SwitchInst,
        // then it is possible that there are multiple edges from current block 
        // to one exit block. 
        if (current->getTerminator()->getNumSuccessors() <= 2) {
          ExitBlocks.push_back(*I);
          continue;
        }

        // In case of multiple edges from current block to exit block, collect
        // only one edge in ExitBlocks. Use switchExitBlocks to keep track of
        // duplicate edges.
        if (std::find(switchExitBlocks.begin(), switchExitBlocks.end(), *I) 
            == switchExitBlocks.end()) {
          switchExitBlocks.push_back(*I);
          ExitBlocks.push_back(*I);
        }
      }
    }
  }

  /// getLoopPreheader - If there is a preheader for this loop, return it.  A
  /// loop has a preheader if there is only one edge to the header of the loop
  /// from outside of the loop.  If this is the case, the block branching to the
  /// header of the loop is the preheader node.
  ///
  /// This method returns null if there is no preheader for the loop.
  ///
  BlockT *getLoopPreheader() const {
    // Keep track of nodes outside the loop branching to the header...
    BlockT *Out = 0;

    // Loop over the predecessors of the header node...
    BlockT *Header = getHeader();
    for (pred_iterator PI = pred_begin(Header), PE = pred_end(Header);
         PI != PE; ++PI)
      if (!contains(*PI)) {     // If the block is not in the loop...
        if (Out && Out != *PI)
          return 0;             // Multiple predecessors outside the loop
        Out = *PI;
      }

    // Make sure there is only one exit out of the preheader.
    assert(Out && "Header of loop has no predecessors from outside loop?");
    succ_iterator SI = succ_begin(Out);
    ++SI;
    if (SI != succ_end(Out))
      return 0;  // Multiple exits from the block, must not be a preheader.

    // If there is exactly one preheader, return it.  If there was zero, then Out
    // is still null.
    return Out;
  }

  /// getLoopLatch - If there is a latch block for this loop, return it.  A
  /// latch block is the canonical backedge for a loop.  A loop header in normal
  /// form has two edges into it: one from a preheader and one from a latch
  /// block.
  BlockT *getLoopLatch() const {
    BlockT *Header = getHeader();
    pred_iterator PI = pred_begin(Header), PE = pred_end(Header);
    if (PI == PE) return 0;  // no preds?

    BlockT *Latch = 0;
    if (contains(*PI))
      Latch = *PI;
    ++PI;
    if (PI == PE) return 0;  // only one pred?

    if (contains(*PI)) {
      if (Latch) return 0;  // multiple backedges
      Latch = *PI;
    }
    ++PI;
    if (PI != PE) return 0;  // more than two preds

    return Latch;
  }
  
  /// getCanonicalInductionVariable - Check to see if the loop has a canonical
  /// induction variable: an integer recurrence that starts at 0 and increments
  /// by one each time through the loop.  If so, return the phi node that
  /// corresponds to it.
  ///
  PHINode *getCanonicalInductionVariable() const {
    BlockT *H = getHeader();

    BlockT *Incoming = 0, *Backedge = 0;
    pred_iterator PI = pred_begin(H);
    assert(PI != pred_end(H) && "Loop must have at least one backedge!");
    Backedge = *PI++;
    if (PI == pred_end(H)) return 0;  // dead loop
    Incoming = *PI++;
    if (PI != pred_end(H)) return 0;  // multiple backedges?

    if (contains(Incoming)) {
      if (contains(Backedge))
        return 0;
      std::swap(Incoming, Backedge);
    } else if (!contains(Backedge))
      return 0;

    // Loop over all of the PHI nodes, looking for a canonical indvar.
    for (typename BlockT::iterator I = H->begin(); isa<PHINode>(I); ++I) {
      PHINode *PN = cast<PHINode>(I);
      if (Instruction *Inc =
          dyn_cast<Instruction>(PN->getIncomingValueForBlock(Backedge)))
        if (Inc->getOpcode() == Instruction::Add && Inc->getOperand(0) == PN)
          if (ConstantInt *CI = dyn_cast<ConstantInt>(Inc->getOperand(1)))
            if (CI->equalsInt(1))
              return PN;
    }
    return 0;
  }

