LLVM  8.0.0svn
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.
150  assert(!isInvalid() && "Loop not in a valid state!");
151  return Blocks;
152  }
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 a direct, mutable handle to the blocks vector so that we can
169  /// mutate it efficiently with techniques like `std::remove`.
170  std::vector<BlockT *> &getBlocksVector() {
171  assert(!isInvalid() && "Loop not in a valid state!");
172  return Blocks;
173  }
174  /// Return a direct, mutable handle to the blocks set so that we can
175  /// mutate it efficiently.
177  assert(!isInvalid() && "Loop not in a valid state!");
178  return DenseBlockSet;
179  }
180 
181  /// Return a direct, immutable handle to the blocks set.
183  assert(!isInvalid() && "Loop not in a valid state!");
184  return DenseBlockSet;
185  }
186 
187  /// Return true if this loop is no longer valid. The only valid use of this
188  /// helper is "assert(L.isInvalid())" or equivalent, since IsInvalid is set to
189  /// true by the destructor. In other words, if this accessor returns true,
190  /// the caller has already triggered UB by calling this accessor; and so it
191  /// can only be called in a context where a return value of true indicates a
192  /// programmer error.
193  bool isInvalid() const {
194 #if LLVM_ENABLE_ABI_BREAKING_CHECKS
195  return IsInvalid;
196 #else
197  return false;
198 #endif
199  }
200 
201  /// True if terminator in the block can branch to another block that is
202  /// outside of the current loop.
203  bool isLoopExiting(const BlockT *BB) const {
204  assert(!isInvalid() && "Loop not in a valid state!");
205  for (const auto &Succ : children<const BlockT *>(BB)) {
206  if (!contains(Succ))
207  return true;
208  }
209  return false;
210  }
211 
212  /// Returns true if \p BB is a loop-latch.
213  /// A latch block is a block that contains a branch back to the header.
214  /// This function is useful when there are multiple latches in a loop
215  /// because \fn getLoopLatch will return nullptr in that case.
216  bool isLoopLatch(const BlockT *BB) const {
217  assert(!isInvalid() && "Loop not in a valid state!");
218  assert(contains(BB) && "block does not belong to the loop");
219 
220  BlockT *Header = getHeader();
221  auto PredBegin = GraphTraits<Inverse<BlockT *>>::child_begin(Header);
222  auto PredEnd = GraphTraits<Inverse<BlockT *>>::child_end(Header);
223  return std::find(PredBegin, PredEnd, BB) != PredEnd;
224  }
225 
226  /// Calculate the number of back edges to the loop header.
227  unsigned getNumBackEdges() const {
228  assert(!isInvalid() && "Loop not in a valid state!");
229  unsigned NumBackEdges = 0;
230  BlockT *H = getHeader();
231 
232  for (const auto Pred : children<Inverse<BlockT *>>(H))
233  if (contains(Pred))
234  ++NumBackEdges;
235 
236  return NumBackEdges;
237  }
238 
239  //===--------------------------------------------------------------------===//
240  // APIs for simple analysis of the loop.
241  //
242  // Note that all of these methods can fail on general loops (ie, there may not
243  // be a preheader, etc). For best success, the loop simplification and
244  // induction variable canonicalization pass should be used to normalize loops
245  // for easy analysis. These methods assume canonical loops.
246 
247  /// Return all blocks inside the loop that have successors outside of the
248  /// loop. These are the blocks _inside of the current loop_ which branch out.
249  /// The returned list is always unique.
250  void getExitingBlocks(SmallVectorImpl<BlockT *> &ExitingBlocks) const;
251 
252  /// If getExitingBlocks would return exactly one block, return that block.
253  /// Otherwise return null.
254  BlockT *getExitingBlock() const;
255 
256  /// Return all of the successor blocks of this loop. These are the blocks
257  /// _outside of the current loop_ which are branched to.
258  void getExitBlocks(SmallVectorImpl<BlockT *> &ExitBlocks) const;
259 
260  /// If getExitBlocks would return exactly one block, return that block.
261  /// Otherwise return null.
262  BlockT *getExitBlock() const;
263 
264  /// Return true if no exit block for the loop has a predecessor that is
265  /// outside the loop.
266  bool hasDedicatedExits() const;
267 
268  /// Return all unique successor blocks of this loop.
269  /// These are the blocks _outside of the current loop_ which are branched to.
270  /// This assumes that loop exits are in canonical form, i.e. all exits are
271  /// dedicated exits.
272  void getUniqueExitBlocks(SmallVectorImpl<BlockT *> &ExitBlocks) const;
273 
274  /// If getUniqueExitBlocks would return exactly one block, return that block.
275  /// Otherwise return null.
276  BlockT *getUniqueExitBlock() const;
277 
278  /// Edge type.
279  typedef std::pair<const BlockT *, const BlockT *> Edge;
280 
281  /// Return all pairs of (_inside_block_,_outside_block_).
282  void getExitEdges(SmallVectorImpl<Edge> &ExitEdges) const;
283 
284  /// If there is a preheader for this loop, return it. A loop has a preheader
285  /// if there is only one edge to the header of the loop from outside of the
286  /// loop. If this is the case, the block branching to the header of the loop
287  /// is the preheader node.
288  ///
289  /// This method returns null if there is no preheader for the loop.
290  BlockT *getLoopPreheader() const;
291 
292  /// If the given loop's header has exactly one unique predecessor outside the
293  /// loop, return it. Otherwise return null.
294  /// This is less strict that the loop "preheader" concept, which requires
295  /// the predecessor to have exactly one successor.
