LLVM  6.0.0svn
LoopInfo.h
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1 //===- llvm/Analysis/LoopInfo.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 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.
14 //
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.
18 //
19 // It can calculate on the fly various bits of information, for example:
20 //
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
25 // * the loop depth
26 // * etc...
27 //
28 // Note that this analysis specifically identifies *Loops* not cycles or SCCs
29 // in the CFG. There can be strongly connected components in the CFG which
30 // this analysis will not recognize and that will not be represented by a Loop
31 // instance. In particular, a Loop might be inside such a non-loop SCC, or a
32 // non-loop SCC might contain a sub-SCC which is a Loop.
33 //
34 //===----------------------------------------------------------------------===//
35 
36 #ifndef LLVM_ANALYSIS_LOOPINFO_H
37 #define LLVM_ANALYSIS_LOOPINFO_H
38 
39 #include "llvm/ADT/DenseMap.h"
40 #include "llvm/ADT/DenseSet.h"
41 #include "llvm/ADT/GraphTraits.h"
42 #include "llvm/ADT/SmallPtrSet.h"
43 #include "llvm/ADT/SmallVector.h"
44 #include "llvm/IR/CFG.h"
45 #include "llvm/IR/Instruction.h"
46 #include "llvm/IR/Instructions.h"
47 #include "llvm/IR/PassManager.h"
48 #include "llvm/Pass.h"
49 #include "llvm/Support/Allocator.h"
50 #include <algorithm>
51 #include <utility>
52 
53 namespace llvm {
54 
55 class DominatorTree;
56 class LoopInfo;
57 class Loop;
58 class MDNode;
59 class PHINode;
60 class raw_ostream;
61 template <class N, bool IsPostDom> class DominatorTreeBase;
62 template <class N, class M> class LoopInfoBase;
63 template <class N, class M> class LoopBase;
64 
65 //===----------------------------------------------------------------------===//
66 /// Instances of this class are used to represent loops that are detected in the
67 /// flow graph.
68 ///
69 template <class BlockT, class LoopT> class LoopBase {
70  LoopT *ParentLoop;
71  // Loops contained entirely within this one.
72  std::vector<LoopT *> SubLoops;
73 
74  // The list of blocks in this loop. First entry is the header node.
75  std::vector<BlockT *> Blocks;
76 
77  SmallPtrSet<const BlockT *, 8> DenseBlockSet;
78 
79 #if LLVM_ENABLE_ABI_BREAKING_CHECKS
80  /// Indicator that this loop is no longer a valid loop.
81  bool IsInvalid = false;
82 #endif
83 
84  LoopBase(const LoopBase<BlockT, LoopT> &) = delete;
86  operator=(const LoopBase<BlockT, LoopT> &) = delete;
87 
88 public:
89  /// Return the nesting level of this loop. An outer-most loop has depth 1,
90  /// for consistency with loop depth values used for basic blocks, where depth
91  /// 0 is used for blocks not inside any loops.
92  unsigned getLoopDepth() const {
93  assert(!isInvalid() && "Loop not in a valid state!");
94  unsigned D = 1;
95  for (const LoopT *CurLoop = ParentLoop; CurLoop;
96  CurLoop = CurLoop->ParentLoop)
97  ++D;
98  return D;
99  }
100  BlockT *getHeader() const { return getBlocks().front(); }
101  LoopT *getParentLoop() const { return ParentLoop; }
102 
103  /// This is a raw interface for bypassing addChildLoop.
104  void setParentLoop(LoopT *L) {
105  assert(!isInvalid() && "Loop not in a valid state!");
106  ParentLoop = L;
107  }
108 
109  /// Return true if the specified loop is contained within in this loop.
110  bool contains(const LoopT *L) const {
111  assert(!isInvalid() && "Loop not in a valid state!");
112  if (L == this)
113  return true;
114  if (!L)
115  return false;
116  return contains(L->getParentLoop());
117  }
118 
119  /// Return true if the specified basic block is in this loop.
120  bool contains(const BlockT *BB) const {
121  assert(!isInvalid() && "Loop not in a valid state!");
122  return DenseBlockSet.count(BB);
123  }
124 
125  /// Return true if the specified instruction is in this loop.
126  template <class InstT> bool contains(const InstT *Inst) const {
127  return contains(Inst->getParent());
128  }
129 
130  /// Return the loops contained entirely within this loop.
131  const std::vector<LoopT *> &getSubLoops() const {
132  assert(!isInvalid() && "Loop not in a valid state!");
133  return SubLoops;
134  }
135  std::vector<LoopT *> &getSubLoopsVector() {
136  assert(!isInvalid() && "Loop not in a valid state!");
137  return SubLoops;
138  }
139  typedef typename std::vector<LoopT *>::const_iterator iterator;
140  typedef
141  typename std::vector<LoopT *>::const_reverse_iterator reverse_iterator;
142  iterator begin() const { return getSubLoops().begin(); }
143  iterator end() const { return getSubLoops().end(); }
144  reverse_iterator rbegin() const { return getSubLoops().rbegin(); }
145  reverse_iterator rend() const { return getSubLoops().rend(); }
146  bool empty() const { return getSubLoops().empty(); }
147 
148  /// Get a list of the basic blocks which make up this loop.
149  const std::vector<BlockT *> &getBlocks() const {
150  assert(!isInvalid() && "Loop not in a valid state!");
151  return Blocks;
152  }
153  typedef typename std::vector<BlockT *>::const_iterator block_iterator;
154  block_iterator block_begin() const { return getBlocks().begin(); }
155  block_iterator block_end() const { return getBlocks().end(); }
157  assert(!isInvalid() && "Loop not in a valid state!");
158  return make_range(block_begin(), block_end());
159  }
160 
161  /// Get the number of blocks in this loop in constant time.
162  /// Invalidate the loop, indicating that it is no longer a loop.
163  unsigned getNumBlocks() const {
164  assert(!isInvalid() && "Loop not in a valid state!");
165  return Blocks.size();
166  }
167 
168  /// Return true if this loop is no longer valid. The only valid use of this
169  /// helper is "assert(L.isInvalid())" or equivalent, since IsInvalid is set to
170  /// true by the destructor. In other words, if this accessor returns true,
171  /// the caller has already triggered UB by calling this accessor; and so it
172  /// can only be called in a context where a return value of true indicates a
173  /// programmer error.
174  bool isInvalid() const {
175 #if LLVM_ENABLE_ABI_BREAKING_CHECKS
176  return IsInvalid;
177 #else
178  return false;
179 #endif
180  }
181 
182  /// True if terminator in the block can branch to another block that is
183  /// outside of the current loop.
