1 //===- llvm/Analysis/LoopInfo.h - Natural Loop Calculator -------*- C++ -*-===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file defines the LoopInfo class that is used to identify natural loops
11 // and determine the loop depth of various nodes of the CFG. A natural loop
12 // has exactly one entry-point, which is called the header. Note that natural
13 // loops may actually be several loops that share the same header node.
15 // This analysis calculates the nesting structure of loops in a function. For
16 // each natural loop identified, this analysis identifies natural loops
17 // contained entirely within the loop and the basic blocks the make up the loop.
19 // It can calculate on the fly various bits of information, for example:
21 // * whether there is a preheader for the loop
22 // * the number of back edges to the header
23 // * whether or not a particular block branches out of the loop
24 // * the successor blocks of the loop
28 //===----------------------------------------------------------------------===//
30 #ifndef LLVM_ANALYSIS_LOOP_INFO_H
31 #define LLVM_ANALYSIS_LOOP_INFO_H
33 #include "llvm/ADT/DenseMap.h"
34 #include "llvm/ADT/DenseSet.h"
35 #include "llvm/ADT/DepthFirstIterator.h"
36 #include "llvm/ADT/GraphTraits.h"
37 #include "llvm/ADT/STLExtras.h"
38 #include "llvm/ADT/SmallVector.h"
39 #include "llvm/Analysis/Dominators.h"
40 #include "llvm/Pass.h"
41 #include "llvm/Support/CFG.h"
42 #include "llvm/Support/raw_ostream.h"
49 inline void RemoveFromVector(std::vector<T*> &V, T *N) {
50 typename std::vector<T*>::iterator I = std::find(V.begin(), V.end(), N);
51 assert(I != V.end() && "N is not in this list!");
59 template<class N, class M> class LoopInfoBase;
60 template<class N, class M> class LoopBase;
62 //===----------------------------------------------------------------------===//
63 /// LoopBase class - Instances of this class are used to represent loops that
64 /// are detected in the flow graph
66 template<class BlockT, class LoopT>
69 // SubLoops - Loops contained entirely within this one.
70 std::vector<LoopT *> SubLoops;
72 // Blocks - The list of blocks in this loop. First entry is the header node.
73 std::vector<BlockT*> Blocks;
75 LoopBase(const LoopBase<BlockT, LoopT> &) LLVM_DELETED_FUNCTION;
76 const LoopBase<BlockT, LoopT>&
77 operator=(const LoopBase<BlockT, LoopT> &) LLVM_DELETED_FUNCTION;
79 /// Loop ctor - This creates an empty loop.
80 LoopBase() : ParentLoop(0) {}
82 for (size_t i = 0, e = SubLoops.size(); i != e; ++i)
86 /// getLoopDepth - Return the nesting level of this loop. An outer-most
87 /// loop has depth 1, for consistency with loop depth values used for basic
88 /// blocks, where depth 0 is used for blocks not inside any loops.
89 unsigned getLoopDepth() const {
91 for (const LoopT *CurLoop = ParentLoop; CurLoop;
92 CurLoop = CurLoop->ParentLoop)
96 BlockT *getHeader() const { return Blocks.front(); }
97 LoopT *getParentLoop() const { return ParentLoop; }
99 /// setParentLoop is a raw interface for bypassing addChildLoop.
100 void setParentLoop(LoopT *L) { ParentLoop = L; }
102 /// contains - Return true if the specified loop is contained within in
105 bool contains(const LoopT *L) const {
106 if (L == this) return true;
107 if (L == 0) return false;
108 return contains(L->getParentLoop());
111 /// contains - Return true if the specified basic block is in this loop.
113 bool contains(const BlockT *BB) const {
114 return std::find(block_begin(), block_end(), BB) != block_end();
117 /// contains - Return true if the specified instruction is in this loop.
119 template<class InstT>
120 bool contains(const InstT *Inst) const {
121 return contains(Inst->getParent());
124 /// iterator/begin/end - Return the loops contained entirely within this loop.
