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_LOOPINFO_H
31 #define LLVM_ANALYSIS_LOOPINFO_H
33 #include "llvm/ADT/DenseMap.h"
34 #include "llvm/ADT/DenseSet.h"
35 #include "llvm/ADT/GraphTraits.h"
36 #include "llvm/ADT/SmallPtrSet.h"
37 #include "llvm/ADT/SmallVector.h"
38 #include "llvm/IR/CFG.h"
39 #include "llvm/IR/Instruction.h"
40 #include "llvm/Pass.h"
45 // FIXME: Replace this brittle forward declaration with the include of the new
46 // PassManager.h when doing so doesn't break the PassManagerBuilder.
47 template <typename IRUnitT> class AnalysisManager;
48 class PreservedAnalyses;
51 inline void RemoveFromVector(std::vector<T*> &V, T *N) {
52 typename std::vector<T*>::iterator I = std::find(V.begin(), V.end(), N);
53 assert(I != V.end() && "N is not in this list!");
63 template<class N> class DominatorTreeBase;
64 template<class N, class M> class LoopInfoBase;
65 template<class N, class M> class LoopBase;
67 //===----------------------------------------------------------------------===//
68 /// LoopBase class - Instances of this class are used to represent loops that
69 /// are detected in the flow graph
71 template<class BlockT, class LoopT>
74 // SubLoops - Loops contained entirely within this one.
75 std::vector<LoopT *> SubLoops;
77 // Blocks - The list of blocks in this loop. First entry is the header node.
78 std::vector<BlockT*> Blocks;
80 SmallPtrSet<const BlockT*, 8> DenseBlockSet;
82 LoopBase(const LoopBase<BlockT, LoopT> &) = delete;
83 const LoopBase<BlockT, LoopT>&
84 operator=(const LoopBase<BlockT, LoopT> &) = delete;
86 /// Loop ctor - This creates an empty loop.
87 LoopBase() : ParentLoop(nullptr) {}
89 for (size_t i = 0, e = SubLoops.size(); i != e; ++i)
93 /// getLoopDepth - Return the nesting level of this loop. An outer-most
94 /// loop has depth 1, for consistency with loop depth values used for basic
95 /// blocks, where depth 0 is used for blocks not inside any loops.
96 unsigned getLoopDepth() const {
98 for (const LoopT *CurLoop = ParentLoop; CurLoop;
99 CurLoop = CurLoop->ParentLoop)
103 BlockT *getHeader() const { return Blocks.front(); }
104 LoopT *getParentLoop() const { return ParentLoop; }
106 /// setParentLoop is a raw interface for bypassing addChildLoop.
107 void setParentLoop(LoopT *L) { ParentLoop = L; }
109 /// contains - Return true if the specified loop is contained within in
112 bool contains(const LoopT *L) const {
113 if (L == this) return true;
114 if (!L) return false;
115 return contains(L->getParentLoop());
118 /// contains - Return true if the specified basic block is in this loop.
120 bool contains(const BlockT *BB) const {
121 return DenseBlockSet.count(BB);
124 /// contains - Return true if the specified instruction is in this loop.
126 template<class InstT>
127 bool contains(const InstT *Inst) const {
128 return contains(Inst->getParent());
131 /// iterator/begin/end - Return the loops contained entirely within this loop.
133 const std::vector<LoopT *> &getSubLoops() const { return SubLoops; }
134 std::vector<LoopT *> &getSubLoopsVector() { return SubLoops; }
135 typedef typename std::vector<LoopT *>::const_iterator iterator;
136 typedef typename std::vector<LoopT *>::const_reverse_iterator
138 iterator begin() const { return SubLoops.begin(); }
139 iterator end() const { return SubLoops.end(); }
140 reverse_iterator rbegin() const { return SubLoops.rbegin(); }
141 reverse_iterator rend() const { return SubLoops.rend(); }
142 bool empty() const { return SubLoops.empty(); }
144 /// getBlocks - Get a list of the basic blocks which make up this loop.