184  bool isLoopExiting(const BlockT *BB) const {
185  assert(!isInvalid() && "Loop not in a valid state!");
186  for (const auto &Succ : children<const BlockT *>(BB)) {
187  if (!contains(Succ))
188  return true;
189  }
190  return false;
191  }
192 
193  /// Returns true if \p BB is a loop-latch.
194  /// A latch block is a block that contains a branch back to the header.
195  /// This function is useful when there are multiple latches in a loop
196  /// because \fn getLoopLatch will return nullptr in that case.
197  bool isLoopLatch(const BlockT *BB) const {
198  assert(!isInvalid() && "Loop not in a valid state!");
199  assert(contains(BB) && "block does not belong to the loop");
200 
201  BlockT *Header = getHeader();
202  auto PredBegin = GraphTraits<Inverse<BlockT *>>::child_begin(Header);
203  auto PredEnd = GraphTraits<Inverse<BlockT *>>::child_end(Header);
204  return std::find(PredBegin, PredEnd, BB) != PredEnd;
205  }
206 
207  /// Calculate the number of back edges to the loop header.
208  unsigned getNumBackEdges() const {
209  assert(!isInvalid() && "Loop not in a valid state!");
210  unsigned NumBackEdges = 0;
211  BlockT *H = getHeader();
212 
213  for (const auto Pred : children<Inverse<BlockT *>>(H))
214  if (contains(Pred))
215  ++NumBackEdges;
216 
217  return NumBackEdges;
218  }
219 
220  //===--------------------------------------------------------------------===//
221  // APIs for simple analysis of the loop.
222  //
223  // Note that all of these methods can fail on general loops (ie, there may not
224  // be a preheader, etc). For best success, the loop simplification and
225  // induction variable canonicalization pass should be used to normalize loops
226  // for easy analysis. These methods assume canonical loops.
227 
228  /// Return all blocks inside the loop that have successors outside of the
229  /// loop. These are the blocks _inside of the current loop_ which branch out.
230  /// The returned list is always unique.
231  void getExitingBlocks(SmallVectorImpl<BlockT *> &ExitingBlocks) const;
232 
233  /// If getExitingBlocks would return exactly one block, return that block.
234  /// Otherwise return null.
235  BlockT *getExitingBlock() const;
236 
237  /// Return all of the successor blocks of this loop. These are the blocks
238  /// _outside of the current loop_ which are branched to.
239  void getExitBlocks(SmallVectorImpl<BlockT *> &ExitBlocks) const;
240 
241  /// If getExitBlocks would return exactly one block, return that block.
242  /// Otherwise return null.
243  BlockT *getExitBlock() const;
244 
245  /// Edge type.
246  typedef std::pair<const BlockT *, const BlockT *> Edge;
247 
248  /// Return all pairs of (_inside_block_,_outside_block_).
249  void getExitEdges(SmallVectorImpl<Edge> &ExitEdges) const;
250 
251  /// If there is a preheader for this loop, return it. A loop has a preheader
252  /// if there is only one edge to the header of the loop from outside of the
253  /// loop. If this is the case, the block branching to the header of the loop
254  /// is the preheader node.
255  ///
256  /// This method returns null if there is no preheader for the loop.
257  BlockT *getLoopPreheader() const;
258 
259  /// If the given loop's header has exactly one unique predecessor outside the
260  /// loop, return it. Otherwise return null.
261  /// This is less strict that the loop "preheader" concept, which requires
262  /// the predecessor to have exactly one successor.
263  BlockT *getLoopPredecessor() const;
264 
265  /// If there is a single latch block for this loop, return it.
266  /// A latch block is a block that contains a branch back to the header.
267  BlockT *getLoopLatch() const;
268 
269  /// Return all loop latch blocks of this loop. A latch block is a block that
270  /// contains a branch back to the header.
271  void getLoopLatches(SmallVectorImpl<BlockT *> &LoopLatches) const {
272  assert(!isInvalid() && "Loop not in a valid state!");
273  BlockT *H = getHeader();
274  for (const auto Pred : children<Inverse<BlockT *>>(H))
275  if (contains(Pred))
276  LoopLatches.push_back(Pred);
277  }
278 
279  //===--------------------------------------------------------------------===//
280  // APIs for updating loop information after changing the CFG
281  //
282 
283  /// This method is used by other analyses to update loop information.
284  /// NewBB is set to be a new member of the current loop.
285  /// Because of this, it is added as a member of all parent loops, and is added
286  /// to the specified LoopInfo object as being in the current basic block. It
287  /// is not valid to replace the loop header with this method.
288  void addBasicBlockToLoop(BlockT *NewBB, LoopInfoBase<BlockT, LoopT> &LI);
289 
290  /// This is used when splitting loops up. It replaces the OldChild entry in
291  /// our children list with NewChild, and updates the parent pointer of
292  /// OldChild to be null and the NewChild to be this loop.
293  /// This updates the loop depth of the new child.
294  void replaceChildLoopWith(LoopT *OldChild, LoopT *NewChild);
295 
296  /// Add the specified loop to be a child of this loop.
297  /// This updates the loop depth of the new child.
298  void addChildLoop(LoopT *NewChild) {
299  assert(!isInvalid() && "Loop not in a valid state!");
300  assert(!NewChild->ParentLoop && "NewChild already has a parent!");
301  NewChild->ParentLoop = static_cast<LoopT *>(this);
302  SubLoops.push_back(NewChild);
303  }
304 
305  /// This removes the specified child from being a subloop of this loop. The
306  /// loop is not deleted, as it will presumably be inserted into another loop.
307  LoopT *removeChildLoop(iterator I) {
308  assert(!isInvalid() && "Loop not in a valid state!");
309  assert(I != SubLoops.end() && "Cannot remove end iterator!");
310  LoopT *Child = *I;
311  assert(Child->ParentLoop == this && "Child is not a child of this loop!");
312  SubLoops.erase(SubLoops.begin() + (I - begin()));
313  Child->ParentLoop = nullptr;
314  return Child;
315  }
316 
317  /// This adds a basic block directly to the basic block list.
318  /// This should only be used by transformations that create new loops. Other
319  /// transformations should use addBasicBlockToLoop.
320  void addBlockEntry(BlockT *BB) {
321  assert(!isInvalid() && "Loop not in a valid state!");
322  Blocks.push_back(BB);
323  DenseBlockSet.insert(BB);
324  }
325 
326  /// interface to reverse Blocks[from, end of loop] in this loop
327  void reverseBlock(unsigned from) {
328  assert(!isInvalid() && "Loop not in a valid state!");
329  std::reverse(Blocks.begin() + from, Blocks.end());
330  }
331 
332  /// interface to do reserve() for Blocks
333  void reserveBlocks(unsigned size) {
334  assert(!isInvalid() && "Loop not in a valid state!");
335  Blocks.reserve(size);
336  }
337 
338  /// This method is used to move BB (which must be part of this loop) to be the
339  /// loop header of the loop (the block that dominates all others).