126 const std::vector<LoopT *> &getSubLoops() const { return SubLoops; }
127 std::vector<LoopT *> &getSubLoopsVector() { return SubLoops; }
128 typedef typename std::vector<LoopT *>::const_iterator iterator;
129 typedef typename std::vector<LoopT *>::const_reverse_iterator
131 iterator begin() const { return SubLoops.begin(); }
132 iterator end() const { return SubLoops.end(); }
133 reverse_iterator rbegin() const { return SubLoops.rbegin(); }
134 reverse_iterator rend() const { return SubLoops.rend(); }
135 bool empty() const { return SubLoops.empty(); }
137 /// getBlocks - Get a list of the basic blocks which make up this loop.
139 const std::vector<BlockT*> &getBlocks() const { return Blocks; }
140 std::vector<BlockT*> &getBlocksVector() { return Blocks; }
141 typedef typename std::vector<BlockT*>::const_iterator block_iterator;
142 block_iterator block_begin() const { return Blocks.begin(); }
143 block_iterator block_end() const { return Blocks.end(); }
145 /// getNumBlocks - Get the number of blocks in this loop in constant time.
146 unsigned getNumBlocks() const {
147 return Blocks.size();
150 /// isLoopExiting - True if terminator in the block can branch to another
151 /// block that is outside of the current loop.
153 bool isLoopExiting(const BlockT *BB) const {
154 typedef GraphTraits<BlockT*> BlockTraits;
155 for (typename BlockTraits::ChildIteratorType SI =
156 BlockTraits::child_begin(const_cast<BlockT*>(BB)),
157 SE = BlockTraits::child_end(const_cast<BlockT*>(BB)); SI != SE; ++SI) {
164 /// getNumBackEdges - Calculate the number of back edges to the loop header
166 unsigned getNumBackEdges() const {
167 unsigned NumBackEdges = 0;
168 BlockT *H = getHeader();
170 typedef GraphTraits<Inverse<BlockT*> > InvBlockTraits;
171 for (typename InvBlockTraits::ChildIteratorType I =
172 InvBlockTraits::child_begin(const_cast<BlockT*>(H)),
173 E = InvBlockTraits::child_end(const_cast<BlockT*>(H)); I != E; ++I)
180 //===--------------------------------------------------------------------===//
181 // APIs for simple analysis of the loop.
183 // Note that all of these methods can fail on general loops (ie, there may not
184 // be a preheader, etc). For best success, the loop simplification and
185 // induction variable canonicalization pass should be used to normalize loops
186 // for easy analysis. These methods assume canonical loops.
188 /// getExitingBlocks - Return all blocks inside the loop that have successors
189 /// outside of the loop. These are the blocks _inside of the current loop_
190 /// which branch out. The returned list is always unique.
192 void getExitingBlocks(SmallVectorImpl<BlockT *> &ExitingBlocks) const;
194 /// getExitingBlock - If getExitingBlocks would return exactly one block,
195 /// return that block. Otherwise return null.
196 BlockT *getExitingBlock() const;
198 /// getExitBlocks - Return all of the successor blocks of this loop. These
199 /// are the blocks _outside of the current loop_ which are branched to.
201 void getExitBlocks(SmallVectorImpl<BlockT*> &ExitBlocks) const;
203 /// getExitBlock - If getExitBlocks would return exactly one block,
204 /// return that block. Otherwise return null.
205 BlockT *getExitBlock() const;
208 typedef std::pair<const BlockT*, const BlockT*> Edge;
210 /// getExitEdges - Return all pairs of (_inside_block_,_outside_block_).
211 void getExitEdges(SmallVectorImpl<Edge> &ExitEdges) const;
213 /// getLoopPreheader - If there is a preheader for this loop, return it. A
214 /// loop has a preheader if there is only one edge to the header of the loop
215 /// from outside of the loop. If this is the case, the block branching to the
216 /// header of the loop is the preheader node.
218 /// This method returns null if there is no preheader for the loop.
220 BlockT *getLoopPreheader() const;
222 /// getLoopPredecessor - If the given loop's header has exactly one unique
223 /// predecessor outside the loop, return it. Otherwise return null.
224 /// This is less strict that the loop "preheader" concept, which requires
225 /// the predecessor to have exactly one successor.
227 BlockT *getLoopPredecessor() const;
229 /// getLoopLatch - If there is a single latch block for this loop, return it.
230 /// A latch block is a block that contains a branch back to the header.
231 BlockT *getLoopLatch() const;
233 //===--------------------------------------------------------------------===//
234 // APIs for updating loop information after changing the CFG
237 /// addBasicBlockToLoop - This method is used by other analyses to update loop
238 /// information. NewBB is set to be a new member of the current loop.