146 const std::vector<BlockT*> &getBlocks() const { return Blocks; }
147 typedef typename std::vector<BlockT*>::const_iterator block_iterator;
148 block_iterator block_begin() const { return Blocks.begin(); }
149 block_iterator block_end() const { return Blocks.end(); }
151 /// getNumBlocks - Get the number of blocks in this loop in constant time.
152 unsigned getNumBlocks() const {
153 return Blocks.size();
156 /// isLoopExiting - True if terminator in the block can branch to another
157 /// block that is outside of the current loop.
159 bool isLoopExiting(const BlockT *BB) const {
160 typedef GraphTraits<const BlockT*> BlockTraits;
161 for (typename BlockTraits::ChildIteratorType SI =
162 BlockTraits::child_begin(BB),
163 SE = BlockTraits::child_end(BB); SI != SE; ++SI) {
170 /// getNumBackEdges - Calculate the number of back edges to the loop header
172 unsigned getNumBackEdges() const {
173 unsigned NumBackEdges = 0;
174 BlockT *H = getHeader();
176 typedef GraphTraits<Inverse<BlockT*> > InvBlockTraits;
177 for (typename InvBlockTraits::ChildIteratorType I =
178 InvBlockTraits::child_begin(H),
179 E = InvBlockTraits::child_end(H); I != E; ++I)
186 //===--------------------------------------------------------------------===//
187 // APIs for simple analysis of the loop.
189 // Note that all of these methods can fail on general loops (ie, there may not
190 // be a preheader, etc). For best success, the loop simplification and
191 // induction variable canonicalization pass should be used to normalize loops
192 // for easy analysis. These methods assume canonical loops.
194 /// getExitingBlocks - Return all blocks inside the loop that have successors
195 /// outside of the loop. These are the blocks _inside of the current loop_
196 /// which branch out. The returned list is always unique.
198 void getExitingBlocks(SmallVectorImpl<BlockT *> &ExitingBlocks) const;
200 /// getExitingBlock - If getExitingBlocks would return exactly one block,
201 /// return that block. Otherwise return null.
202 BlockT *getExitingBlock() const;
204 /// getExitBlocks - Return all of the successor blocks of this loop. These
205 /// are the blocks _outside of the current loop_ which are branched to.
207 void getExitBlocks(SmallVectorImpl<BlockT*> &ExitBlocks) const;
209 /// getExitBlock - If getExitBlocks would return exactly one block,
210 /// return that block. Otherwise return null.
211 BlockT *getExitBlock() const;
214 typedef std::pair<const BlockT*, const BlockT*> Edge;
216 /// getExitEdges - Return all pairs of (_inside_block_,_outside_block_).
217 void getExitEdges(SmallVectorImpl<Edge> &ExitEdges) const;
219 /// getLoopPreheader - If there is a preheader for this loop, return it. A
220 /// loop has a preheader if there is only one edge to the header of the loop
221 /// from outside of the loop. If this is the case, the block branching to the
222 /// header of the loop is the preheader node.
224 /// This method returns null if there is no preheader for the loop.
226 BlockT *getLoopPreheader() const;
228 /// getLoopPredecessor - If the given loop's header has exactly one unique
229 /// predecessor outside the loop, return it. Otherwise return null.
230 /// This is less strict that the loop "preheader" concept, which requires
231 /// the predecessor to have exactly one successor.
233 BlockT *getLoopPredecessor() const;
235 /// getLoopLatch - If there is a single latch block for this loop, return it.
236 /// A latch block is a block that contains a branch back to the header.
237 BlockT *getLoopLatch() const;
239 /// getLoopLatches - Return all loop latch blocks of this loop. A latch block
240 /// is a block that contains a branch back to the header.