340  void moveToHeader(BlockT *BB) {
341  assert(!isInvalid() && "Loop not in a valid state!");
342  if (Blocks[0] == BB)
343  return;
344  for (unsigned i = 0;; ++i) {
345  assert(i != Blocks.size() && "Loop does not contain BB!");
346  if (Blocks[i] == BB) {
347  Blocks[i] = Blocks[0];
348  Blocks[0] = BB;
349  return;
350  }
351  }
352  }
353 
354  /// This removes the specified basic block from the current loop, updating the
355  /// Blocks as appropriate. This does not update the mapping in the LoopInfo
356  /// class.
357  void removeBlockFromLoop(BlockT *BB) {
358  assert(!isInvalid() && "Loop not in a valid state!");
359  auto I = find(Blocks, BB);
360  assert(I != Blocks.end() && "N is not in this list!");
361  Blocks.erase(I);
362 
363  DenseBlockSet.erase(BB);
364  }
365 
366  /// Verify loop structure
367  void verifyLoop() const;
368 
369  /// Verify loop structure of this loop and all nested loops.
371 
372  /// Print loop with all the BBs inside it.
373  void print(raw_ostream &OS, unsigned Depth = 0, bool Verbose = false) const;
374 
375 protected:
376  friend class LoopInfoBase<BlockT, LoopT>;
377 
378  /// This creates an empty loop.
379  LoopBase() : ParentLoop(nullptr) {}
380 
381  explicit LoopBase(BlockT *BB) : ParentLoop(nullptr) {
382  Blocks.push_back(BB);
383  DenseBlockSet.insert(BB);
384  }
385 
386  // Since loop passes like SCEV are allowed to key analysis results off of
387  // `Loop` pointers, we cannot re-use pointers within a loop pass manager.
388  // This means loop passes should not be `delete` ing `Loop` objects directly
389  // (and risk a later `Loop` allocation re-using the address of a previous one)
390  // but should be using LoopInfo::markAsRemoved, which keeps around the `Loop`
391  // pointer till the end of the lifetime of the `LoopInfo` object.
392  //
393  // To make it easier to follow this rule, we mark the destructor as
394  // non-public.
396  for (auto *SubLoop : SubLoops)
397  SubLoop->~LoopT();
398 
399 #if LLVM_ENABLE_ABI_BREAKING_CHECKS
400  IsInvalid = true;
401 #endif
402  SubLoops.clear();
403  Blocks.clear();
404  DenseBlockSet.clear();
405  ParentLoop = nullptr;
406  }
407 };
408 
409 template <class BlockT, class LoopT>
410 raw_ostream &operator<<(raw_ostream &OS, const LoopBase<BlockT, LoopT> &Loop) {
411  Loop.print(OS);
412  return OS;
413 }
414 
415 // Implementation in LoopInfoImpl.h
416 extern template class LoopBase<BasicBlock, Loop>;
417 
418 /// Represents a single loop in the control flow graph. Note that not all SCCs
419 /// in the CFG are necessarily loops.
421 public:
422  /// \brief A range representing the start and end location of a loop.
423  class LocRange {
424  DebugLoc Start;
425  DebugLoc End;
426 
427  public:
428  LocRange() {}
429  LocRange(DebugLoc Start) : Start(std::move(Start)), End(std::move(Start)) {}
431  : Start(std::move(Start)), End(std::move(End)) {}
432 
433  const DebugLoc &getStart() const { return Start; }
434  const DebugLoc &getEnd() const { return End; }
435 
436  /// \brief Check for null.
437  ///
438  explicit operator bool() const { return Start && End; }
439  };
440 
441  /// Return true if the specified value is loop invariant.
442  bool isLoopInvariant(const Value *V) const;
443 
444  /// Return true if all the operands of the specified instruction are loop
445  /// invariant.
446  bool hasLoopInvariantOperands(const Instruction *I) const;
447 
448  /// If the given value is an instruction inside of the loop and it can be
449  /// hoisted, do so to make it trivially loop-invariant.
450  /// Return true if the value after any hoisting is loop invariant. This
451  /// function can be used as a slightly more aggressive replacement for
452  /// isLoopInvariant.
453  ///
454  /// If InsertPt is specified, it is the point to hoist instructions to.
455  /// If null, the terminator of the loop preheader is used.
456  bool makeLoopInvariant(Value *V, bool &Changed,
457  Instruction *InsertPt = nullptr) const;
458 
459  /// If the given instruction is inside of the loop and it can be hoisted, do
460  /// so to make it trivially loop-invariant.
461  /// Return true if the instruction after any hoisting is loop invariant. This
462  /// function can be used as a slightly more aggressive replacement for
463  /// isLoopInvariant.
464  ///
465  /// If InsertPt is specified, it is the point to hoist instructions to.
466  /// If null, the terminator of the loop preheader is used.
467  ///
468  bool makeLoopInvariant(Instruction *I, bool &Changed,
469  Instruction *InsertPt = nullptr) const;
470 
471  /// Check to see if the loop has a canonical induction variable: an integer
472  /// recurrence that starts at 0 and increments by one each time through the
473  /// loop. If so, return the phi node that corresponds to it.
474  ///
475  /// The IndVarSimplify pass transforms loops to have a canonical induction
476  /// variable.
477  ///
478  PHINode *getCanonicalInductionVariable() const;
479 
480  /// Return true if the Loop is in LCSSA form.
481  bool isLCSSAForm(DominatorTree &DT) const;
482 
483  /// Return true if this Loop and all inner subloops are in LCSSA form.
484  bool isRecursivelyLCSSAForm(DominatorTree &DT, const LoopInfo &LI) const;
485 
486  /// Return true if the Loop is in the form that the LoopSimplify form
487  /// transforms loops to, which is sometimes called normal form.
488  bool isLoopSimplifyForm() const;
489 
490  /// Return true if the loop body is safe to clone in practice.
491  bool isSafeToClone() const;
492 
493  /// Returns true if the loop is annotated parallel.
494  ///
495  /// A parallel loop can be assumed to not contain any dependencies between
496  /// iterations by the compiler. That is, any loop-carried dependency checking
497  /// can be skipped completely when parallelizing the loop on the target
498  /// machine. Thus, if the parallel loop information originates from the
499  /// programmer, e.g. via the OpenMP parallel for pragma, it is the
500  /// programmer's responsibility to ensure there are no loop-carried
501  /// dependencies. The final execution order of the instructions across
502  /// iterations is not guaranteed, thus, the end result might or might not
503  /// implement actual concurrent execution of instructions across multiple
504  /// iterations.
505  bool isAnnotatedParallel() const;
506 
507  /// Return the llvm.loop loop id metadata node for this loop if it is present.