296  BlockT *getLoopPredecessor() const;
297 
298  /// If there is a single latch block for this loop, return it.
299  /// A latch block is a block that contains a branch back to the header.
300  BlockT *getLoopLatch() const;
301 
302  /// Return all loop latch blocks of this loop. A latch block is a block that
303  /// contains a branch back to the header.
304  void getLoopLatches(SmallVectorImpl<BlockT *> &LoopLatches) const {
305  assert(!isInvalid() && "Loop not in a valid state!");
306  BlockT *H = getHeader();
307  for (const auto Pred : children<Inverse<BlockT *>>(H))
308  if (contains(Pred))
309  LoopLatches.push_back(Pred);
310  }
311 
312  //===--------------------------------------------------------------------===//
313  // APIs for updating loop information after changing the CFG
314  //
315 
316  /// This method is used by other analyses to update loop information.
317  /// NewBB is set to be a new member of the current loop.
318  /// Because of this, it is added as a member of all parent loops, and is added
319  /// to the specified LoopInfo object as being in the current basic block. It
320  /// is not valid to replace the loop header with this method.
321  void addBasicBlockToLoop(BlockT *NewBB, LoopInfoBase<BlockT, LoopT> &LI);
322 
323  /// This is used when splitting loops up. It replaces the OldChild entry in
324  /// our children list with NewChild, and updates the parent pointer of
325  /// OldChild to be null and the NewChild to be this loop.
326  /// This updates the loop depth of the new child.
327  void replaceChildLoopWith(LoopT *OldChild, LoopT *NewChild);
328 
329  /// Add the specified loop to be a child of this loop.
330  /// This updates the loop depth of the new child.
331  void addChildLoop(LoopT *NewChild) {
332  assert(!isInvalid() && "Loop not in a valid state!");
333  assert(!NewChild->ParentLoop && "NewChild already has a parent!");
334  NewChild->ParentLoop = static_cast<LoopT *>(this);
335  SubLoops.push_back(NewChild);
336  }
337 
338  /// This removes the specified child from being a subloop of this loop. The
339  /// loop is not deleted, as it will presumably be inserted into another loop.
340  LoopT *removeChildLoop(iterator I) {
341  assert(!isInvalid() && "Loop not in a valid state!");
342  assert(I != SubLoops.end() && "Cannot remove end iterator!");
343  LoopT *Child = *I;
344  assert(Child->ParentLoop == this && "Child is not a child of this loop!");
345  SubLoops.erase(SubLoops.begin() + (I - begin()));
346  Child->ParentLoop = nullptr;
347  return Child;
348  }
349 
350  /// This removes the specified child from being a subloop of this loop. The
351  /// loop is not deleted, as it will presumably be inserted into another loop.
352  LoopT *removeChildLoop(LoopT *Child) {
353  return removeChildLoop(llvm::find(*this, Child));
354  }
355 
356  /// This adds a basic block directly to the basic block list.
357  /// This should only be used by transformations that create new loops. Other
358  /// transformations should use addBasicBlockToLoop.
359  void addBlockEntry(BlockT *BB) {
360  assert(!isInvalid() && "Loop not in a valid state!");
361  Blocks.push_back(BB);
362  DenseBlockSet.insert(BB);
363  }
364 
365  /// interface to reverse Blocks[from, end of loop] in this loop
366  void reverseBlock(unsigned from) {
367  assert(!isInvalid() && "Loop not in a valid state!");
368  std::reverse(Blocks.begin() + from, Blocks.end());
369  }
370 
371  /// interface to do reserve() for Blocks
372  void reserveBlocks(unsigned size) {
373  assert(!isInvalid() && "Loop not in a valid state!");
374  Blocks.reserve(size);
375  }
376 
377  /// This method is used to move BB (which must be part of this loop) to be the
378  /// loop header of the loop (the block that dominates all others).
379  void moveToHeader(BlockT *BB) {
380  assert(!isInvalid() && "Loop not in a valid state!");
381  if (Blocks[0] == BB)
382  return;
383  for (unsigned i = 0;; ++i) {
384  assert(i != Blocks.size() && "Loop does not contain BB!");
385  if (Blocks[i] == BB) {
386  Blocks[i] = Blocks[0];
387  Blocks[0] = BB;
388  return;
389  }
390  }
391  }
392 
393  /// This removes the specified basic block from the current loop, updating the
394  /// Blocks as appropriate. This does not update the mapping in the LoopInfo
395  /// class.
396  void removeBlockFromLoop(BlockT *BB) {
397  assert(!isInvalid() && "Loop not in a valid state!");
398  auto I = find(Blocks, BB);
399  assert(I != Blocks.end() && "N is not in this list!");
400  Blocks.erase(I);
401 
402  DenseBlockSet.erase(BB);
403  }
404 
405  /// Verify loop structure
406  void verifyLoop() const;
407 
408  /// Verify loop structure of this loop and all nested loops.
410 
411  /// Print loop with all the BBs inside it.
412  void print(raw_ostream &OS, unsigned Depth = 0, bool Verbose = false) const;
413 
414 protected:
415  friend class LoopInfoBase<BlockT, LoopT>;
416 
417  /// This creates an empty loop.
418  LoopBase() : ParentLoop(nullptr) {}
419 
420  explicit LoopBase(BlockT *BB) : ParentLoop(nullptr) {
421  Blocks.push_back(BB);
422  DenseBlockSet.insert(BB);
423  }
424 
425  // Since loop passes like SCEV are allowed to key analysis results off of
426  // `Loop` pointers, we cannot re-use pointers within a loop pass manager.