241 void getLoopLatches(SmallVectorImpl<BlockT *> &LoopLatches) const {
242 BlockT *H = getHeader();
243 typedef GraphTraits<Inverse<BlockT*> > InvBlockTraits;
244 for (typename InvBlockTraits::ChildIteratorType I =
245 InvBlockTraits::child_begin(H),
246 E = InvBlockTraits::child_end(H); I != E; ++I)
248 LoopLatches.push_back(*I);
251 //===--------------------------------------------------------------------===//
252 // APIs for updating loop information after changing the CFG
255 /// addBasicBlockToLoop - This method is used by other analyses to update loop
256 /// information. NewBB is set to be a new member of the current loop.
257 /// Because of this, it is added as a member of all parent loops, and is added
258 /// to the specified LoopInfo object as being in the current basic block. It
259 /// is not valid to replace the loop header with this method.
261 void addBasicBlockToLoop(BlockT *NewBB, LoopInfoBase<BlockT, LoopT> &LI);
263 /// replaceChildLoopWith - This is used when splitting loops up. It replaces
264 /// the OldChild entry in our children list with NewChild, and updates the
265 /// parent pointer of OldChild to be null and the NewChild to be this loop.
266 /// This updates the loop depth of the new child.
267 void replaceChildLoopWith(LoopT *OldChild, LoopT *NewChild);
269 /// addChildLoop - Add the specified loop to be a child of this loop. This
270 /// updates the loop depth of the new child.
272 void addChildLoop(LoopT *NewChild) {
273 assert(!NewChild->ParentLoop && "NewChild already has a parent!");
274 NewChild->ParentLoop = static_cast<LoopT *>(this);
275 SubLoops.push_back(NewChild);
278 /// removeChildLoop - This removes the specified child from being a subloop of
279 /// this loop. The loop is not deleted, as it will presumably be inserted
280 /// into another loop.
281 LoopT *removeChildLoop(iterator I) {
282 assert(I != SubLoops.end() && "Cannot remove end iterator!");
284 assert(Child->ParentLoop == this && "Child is not a child of this loop!");
285 SubLoops.erase(SubLoops.begin()+(I-begin()));
286 Child->ParentLoop = nullptr;
290 /// addBlockEntry - This adds a basic block directly to the basic block list.
291 /// This should only be used by transformations that create new loops. Other
292 /// transformations should use addBasicBlockToLoop.
293 void addBlockEntry(BlockT *BB) {
294 Blocks.push_back(BB);
295 DenseBlockSet.insert(BB);
298 /// reverseBlocks - interface to reverse Blocks[from, end of loop] in this loop
299 void reverseBlock(unsigned from) {
300 std::reverse(Blocks.begin() + from, Blocks.end());
303 /// reserveBlocks- interface to do reserve() for Blocks
304 void reserveBlocks(unsigned size) {
305 Blocks.reserve(size);
308 /// moveToHeader - This method is used to move BB (which must be part of this
309 /// loop) to be the loop header of the loop (the block that dominates all
311 void moveToHeader(BlockT *BB) {
312 if (Blocks[0] == BB) return;
313 for (unsigned i = 0; ; ++i) {
314 assert(i != Blocks.size() && "Loop does not contain BB!");
315 if (Blocks[i] == BB) {
316 Blocks[i] = Blocks[0];
323 /// removeBlockFromLoop - This removes the specified basic block from the
324 /// current loop, updating the Blocks as appropriate. This does not update
325 /// the mapping in the LoopInfo class.
326 void removeBlockFromLoop(BlockT *BB) {
327 RemoveFromVector(Blocks, BB);
328 DenseBlockSet.erase(BB);
331 /// verifyLoop - Verify loop structure
332 void verifyLoop() const;
334 /// verifyLoop - Verify loop structure of this loop and all nested loops.
