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      1 //===- llvm/Analysis/LoopInfoImpl.h - Natural Loop Calculator ---*- C++ -*-===//
      2 //
      3 //                     The LLVM Compiler Infrastructure
      4 //
      5 // This file is distributed under the University of Illinois Open Source
      6 // License. See LICENSE.TXT for details.
      7 //
      8 //===----------------------------------------------------------------------===//
      9 //
     10 // This is the generic implementation of LoopInfo used for both Loops and
     11 // MachineLoops.
     12 //
     13 //===----------------------------------------------------------------------===//
     14 
     15 #ifndef LLVM_ANALYSIS_LOOPINFOIMPL_H
     16 #define LLVM_ANALYSIS_LOOPINFOIMPL_H
     17 
     18 #include "llvm/ADT/DepthFirstIterator.h"
     19 #include "llvm/ADT/PostOrderIterator.h"
     20 #include "llvm/ADT/STLExtras.h"
     21 #include "llvm/Analysis/LoopInfo.h"
     22 #include "llvm/IR/Dominators.h"
     23 
     24 namespace llvm {
     25 
     26 //===----------------------------------------------------------------------===//
     27 // APIs for simple analysis of the loop. See header notes.
     28 
     29 /// getExitingBlocks - Return all blocks inside the loop that have successors
     30 /// outside of the loop.  These are the blocks _inside of the current loop_
     31 /// which branch out.  The returned list is always unique.
     32 ///
     33 template<class BlockT, class LoopT>
     34 void LoopBase<BlockT, LoopT>::
     35 getExitingBlocks(SmallVectorImpl<BlockT *> &ExitingBlocks) const {
     36   typedef GraphTraits<BlockT*> BlockTraits;
     37   for (block_iterator BI = block_begin(), BE = block_end(); BI != BE; ++BI)
     38     for (typename BlockTraits::ChildIteratorType I =
     39            BlockTraits::child_begin(*BI), E = BlockTraits::child_end(*BI);
     40          I != E; ++I)
     41       if (!contains(*I)) {
     42         // Not in current loop? It must be an exit block.
     43         ExitingBlocks.push_back(*BI);
     44         break;
     45       }
     46 }
     47 
     48 /// getExitingBlock - If getExitingBlocks would return exactly one block,
     49 /// return that block. Otherwise return null.
     50 template<class BlockT, class LoopT>
     51 BlockT *LoopBase<BlockT, LoopT>::getExitingBlock() const {
     52   SmallVector<BlockT*, 8> ExitingBlocks;
     53   getExitingBlocks(ExitingBlocks);
     54   if (ExitingBlocks.size() == 1)
     55     return ExitingBlocks[0];
     56   return nullptr;
     57 }
     58 
     59 /// getExitBlocks - Return all of the successor blocks of this loop.  These
     60 /// are the blocks _outside of the current loop_ which are branched to.
     61 ///
     62 template<class BlockT, class LoopT>
     63 void LoopBase<BlockT, LoopT>::
     64 getExitBlocks(SmallVectorImpl<BlockT*> &ExitBlocks) const {
     65   typedef GraphTraits<BlockT*> BlockTraits;
     66   for (block_iterator BI = block_begin(), BE = block_end(); BI != BE; ++BI)
     67     for (typename BlockTraits::ChildIteratorType I =
     68            BlockTraits::child_begin(*BI), E = BlockTraits::child_end(*BI);
     69          I != E; ++I)
     70       if (!contains(*I))
     71         // Not in current loop? It must be an exit block.
     72         ExitBlocks.push_back(*I);
     73 }
     74 
     75 /// getExitBlock - If getExitBlocks would return exactly one block,
     76 /// return that block. Otherwise return null.
     77 template<class BlockT, class LoopT>
     78 BlockT *LoopBase<BlockT, LoopT>::getExitBlock() const {
     79   SmallVector<BlockT*, 8> ExitBlocks;
     80   getExitBlocks(ExitBlocks);
     81   if (ExitBlocks.size() == 1)
     82     return ExitBlocks[0];
     83   return nullptr;
     84 }
     85 
     86 /// getExitEdges - Return all pairs of (_inside_block_,_outside_block_).