427  // This means loop passes should not be `delete` ing `Loop` objects directly
428  // (and risk a later `Loop` allocation re-using the address of a previous one)
429  // but should be using LoopInfo::markAsRemoved, which keeps around the `Loop`
430  // pointer till the end of the lifetime of the `LoopInfo` object.
431  //
432  // To make it easier to follow this rule, we mark the destructor as
433  // non-public.
435  for (auto *SubLoop : SubLoops)
436  SubLoop->~LoopT();
437 
438 #if LLVM_ENABLE_ABI_BREAKING_CHECKS
439  IsInvalid = true;
440 #endif
441  SubLoops.clear();
442  Blocks.clear();
443  DenseBlockSet.clear();
444  ParentLoop = nullptr;
445  }
446 };
447 
448 template <class BlockT, class LoopT>
449 raw_ostream &operator<<(raw_ostream &OS, const LoopBase<BlockT, LoopT> &Loop) {
450  Loop.print(OS);
451  return OS;
452 }
453 
454 // Implementation in LoopInfoImpl.h
455 extern template class LoopBase<BasicBlock, Loop>;
456 
457 /// Represents a single loop in the control flow graph. Note that not all SCCs
458 /// in the CFG are necessarily loops.
460 public:
461  /// A range representing the start and end location of a loop.
462  class LocRange {
463  DebugLoc Start;
464  DebugLoc End;
465 
466  public:
467  LocRange() {}
468  LocRange(DebugLoc Start) : Start(std::move(Start)), End(std::move(Start)) {}
470  : Start(std::move(Start)), End(std::move(End)) {}
471 
472  const DebugLoc &getStart() const { return Start; }
473  const DebugLoc &getEnd() const { return End; }
474 
475  /// Check for null.
476  ///
477  explicit operator bool() const { return Start && End; }
478  };
479 
480  /// Return true if the specified value is loop invariant.
481  bool isLoopInvariant(const Value *V) const;
482 
483  /// Return true if all the operands of the specified instruction are loop
484  /// invariant.
485  bool hasLoopInvariantOperands(const Instruction *I) const;
486 
487  /// If the given value is an instruction inside of the loop and it can be
488  /// hoisted, do so to make it trivially loop-invariant.
489  /// Return true if the value after any hoisting is loop invariant. This
490  /// function can be used as a slightly more aggressive replacement for
491  /// isLoopInvariant.
492  ///
493  /// If InsertPt is specified, it is the point to hoist instructions to.
494  /// If null, the terminator of the loop preheader is used.
495  bool makeLoopInvariant(Value *V, bool &Changed,
496  Instruction *InsertPt = nullptr) const;
497 
498  /// If the given instruction is inside of the loop and it can be hoisted, do
499  /// so to make it trivially loop-invariant.
500  /// Return true if the instruction after any hoisting is loop invariant. This
501  /// function can be used as a slightly more aggressive replacement for
502  /// isLoopInvariant.
503  ///
504  /// If InsertPt is specified, it is the point to hoist instructions to.
505  /// If null, the terminator of the loop preheader is used.
506  ///
507  bool makeLoopInvariant(Instruction *I, bool &Changed,
508  Instruction *InsertPt = nullptr) const;
509 
510  /// Check to see if the loop has a canonical induction variable: an integer
511  /// recurrence that starts at 0 and increments by one each time through the
512  /// loop. If so, return the phi node that corresponds to it.
513  ///
514  /// The IndVarSimplify pass transforms loops to have a canonical induction
515  /// variable.
516  ///
517  PHINode *getCanonicalInductionVariable() const;
518 
519  /// Return true if the Loop is in LCSSA form.
520  bool isLCSSAForm(DominatorTree &DT) const;
521 
522  /// Return true if this Loop and all inner subloops are in LCSSA form.
523  bool isRecursivelyLCSSAForm(DominatorTree &DT, const LoopInfo &LI) const;
524 
525  /// Return true if the Loop is in the form that the LoopSimplify form
526  /// transforms loops to, which is sometimes called normal form.
527  bool isLoopSimplifyForm() const;
528 
529  /// Return true if the loop body is safe to clone in practice.
530  bool isSafeToClone() const;
531 
532  /// Returns true if the loop is annotated parallel.
533  ///
534  /// A parallel loop can be assumed to not contain any dependencies between
535  /// iterations by the compiler. That is, any loop-carried dependency checking
536  /// can be skipped completely when parallelizing the loop on the target
537  /// machine. Thus, if the parallel loop information originates from the
538  /// programmer, e.g. via the OpenMP parallel for pragma, it is the
539  /// programmer's responsibility to ensure there are no loop-carried
540  /// dependencies. The final execution order of the instructions across
541  /// iterations is not guaranteed, thus, the end result might or might not
542  /// implement actual concurrent execution of instructions across multiple
543  /// iterations.
544  bool isAnnotatedParallel() const;
545 
546  /// Return the llvm.loop loop id metadata node for this loop if it is present.
547  ///
548  /// If this loop contains the same llvm.loop metadata on each branch to the
549  /// header then the node is returned. If any latch instruction does not
550  /// contain llvm.loop or if multiple latches contain different nodes then
551  /// 0 is returned.
552  MDNode *getLoopID() const;
553  /// Set the llvm.loop loop id metadata for this loop.
554  ///
555  /// The LoopID metadata node will be added to each terminator instruction in
556  /// the loop that branches to the loop header.
557  ///
558  /// The LoopID metadata node should have one or more operands and the first
559  /// operand should be the node itself.