335 void verifyLoopNest(DenseSet<const LoopT*> *Loops) const;
337 void print(raw_ostream &OS, unsigned Depth = 0) const;
340 friend class LoopInfoBase<BlockT, LoopT>;
341 explicit LoopBase(BlockT *BB) : ParentLoop(nullptr) {
342 Blocks.push_back(BB);
343 DenseBlockSet.insert(BB);
347 template<class BlockT, class LoopT>
348 raw_ostream& operator<<(raw_ostream &OS, const LoopBase<BlockT, LoopT> &Loop) {
353 // Implementation in LoopInfoImpl.h
355 __extension__ extern template class LoopBase<BasicBlock, Loop>;
358 class Loop : public LoopBase<BasicBlock, Loop> {
362 /// isLoopInvariant - Return true if the specified value is loop invariant
364 bool isLoopInvariant(Value *V) const;
366 /// hasLoopInvariantOperands - Return true if all the operands of the
367 /// specified instruction are loop invariant.
368 bool hasLoopInvariantOperands(Instruction *I) const;
370 /// makeLoopInvariant - If the given value is an instruction inside of the
371 /// loop and it can be hoisted, do so to make it trivially loop-invariant.
372 /// Return true if the value after any hoisting is loop invariant. This
373 /// function can be used as a slightly more aggressive replacement for
376 /// If InsertPt is specified, it is the point to hoist instructions to.
377 /// If null, the terminator of the loop preheader is used.
379 bool makeLoopInvariant(Value *V, bool &Changed,
380 Instruction *InsertPt = nullptr) const;
382 /// makeLoopInvariant - If the given instruction is inside of the
383 /// loop and it can be hoisted, do so to make it trivially loop-invariant.
384 /// Return true if the instruction after any hoisting is loop invariant. This
385 /// function can be used as a slightly more aggressive replacement for
388 /// If InsertPt is specified, it is the point to hoist instructions to.
389 /// If null, the terminator of the loop preheader is used.
391 bool makeLoopInvariant(Instruction *I, bool &Changed,
392 Instruction *InsertPt = nullptr) const;
394 /// getCanonicalInductionVariable - Check to see if the loop has a canonical
395 /// induction variable: an integer recurrence that starts at 0 and increments
396 /// by one each time through the loop. If so, return the phi node that
397 /// corresponds to it.
399 /// The IndVarSimplify pass transforms loops to have a canonical induction
402 PHINode *getCanonicalInductionVariable() const;
404 /// isLCSSAForm - Return true if the Loop is in LCSSA form
405 bool isLCSSAForm(DominatorTree &DT) const;
407 /// isLoopSimplifyForm - Return true if the Loop is in the form that
408 /// the LoopSimplify form transforms loops to, which is sometimes called
410 bool isLoopSimplifyForm() const;
412 /// isSafeToClone - Return true if the loop body is safe to clone in practice.
413 bool isSafeToClone() const;
415 /// Returns true if the loop is annotated parallel.
417 /// A parallel loop can be assumed to not contain any dependencies between
418 /// iterations by the compiler. That is, any loop-carried dependency checking
419 /// can be skipped completely when parallelizing the loop on the target
420 /// machine. Thus, if the parallel loop information originates from the
421 /// programmer, e.g. via the OpenMP parallel for pragma, it is the
422 /// programmer's responsibility to ensure there are no loop-carried
423 /// dependencies. The final execution order of the instructions across
424 /// iterations is not guaranteed, thus, the end result might or might not
425 /// implement actual concurrent execution of instructions across multiple
427 bool isAnnotatedParallel() const;
429 /// Return the llvm.loop loop id metadata node for this loop if it is present.
431 /// If this loop contains the same llvm.loop metadata on each branch to the
432 /// header then the node is returned. If any latch instruction does not
433 /// contain llvm.loop or or if multiple latches contain different nodes then
435 MDNode *getLoopID() const;
436 /// Set the llvm.loop loop id metadata for this loop.
438 /// The LoopID metadata node will be added to each terminator instruction in
439 /// the loop that branches to the loop header.