239 /// Because of this, it is added as a member of all parent loops, and is added
240 /// to the specified LoopInfo object as being in the current basic block. It
241 /// is not valid to replace the loop header with this method.
243 void addBasicBlockToLoop(BlockT *NewBB, LoopInfoBase<BlockT, LoopT> &LI);
245 /// replaceChildLoopWith - This is used when splitting loops up. It replaces
246 /// the OldChild entry in our children list with NewChild, and updates the
247 /// parent pointer of OldChild to be null and the NewChild to be this loop.
248 /// This updates the loop depth of the new child.
249 void replaceChildLoopWith(LoopT *OldChild, LoopT *NewChild);
251 /// addChildLoop - Add the specified loop to be a child of this loop. This
252 /// updates the loop depth of the new child.
254 void addChildLoop(LoopT *NewChild) {
255 assert(NewChild->ParentLoop == 0 && "NewChild already has a parent!");
256 NewChild->ParentLoop = static_cast<LoopT *>(this);
257 SubLoops.push_back(NewChild);
260 /// removeChildLoop - This removes the specified child from being a subloop of
261 /// this loop. The loop is not deleted, as it will presumably be inserted
262 /// into another loop.
263 LoopT *removeChildLoop(iterator I) {
264 assert(I != SubLoops.end() && "Cannot remove end iterator!");
266 assert(Child->ParentLoop == this && "Child is not a child of this loop!");
267 SubLoops.erase(SubLoops.begin()+(I-begin()));
268 Child->ParentLoop = 0;
272 /// addBlockEntry - This adds a basic block directly to the basic block list.
273 /// This should only be used by transformations that create new loops. Other
274 /// transformations should use addBasicBlockToLoop.
275 void addBlockEntry(BlockT *BB) {
276 Blocks.push_back(BB);
279 /// moveToHeader - This method is used to move BB (which must be part of this
280 /// loop) to be the loop header of the loop (the block that dominates all
282 void moveToHeader(BlockT *BB) {
283 if (Blocks[0] == BB) return;
284 for (unsigned i = 0; ; ++i) {
285 assert(i != Blocks.size() && "Loop does not contain BB!");
286 if (Blocks[i] == BB) {
287 Blocks[i] = Blocks[0];
294 /// removeBlockFromLoop - This removes the specified basic block from the
295 /// current loop, updating the Blocks as appropriate. This does not update
296 /// the mapping in the LoopInfo class.
297 void removeBlockFromLoop(BlockT *BB) {
298 RemoveFromVector(Blocks, BB);
301 /// verifyLoop - Verify loop structure
302 void verifyLoop() const;
304 /// verifyLoop - Verify loop structure of this loop and all nested loops.
305 void verifyLoopNest(DenseSet<const LoopT*> *Loops) const;
307 void print(raw_ostream &OS, unsigned Depth = 0) const;
310 friend class LoopInfoBase<BlockT, LoopT>;
311 explicit LoopBase(BlockT *BB) : ParentLoop(0) {
312 Blocks.push_back(BB);
316 template<class BlockT, class LoopT>
317 raw_ostream& operator<<(raw_ostream &OS, const LoopBase<BlockT, LoopT> &Loop) {
322 // Implementation in LoopInfoImpl.h
324 __extension__ extern template class LoopBase<BasicBlock, Loop>;
327 class Loop : public LoopBase<BasicBlock, Loop> {
331 /// isLoopInvariant - Return true if the specified value is loop invariant
333 bool isLoopInvariant(Value *V) const;
335 /// hasLoopInvariantOperands - Return true if all the operands of the
336 /// specified instruction are loop invariant.
337 bool hasLoopInvariantOperands(Instruction *I) const;
339 /// makeLoopInvariant - If the given value is an instruction inside of the
340 /// loop and it can be hoisted, do so to make it trivially loop-invariant.
341 /// Return true if the value after any hoisting is loop invariant. This
342 /// function can be used as a slightly more aggressive replacement for
345 /// If InsertPt is specified, it is the point to hoist instructions to.
346 /// If null, the terminator of the loop preheader is used.