     87 template<class BlockT, class LoopT>
     88 void LoopBase<BlockT, LoopT>::
     89 getExitEdges(SmallVectorImpl<Edge> &ExitEdges) const {
     90   typedef GraphTraits<BlockT*> BlockTraits;
     91   for (block_iterator BI = block_begin(), BE = block_end(); BI != BE; ++BI)
     92     for (typename BlockTraits::ChildIteratorType I =
     93            BlockTraits::child_begin(*BI), E = BlockTraits::child_end(*BI);
     94          I != E; ++I)
     95       if (!contains(*I))
     96         // Not in current loop? It must be an exit block.
     97         ExitEdges.push_back(Edge(*BI, *I));
     98 }
     99 
    100 /// getLoopPreheader - If there is a preheader for this loop, return it.  A
    101 /// loop has a preheader if there is only one edge to the header of the loop
    102 /// from outside of the loop.  If this is the case, the block branching to the
    103 /// header of the loop is the preheader node.
    104 ///
    105 /// This method returns null if there is no preheader for the loop.
    106 ///
    107 template<class BlockT, class LoopT>
    108 BlockT *LoopBase<BlockT, LoopT>::getLoopPreheader() const {
    109   // Keep track of nodes outside the loop branching to the header...
    110   BlockT *Out = getLoopPredecessor();
    111   if (!Out) return nullptr;
    112 
    113   // Make sure there is only one exit out of the preheader.
    114   typedef GraphTraits<BlockT*> BlockTraits;
    115   typename BlockTraits::ChildIteratorType SI = BlockTraits::child_begin(Out);
    116   ++SI;
    117   if (SI != BlockTraits::child_end(Out))
    118     return nullptr;  // Multiple exits from the block, must not be a preheader.
    119 
    120   // The predecessor has exactly one successor, so it is a preheader.
    121   return Out;
    122 }
    123 
    124 /// getLoopPredecessor - If the given loop's header has exactly one unique
    125 /// predecessor outside the loop, return it. Otherwise return null.
    126 /// This is less strict that the loop "preheader" concept, which requires
    127 /// the predecessor to have exactly one successor.
    128 ///
    129 template<class BlockT, class LoopT>
    130 BlockT *LoopBase<BlockT, LoopT>::getLoopPredecessor() const {
    131   // Keep track of nodes outside the loop branching to the header...
    132   BlockT *Out = nullptr;
    133 
    134   // Loop over the predecessors of the header node...
    135   BlockT *Header = getHeader();
    136   typedef GraphTraits<Inverse<BlockT*> > InvBlockTraits;
    137   for (typename InvBlockTraits::ChildIteratorType PI =
    138          InvBlockTraits::child_begin(Header),
    139          PE = InvBlockTraits::child_end(Header); PI != PE; ++PI) {
    140     typename InvBlockTraits::NodeType *N = *PI;
    141     if (!contains(N)) {     // If the block is not in the loop...
    142       if (Out && Out != N)
    143         return nullptr;     // Multiple predecessors outside the loop
    144       Out = N;
    145     }
    146   }
    147 
    148   // Make sure there is only one exit out of the preheader.
    149   assert(Out && "Header of loop has no predecessors from outside loop?");
    150   return Out;
    151 }
    152 
    153 /// getLoopLatch - If there is a single latch block for this loop, return it.
    154 /// A latch block is a block that contains a branch back to the header.
    155 template<class BlockT, class LoopT>
    156 BlockT *LoopBase<BlockT, LoopT>::getLoopLatch() const {
    157   BlockT *Header = getHeader();
    158   typedef GraphTraits<Inverse<BlockT*> > InvBlockTraits;
    159   typename InvBlockTraits::ChildIteratorType PI =
    160     InvBlockTraits::child_begin(Header);
    161   typename InvBlockTraits::ChildIteratorType PE =
    162     InvBlockTraits::child_end(Header);
    163   BlockT *Latch = nullptr;
    164   for (; PI != PE; ++PI) {
    165     typename InvBlockTraits::NodeType *N = *PI;
    166     if (contains(N)) {
    167       if (Latch) return nullptr;
    168       Latch = N;
    169     }
    170   }
    171 
    172   return Latch;
    173 }
    174 
    175 //===----------------------------------------------------------------------===//
    176 // APIs for updating loop information after changing the CFG
    177 //
    178 
    179 /// addBasicBlockToLoop - This method is used by other analyses to update loop
    180 /// information.  NewBB is set to be a new member of the current loop.