441 /// The LoopID metadata node should have one or more operands and the first
442 /// operand should should be the node itself.
443 void setLoopID(MDNode *LoopID) const;
445 /// hasDedicatedExits - Return true if no exit block for the loop
446 /// has a predecessor that is outside the loop.
447 bool hasDedicatedExits() const;
449 /// getUniqueExitBlocks - Return all unique successor blocks of this loop.
450 /// These are the blocks _outside of the current loop_ which are branched to.
451 /// This assumes that loop exits are in canonical form.
453 void getUniqueExitBlocks(SmallVectorImpl<BasicBlock *> &ExitBlocks) const;
455 /// getUniqueExitBlock - If getUniqueExitBlocks would return exactly one
456 /// block, return that block. Otherwise return null.
457 BasicBlock *getUniqueExitBlock() const;
461 /// \brief Return the debug location of the start of this loop.
462 /// This looks for a BB terminating instruction with a known debug
463 /// location by looking at the preheader and header blocks. If it
464 /// cannot find a terminating instruction with location information,
465 /// it returns an unknown location.
466 DebugLoc getStartLoc() const {
469 // Try the pre-header first.
470 if ((HeadBB = getLoopPreheader()) != nullptr)
471 if (DebugLoc DL = HeadBB->getTerminator()->getDebugLoc())
474 // If we have no pre-header or there are no instructions with debug
475 // info in it, try the header.
476 HeadBB = getHeader();
478 return HeadBB->getTerminator()->getDebugLoc();
484 friend class LoopInfoBase<BasicBlock, Loop>;
485 explicit Loop(BasicBlock *BB) : LoopBase<BasicBlock, Loop>(BB) {}
488 //===----------------------------------------------------------------------===//
489 /// LoopInfo - This class builds and contains all of the top level loop
490 /// structures in the specified function.
493 template<class BlockT, class LoopT>
495 // BBMap - Mapping of basic blocks to the inner most loop they occur in
496 DenseMap<BlockT *, LoopT *> BBMap;
497 std::vector<LoopT *> TopLevelLoops;
498 friend class LoopBase<BlockT, LoopT>;
499 friend class LoopInfo;
501 void operator=(const LoopInfoBase &) = delete;
502 LoopInfoBase(const LoopInfoBase &) = delete;
505 ~LoopInfoBase() { releaseMemory(); }
507 LoopInfoBase(LoopInfoBase &&Arg)
508 : BBMap(std::move(Arg.BBMap)),
509 TopLevelLoops(std::move(Arg.TopLevelLoops)) {
510 // We have to clear the arguments top level loops as we've taken ownership.
511 Arg.TopLevelLoops.clear();
513 LoopInfoBase &operator=(LoopInfoBase &&RHS) {
514 BBMap = std::move(RHS.BBMap);
516 for (auto *L : TopLevelLoops)
518 TopLevelLoops = std::move(RHS.TopLevelLoops);
519 RHS.TopLevelLoops.clear();
523 void releaseMemory() {
526 for (auto *L : TopLevelLoops)
528 TopLevelLoops.clear();
531 /// iterator/begin/end - The interface to the top-level loops in the current
534 typedef typename std::vector<LoopT *>::const_iterator iterator;
535 typedef typename std::vector<LoopT *>::const_reverse_iterator
537 iterator begin() const { return TopLevelLoops.begin(); }
538 iterator end() const { return TopLevelLoops.end(); }
539 reverse_iterator rbegin() const { return TopLevelLoops.rbegin(); }
540 reverse_iterator rend() const { return TopLevelLoops.rend(); }
541 bool empty() const { return TopLevelLoops.empty(); }
543 /// getLoopFor - Return the inner most loop that BB lives in. If a basic
544 /// block is in no loop (for example the entry node), null is returned.