560  void setLoopID(MDNode *LoopID) const;
561 
562  /// Add llvm.loop.unroll.disable to this loop's loop id metadata.
563  ///
564  /// Remove existing unroll metadata and add unroll disable metadata to
565  /// indicate the loop has already been unrolled. This prevents a loop
566  /// from being unrolled more than is directed by a pragma if the loop
567  /// unrolling pass is run more than once (which it generally is).
568  void setLoopAlreadyUnrolled();
569 
570  void dump() const;
571  void dumpVerbose() const;
572 
573  /// Return the debug location of the start of this loop.
574  /// This looks for a BB terminating instruction with a known debug
575  /// location by looking at the preheader and header blocks. If it
576  /// cannot find a terminating instruction with location information,
577  /// it returns an unknown location.
578  DebugLoc getStartLoc() const;
579 
580  /// Return the source code span of the loop.
581  LocRange getLocRange() const;
582 
583  StringRef getName() const {
584  if (BasicBlock *Header = getHeader())
585  if (Header->hasName())
586  return Header->getName();
587  return "<unnamed loop>";
588  }
589 
590 private:
591  Loop() = default;
592 
595  explicit Loop(BasicBlock *BB) : LoopBase<BasicBlock, Loop>(BB) {}
596  ~Loop() = default;
597 };
598 
599 //===----------------------------------------------------------------------===//
600 /// This class builds and contains all of the top-level loop
601 /// structures in the specified function.
602 ///
603 
604 template <class BlockT, class LoopT> class LoopInfoBase {
605  // BBMap - Mapping of basic blocks to the inner most loop they occur in
607  std::vector<LoopT *> TopLevelLoops;
608  BumpPtrAllocator LoopAllocator;
609 
611  friend class LoopInfo;
612 
613  void operator=(const LoopInfoBase &) = delete;
614  LoopInfoBase(const LoopInfoBase &) = delete;
615 
616 public:
618  ~LoopInfoBase() { releaseMemory(); }
619 
621  : BBMap(std::move(Arg.BBMap)),
622  TopLevelLoops(std::move(Arg.TopLevelLoops)),
623  LoopAllocator(std::move(Arg.LoopAllocator)) {
624  // We have to clear the arguments top level loops as we've taken ownership.
625  Arg.TopLevelLoops.clear();
626  }
628  BBMap = std::move(RHS.BBMap);
629 
630  for (auto *L : TopLevelLoops)
631  L->~LoopT();
632 
633  TopLevelLoops = std::move(RHS.TopLevelLoops);
634  LoopAllocator = std::move(RHS.LoopAllocator);
635  RHS.TopLevelLoops.clear();
636  return *this;
637  }
638 
639  void releaseMemory() {
640  BBMap.clear();
641 
642  for (auto *L : TopLevelLoops)
643  L->~LoopT();
644  TopLevelLoops.clear();
645  LoopAllocator.Reset();
646  }
647 
648  template <typename... ArgsTy> LoopT *AllocateLoop(ArgsTy &&... Args) {
649  LoopT *Storage = LoopAllocator.Allocate<LoopT>();
650  return new (Storage) LoopT(std::forward<ArgsTy>(Args)...);
651  }
652 
653  /// iterator/begin/end - The interface to the top-level loops in the current
654  /// function.
655  ///
656  typedef typename std::vector<LoopT *>::const_iterator iterator;
657  typedef
658  typename std::vector<LoopT *>::const_reverse_iterator reverse_iterator;
659  iterator begin() const { return TopLevelLoops.begin(); }
660  iterator end() const { return TopLevelLoops.end(); }
661  reverse_iterator rbegin() const { return TopLevelLoops.rbegin(); }
662  reverse_iterator rend() const { return TopLevelLoops.rend(); }
663  bool empty() const { return TopLevelLoops.empty(); }
664 
665  /// Return all of the loops in the function in preorder across the loop
666  /// nests, with siblings in forward program order.
667  ///
668  /// Note that because loops form a forest of trees, preorder is equivalent to
669  /// reverse postorder.
670  SmallVector<LoopT *, 4> getLoopsInPreorder();
671 
672  /// Return all of the loops in the function in preorder across the loop
673  /// nests, with siblings in *reverse* program order.
674  ///
675  /// Note that because loops form a forest of trees, preorder is equivalent to
676  /// reverse postorder.
677  ///
678  /// Also note that this is *not* a reverse preorder. Only the siblings are in
679  /// reverse program order.
680  SmallVector<LoopT *, 4> getLoopsInReverseSiblingPreorder();
681 
682  /// Return the inner most loop that BB lives in. If a basic block is in no
683  /// loop (for example the entry node), null is returned.
684  LoopT *getLoopFor(const BlockT *BB) const { return BBMap.lookup(BB); }
685 
686  /// Same as getLoopFor.
687  const LoopT *operator[](const BlockT *BB) const { return getLoopFor(BB); }
688 
689  /// Return the loop nesting level of the specified block. A depth of 0 means
690  /// the block is not inside any loop.
691  unsigned getLoopDepth(const BlockT *BB) const {
692  const LoopT *L = getLoopFor(BB);
693  return L ? L->getLoopDepth() : 0;
694  }
695 
696  // True if the block is a loop header node
697  bool isLoopHeader(const BlockT *BB) const {
698  const LoopT *L = getLoopFor(BB);
699  return L && L->getHeader() == BB;
700  }
701 
702  /// This removes the specified top-level loop from this loop info object.
703  /// The loop is not deleted, as it will presumably be inserted into
704  /// another loop.