348 bool makeLoopInvariant(Value *V, bool &Changed,
349 Instruction *InsertPt = 0) const;
351 /// makeLoopInvariant - If the given instruction is inside of the
352 /// loop and it can be hoisted, do so to make it trivially loop-invariant.
353 /// Return true if the instruction after any hoisting is loop invariant. This
354 /// function can be used as a slightly more aggressive replacement for
357 /// If InsertPt is specified, it is the point to hoist instructions to.
358 /// If null, the terminator of the loop preheader is used.
360 bool makeLoopInvariant(Instruction *I, bool &Changed,
361 Instruction *InsertPt = 0) const;
363 /// getCanonicalInductionVariable - Check to see if the loop has a canonical
364 /// induction variable: an integer recurrence that starts at 0 and increments
365 /// by one each time through the loop. If so, return the phi node that
366 /// corresponds to it.
368 /// The IndVarSimplify pass transforms loops to have a canonical induction
371 PHINode *getCanonicalInductionVariable() const;
373 /// isLCSSAForm - Return true if the Loop is in LCSSA form
374 bool isLCSSAForm(DominatorTree &DT) const;
376 /// isLoopSimplifyForm - Return true if the Loop is in the form that
377 /// the LoopSimplify form transforms loops to, which is sometimes called
379 bool isLoopSimplifyForm() const;
381 /// isSafeToClone - Return true if the loop body is safe to clone in practice.
382 bool isSafeToClone() const;
384 /// hasDedicatedExits - Return true if no exit block for the loop
385 /// has a predecessor that is outside the loop.
386 bool hasDedicatedExits() const;
388 /// getUniqueExitBlocks - Return all unique successor blocks of this loop.
389 /// These are the blocks _outside of the current loop_ which are branched to.
390 /// This assumes that loop exits are in canonical form.
392 void getUniqueExitBlocks(SmallVectorImpl<BasicBlock *> &ExitBlocks) const;
394 /// getUniqueExitBlock - If getUniqueExitBlocks would return exactly one
395 /// block, return that block. Otherwise return null.
396 BasicBlock *getUniqueExitBlock() const;
401 friend class LoopInfoBase<BasicBlock, Loop>;
402 explicit Loop(BasicBlock *BB) : LoopBase<BasicBlock, Loop>(BB) {}
405 //===----------------------------------------------------------------------===//
406 /// LoopInfo - This class builds and contains all of the top level loop
407 /// structures in the specified function.
410 template<class BlockT, class LoopT>
412 // BBMap - Mapping of basic blocks to the inner most loop they occur in
413 DenseMap<BlockT *, LoopT *> BBMap;
414 std::vector<LoopT *> TopLevelLoops;
415 friend class LoopBase<BlockT, LoopT>;
416 friend class LoopInfo;
418 void operator=(const LoopInfoBase &) LLVM_DELETED_FUNCTION;
419 LoopInfoBase(const LoopInfo &) LLVM_DELETED_FUNCTION;
422 ~LoopInfoBase() { releaseMemory(); }
424 void releaseMemory() {
425 for (typename std::vector<LoopT *>::iterator I =
426 TopLevelLoops.begin(), E = TopLevelLoops.end(); I != E; ++I)
427 delete *I; // Delete all of the loops...
429 BBMap.clear(); // Reset internal state of analysis
430 TopLevelLoops.clear();
433 /// iterator/begin/end - The interface to the top-level loops in the current
436 typedef typename std::vector<LoopT *>::const_iterator iterator;
437 typedef typename std::vector<LoopT *>::const_reverse_iterator
439 iterator begin() const { return TopLevelLoops.begin(); }
440 iterator end() const { return TopLevelLoops.end(); }
441 reverse_iterator rbegin() const { return TopLevelLoops.rbegin(); }
442 reverse_iterator rend() const { return TopLevelLoops.rend(); }
443 bool empty() const { return TopLevelLoops.empty(); }
445 /// getLoopFor - Return the inner most loop that BB lives in. If a basic
446 /// block is in no loop (for example the entry node), null is returned.
448 LoopT *getLoopFor(const BlockT *BB) const {
449 return BBMap.lookup(const_cast<BlockT*>(BB));
452 /// operator[] - same as getLoopFor...
454 const LoopT *operator[](const BlockT *BB) const {
455 return getLoopFor(BB);
458 /// getLoopDepth - Return the loop nesting level of the specified block. A
459 /// depth of 0 means the block is not inside any loop.