546 LoopT *getLoopFor(const BlockT *BB) const {
547 return BBMap.lookup(const_cast<BlockT*>(BB));
550 /// operator[] - same as getLoopFor...
552 const LoopT *operator[](const BlockT *BB) const {
553 return getLoopFor(BB);
556 /// getLoopDepth - Return the loop nesting level of the specified block. A
557 /// depth of 0 means the block is not inside any loop.
559 unsigned getLoopDepth(const BlockT *BB) const {
560 const LoopT *L = getLoopFor(BB);
561 return L ? L->getLoopDepth() : 0;
564 // isLoopHeader - True if the block is a loop header node
565 bool isLoopHeader(BlockT *BB) const {
566 const LoopT *L = getLoopFor(BB);
567 return L && L->getHeader() == BB;
570 /// removeLoop - This removes the specified top-level loop from this loop info
571 /// object. The loop is not deleted, as it will presumably be inserted into
573 LoopT *removeLoop(iterator I) {
574 assert(I != end() && "Cannot remove end iterator!");
576 assert(!L->getParentLoop() && "Not a top-level loop!");
577 TopLevelLoops.erase(TopLevelLoops.begin() + (I-begin()));
581 /// changeLoopFor - Change the top-level loop that contains BB to the
582 /// specified loop. This should be used by transformations that restructure
583 /// the loop hierarchy tree.
584 void changeLoopFor(BlockT *BB, LoopT *L) {
592 /// changeTopLevelLoop - Replace the specified loop in the top-level loops
593 /// list with the indicated loop.
594 void changeTopLevelLoop(LoopT *OldLoop,
596 auto I = std::find(TopLevelLoops.begin(), TopLevelLoops.end(), OldLoop);
597 assert(I != TopLevelLoops.end() && "Old loop not at top level!");
599 assert(!NewLoop->ParentLoop && !OldLoop->ParentLoop &&
600 "Loops already embedded into a subloop!");
603 /// addTopLevelLoop - This adds the specified loop to the collection of
605 void addTopLevelLoop(LoopT *New) {
606 assert(!New->getParentLoop() && "Loop already in subloop!");
607 TopLevelLoops.push_back(New);
610 /// removeBlock - This method completely removes BB from all data structures,
611 /// including all of the Loop objects it is nested in and our mapping from
612 /// BasicBlocks to loops.
613 void removeBlock(BlockT *BB) {
614 auto I = BBMap.find(BB);
615 if (I != BBMap.end()) {
616 for (LoopT *L = I->second; L; L = L->getParentLoop())
617 L->removeBlockFromLoop(BB);
625 static bool isNotAlreadyContainedIn(const LoopT *SubLoop,
626 const LoopT *ParentLoop) {
627 if (!SubLoop) return true;
628 if (SubLoop == ParentLoop) return false;
629 return isNotAlreadyContainedIn(SubLoop->getParentLoop(), ParentLoop);
632 /// Create the loop forest using a stable algorithm.
633 void Analyze(DominatorTreeBase<BlockT> &DomTree);
636 void print(raw_ostream &OS) const;
641 // Implementation in LoopInfoImpl.h
643 __extension__ extern template class LoopInfoBase<BasicBlock, Loop>;
646 class LoopInfo : public LoopInfoBase<BasicBlock, Loop> {
647 typedef LoopInfoBase<BasicBlock, Loop> BaseT;
649 friend class LoopBase<BasicBlock, Loop>;
651 void operator=(const LoopInfo &) = delete;
652 LoopInfo(const LoopInfo &) = delete;
656 LoopInfo(LoopInfo &&Arg) : BaseT(std::move(static_cast<BaseT &>(Arg))) {}
657 LoopInfo &operator=(LoopInfo &&RHS) {
658 BaseT::operator=(std::move(static_cast<BaseT &>(RHS)));
662 // Most of the public interface is provided via LoopInfoBase.