    181 /// Because of this, it is added as a member of all parent loops, and is added
    182 /// to the specified LoopInfo object as being in the current basic block.  It
    183 /// is not valid to replace the loop header with this method.
    184 ///
    185 template<class BlockT, class LoopT>
    186 void LoopBase<BlockT, LoopT>::
    187 addBasicBlockToLoop(BlockT *NewBB, LoopInfoBase<BlockT, LoopT> &LIB) {
    188   assert((Blocks.empty() || LIB[getHeader()] == this) &&
    189          "Incorrect LI specified for this loop!");
    190   assert(NewBB && "Cannot add a null basic block to the loop!");
    191   assert(!LIB[NewBB] && "BasicBlock already in the loop!");
    192 
    193   LoopT *L = static_cast<LoopT *>(this);
    194 
    195   // Add the loop mapping to the LoopInfo object...
    196   LIB.BBMap[NewBB] = L;
    197 
    198   // Add the basic block to this loop and all parent loops...
    199   while (L) {
    200     L->addBlockEntry(NewBB);
    201     L = L->getParentLoop();
    202   }
    203 }
    204 
    205 /// replaceChildLoopWith - This is used when splitting loops up.  It replaces
    206 /// the OldChild entry in our children list with NewChild, and updates the
    207 /// parent pointer of OldChild to be null and the NewChild to be this loop.
    208 /// This updates the loop depth of the new child.
    209 template<class BlockT, class LoopT>
    210 void LoopBase<BlockT, LoopT>::
    211 replaceChildLoopWith(LoopT *OldChild, LoopT *NewChild) {
    212   assert(OldChild->ParentLoop == this && "This loop is already broken!");
    213   assert(!NewChild->ParentLoop && "NewChild already has a parent!");
    214   typename std::vector<LoopT *>::iterator I =
    215     std::find(SubLoops.begin(), SubLoops.end(), OldChild);
    216   assert(I != SubLoops.end() && "OldChild not in loop!");
    217   *I = NewChild;
    218   OldChild->ParentLoop = nullptr;
    219   NewChild->ParentLoop = static_cast<LoopT *>(this);
    220 }
    221 
    222 /// verifyLoop - Verify loop structure
    223 template<class BlockT, class LoopT>
    224 void LoopBase<BlockT, LoopT>::verifyLoop() const {
    225 #ifndef NDEBUG
    226   assert(!Blocks.empty() && "Loop header is missing");
    227 
    228   // Setup for using a depth-first iterator to visit every block in the loop.
    229   SmallVector<BlockT*, 8> ExitBBs;
    230   getExitBlocks(ExitBBs);
    231   llvm::SmallPtrSet<BlockT*, 8> VisitSet;
    232   VisitSet.insert(ExitBBs.begin(), ExitBBs.end());
    233   df_ext_iterator<BlockT*, llvm::SmallPtrSet<BlockT*, 8> >
    234     BI = df_ext_begin(getHeader(), VisitSet),
    235     BE = df_ext_end(getHeader(), VisitSet);
    236 
    237   // Keep track of the number of BBs visited.
    238   unsigned NumVisited = 0;
    239 
    240   // Check the individual blocks.
    241   for ( ; BI != BE; ++BI) {
    242     BlockT *BB = *BI;
    243     bool HasInsideLoopSuccs = false;
    244     bool HasInsideLoopPreds = false;
    245     SmallVector<BlockT *, 2> OutsideLoopPreds;
    246 
    247     typedef GraphTraits<BlockT*> BlockTraits;
    248     for (typename BlockTraits::ChildIteratorType SI =
    249            BlockTraits::child_begin(BB), SE = BlockTraits::child_end(BB);
    250          SI != SE; ++SI)
    251       if (contains(*SI)) {
    252         HasInsideLoopSuccs = true;
    253         break;
    254       }
    255     typedef GraphTraits<Inverse<BlockT*> > InvBlockTraits;
    256     for (typename InvBlockTraits::ChildIteratorType PI =
    257            InvBlockTraits::child_begin(BB), PE = InvBlockTraits::child_end(BB);
    258          PI != PE; ++PI) {
    259       BlockT *N = *PI;
    260       if (contains(N))
    261         HasInsideLoopPreds = true;
    262       else
    263         OutsideLoopPreds.push_back(N);
    264     }
    265 
    266     if (BB == getHeader()) {
    267         assert(!OutsideLoopPreds.empty() && "Loop is unreachable!");
    268     } else if (!OutsideLoopPreds.empty()) {
    269       // A non-header loop shouldn't be reachable from outside the loop,
    270       // though it is permitted if the predecessor is not itself actually
    271       // reachable.