705  LoopT *removeLoop(iterator I) {
706  assert(I != end() && "Cannot remove end iterator!");
707  LoopT *L = *I;
708  assert(!L->getParentLoop() && "Not a top-level loop!");
709  TopLevelLoops.erase(TopLevelLoops.begin() + (I - begin()));
710  return L;
711  }
712 
713  /// Change the top-level loop that contains BB to the specified loop.
714  /// This should be used by transformations that restructure the loop hierarchy
715  /// tree.
716  void changeLoopFor(BlockT *BB, LoopT *L) {
717  if (!L) {
718  BBMap.erase(BB);
719  return;
720  }
721  BBMap[BB] = L;
722  }
723 
724  /// Replace the specified loop in the top-level loops list with the indicated
725  /// loop.
726  void changeTopLevelLoop(LoopT *OldLoop, LoopT *NewLoop) {
727  auto I = find(TopLevelLoops, OldLoop);
728  assert(I != TopLevelLoops.end() && "Old loop not at top level!");
729  *I = NewLoop;
730  assert(!NewLoop->ParentLoop && !OldLoop->ParentLoop &&
731  "Loops already embedded into a subloop!");
732  }
733 
734  /// This adds the specified loop to the collection of top-level loops.
735  void addTopLevelLoop(LoopT *New) {
736  assert(!New->getParentLoop() && "Loop already in subloop!");
737  TopLevelLoops.push_back(New);
738  }
739 
740  /// This method completely removes BB from all data structures,
741  /// including all of the Loop objects it is nested in and our mapping from
742  /// BasicBlocks to loops.
743  void removeBlock(BlockT *BB) {
744  auto I = BBMap.find(BB);
745  if (I != BBMap.end()) {
746  for (LoopT *L = I->second; L; L = L->getParentLoop())
747  L->removeBlockFromLoop(BB);
748 
749  BBMap.erase(I);
750  }
751  }
752 
753  // Internals
754 
755  static bool isNotAlreadyContainedIn(const LoopT *SubLoop,
756  const LoopT *ParentLoop) {
757  if (!SubLoop)
758  return true;
759  if (SubLoop == ParentLoop)
760  return false;
761  return isNotAlreadyContainedIn(SubLoop->getParentLoop(), ParentLoop);
762  }
763 
764  /// Create the loop forest using a stable algorithm.
765  void analyze(const DominatorTreeBase<BlockT, false> &DomTree);
766 
767  // Debugging
768  void print(raw_ostream &OS) const;
769 
770  void verify(const DominatorTreeBase<BlockT, false> &DomTree) const;
771 
772  /// Destroy a loop that has been removed from the `LoopInfo` nest.
773  ///
774  /// This runs the destructor of the loop object making it invalid to
775  /// reference afterward. The memory is retained so that the *pointer* to the
776  /// loop remains valid.
777  ///
778  /// The caller is responsible for removing this loop from the loop nest and
779  /// otherwise disconnecting it from the broader `LoopInfo` data structures.
780  /// Callers that don't naturally handle this themselves should probably call
781  /// `erase' instead.
782  void destroy(LoopT *L) {
783  L->~LoopT();
784 
785  // Since LoopAllocator is a BumpPtrAllocator, this Deallocate only poisons
786  // \c L, but the pointer remains valid for non-dereferencing uses.
787  LoopAllocator.Deallocate(L);
788  }
789 };
790 
791 // Implementation in LoopInfoImpl.h
792 extern template class LoopInfoBase<BasicBlock, Loop>;
793 
796 
798 
799  void operator=(const LoopInfo &) = delete;
800  LoopInfo(const LoopInfo &) = delete;
801 
802 public:
803  LoopInfo() {}
804  explicit LoopInfo(const DominatorTreeBase<BasicBlock, false> &DomTree);
805 
806  LoopInfo(LoopInfo &&Arg) : BaseT(std::move(static_cast<BaseT &>(Arg))) {}
808  BaseT::operator=(std::move(static_cast<BaseT &>(RHS)));
809  return *this;
810  }
811 
812  /// Handle invalidation explicitly.
813  bool invalidate(Function &F, const PreservedAnalyses &PA,
815 
816  // Most of the public interface is provided via LoopInfoBase.
817 
818  /// Update LoopInfo after removing the last backedge from a loop. This updates
819  /// the loop forest and parent loops for each block so that \c L is no longer
820  /// referenced, but does not actually delete \c L immediately. The pointer
821  /// will remain valid until this LoopInfo's memory is released.
822  void erase(Loop *L);
823 
824  /// Returns true if replacing From with To everywhere is guaranteed to
825  /// preserve LCSSA form.
827  // Preserving LCSSA form is only problematic if the replacing value is an
828  // instruction.
830  if (!I)
831  return true;
832  // If both instructions are defined in the same basic block then replacement
833  // cannot break LCSSA form.
834  if (I->getParent() == From->getParent())
835  return true;
836  // If the instruction is not defined in a loop then it can safely replace
837  // anything.
838  Loop *ToLoop = getLoopFor(I->getParent());
839  if (!ToLoop)
840  return true;
841  // If the replacing instruction is defined in the same loop as the original
842  // instruction, or in a loop that contains it as an inner loop, then using
843  // it as a replacement will not break LCSSA form.
844  return ToLoop->contains(getLoopFor(From->getParent()));
845  }
846 
847  /// Checks if moving a specific instruction can break LCSSA in any loop.
848  ///
849  /// Return true if moving \p Inst to before \p NewLoc will break LCSSA,
850  /// assuming that the function containing \p Inst and \p NewLoc is currently
851  /// in LCSSA form.