508  ///
509  /// If this loop contains the same llvm.loop metadata on each branch to the
510  /// header then the node is returned. If any latch instruction does not
511  /// contain llvm.loop or or if multiple latches contain different nodes then
512  /// 0 is returned.
513  MDNode *getLoopID() const;
514  /// Set the llvm.loop loop id metadata for this loop.
515  ///
516  /// The LoopID metadata node will be added to each terminator instruction in
517  /// the loop that branches to the loop header.
518  ///
519  /// The LoopID metadata node should have one or more operands and the first
520  /// operand should be the node itself.
521  void setLoopID(MDNode *LoopID) const;
522 
523  /// Add llvm.loop.unroll.disable to this loop's loop id metadata.
524  ///
525  /// Remove existing unroll metadata and add unroll disable metadata to
526  /// indicate the loop has already been unrolled. This prevents a loop
527  /// from being unrolled more than is directed by a pragma if the loop
528  /// unrolling pass is run more than once (which it generally is).
529  void setLoopAlreadyUnrolled();
530 
531  /// Return true if no exit block for the loop has a predecessor that is
532  /// outside the loop.
533  bool hasDedicatedExits() const;
534 
535  /// Return all unique successor blocks of this loop.
536  /// These are the blocks _outside of the current loop_ which are branched to.
537  /// This assumes that loop exits are in canonical form, i.e. all exits are
538  /// dedicated exits.
539  void getUniqueExitBlocks(SmallVectorImpl<BasicBlock *> &ExitBlocks) const;
540 
541  /// If getUniqueExitBlocks would return exactly one block, return that block.
542  /// Otherwise return null.
543  BasicBlock *getUniqueExitBlock() const;
544 
545  void dump() const;
546  void dumpVerbose() const;
547 
548  /// Return the debug location of the start of this loop.
549  /// This looks for a BB terminating instruction with a known debug
550  /// location by looking at the preheader and header blocks. If it
551  /// cannot find a terminating instruction with location information,
552  /// it returns an unknown location.
553  DebugLoc getStartLoc() const;
554 
555  /// Return the source code span of the loop.
556  LocRange getLocRange() const;
557 
558  StringRef getName() const {
559  if (BasicBlock *Header = getHeader())
560  if (Header->hasName())
561  return Header->getName();
562  return "<unnamed loop>";
563  }
564 
565 private:
566  Loop() = default;
567 
570  explicit Loop(BasicBlock *BB) : LoopBase<BasicBlock, Loop>(BB) {}
571  ~Loop() = default;
572 };
573 
574 //===----------------------------------------------------------------------===//
575 /// This class builds and contains all of the top-level loop
576 /// structures in the specified function.
577 ///
578 
579 template <class BlockT, class LoopT> class LoopInfoBase {
580  // BBMap - Mapping of basic blocks to the inner most loop they occur in
582  std::vector<LoopT *> TopLevelLoops;
583  BumpPtrAllocator LoopAllocator;
584 
586  friend class LoopInfo;
587 
588  void operator=(const LoopInfoBase &) = delete;
589  LoopInfoBase(const LoopInfoBase &) = delete;
590 
591 public:
593  ~LoopInfoBase() { releaseMemory(); }
594 
596  : BBMap(std::move(Arg.BBMap)),
597  TopLevelLoops(std::move(Arg.TopLevelLoops)),
598  LoopAllocator(std::move(Arg.LoopAllocator)) {
599  // We have to clear the arguments top level loops as we've taken ownership.
600  Arg.TopLevelLoops.clear();
601  }
603  BBMap = std::move(RHS.BBMap);
604 
605  for (auto *L : TopLevelLoops)
606  L->~LoopT();
607 
608  TopLevelLoops = std::move(RHS.TopLevelLoops);
609  LoopAllocator = std::move(RHS.LoopAllocator);
610  RHS.TopLevelLoops.clear();
611  return *this;
612  }
613 
614  void releaseMemory() {
615  BBMap.clear();
616 
617  for (auto *L : TopLevelLoops)
618  L->~LoopT();
619  TopLevelLoops.clear();
620  LoopAllocator.Reset();
621  }
622 
623  template <typename... ArgsTy> LoopT *AllocateLoop(ArgsTy &&... Args) {
624  LoopT *Storage = LoopAllocator.Allocate<LoopT>();
625  return new (Storage) LoopT(std::forward<ArgsTy>(Args)...);
626  }
627 
628  /// iterator/begin/end - The interface to the top-level loops in the current
629  /// function.
630  ///
631  typedef typename std::vector<LoopT *>::const_iterator iterator;
632  typedef
633  typename std::vector<LoopT *>::const_reverse_iterator reverse_iterator;
634  iterator begin() const { return TopLevelLoops.begin(); }
635  iterator end() const { return TopLevelLoops.end(); }
636  reverse_iterator rbegin() const { return TopLevelLoops.rbegin(); }
637  reverse_iterator rend() const { return TopLevelLoops.rend(); }
638  bool empty() const { return TopLevelLoops.empty(); }
639 
640  /// Return all of the loops in the function in preorder across the loop
641  /// nests, with siblings in forward program order.
642  ///
643  /// Note that because loops form a forest of trees, preorder is equivalent to
644  /// reverse postorder.
645  SmallVector<LoopT *, 4> getLoopsInPreorder();
646 
647  /// Return all of the loops in the function in preorder across the loop
648  /// nests, with siblings in *reverse* program order.
649  ///
650  /// Note that because loops form a forest of trees, preorder is equivalent to
651  /// reverse postorder.
652  ///
653  /// Also note that this is *not* a reverse preorder. Only the siblings are in
654  /// reverse program order.
655  SmallVector<LoopT *, 4> getLoopsInReverseSiblingPreorder();
656 
657  /// Return the inner most loop that BB lives in. If a basic block is in no
658  /// loop (for example the entry node), null is returned.
659  LoopT *getLoopFor(const BlockT *BB) const { return BBMap.lookup(BB); }
660 
661  /// Same as getLoopFor.
662  const LoopT *operator[](const BlockT *BB) const { return getLoopFor(BB); }
663 
664  /// Return the loop nesting level of the specified block. A depth of 0 means
665  /// the block is not inside any loop.
666  unsigned getLoopDepth(const BlockT *BB) const {
667  const LoopT *L = getLoopFor(BB);
668  return L ? L->getLoopDepth() : 0;
669  }
670 
671  // True if the block is a loop header node
672  bool isLoopHeader(const BlockT *BB) const {
673  const LoopT *L = getLoopFor(BB);
674  return L && L->getHeader() == BB;
675  }
676 
677  /// This removes the specified top-level loop from this loop info object.
678  /// The loop is not deleted, as it will presumably be inserted into
679  /// another loop.