461 unsigned getLoopDepth(const BlockT *BB) const {
462 const LoopT *L = getLoopFor(BB);
463 return L ? L->getLoopDepth() : 0;
466 // isLoopHeader - True if the block is a loop header node
467 bool isLoopHeader(BlockT *BB) const {
468 const LoopT *L = getLoopFor(BB);
469 return L && L->getHeader() == BB;
472 /// removeLoop - This removes the specified top-level loop from this loop info
473 /// object. The loop is not deleted, as it will presumably be inserted into
475 LoopT *removeLoop(iterator I) {
476 assert(I != end() && "Cannot remove end iterator!");
478 assert(L->getParentLoop() == 0 && "Not a top-level loop!");
479 TopLevelLoops.erase(TopLevelLoops.begin() + (I-begin()));
483 /// changeLoopFor - Change the top-level loop that contains BB to the
484 /// specified loop. This should be used by transformations that restructure
485 /// the loop hierarchy tree.
486 void changeLoopFor(BlockT *BB, LoopT *L) {
494 /// changeTopLevelLoop - Replace the specified loop in the top-level loops
495 /// list with the indicated loop.
496 void changeTopLevelLoop(LoopT *OldLoop,
498 typename std::vector<LoopT *>::iterator I =
499 std::find(TopLevelLoops.begin(), TopLevelLoops.end(), OldLoop);
500 assert(I != TopLevelLoops.end() && "Old loop not at top level!");
502 assert(NewLoop->ParentLoop == 0 && OldLoop->ParentLoop == 0 &&
503 "Loops already embedded into a subloop!");
506 /// addTopLevelLoop - This adds the specified loop to the collection of
508 void addTopLevelLoop(LoopT *New) {
509 assert(New->getParentLoop() == 0 && "Loop already in subloop!");
510 TopLevelLoops.push_back(New);
513 /// removeBlock - This method completely removes BB from all data structures,
514 /// including all of the Loop objects it is nested in and our mapping from
515 /// BasicBlocks to loops.
516 void removeBlock(BlockT *BB) {
517 typename DenseMap<BlockT *, LoopT *>::iterator I = BBMap.find(BB);
518 if (I != BBMap.end()) {
519 for (LoopT *L = I->second; L; L = L->getParentLoop())
520 L->removeBlockFromLoop(BB);
528 static bool isNotAlreadyContainedIn(const LoopT *SubLoop,
529 const LoopT *ParentLoop) {
530 if (SubLoop == 0) return true;
531 if (SubLoop == ParentLoop) return false;
532 return isNotAlreadyContainedIn(SubLoop->getParentLoop(), ParentLoop);
535 /// Create the loop forest using a stable algorithm.
536 void Analyze(DominatorTreeBase<BlockT> &DomTree);
540 void print(raw_ostream &OS) const;
543 // Implementation in LoopInfoImpl.h
545 __extension__ extern template class LoopInfoBase<BasicBlock, Loop>;
548 class LoopInfo : public FunctionPass {
549 LoopInfoBase<BasicBlock, Loop> LI;
550 friend class LoopBase<BasicBlock, Loop>;
552 void operator=(const LoopInfo &) LLVM_DELETED_FUNCTION;
553 LoopInfo(const LoopInfo &) LLVM_DELETED_FUNCTION;
555 static char ID; // Pass identification, replacement for typeid
557 LoopInfo() : FunctionPass(ID) {
558 initializeLoopInfoPass(*PassRegistry::getPassRegistry());
561 LoopInfoBase<BasicBlock, Loop>& getBase() { return LI; }
563 /// iterator/begin/end - The interface to the top-level loops in the current
566 typedef LoopInfoBase<BasicBlock, Loop>::iterator iterator;
567 typedef LoopInfoBase<BasicBlock, Loop>::reverse_iterator reverse_iterator;
568 inline iterator begin() const { return LI.begin(); }
569 inline iterator end() const { return LI.end(); }
570 inline reverse_iterator rbegin() const { return LI.rbegin(); }
571 inline reverse_iterator rend() const { return LI.rend(); }
572 bool empty() const { return LI.empty(); }
574 /// getLoopFor - Return the inner most loop that BB lives in. If a basic
575 /// block is in no loop (for example the entry node), null is returned.