853  assert(Inst->getFunction() == NewLoc->getFunction() &&
854  "Can't reason about IPO!");
855 
856  auto *OldBB = Inst->getParent();
857  auto *NewBB = NewLoc->getParent();
858 
859  // Movement within the same loop does not break LCSSA (the equality check is
860  // to avoid doing a hashtable lookup in case of intra-block movement).
861  if (OldBB == NewBB)
862  return true;
863 
864  auto *OldLoop = getLoopFor(OldBB);
865  auto *NewLoop = getLoopFor(NewBB);
866 
867  if (OldLoop == NewLoop)
868  return true;
869 
870  // Check if Outer contains Inner; with the null loop counting as the
871  // "outermost" loop.
872  auto Contains = [](const Loop *Outer, const Loop *Inner) {
873  return !Outer || Outer->contains(Inner);
874  };
875 
876  // To check that the movement of Inst to before NewLoc does not break LCSSA,
877  // we need to check two sets of uses for possible LCSSA violations at
878  // NewLoc: the users of NewInst, and the operands of NewInst.
879 
880  // If we know we're hoisting Inst out of an inner loop to an outer loop,
881  // then the uses *of* Inst don't need to be checked.
882 
883  if (!Contains(NewLoop, OldLoop)) {
884  for (Use &U : Inst->uses()) {
885  auto *UI = cast<Instruction>(U.getUser());
886  auto *UBB = isa<PHINode>(UI) ? cast<PHINode>(UI)->getIncomingBlock(U)
887  : UI->getParent();
888  if (UBB != NewBB && getLoopFor(UBB) != NewLoop)
889  return false;
890  }
891  }
892 
893  // If we know we're sinking Inst from an outer loop into an inner loop, then
894  // the *operands* of Inst don't need to be checked.
895 
896  if (!Contains(OldLoop, NewLoop)) {
897  // See below on why we can't handle phi nodes here.
898  if (isa<PHINode>(Inst))
899  return false;
900 
901  for (Use &U : Inst->operands()) {
902  auto *DefI = dyn_cast<Instruction>(U.get());
903  if (!DefI)
904  return false;
905 
906  // This would need adjustment if we allow Inst to be a phi node -- the
907  // new use block won't simply be NewBB.
908 
909  auto *DefBlock = DefI->getParent();
910  if (DefBlock != NewBB && getLoopFor(DefBlock) != NewLoop)
911  return false;
912  }
913  }
914 
915  return true;
916  }
917 };
918 
919 // Allow clients to walk the list of nested loops...
920 template <> struct GraphTraits<const Loop *> {
921  typedef const Loop *NodeRef;
923 
924  static NodeRef getEntryNode(const Loop *L) { return L; }
925  static ChildIteratorType child_begin(NodeRef N) { return N->begin(); }
926  static ChildIteratorType child_end(NodeRef N) { return N->end(); }
927 };
928 
929 template <> struct GraphTraits<Loop *> {
930  typedef Loop *NodeRef;
932 
933  static NodeRef getEntryNode(Loop *L) { return L; }
934  static ChildIteratorType child_begin(NodeRef N) { return N->begin(); }
935  static ChildIteratorType child_end(NodeRef N) { return N->end(); }
936 };
937 
938 /// Analysis pass that exposes the \c LoopInfo for a function.
939 class LoopAnalysis : public AnalysisInfoMixin<LoopAnalysis> {
941  static AnalysisKey Key;
942 
943 public:
944  typedef LoopInfo Result;
945 
947 };
948 
949 /// Printer pass for the \c LoopAnalysis results.
950 class LoopPrinterPass : public PassInfoMixin<LoopPrinterPass> {
951  raw_ostream &OS;
952 
953 public:
954  explicit LoopPrinterPass(raw_ostream &OS) : OS(OS) {}
956 };
957 
958 /// Verifier pass for the \c LoopAnalysis results.
959 struct LoopVerifierPass : public PassInfoMixin<LoopVerifierPass> {
961 };
962 
963 /// The legacy pass manager's analysis pass to compute loop information.
965  LoopInfo LI;
966 
967 public:
968  static char ID; // Pass identification, replacement for typeid
969 
972  }
973 
974  LoopInfo &getLoopInfo() { return LI; }
975  const LoopInfo &getLoopInfo() const { return LI; }
976 
977  /// Calculate the natural loop information for a given function.
978  bool runOnFunction(Function &F) override;
979 
980  void verifyAnalysis() const override;
981 
982  void releaseMemory() override { LI.releaseMemory(); }
983 
984  void print(raw_ostream &O, const Module *M = nullptr) const override;
985 
986  void getAnalysisUsage(AnalysisUsage &AU) const override;
987 };
988 
989 /// Function to print a loop's contents as LLVM's text IR assembly.
990 void printLoop(Loop &L, raw_ostream &OS, const std::string &Banner = "");
991 
992 } // End llvm namespace
993 
994 #endif
LoopInfo::iterator ChildIteratorType
Definition: LoopInfo.h:922
void destroy(LoopT *L)
Destroy a loop that has been removed from the LoopInfo nest.
Definition: LoopInfo.h:782
void push_back(const T &Elt)
Definition: SmallVector.h:218
LoopInfo Result
Definition: LoopInfo.h:944
iterator_range< typename GraphTraits< GraphType >::ChildIteratorType > children(const typename GraphTraits< GraphType >::NodeRef &G)
Definition: GraphTraits.h:122
iterator_range< use_iterator > uses()
Definition: Value.h:355
BlockT * getLoopLatch() const
If there is a single latch block for this loop, return it.