    272       BlockT *EntryBB = &BB->getParent()->front();
    273       for (BlockT *CB : depth_first(EntryBB))
    274         for (unsigned i = 0, e = OutsideLoopPreds.size(); i != e; ++i)
    275           assert(CB != OutsideLoopPreds[i] &&
    276                  "Loop has multiple entry points!");
    277     }
    278     assert(HasInsideLoopPreds && "Loop block has no in-loop predecessors!");
    279     assert(HasInsideLoopSuccs && "Loop block has no in-loop successors!");
    280     assert(BB != getHeader()->getParent()->begin() &&
    281            "Loop contains function entry block!");
    282 
    283     NumVisited++;
    284   }
    285 
    286   assert(NumVisited == getNumBlocks() && "Unreachable block in loop");
    287 
    288   // Check the subloops.
    289   for (iterator I = begin(), E = end(); I != E; ++I)
    290     // Each block in each subloop should be contained within this loop.
    291     for (block_iterator BI = (*I)->block_begin(), BE = (*I)->block_end();
    292          BI != BE; ++BI) {
    293         assert(contains(*BI) &&
    294                "Loop does not contain all the blocks of a subloop!");
    295     }
    296 
    297   // Check the parent loop pointer.
    298   if (ParentLoop) {
    299     assert(std::find(ParentLoop->begin(), ParentLoop->end(), this) !=
    300            ParentLoop->end() &&
    301            "Loop is not a subloop of its parent!");
    302   }
    303 #endif
    304 }
    305 
    306 /// verifyLoop - Verify loop structure of this loop and all nested loops.
    307 template<class BlockT, class LoopT>
    308 void LoopBase<BlockT, LoopT>::verifyLoopNest(
    309   DenseSet<const LoopT*> *Loops) const {
    310   Loops->insert(static_cast<const LoopT *>(this));
    311   // Verify this loop.
    312   verifyLoop();
    313   // Verify the subloops.
    314   for (iterator I = begin(), E = end(); I != E; ++I)
    315     (*I)->verifyLoopNest(Loops);
    316 }
    317 
    318 template<class BlockT, class LoopT>
    319 void LoopBase<BlockT, LoopT>::print(raw_ostream &OS, unsigned Depth) const {
    320   OS.indent(Depth*2) << "Loop at depth " << getLoopDepth()
    321        << " containing: ";
    322 
    323   for (unsigned i = 0; i < getBlocks().size(); ++i) {
    324     if (i) OS << ",";
    325     BlockT *BB = getBlocks()[i];
    326     BB->printAsOperand(OS, false);
    327     if (BB == getHeader())    OS << "<header>";
    328     if (BB == getLoopLatch()) OS << "<latch>";
    329     if (isLoopExiting(BB))    OS << "<exiting>";
    330   }
    331   OS << "\n";
    332 
    333   for (iterator I = begin(), E = end(); I != E; ++I)
    334     (*I)->print(OS, Depth+2);
    335 }
    336 
    337 //===----------------------------------------------------------------------===//
    338 /// Stable LoopInfo Analysis - Build a loop tree using stable iterators so the
    339 /// result does / not depend on use list (block predecessor) order.
    340 ///
    341 
    342 /// Discover a subloop with the specified backedges such that: All blocks within
    343 /// this loop are mapped to this loop or a subloop. And all subloops within this
    344 /// loop have their parent loop set to this loop or a subloop.
    345 template<class BlockT, class LoopT>
    346 static void discoverAndMapSubloop(LoopT *L, ArrayRef<BlockT*> Backedges,
    347                                   LoopInfoBase<BlockT, LoopT> *LI,
    348                                   const DominatorTreeBase<BlockT> &DomTree) {
    349   typedef GraphTraits<Inverse<BlockT*> > InvBlockTraits;
    350 
    351   unsigned NumBlocks = 0;
    352   unsigned NumSubloops = 0;
    353 
    354   // Perform a backward CFG traversal using a worklist.