  /// getCanonicalInductionVariableIncrement - Return the LLVM value that holds
  /// the canonical induction variable value for the "next" iteration of the
  /// loop.  This always succeeds if getCanonicalInductionVariable succeeds.
  ///
  Instruction *getCanonicalInductionVariableIncrement() const {
    if (PHINode *PN = getCanonicalInductionVariable()) {
      bool P1InLoop = contains(PN->getIncomingBlock(1));
      return cast<Instruction>(PN->getIncomingValue(P1InLoop));
    }
    return 0;
  }

  /// getTripCount - Return a loop-invariant LLVM value indicating the number of
  /// times the loop will be executed.  Note that this means that the backedge
  /// of the loop executes N-1 times.  If the trip-count cannot be determined,
  /// this returns null.
  ///
  Value *getTripCount() const {
    // Canonical loops will end with a 'cmp ne I, V', where I is the incremented
    // canonical induction variable and V is the trip count of the loop.
    Instruction *Inc = getCanonicalInductionVariableIncrement();
    if (Inc == 0) return 0;
    PHINode *IV = cast<PHINode>(Inc->getOperand(0));

    BlockT *BackedgeBlock =
            IV->getIncomingBlock(contains(IV->getIncomingBlock(1)));

    if (BranchInst *BI = dyn_cast<BranchInst>(BackedgeBlock->getTerminator()))
      if (BI->isConditional()) {
        if (ICmpInst *ICI = dyn_cast<ICmpInst>(BI->getCondition())) {
          if (ICI->getOperand(0) == Inc)
            if (BI->getSuccessor(0) == getHeader()) {
              if (ICI->getPredicate() == ICmpInst::ICMP_NE)
                return ICI->getOperand(1);
            } else if (ICI->getPredicate() == ICmpInst::ICMP_EQ) {
              return ICI->getOperand(1);
            }
        }
      }

    return 0;
  }
  
  /// isLCSSAForm - Return true if the Loop is in LCSSA form
  bool isLCSSAForm() const {
    // Sort the blocks vector so that we can use binary search to do quick
    // lookups.
    SmallPtrSet<BlockT*, 16> LoopBBs(block_begin(), block_end());

    for (block_iterator BI = block_begin(), E = block_end(); BI != E; ++BI) {
      BlockT *BB = *BI;
      for (typename BlockT::iterator I = BB->begin(), E = BB->end(); I != E; ++I)
        for (Value::use_iterator UI = I->use_begin(), E = I->use_end(); UI != E;
             ++UI) {
          BlockT *UserBB = cast<Instruction>(*UI)->getParent();
          if (PHINode *P = dyn_cast<PHINode>(*UI)) {
            unsigned OperandNo = UI.getOperandNo();
            UserBB = P->getIncomingBlock(OperandNo/2);
          }

          // Check the current block, as a fast-path.  Most values are used in the
          // same block they are defined in.
          if (UserBB != BB && !LoopBBs.count(UserBB))
            return false;
        }
    }

    return true;
  }

  //===--------------------------------------------------------------------===//
  // APIs for updating loop information after changing the CFG
  //

  /// addBasicBlockToLoop - This method is used by other analyses to update loop
  /// information.  NewBB is set to be a new member of the current loop.
  /// Because of this, it is added as a member of all parent loops, and is added
  /// to the specified LoopInfo object as being in the current basic block.  It
  /// is not valid to replace the loop header with this method.
  ///
  void addBasicBlockToLoop(BlockT *NewBB, LoopInfo &LI);

  /// replaceChildLoopWith - This is used when splitting loops up.  It replaces
  /// the OldChild entry in our children list with NewChild, and updates the
  /// parent pointer of OldChild to be null and the NewChild to be this loop.
  /// This updates the loop depth of the new child.
  void replaceChildLoopWith(LoopBase<BlockT> *OldChild,
                            LoopBase<BlockT> *NewChild) {
    assert(OldChild->ParentLoop == this && "This loop is already broken!");
    assert(NewChild->ParentLoop == 0 && "NewChild already has a parent!");
    typename std::vector<LoopBase<BlockT>*>::iterator I =
                          std::find(SubLoops.begin(), SubLoops.end(), OldChild);
    assert(I != SubLoops.end() && "OldChild not in loop!");
    *I = NewChild;
    OldChild->ParentLoop = 0;
    NewChild->ParentLoop = this;
  }