577 inline Loop *getLoopFor(const BasicBlock *BB) const {
578 return LI.getLoopFor(BB);
581 /// operator[] - same as getLoopFor...
583 inline const Loop *operator[](const BasicBlock *BB) const {
584 return LI.getLoopFor(BB);
587 /// getLoopDepth - Return the loop nesting level of the specified block. A
588 /// depth of 0 means the block is not inside any loop.
590 inline unsigned getLoopDepth(const BasicBlock *BB) const {
591 return LI.getLoopDepth(BB);
594 // isLoopHeader - True if the block is a loop header node
595 inline bool isLoopHeader(BasicBlock *BB) const {
596 return LI.isLoopHeader(BB);
599 /// runOnFunction - Calculate the natural loop information.
601 virtual bool runOnFunction(Function &F);
603 virtual void verifyAnalysis() const;
605 virtual void releaseMemory() { LI.releaseMemory(); }
607 virtual void print(raw_ostream &O, const Module* M = 0) const;
609 virtual void getAnalysisUsage(AnalysisUsage &AU) const;
611 /// removeLoop - This removes the specified top-level loop from this loop info
612 /// object. The loop is not deleted, as it will presumably be inserted into
614 inline Loop *removeLoop(iterator I) { return LI.removeLoop(I); }
616 /// changeLoopFor - Change the top-level loop that contains BB to the
617 /// specified loop. This should be used by transformations that restructure
618 /// the loop hierarchy tree.
619 inline void changeLoopFor(BasicBlock *BB, Loop *L) {
620 LI.changeLoopFor(BB, L);
623 /// changeTopLevelLoop - Replace the specified loop in the top-level loops
624 /// list with the indicated loop.
625 inline void changeTopLevelLoop(Loop *OldLoop, Loop *NewLoop) {
626 LI.changeTopLevelLoop(OldLoop, NewLoop);
629 /// addTopLevelLoop - This adds the specified loop to the collection of
631 inline void addTopLevelLoop(Loop *New) {
632 LI.addTopLevelLoop(New);
635 /// removeBlock - This method completely removes BB from all data structures,
636 /// including all of the Loop objects it is nested in and our mapping from
637 /// BasicBlocks to loops.
638 void removeBlock(BasicBlock *BB) {
642 /// updateUnloop - Update LoopInfo after removing the last backedge from a
643 /// loop--now the "unloop". This updates the loop forest and parent loops for
644 /// each block so that Unloop is no longer referenced, but the caller must
645 /// actually delete the Unloop object.
646 void updateUnloop(Loop *Unloop);
648 /// replacementPreservesLCSSAForm - Returns true if replacing From with To
649 /// everywhere is guaranteed to preserve LCSSA form.
650 bool replacementPreservesLCSSAForm(Instruction *From, Value *To) {
651 // Preserving LCSSA form is only problematic if the replacing value is an
653 Instruction *I = dyn_cast<Instruction>(To);
655 // If both instructions are defined in the same basic block then replacement
656 // cannot break LCSSA form.
657 if (I->getParent() == From->getParent())
659 // If the instruction is not defined in a loop then it can safely replace
661 Loop *ToLoop = getLoopFor(I->getParent());
662 if (!ToLoop) return true;
663 // If the replacing instruction is defined in the same loop as the original
664 // instruction, or in a loop that contains it as an inner loop, then using
665 // it as a replacement will not break LCSSA form.
666 return ToLoop->contains(getLoopFor(From->getParent()));
671 // Allow clients to walk the list of nested loops...
672 template <> struct GraphTraits<const Loop*> {
673 typedef const Loop NodeType;
674 typedef LoopInfo::iterator ChildIteratorType;
676 static NodeType *getEntryNode(const Loop *L) { return L; }
677 static inline ChildIteratorType child_begin(NodeType *N) {
680 static inline ChildIteratorType child_end(NodeType *N) {
685 template <> struct GraphTraits<Loop*> {
686 typedef Loop NodeType;
687 typedef LoopInfo::iterator ChildIteratorType;
689 static NodeType *getEntryNode(Loop *L) { return L; }
690 static inline ChildIteratorType child_begin(NodeType *N) {
693 static inline ChildIteratorType child_end(NodeType *N) {
698 } // End llvm namespace