680  LoopT *removeLoop(iterator I) {
681  assert(I != end() && "Cannot remove end iterator!");
682  LoopT *L = *I;
683  assert(!L->getParentLoop() && "Not a top-level loop!");
684  TopLevelLoops.erase(TopLevelLoops.begin() + (I - begin()));
685  return L;
686  }
687 
688  /// Change the top-level loop that contains BB to the specified loop.
689  /// This should be used by transformations that restructure the loop hierarchy
690  /// tree.
691  void changeLoopFor(BlockT *BB, LoopT *L) {
692  if (!L) {
693  BBMap.erase(BB);
694  return;
695  }
696  BBMap[BB] = L;
697  }
698 
699  /// Replace the specified loop in the top-level loops list with the indicated
700  /// loop.
701  void changeTopLevelLoop(LoopT *OldLoop, LoopT *NewLoop) {
702  auto I = find(TopLevelLoops, OldLoop);
703  assert(I != TopLevelLoops.end() && "Old loop not at top level!");
704  *I = NewLoop;
705  assert(!NewLoop->ParentLoop && !OldLoop->ParentLoop &&
706  "Loops already embedded into a subloop!");
707  }
708 
709  /// This adds the specified loop to the collection of top-level loops.
710  void addTopLevelLoop(LoopT *New) {
711  assert(!New->getParentLoop() && "Loop already in subloop!");
712  TopLevelLoops.push_back(New);
713  }
714 
715  /// This method completely removes BB from all data structures,
716  /// including all of the Loop objects it is nested in and our mapping from
717  /// BasicBlocks to loops.
718  void removeBlock(BlockT *BB) {
719  auto I = BBMap.find(BB);
720  if (I != BBMap.end()) {
721  for (LoopT *L = I->second; L; L = L->getParentLoop())
722  L->removeBlockFromLoop(BB);
723 
724  BBMap.erase(I);
725  }
726  }
727 
728  // Internals
729 
730  static bool isNotAlreadyContainedIn(const LoopT *SubLoop,
731  const LoopT *ParentLoop) {
732  if (!SubLoop)
733  return true;
734  if (SubLoop == ParentLoop)
735  return false;
736  return isNotAlreadyContainedIn(SubLoop->getParentLoop(), ParentLoop);
737  }
738 
739  /// Create the loop forest using a stable algorithm.
740  void analyze(const DominatorTreeBase<BlockT, false> &DomTree);
741 
742  // Debugging
743  void print(raw_ostream &OS) const;
744 
745  void verify(const DominatorTreeBase<BlockT, false> &DomTree) const;
746 
747 protected:
748  // Calls the destructor for \p L but keeps the memory for \p L around so that
749  // the pointer value does not get re-used.
750  void destroy(LoopT *L) {
751  L->~LoopT();
752 
753  // Since LoopAllocator is a BumpPtrAllocator, this Deallocate only poisons
754  // \c L, but the pointer remains valid for non-dereferencing uses.
755  LoopAllocator.Deallocate(L);
756  }
757 };
758 
759 // Implementation in LoopInfoImpl.h
760 extern template class LoopInfoBase<BasicBlock, Loop>;
761 
764 
766 
767  void operator=(const LoopInfo &) = delete;
768  LoopInfo(const LoopInfo &) = delete;
769 
770 public:
771  LoopInfo() {}
772  explicit LoopInfo(const DominatorTreeBase<BasicBlock, false> &DomTree);
773 
774  LoopInfo(LoopInfo &&Arg) : BaseT(std::move(static_cast<BaseT &>(Arg))) {}
776  BaseT::operator=(std::move(static_cast<BaseT &>(RHS)));
777  return *this;
778  }
779 
780  /// Handle invalidation explicitly.
781  bool invalidate(Function &F, const PreservedAnalyses &PA,
783 
784  // Most of the public interface is provided via LoopInfoBase.
785 
786  /// Update LoopInfo after removing the last backedge from a loop. This updates
787  /// the loop forest and parent loops for each block so that \c L is no longer
788  /// referenced, but does not actually delete \c L immediately. The pointer
789  /// will remain valid until this LoopInfo's memory is released.
790  void erase(Loop *L);
791 
792  /// Returns true if replacing From with To everywhere is guaranteed to
793  /// preserve LCSSA form.
795  // Preserving LCSSA form is only problematic if the replacing value is an
796  // instruction.
798  if (!I)
799  return true;
800  // If both instructions are defined in the same basic block then replacement
801  // cannot break LCSSA form.
802  if (I->getParent() == From->getParent())
803  return true;
804  // If the instruction is not defined in a loop then it can safely replace
805  // anything.
806  Loop *ToLoop = getLoopFor(I->getParent());
807  if (!ToLoop)
808  return true;
809  // If the replacing instruction is defined in the same loop as the original
810  // instruction, or in a loop that contains it as an inner loop, then using
811  // it as a replacement will not break LCSSA form.
812  return ToLoop->contains(getLoopFor(From->getParent()));
813  }
814 
815  /// Checks if moving a specific instruction can break LCSSA in any loop.
816  ///
817  /// Return true if moving \p Inst to before \p NewLoc will break LCSSA,
818  /// assuming that the function containing \p Inst and \p NewLoc is currently
819  /// in LCSSA form.
821  assert(Inst->getFunction() == NewLoc->getFunction() &&
822  "Can't reason about IPO!");
823 
824  auto *OldBB = Inst->getParent();
825  auto *NewBB = NewLoc->getParent();
826 
827  // Movement within the same loop does not break LCSSA (the equality check is
828  // to avoid doing a hashtable lookup in case of intra-block movement).
829  if (OldBB == NewBB)
830  return true;
831 
832  auto *OldLoop = getLoopFor(OldBB);
833  auto *NewLoop = getLoopFor(NewBB);
834 
835  if (OldLoop == NewLoop)
836  return true;
837 
838  // Check if Outer contains Inner; with the null loop counting as the
839  // "outermost" loop.
840  auto Contains = [](const Loop *Outer, const Loop *Inner) {
841  return !Outer || Outer->contains(Inner);
842  };
843 
844  // To check that the movement of Inst to before NewLoc does not break LCSSA,
845  // we need to check two sets of uses for possible LCSSA violations at
846  // NewLoc: the users of NewInst, and the operands of NewInst.
847 
848  // If we know we're hoisting Inst out of an inner loop to an outer loop,
849  // then the uses *of* Inst don't need to be checked.
850 
851  if (!Contains(NewLoop, OldLoop)) {
852  for (Use &U : Inst->uses()) {
853  auto *UI = cast<Instruction>(U.getUser());
854  auto *UBB = isa<PHINode>(UI) ? cast<PHINode>(UI)->getIncomingBlock(U)
855  : UI->getParent();
856  if (UBB != NewBB && getLoopFor(UBB) != NewLoop)
857  return false;
858  }
859  }
860 
861  // If we know we're sinking Inst from an outer loop into an inner loop, then
862  // the *operands* of Inst don't need to be checked.