    355   std::vector<BlockT *> ReverseCFGWorklist(Backedges.begin(), Backedges.end());
    356   while (!ReverseCFGWorklist.empty()) {
    357     BlockT *PredBB = ReverseCFGWorklist.back();
    358     ReverseCFGWorklist.pop_back();
    359 
    360     LoopT *Subloop = LI->getLoopFor(PredBB);
    361     if (!Subloop) {
    362       if (!DomTree.isReachableFromEntry(PredBB))
    363         continue;
    364 
    365       // This is an undiscovered block. Map it to the current loop.
    366       LI->changeLoopFor(PredBB, L);
    367       ++NumBlocks;
    368       if (PredBB == L->getHeader())
    369           continue;
    370       // Push all block predecessors on the worklist.
    371       ReverseCFGWorklist.insert(ReverseCFGWorklist.end(),
    372                                 InvBlockTraits::child_begin(PredBB),
    373                                 InvBlockTraits::child_end(PredBB));
    374     }
    375     else {
    376       // This is a discovered block. Find its outermost discovered loop.
    377       while (LoopT *Parent = Subloop->getParentLoop())
    378         Subloop = Parent;
    379 
    380       // If it is already discovered to be a subloop of this loop, continue.
    381       if (Subloop == L)
    382         continue;
    383 
    384       // Discover a subloop of this loop.
    385       Subloop->setParentLoop(L);
    386       ++NumSubloops;
    387       NumBlocks += Subloop->getBlocks().capacity();
    388       PredBB = Subloop->getHeader();
    389       // Continue traversal along predecessors that are not loop-back edges from
    390       // within this subloop tree itself. Note that a predecessor may directly
    391       // reach another subloop that is not yet discovered to be a subloop of
    392       // this loop, which we must traverse.
    393       for (typename InvBlockTraits::ChildIteratorType PI =
    394              InvBlockTraits::child_begin(PredBB),
    395              PE = InvBlockTraits::child_end(PredBB); PI != PE; ++PI) {
    396         if (LI->getLoopFor(*PI) != Subloop)
    397           ReverseCFGWorklist.push_back(*PI);
    398       }
    399     }
    400   }
    401   L->getSubLoopsVector().reserve(NumSubloops);
    402   L->reserveBlocks(NumBlocks);
    403 }
    404 
    405 /// Populate all loop data in a stable order during a single forward DFS.
    406 template<class BlockT, class LoopT>
    407 class PopulateLoopsDFS {
    408   typedef GraphTraits<BlockT*> BlockTraits;
    409   typedef typename BlockTraits::ChildIteratorType SuccIterTy;
    410 
    411   LoopInfoBase<BlockT, LoopT> *LI;
    412 public:
    413   PopulateLoopsDFS(LoopInfoBase<BlockT, LoopT> *li):
    414     LI(li) {}
    415 
    416   void traverse(BlockT *EntryBlock);
    417 
    418 protected:
    419   void insertIntoLoop(BlockT *Block);
    420 };
    421 
    422 /// Top-level driver for the forward DFS within the loop.
    423 template<class BlockT, class LoopT>
    424 void PopulateLoopsDFS<BlockT, LoopT>::traverse(BlockT *EntryBlock) {
    425   for (BlockT *BB : post_order(EntryBlock))
    426     insertIntoLoop(BB);
    427 }
    428 
    429 /// Add a single Block to its ancestor loops in PostOrder. If the block is a
    430 /// subloop header, add the subloop to its parent in PostOrder, then reverse the
    431 /// Block and Subloop vectors of the now complete subloop to achieve RPO.
    432 template<class BlockT, class LoopT>
    433 void PopulateLoopsDFS<BlockT, LoopT>::insertIntoLoop(BlockT *Block) {
    434   LoopT *Subloop = LI->getLoopFor(Block);
    435   if (Subloop && Block == Subloop->getHeader()) {
    436     // We reach this point once per subloop after processing all the blocks in
    437     // the subloop.
    438     if (Subloop->getParentLoop())
    439       Subloop->getParentLoop()->getSubLoopsVector().push_back(Subloop);
    440     else
    441       LI->addTopLevelLoop(Subloop);
    442 
    443     // For convenience, Blocks and Subloops are inserted in postorder. Reverse
    444     // the lists, except for the loop header, which is always at the beginning.