Definition: LoopInfoImpl.h:225
static PassRegistry * getPassRegistry()
getPassRegistry - Access the global registry object, which is automatically initialized at applicatio...
std::vector< BlockT * > & getBlocksVector()
Return a direct, mutable handle to the blocks vector so that we can mutate it efficiently with techni...
Definition: LoopInfo.h:170
bool empty() const
Definition: LoopInfo.h:663
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
ArrayRef< BlockT * >::const_iterator block_iterator
Definition: LoopInfo.h:153
A Module instance is used to store all the information related to an LLVM module. ...
Definition: Module.h:64
bool hasDedicatedExits() const
Return true if no exit block for the loop has a predecessor that is outside the loop.
Definition: LoopInfoImpl.h:86
unsigned getLoopDepth(const BlockT *BB) const
Return the loop nesting level of the specified block.
Definition: LoopInfo.h:691
Implements a dense probed hash-table based set.
Definition: DenseSet.h:250
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:379
void reserveBlocks(unsigned size)
interface to do reserve() for Blocks
Definition: LoopInfo.h:372
LoopT * removeChildLoop(iterator I)
This removes the specified child from being a subloop of this loop.
Definition: LoopInfo.h:340
std::pair< const BlockT *, const BlockT * > Edge
Edge type.
Definition: LoopInfo.h:279
BlockT * getLoopPreheader() const
If there is a preheader for this loop, return it.
Definition: LoopInfoImpl.h:174
void replaceChildLoopWith(LoopT *OldChild, LoopT *NewChild)
This is used when splitting loops up.
Definition: LoopInfoImpl.h:281
std::vector< LoopT * > & getSubLoopsVector()
Definition: LoopInfo.h:135
A debug info location.
Definition: DebugLoc.h:34
Metadata node.
Definition: Metadata.h:864
F(f)
const SmallPtrSetImpl< const BlockT * > & getBlocksSet() const
Return a direct, immutable handle to the blocks set.
Definition: LoopInfo.h:182
LoopBase()
This creates an empty loop.
Definition: LoopInfo.h:418
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:193
void print(raw_ostream &OS, unsigned Depth=0, bool Verbose=false) const
Print loop with all the BBs inside it.
Definition: LoopInfoImpl.h:393
Hexagon Hardware Loops
Definition: BitVector.h:938
unsigned getNumBackEdges() const
Calculate the number of back edges to the loop header.
Definition: LoopInfo.h:227
void initializeLoopInfoWrapperPassPass(PassRegistry &)
void Reset()
Deallocate all but the current slab and reset the current pointer to the beginning of it...
Definition: Allocator.h:195
LoopT * getLoopFor(const BlockT *BB) const
Return the inner most loop that BB lives in.
Definition: LoopInfo.h:684
SmallPtrSetImpl< const BlockT * > & getBlocksSet()
Return a direct, mutable handle to the blocks set so that we can mutate it efficiently.
Definition: LoopInfo.h:176
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:359
static bool isNotAlreadyContainedIn(const LoopT *SubLoop, const LoopT *ParentLoop)
Definition: LoopInfo.h:755
std::vector< LoopT * >::const_iterator iterator
iterator/begin/end - The interface to the top-level loops in the current function.
Definition: LoopInfo.h:656
void getLoopLatches(SmallVectorImpl< BlockT *> &LoopLatches) const
Return all loop latch blocks of this loop.
Definition: LoopInfo.h:304
Printer pass for the LoopAnalysis results.
Definition: LoopInfo.h:950
Analysis pass that exposes the LoopInfo for a function.
Definition: LoopInfo.h:939
void Deallocate(const void *Ptr, size_t Size)
Definition: Allocator.h:278
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:975
auto reverse(ContainerTy &&C, typename std::enable_if< has_rbegin< ContainerTy >::value >::type *=nullptr) -> decltype(make_range(C.rbegin(), C.rend()))
Definition: STLExtras.h:251
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:251
A CRTP mix-in to automatically provide informational APIs needed for passes.
Definition: PassManager.h:366
void addTopLevelLoop(LoopT *New)
This adds the specified loop to the collection of top-level loops.
Definition: LoopInfo.h:735
ArrayRef - Represent a constant reference to an array (0 or more elements consecutively in memory)...
Definition: APInt.h:33
LoopInfo & operator=(LoopInfo &&RHS)
Definition: LoopInfo.h:807
LocRange(DebugLoc Start, DebugLoc End)
Definition: LoopInfo.h:469
const DebugLoc & getEnd() const
Definition: LoopInfo.h:473
Concrete subclass of DominatorTreeBase that is used to compute a normal dominator tree...
Definition: Dominators.h:145
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:982
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:154
reverse_iterator rbegin() const
Definition: LoopInfo.h:144
LLVM Basic Block Representation.
Definition: BasicBlock.h:58
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:203
Allocate memory in an ever growing pool, as if by bump-pointer.
Definition: Allocator.h:141
static ChildIteratorType child_begin(NodeRef N)
Definition: LoopInfo.h:925
iterator end() const
Definition: LoopInfo.h:660
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:215
#define H(x, y, z)
Definition: MD5.cpp:57
LoopPrinterPass(raw_ostream &OS)
Definition: LoopInfo.h:954
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:383
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
FunctionPass class - This class is used to implement most global optimizations.
Definition: Pass.h:285
op_range operands()
Definition: User.h:238
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:60
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
BlockT * getUniqueExitBlock() const
If getUniqueExitBlocks would return exactly one block, return that block.
Definition: LoopInfoImpl.h:145
A range representing the start and end location of a loop.