  /// addChildLoop - Add the specified loop to be a child of this loop.  This
  /// updates the loop depth of the new child.
  ///
  void addChildLoop(LoopBase<BlockT> *NewChild) {
    assert(NewChild->ParentLoop == 0 && "NewChild already has a parent!");
    NewChild->ParentLoop = this;
    SubLoops.push_back(NewChild);
  }

  /// removeChildLoop - This removes the specified child from being a subloop of
  /// this loop.  The loop is not deleted, as it will presumably be inserted
  /// into another loop.
  LoopBase<BlockT> *removeChildLoop(iterator I) {
    assert(I != SubLoops.end() && "Cannot remove end iterator!");
    LoopBase<BlockT> *Child = *I;
    assert(Child->ParentLoop == this && "Child is not a child of this loop!");
    SubLoops.erase(SubLoops.begin()+(I-begin()));
    Child->ParentLoop = 0;
    return Child;
  }

  /// addBlockEntry - This adds a basic block directly to the basic block list.
  /// This should only be used by transformations that create new loops.  Other
  /// transformations should use addBasicBlockToLoop.
  void addBlockEntry(BlockT *BB) {
    Blocks.push_back(BB);
  }

  /// moveToHeader - This method is used to move BB (which must be part of this
  /// loop) to be the loop header of the loop (the block that dominates all
  /// others).
  void moveToHeader(BlockT *BB) {
    if (Blocks[0] == BB) return;
    for (unsigned i = 0; ; ++i) {
      assert(i != Blocks.size() && "Loop does not contain BB!");
      if (Blocks[i] == BB) {
        Blocks[i] = Blocks[0];
        Blocks[0] = BB;
        return;
      }
    }
  }

  /// removeBlockFromLoop - This removes the specified basic block from the
  /// current loop, updating the Blocks as appropriate.  This does not update
  /// the mapping in the LoopInfo class.
  void removeBlockFromLoop(BlockT *BB) {
    RemoveFromVector(Blocks, BB);
  }

  /// verifyLoop - Verify loop structure
  void verifyLoop() const {
#ifndef NDEBUG
    assert (getHeader() && "Loop header is missing");
    assert (getLoopPreheader() && "Loop preheader is missing");
    assert (getLoopLatch() && "Loop latch is missing");
    for (typename std::vector<LoopBase<BlockT>*>::const_iterator I =
         SubLoops.begin(), E = SubLoops.end(); I != E; ++I)
      (*I)->verifyLoop();
#endif
  }

  void print(std::ostream &OS, unsigned Depth = 0) const {
    OS << std::string(Depth*2, ' ') << "Loop Containing: ";

    for (unsigned i = 0; i < getBlocks().size(); ++i) {
      if (i) OS << ",";
      WriteAsOperand(OS, getBlocks()[i], false);
    }
    OS << "\n";

    for (iterator I = begin(), E = end(); I != E; ++I)
      (*I)->print(OS, Depth+2);
  }
  
  void print(std::ostream *O, unsigned Depth = 0) const {
    if (O) print(*O, Depth);
  }
  
  void dump() const {
    print(cerr);
  }
  
private:
  friend class LoopInfo;
  LoopBase(BlockT *BB) : ParentLoop(0) {
    Blocks.push_back(BB);
  }
};

typedef LoopBase<BasicBlock> Loop;


//===----------------------------------------------------------------------===//
/// LoopInfo - This class builds and contains all of the top level loop
/// structures in the specified function.
///
class LoopInfo : public FunctionPass {
  // BBMap - Mapping of basic blocks to the inner most loop they occur in
  std::map<BasicBlock*, Loop*> BBMap;
  std::vector<Loop*> TopLevelLoops;
  friend class LoopBase<BasicBlock>;
public:
  static char ID; // Pass identification, replacement for typeid

  LoopInfo() : FunctionPass(intptr_t(&ID)) {}
  ~LoopInfo() { releaseMemory(); }

  /// iterator/begin/end - The interface to the top-level loops in the current
  /// function.
  ///
  typedef std::vector<Loop*>::const_iterator iterator;
  iterator begin() const { return TopLevelLoops.begin(); }
  iterator end() const { return TopLevelLoops.end(); }

  /// getLoopFor - Return the inner most loop that BB lives in.  If a basic
  /// block is in no loop (for example the entry node), null is returned.
  ///
  Loop *getLoopFor(const BasicBlock *BB) const {
    std::map<BasicBlock *, Loop*>::const_iterator I=
      BBMap.find(const_cast<BasicBlock*>(BB));
    return I != BBMap.end() ? I->second : 0;
  }