863 
864  if (!Contains(OldLoop, NewLoop)) {
865  // See below on why we can't handle phi nodes here.
866  if (isa<PHINode>(Inst))
867  return false;
868 
869  for (Use &U : Inst->operands()) {
870  auto *DefI = dyn_cast<Instruction>(U.get());
871  if (!DefI)
872  return false;
873 
874  // This would need adjustment if we allow Inst to be a phi node -- the
875  // new use block won't simply be NewBB.
876 
877  auto *DefBlock = DefI->getParent();
878  if (DefBlock != NewBB && getLoopFor(DefBlock) != NewLoop)
879  return false;
880  }
881  }
882 
883  return true;
884  }
885 };
886 
887 // Allow clients to walk the list of nested loops...
888 template <> struct GraphTraits<const Loop *> {
889  typedef const Loop *NodeRef;
891 
892  static NodeRef getEntryNode(const Loop *L) { return L; }
893  static ChildIteratorType child_begin(NodeRef N) { return N->begin(); }
894  static ChildIteratorType child_end(NodeRef N) { return N->end(); }
895 };
896 
897 template <> struct GraphTraits<Loop *> {
898  typedef Loop *NodeRef;
900 
901  static NodeRef getEntryNode(Loop *L) { return L; }
902  static ChildIteratorType child_begin(NodeRef N) { return N->begin(); }
903  static ChildIteratorType child_end(NodeRef N) { return N->end(); }
904 };
905 
906 /// \brief Analysis pass that exposes the \c LoopInfo for a function.
907 class LoopAnalysis : public AnalysisInfoMixin<LoopAnalysis> {
909  static AnalysisKey Key;
910 
911 public:
912  typedef LoopInfo Result;
913 
915 };
916 
917 /// \brief Printer pass for the \c LoopAnalysis results.
918 class LoopPrinterPass : public PassInfoMixin<LoopPrinterPass> {
919  raw_ostream &OS;
920 
921 public:
922  explicit LoopPrinterPass(raw_ostream &OS) : OS(OS) {}
924 };
925 
926 /// \brief Verifier pass for the \c LoopAnalysis results.
927 struct LoopVerifierPass : public PassInfoMixin<LoopVerifierPass> {
929 };
930 
931 /// \brief The legacy pass manager's analysis pass to compute loop information.
933  LoopInfo LI;
934 
935 public:
936  static char ID; // Pass identification, replacement for typeid
937 
940  }
941 
942  LoopInfo &getLoopInfo() { return LI; }
943  const LoopInfo &getLoopInfo() const { return LI; }
944 
945  /// \brief Calculate the natural loop information for a given function.
946  bool runOnFunction(Function &F) override;
947 
948  void verifyAnalysis() const override;
949 
950  void releaseMemory() override { LI.releaseMemory(); }
951 
952  void print(raw_ostream &O, const Module *M = nullptr) const override;
953 
954  void getAnalysisUsage(AnalysisUsage &AU) const override;
955 };
956 
957 /// Function to print a loop's contents as LLVM's text IR assembly.
958 void printLoop(Loop &L, raw_ostream &OS, const std::string &Banner = "");
959 
960 } // End llvm namespace
961 
962 #endif
LoopInfo::iterator ChildIteratorType
Definition: LoopInfo.h:890
void destroy(LoopT *L)
Definition: LoopInfo.h:750
void push_back(const T &Elt)
Definition: SmallVector.h:212
LoopInfo Result
Definition: LoopInfo.h:912
iterator_range< typename GraphTraits< GraphType >::ChildIteratorType > children(const typename GraphTraits< GraphType >::NodeRef &G)
Definition: GraphTraits.h:102
iterator_range< use_iterator > uses()
Definition: Value.h:356
BlockT * getLoopLatch() const
If there is a single latch block for this loop, return it.
Definition: LoopInfoImpl.h:157
static PassRegistry * getPassRegistry()
getPassRegistry - Access the global registry object, which is automatically initialized at applicatio...
bool empty() const
Definition: LoopInfo.h:638
static bool isLoopInvariant(Value *V, const Loop *L, const DominatorTree *DT)
Perform a quick domtree based check for loop invariance assuming that V is used within the loop...
Compute iterated dominance frontiers using a linear time algorithm.
Definition: AllocatorList.h:24
void setParentLoop(LoopT *L)
This is a raw interface for bypassing addChildLoop.
Definition: LoopInfo.h:104
A Module instance is used to store all the information related to an LLVM module. ...
Definition: Module.h:63
unsigned getLoopDepth(const BlockT *BB) const
Return the loop nesting level of the specified block.
Definition: LoopInfo.h:666
Implements a dense probed hash-table based set.
Definition: DenseSet.h:221
unsigned getLoopDepth() const
Return the nesting level of this loop.
Definition: LoopInfo.h:92
void moveToHeader(BlockT *BB)
This method is used to move BB (which must be part of this loop) to be the loop header of the loop (t...
Definition: LoopInfo.h:340
void reserveBlocks(unsigned size)
interface to do reserve() for Blocks
Definition: LoopInfo.h:333
LoopT * removeChildLoop(iterator I)
This removes the specified child from being a subloop of this loop.
Definition: LoopInfo.h:307
std::pair< const BlockT *, const BlockT * > Edge
Edge type.
Definition: LoopInfo.h:246
BlockT * getLoopPreheader() const
If there is a preheader for this loop, return it.
Definition: LoopInfoImpl.h:106
void replaceChildLoopWith(LoopT *OldChild, LoopT *NewChild)
This is used when splitting loops up.
Definition: LoopInfoImpl.h:213
std::vector< LoopT * > & getSubLoopsVector()
Definition: LoopInfo.h:135
A debug info location.
Definition: DebugLoc.h:34
Metadata node.
Definition: Metadata.h:862
F(f)
LoopBase()
This creates an empty loop.
Definition: LoopInfo.h:379
Instances of this class are used to represent loops that are detected in the flow graph...
Definition: LoopInfo.h:63
This file defines the MallocAllocator and BumpPtrAllocator interfaces.
bool isInvalid() const
Return true if this loop is no longer valid.
Definition: LoopInfo.h:174
void print(raw_ostream &OS, unsigned Depth=0, bool Verbose=false) const
Print loop with all the BBs inside it.
Definition: LoopInfoImpl.h:325
Hexagon Hardware Loops
Definition: BitVector.h:920
unsigned getNumBackEdges() const
Calculate the number of back edges to the loop header.
Definition: LoopInfo.h:208
void initializeLoopInfoWrapperPassPass(PassRegistry &)
void Reset()
Deallocate all but the current slab and reset the current pointer to the beginning of it...