Definition: LoopInfo.h:462
auto find(R &&Range, const T &Val) -> decltype(adl_begin(Range))
Provide wrappers to std::find which take ranges instead of having to pass begin/end explicitly...
Definition: STLExtras.h:1063
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:155
iterator_range< T > make_range(T x, T y)
Convenience function for iterating over sub-ranges.
LoopInfoBase & operator=(LoopInfoBase &&RHS)
Definition: LoopInfo.h:627
BlockT * getLoopPredecessor() const
If the given loop&#39;s header has exactly one unique predecessor outside the loop, return it...
Definition: LoopInfoImpl.h:202
bool contains(const LoopT *L) const
Return true if the specified loop is contained within in this loop.
Definition: LoopInfo.h:110
auto size(R &&Range, typename std::enable_if< std::is_same< typename std::iterator_traits< decltype(Range.begin())>::iterator_category, std::random_access_iterator_tag >::value, void >::type *=nullptr) -> decltype(std::distance(Range.begin(), Range.end()))
Get the size of a range.
Definition: STLExtras.h:1023
BlockVerifier::State From
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:852
reverse_iterator rend() const
Definition: LoopInfo.h:662
Verifier pass for the LoopAnalysis results.
Definition: LoopInfo.h:959
This is a &#39;vector&#39; (really, a variable-sized array), optimized for the case when the array is small...
Definition: SmallVector.h:847
const T * const_iterator
Definition: ArrayRef.h:45
iterator begin() const
Definition: LoopInfo.h:142
LoopInfo & getLoopInfo()
Definition: LoopInfo.h:974
LoopT * removeLoop(iterator I)
This removes the specified top-level loop from this loop info object.
Definition: LoopInfo.h:705
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:924
LoopT * AllocateLoop(ArgsTy &&... Args)
Definition: LoopInfo.h:648
LoopInfo(LoopInfo &&Arg)
Definition: LoopInfo.h:806
static ChildIteratorType child_end(NodeRef N)
Definition: LoopInfo.h:926
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:216
iterator begin() const
Definition: LoopInfo.h:659
A range adaptor for a pair of iterators.
LoopInfo::iterator ChildIteratorType
Definition: LoopInfo.h:931
bool isLoopHeader(const BlockT *BB) const
Definition: LoopInfo.h:697
reverse_iterator rbegin() const
Definition: LoopInfo.h:661
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
This file provides various utilities for inspecting and working with the control flow graph in LLVM I...
void verifyLoopNest(DenseSet< const LoopT *> *Loops) const
Verify loop structure of this loop and all nested loops.
Definition: LoopInfoImpl.h:381
static NodeRef getEntryNode(Loop *L)
Definition: LoopInfo.h:933
const DebugLoc & getStart() const
Definition: LoopInfo.h:472
void addChildLoop(LoopT *NewChild)
Add the specified loop to be a child of this loop.
Definition: LoopInfo.h:331
StringRef getName() const
Definition: LoopInfo.h:583
Represents a single loop in the control flow graph.
Definition: LoopInfo.h:459
ArrayRef< BlockT * > getBlocks() const
Get a list of the basic blocks which make up this loop.
Definition: LoopInfo.h:149
#define I(x, y, z)
Definition: MD5.cpp:58
#define N
static ChildIteratorType child_end(NodeRef N)
Definition: LoopInfo.h:935
void changeTopLevelLoop(LoopT *OldLoop, LoopT *NewLoop)
Replace the specified loop in the top-level loops list with the indicated loop.
Definition: LoopInfo.h:726
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:716
friend class LoopInfo
Definition: LoopInfo.h:611
void removeBlockFromLoop(BlockT *BB)
This removes the specified basic block from the current loop, updating the Blocks as appropriate...
Definition: LoopInfo.h:396
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:186
API to communicate dependencies between analyses during invalidation.
Definition: PassManager.h:642
bool empty() const
Definition: LoopInfo.h:146
LoopT * removeChildLoop(LoopT *Child)
This removes the specified child from being a subloop of this loop.
Definition: LoopInfo.h:352
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:687
void reverseBlock(unsigned from)
interface to reverse Blocks[from, end of loop] in this loop
Definition: LoopInfo.h:366
This class implements an extremely fast bulk output stream that can only output to a stream...
Definition: raw_ostream.h:46
The legacy pass manager&#39;s analysis pass to compute loop information.
Definition: LoopInfo.h:964
void verifyLoop() const
Verify loop structure.
Definition: LoopInfoImpl.h:295
void getUniqueExitBlocks(SmallVectorImpl< BlockT *> &ExitBlocks) const
Return all unique successor blocks of this loop.
Definition: LoopInfoImpl.h:100
LoopInfoBase(LoopInfoBase &&Arg)
Definition: LoopInfo.h:620
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:639
std::vector< LoopT * >::const_reverse_iterator reverse_iterator
Definition: LoopInfo.h:658
bool replacementPreservesLCSSAForm(Instruction *From, Value *To)
Returns true if replacing From with To everywhere is guaranteed to preserve LCSSA form...
Definition: LoopInfo.h:826
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:660
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:71
static ChildIteratorType child_begin(NodeRef N)
Definition: LoopInfo.h:934
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:743
constexpr char Args[]
Key for Kernel::Metadata::mArgs.
const BasicBlock * getParent() const
Definition: Instruction.h:67
LoopBase(BlockT *BB)
Definition: LoopInfo.h:420
LocRange(DebugLoc Start)
Definition: LoopInfo.h:468
This class builds and contains all of the top-level loop structures in the specified function...
Definition: LoopInfo.h:62