    445     Subloop->reverseBlock(1);
    446     std::reverse(Subloop->getSubLoopsVector().begin(),
    447                  Subloop->getSubLoopsVector().end());
    448 
    449     Subloop = Subloop->getParentLoop();
    450   }
    451   for (; Subloop; Subloop = Subloop->getParentLoop())
    452     Subloop->addBlockEntry(Block);
    453 }
    454 
    455 /// Analyze LoopInfo discovers loops during a postorder DominatorTree traversal
    456 /// interleaved with backward CFG traversals within each subloop
    457 /// (discoverAndMapSubloop). The backward traversal skips inner subloops, so
    458 /// this part of the algorithm is linear in the number of CFG edges. Subloop and
    459 /// Block vectors are then populated during a single forward CFG traversal
    460 /// (PopulateLoopDFS).
    461 ///
    462 /// During the two CFG traversals each block is seen three times:
    463 /// 1) Discovered and mapped by a reverse CFG traversal.
    464 /// 2) Visited during a forward DFS CFG traversal.
    465 /// 3) Reverse-inserted in the loop in postorder following forward DFS.
    466 ///
    467 /// The Block vectors are inclusive, so step 3 requires loop-depth number of
    468 /// insertions per block.
    469 template<class BlockT, class LoopT>
    470 void LoopInfoBase<BlockT, LoopT>::
    471 analyze(const DominatorTreeBase<BlockT> &DomTree) {
    472 
    473   // Postorder traversal of the dominator tree.
    474   const DomTreeNodeBase<BlockT> *DomRoot = DomTree.getRootNode();
    475   for (auto DomNode : post_order(DomRoot)) {
    476 
    477     BlockT *Header = DomNode->getBlock();
    478     SmallVector<BlockT *, 4> Backedges;
    479 
    480     // Check each predecessor of the potential loop header.
    481     typedef GraphTraits<Inverse<BlockT*> > InvBlockTraits;
    482     for (typename InvBlockTraits::ChildIteratorType PI =
    483            InvBlockTraits::child_begin(Header),
    484            PE = InvBlockTraits::child_end(Header); PI != PE; ++PI) {
    485 
    486       BlockT *Backedge = *PI;
    487 
    488       // If Header dominates predBB, this is a new loop. Collect the backedges.
    489       if (DomTree.dominates(Header, Backedge)
    490           && DomTree.isReachableFromEntry(Backedge)) {
    491         Backedges.push_back(Backedge);
    492       }
    493     }
    494     // Perform a backward CFG traversal to discover and map blocks in this loop.
    495     if (!Backedges.empty()) {
    496       LoopT *L = new LoopT(Header);
    497       discoverAndMapSubloop(L, ArrayRef<BlockT*>(Backedges), this, DomTree);
    498     }
    499   }
    500   // Perform a single forward CFG traversal to populate block and subloop
    501   // vectors for all loops.
    502   PopulateLoopsDFS<BlockT, LoopT> DFS(this);
    503   DFS.traverse(DomRoot->getBlock());
    504 }
    505 
    506 // Debugging
    507 template<class BlockT, class LoopT>
    508 void LoopInfoBase<BlockT, LoopT>::print(raw_ostream &OS) const {
    509   for (unsigned i = 0; i < TopLevelLoops.size(); ++i)
    510     TopLevelLoops[i]->print(OS);
    511 #if 0
    512   for (DenseMap<BasicBlock*, LoopT*>::const_iterator I = BBMap.begin(),
    513          E = BBMap.end(); I != E; ++I)
    514     OS << "BB '" << I->first->getName() << "' level = "
    515        << I->second->getLoopDepth() << "\n";
    516 #endif
    517 }
    518 
    519 template<class BlockT, class LoopT>
    520 void LoopInfoBase<BlockT, LoopT>::verify() const {
    521   DenseSet<const LoopT*> Loops;
    522   for (iterator I = begin(), E = end(); I != E; ++I) {
    523     assert(!(*I)->getParentLoop() && "Top-level loop has a parent!");
    524     (*I)->verifyLoopNest(&Loops);
    525   }
    526 
    527   // Verify that blocks are mapped to valid loops.
    528 #ifndef NDEBUG
    529   for (auto &Entry : BBMap) {
    530     const BlockT *BB = Entry.first;
    531     LoopT *L = Entry.second;
    532     assert(Loops.count(L) && "orphaned loop");
    533     assert(L->contains(BB) && "orphaned block");
    534   }
    535 #endif
    536 }
    537 
    538 } // End llvm namespace
    539 
    540 #endif
    541