Definition: Allocator.h:192
LoopT * getLoopFor(const BlockT *BB) const
Return the inner most loop that BB lives in.
Definition: LoopInfo.h:659
A Use represents the edge between a Value definition and its users.
Definition: Use.h:56
void addBlockEntry(BlockT *BB)
This adds a basic block directly to the basic block list.
Definition: LoopInfo.h:320
static bool isNotAlreadyContainedIn(const LoopT *SubLoop, const LoopT *ParentLoop)
Definition: LoopInfo.h:730
std::vector< LoopT * >::const_iterator iterator
iterator/begin/end - The interface to the top-level loops in the current function.
Definition: LoopInfo.h:631
void getLoopLatches(SmallVectorImpl< BlockT *> &LoopLatches) const
Return all loop latch blocks of this loop.
Definition: LoopInfo.h:271
Printer pass for the LoopAnalysis results.
Definition: LoopInfo.h:918
Analysis pass that exposes the LoopInfo for a function.
Definition: LoopInfo.h:907
void Deallocate(const void *Ptr, size_t Size)
Definition: Allocator.h:275
BlockT * getHeader() const
Definition: LoopInfo.h:100
void getExitBlocks(SmallVectorImpl< BlockT *> &ExitBlocks) const
Return all of the successor blocks of this loop.
Definition: LoopInfoImpl.h:63
const LoopInfo & getLoopInfo() const
Definition: LoopInfo.h:943
auto reverse(ContainerTy &&C, typename std::enable_if< has_rbegin< ContainerTy >::value >::type *=nullptr) -> decltype(make_range(C.rbegin(), C.rend()))
Definition: STLExtras.h:186
std::vector< LoopT * >::const_iterator iterator
Definition: LoopInfo.h:139
Key
PAL metadata keys.
void addBasicBlockToLoop(BlockT *NewBB, LoopInfoBase< BlockT, LoopT > &LI)
This method is used by other analyses to update loop information.
Definition: LoopInfoImpl.h:183
A CRTP mix-in to automatically provide informational APIs needed for passes.
Definition: PassManager.h:365
void addTopLevelLoop(LoopT *New)
This adds the specified loop to the collection of top-level loops.
Definition: LoopInfo.h:710
LoopInfo & operator=(LoopInfo &&RHS)
Definition: LoopInfo.h:775
LocRange(DebugLoc Start, DebugLoc End)
Definition: LoopInfo.h:430
const DebugLoc & getEnd() const
Definition: LoopInfo.h:434
Concrete subclass of DominatorTreeBase that is used to compute a normal dominator tree...
Definition: Dominators.h:140
void releaseMemory() override
releaseMemory() - This member can be implemented by a pass if it wants to be able to release its memo...
Definition: LoopInfo.h:950
Core dominator tree base class.
Definition: LoopInfo.h:61
static bool runOnFunction(Function &F, bool PostInlining)
reverse_iterator rend() const
Definition: LoopInfo.h:145
void dump(const SparseBitVector< ElementSize > &LHS, raw_ostream &out)
A set of analyses that are preserved following a run of a transformation pass.
Definition: PassManager.h:153
reverse_iterator rbegin() const
Definition: LoopInfo.h:144
LLVM Basic Block Representation.
Definition: BasicBlock.h:59
bool isLoopExiting(const BlockT *BB) const
True if terminator in the block can branch to another block that is outside of the current loop...
Definition: LoopInfo.h:184
Allocate memory in an ever growing pool, as if by bump-pointer.
Definition: Allocator.h:138
static ChildIteratorType child_begin(NodeRef N)
Definition: LoopInfo.h:893
iterator end() const
Definition: LoopInfo.h:635
LLVM_ATTRIBUTE_RETURNS_NONNULL LLVM_ATTRIBUTE_RETURNS_NOALIAS void * Allocate(size_t Size, size_t Alignment)
Allocate space at the specified alignment.
Definition: Allocator.h:212
#define H(x, y, z)
Definition: MD5.cpp:57
LoopPrinterPass(raw_ostream &OS)
Definition: LoopInfo.h:922
std::pair< iterator, bool > insert(PtrType Ptr)
Inserts Ptr if and only if there is no element in the container equal to Ptr.
Definition: SmallPtrSet.h:371
A CRTP mix-in that provides informational APIs needed for analysis passes.
Definition: PassManager.h:382
const std::vector< BlockT * > & getBlocks() const
Get a list of the basic blocks which make up this loop.
Definition: LoopInfo.h:149
Represent the analysis usage information of a pass.
bool contains(const BlockT *BB) const
Return true if the specified basic block is in this loop.
Definition: LoopInfo.h:120
static const unsigned End
std::vector< BlockT * >::const_iterator block_iterator
Definition: LoopInfo.h:153
FunctionPass class - This class is used to implement most global optimizations.
Definition: Pass.h:285
op_range operands()
Definition: User.h:222
size_type count(ConstPtrType Ptr) const
count - Return 1 if the specified pointer is in the set, 0 otherwise.
Definition: SmallPtrSet.h:382
const Function * getFunction() const
Return the function this instruction belongs to.
Definition: Instruction.cpp:61
BlockT * getExitBlock() const
If getExitBlocks would return exactly one block, return that block.
Definition: LoopInfoImpl.h:76
void getExitingBlocks(SmallVectorImpl< BlockT *> &ExitingBlocks) const
Return all blocks inside the loop that have successors outside of the loop.
Definition: LoopInfoImpl.h:35
A range representing the start and end location of a loop.
Definition: LoopInfo.h:423
bool verify(const TargetRegisterInfo &TRI) const
Check that information hold by this instance make sense for the given TRI.
void getExitEdges(SmallVectorImpl< Edge > &ExitEdges) const
Return all pairs of (inside_block,outside_block).
Definition: LoopInfoImpl.h:87
iterator_range< T > make_range(T x, T y)
Convenience function for iterating over sub-ranges.
LoopInfoBase & operator=(LoopInfoBase &&RHS)
Definition: LoopInfo.h:602
BlockT * getLoopPredecessor() const
If the given loop&#39;s header has exactly one unique predecessor outside the loop, return it...
Definition: LoopInfoImpl.h:134
bool contains(const LoopT *L) const
Return true if the specified loop is contained within in this loop.
Definition: LoopInfo.h:110
auto find(R &&Range, const T &Val) -> decltype(std::begin(Range))
Provide wrappers to std::find which take ranges instead of having to pass begin/end explicitly...
Definition: STLExtras.h:788
bool erase(PtrType Ptr)
erase - If the set contains the specified pointer, remove it and return true, otherwise return false...