664 /// updateUnloop - Update LoopInfo after removing the last backedge from a
665 /// loop--now the "unloop". This updates the loop forest and parent loops for
666 /// each block so that Unloop is no longer referenced, but the caller must
667 /// actually delete the Unloop object.
668 void updateUnloop(Loop *Unloop);
670 /// replacementPreservesLCSSAForm - Returns true if replacing From with To
671 /// everywhere is guaranteed to preserve LCSSA form.
672 bool replacementPreservesLCSSAForm(Instruction *From, Value *To) {
673 // Preserving LCSSA form is only problematic if the replacing value is an
675 Instruction *I = dyn_cast<Instruction>(To);
677 // If both instructions are defined in the same basic block then replacement
678 // cannot break LCSSA form.
679 if (I->getParent() == From->getParent())
681 // If the instruction is not defined in a loop then it can safely replace
683 Loop *ToLoop = getLoopFor(I->getParent());
684 if (!ToLoop) return true;
685 // If the replacing instruction is defined in the same loop as the original
686 // instruction, or in a loop that contains it as an inner loop, then using
687 // it as a replacement will not break LCSSA form.
688 return ToLoop->contains(getLoopFor(From->getParent()));
692 // Allow clients to walk the list of nested loops...
693 template <> struct GraphTraits<const Loop*> {
694 typedef const Loop NodeType;
695 typedef LoopInfo::iterator ChildIteratorType;
697 static NodeType *getEntryNode(const Loop *L) { return L; }
698 static inline ChildIteratorType child_begin(NodeType *N) {
701 static inline ChildIteratorType child_end(NodeType *N) {
706 template <> struct GraphTraits<Loop*> {
707 typedef Loop NodeType;
708 typedef LoopInfo::iterator ChildIteratorType;
710 static NodeType *getEntryNode(Loop *L) { return L; }
711 static inline ChildIteratorType child_begin(NodeType *N) {
714 static inline ChildIteratorType child_end(NodeType *N) {
719 /// \brief Analysis pass that exposes the \c LoopInfo for a function.
724 typedef LoopInfo Result;
726 /// \brief Opaque, unique identifier for this analysis pass.
727 static void *ID() { return (void *)&PassID; }
729 /// \brief Provide a name for the analysis for debugging and logging.
730 static StringRef name() { return "LoopAnalysis"; }
733 LoopAnalysis(const LoopAnalysis &Arg) {}
734 LoopAnalysis(LoopAnalysis &&Arg) {}
735 LoopAnalysis &operator=(const LoopAnalysis &RHS) { return *this; }
736 LoopAnalysis &operator=(LoopAnalysis &&RHS) { return *this; }
738 LoopInfo run(Function &F, AnalysisManager<Function> *AM);
741 /// \brief Printer pass for the \c LoopAnalysis results.
742 class LoopPrinterPass {
746 explicit LoopPrinterPass(raw_ostream &OS) : OS(OS) {}
747 PreservedAnalyses run(Function &F, AnalysisManager<Function> *AM);
749 static StringRef name() { return "LoopPrinterPass"; }
752 /// \brief The legacy pass manager's analysis pass to compute loop information.
753 class LoopInfoWrapperPass : public FunctionPass {
757 static char ID; // Pass identification, replacement for typeid
759 LoopInfoWrapperPass() : FunctionPass(ID) {
760 initializeLoopInfoWrapperPassPass(*PassRegistry::getPassRegistry());
763 LoopInfo &getLoopInfo() { return LI; }
764 const LoopInfo &getLoopInfo() const { return LI; }
766 /// \brief Calculate the natural loop information for a given function.
767 bool runOnFunction(Function &F) override;
769 void verifyAnalysis() const override;
771 void releaseMemory() override { LI.releaseMemory(); }
773 void print(raw_ostream &O, const Module *M = nullptr) const override;
775 void getAnalysisUsage(AnalysisUsage &AU) const override;
778 } // End llvm namespace