  /// operator[] - same as getLoopFor...
  ///
  const Loop *operator[](const BasicBlock *BB) const {
    return getLoopFor(BB);
  }

  /// getLoopDepth - Return the loop nesting level of the specified block...
  ///
  unsigned getLoopDepth(const BasicBlock *BB) const {
    const Loop *L = getLoopFor(BB);
    return L ? L->getLoopDepth() : 0;
  }

  // isLoopHeader - True if the block is a loop header node
  bool isLoopHeader(BasicBlock *BB) const {
    const Loop *L = getLoopFor(BB);
    return L && L->getHeader() == BB;
  }

  /// runOnFunction - Calculate the natural loop information.
  ///
  virtual bool runOnFunction(Function &F);

  virtual void releaseMemory();

  void print(std::ostream &O, const Module* = 0) const;
  void print(std::ostream *O, const Module* M = 0) const {
    if (O) print(*O, M);
  }

  virtual void getAnalysisUsage(AnalysisUsage &AU) const;

  /// removeLoop - This removes the specified top-level loop from this loop info
  /// object.  The loop is not deleted, as it will presumably be inserted into
  /// another loop.
  Loop *removeLoop(iterator I);

  /// changeLoopFor - Change the top-level loop that contains BB to the
  /// specified loop.  This should be used by transformations that restructure
  /// the loop hierarchy tree.
  void changeLoopFor(BasicBlock *BB, Loop *L);

  /// changeTopLevelLoop - Replace the specified loop in the top-level loops
  /// list with the indicated loop.
  void changeTopLevelLoop(Loop *OldLoop, Loop *NewLoop);

  /// addTopLevelLoop - This adds the specified loop to the collection of
  /// top-level loops.
  void addTopLevelLoop(Loop *New) {
    assert(New->getParentLoop() == 0 && "Loop already in subloop!");
    TopLevelLoops.push_back(New);
  }

  /// removeBlock - This method completely removes BB from all data structures,
  /// including all of the Loop objects it is nested in and our mapping from
  /// BasicBlocks to loops.
  void removeBlock(BasicBlock *BB);

private:
  void Calculate(DominatorTree &DT);
  Loop *ConsiderForLoop(BasicBlock *BB, DominatorTree &DT);
  void MoveSiblingLoopInto(Loop *NewChild, Loop *NewParent);
  void InsertLoopInto(Loop *L, Loop *Parent);
};


// Allow clients to walk the list of nested loops...
template <> struct GraphTraits<const Loop*> {
  typedef const Loop NodeType;
  typedef std::vector<Loop*>::const_iterator ChildIteratorType;

  static NodeType *getEntryNode(const Loop *L) { return L; }
  static inline ChildIteratorType child_begin(NodeType *N) {
    return N->begin();
  }
  static inline ChildIteratorType child_end(NodeType *N) {
    return N->end();
  }
};

template <> struct GraphTraits<Loop*> {
  typedef Loop NodeType;
  typedef std::vector<Loop*>::const_iterator ChildIteratorType;

  static NodeType *getEntryNode(Loop *L) { return L; }
  static inline ChildIteratorType child_begin(NodeType *N) {
    return N->begin();
  }
  static inline ChildIteratorType child_end(NodeType *N) {
    return N->end();
  }
};

template<class BlockT>
void LoopBase<BlockT>::addBasicBlockToLoop(BlockT *NewBB, LoopInfo &LI) {
  assert((Blocks.empty() || LI[getHeader()] == this) &&
         "Incorrect LI specified for this loop!");
  assert(NewBB && "Cannot add a null basic block to the loop!");
  assert(LI[NewBB] == 0 && "BasicBlock already in the loop!");

  // Add the loop mapping to the LoopInfo object...
  LI.BBMap[NewBB] = this;

  // Add the basic block to this loop and all parent loops...
  LoopBase<BlockT> *L = this;
  while (L) {
    L->Blocks.push_back(NewBB);
    L = L->getParentLoop();
  }
}

} // End llvm namespace

// Make sure that any clients of this file link in LoopInfo.cpp
FORCE_DEFINING_FILE_TO_BE_LINKED(LoopInfo)

#endif