Definition: SmallPtrSet.h:378
bool movementPreservesLCSSAForm(Instruction *Inst, Instruction *NewLoc)
Checks if moving a specific instruction can break LCSSA in any loop.
Definition: LoopInfo.h:820
reverse_iterator rend() const
Definition: LoopInfo.h:637
Verifier pass for the LoopAnalysis results.
Definition: LoopInfo.h:927
This is a &#39;vector&#39; (really, a variable-sized array), optimized for the case when the array is small...
Definition: SmallVector.h:864
iterator begin() const
Definition: LoopInfo.h:142
LoopInfo & getLoopInfo()
Definition: LoopInfo.h:942
LoopT * removeLoop(iterator I)
This removes the specified top-level loop from this loop info object.
Definition: LoopInfo.h:680
bool contains(const InstT *Inst) const
Return true if the specified instruction is in this loop.
Definition: LoopInfo.h:126
static NodeRef getEntryNode(const Loop *L)
Definition: LoopInfo.h:892
LoopT * AllocateLoop(ArgsTy &&... Args)
Definition: LoopInfo.h:623
LoopInfo(LoopInfo &&Arg)
Definition: LoopInfo.h:774
static ChildIteratorType child_end(NodeRef N)
Definition: LoopInfo.h:894
static GCRegistry::Add< StatepointGC > D("statepoint-example", "an example strategy for statepoint")
std::vector< LoopT * >::const_reverse_iterator reverse_iterator
Definition: LoopInfo.h:141
bool isLoopLatch(const BlockT *BB) const
Definition: LoopInfo.h:197
iterator begin() const
Definition: LoopInfo.h:634
A range adaptor for a pair of iterators.
LoopInfo::iterator ChildIteratorType
Definition: LoopInfo.h:899
bool isLoopHeader(const BlockT *BB) const
Definition: LoopInfo.h:672
reverse_iterator rbegin() const
Definition: LoopInfo.h:636
amdgpu Simplify well known AMD library false Value Value * Arg
LoopT * getParentLoop() const
Definition: LoopInfo.h:101
const std::vector< LoopT * > & getSubLoops() const
Return the loops contained entirely within this loop.
Definition: LoopInfo.h:131
unsigned getNumBlocks() const
Get the number of blocks in this loop in constant time.
Definition: LoopInfo.h:163
void verifyLoopNest(DenseSet< const LoopT *> *Loops) const
Verify loop structure of this loop and all nested loops.
Definition: LoopInfoImpl.h:313
static NodeRef getEntryNode(Loop *L)
Definition: LoopInfo.h:901
const DebugLoc & getStart() const
Definition: LoopInfo.h:433
void addChildLoop(LoopT *NewChild)
Add the specified loop to be a child of this loop.
Definition: LoopInfo.h:298
StringRef getName() const
Definition: LoopInfo.h:558
Represents a single loop in the control flow graph.
Definition: LoopInfo.h:420
#define I(x, y, z)
Definition: MD5.cpp:58
#define N
static ChildIteratorType child_end(NodeRef N)
Definition: LoopInfo.h:903
void changeTopLevelLoop(LoopT *OldLoop, LoopT *NewLoop)
Replace the specified loop in the top-level loops list with the indicated loop.
Definition: LoopInfo.h:701
iterator end() const
Definition: LoopInfo.h:143
LLVM_NODISCARD std::enable_if<!is_simple_type< Y >::value, typename cast_retty< X, const Y >::ret_type >::type dyn_cast(const Y &Val)
Definition: Casting.h:323
block_iterator block_end() const
Definition: LoopInfo.h:155
void changeLoopFor(BlockT *BB, LoopT *L)
Change the top-level loop that contains BB to the specified loop.
Definition: LoopInfo.h:691
friend class LoopInfo
Definition: LoopInfo.h:586
void removeBlockFromLoop(BlockT *BB)
This removes the specified basic block from the current loop, updating the Blocks as appropriate...
Definition: LoopInfo.h:357
ValueT lookup(const_arg_type_t< KeyT > Val) const
lookup - Return the entry for the specified key, or a default constructed value if no such entry exis...
Definition: DenseMap.h:181
API to communicate dependencies between analyses during invalidation.
Definition: PassManager.h:559
bool empty() const
Definition: LoopInfo.h:146
assert(ImpDefSCC.getReg()==AMDGPU::SCC &&ImpDefSCC.isDef())
aarch64 promote const
LLVM Value Representation.
Definition: Value.h:73
const LoopT * operator[](const BlockT *BB) const
Same as getLoopFor.
Definition: LoopInfo.h:662
void reverseBlock(unsigned from)
interface to reverse Blocks[from, end of loop] in this loop
Definition: LoopInfo.h:327
This class implements an extremely fast bulk output stream that can only output to a stream...
Definition: raw_ostream.h:44
The legacy pass manager&#39;s analysis pass to compute loop information.
Definition: LoopInfo.h:932
void verifyLoop() const
Verify loop structure.
Definition: LoopInfoImpl.h:227
LoopInfoBase(LoopInfoBase &&Arg)
Definition: LoopInfo.h:595
StringRef - Represent a constant reference to a string, i.e.
Definition: StringRef.h:49
A container for analyses that lazily runs them and caches their results.
void releaseMemory()
Definition: LoopInfo.h:614
std::vector< LoopT * >::const_reverse_iterator reverse_iterator
Definition: LoopInfo.h:633
bool replacementPreservesLCSSAForm(Instruction *From, Value *To)
Returns true if replacing From with To everywhere is guaranteed to preserve LCSSA form...
Definition: LoopInfo.h:794
This header defines various interfaces for pass management in LLVM.
iterator_range< block_iterator > blocks() const
Definition: LoopInfo.h:156
void printLoop(Loop &L, raw_ostream &OS, const std::string &Banner="")
Function to print a loop&#39;s contents as LLVM&#39;s text IR assembly.
Definition: LoopInfo.cpp:733
block_iterator block_begin() const
Definition: LoopInfo.h:154
BlockT * getExitingBlock() const
If getExitingBlocks would return exactly one block, return that block.
Definition: LoopInfoImpl.h:50
A special type used by analysis passes to provide an address that identifies that particular analysis...
Definition: PassManager.h:70
static ChildIteratorType child_begin(NodeRef N)
Definition: LoopInfo.h:902
void removeBlock(BlockT *BB)
This method completely removes BB from all data structures, including all of the Loop objects it is n...
Definition: LoopInfo.h:718
constexpr char Args[]
Key for Kernel::Metadata::mArgs.
const BasicBlock * getParent() const
Definition: Instruction.h:66
LoopBase(BlockT *BB)
Definition: LoopInfo.h:381
LocRange(DebugLoc Start)
Definition: LoopInfo.h:429
This class builds and contains all of the top-level loop structures in the specified function...
Definition: LoopInfo.h:62