LLVM  7.0.0svn
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 true if this loop is no longer valid. The only valid use of this
182  /// helper is "assert(L.isInvalid())" or equivalent, since IsInvalid is set to
183  /// true by the destructor. In other words, if this accessor returns true,
184  /// the caller has already triggered UB by calling this accessor; and so it
185  /// can only be called in a context where a return value of true indicates a
186  /// programmer error.
187  bool isInvalid() const {
188 #if LLVM_ENABLE_ABI_BREAKING_CHECKS
189  return IsInvalid;
190 #else
191  return false;
192 #endif
193  }
194 
195  /// True if terminator in the block can branch to another block that is
196  /// outside of the current loop.
197  bool isLoopExiting(const BlockT *BB) const {
198  assert(!isInvalid() && "Loop not in a valid state!");
199  for (const auto &Succ : children<const BlockT *>(BB)) {
200  if (!contains(Succ))
201  return true;
202  }
203  return false;
204  }
205 
206  /// Returns true if \p BB is a loop-latch.
207  /// A latch block is a block that contains a branch back to the header.
208  /// This function is useful when there are multiple latches in a loop
209  /// because \fn getLoopLatch will return nullptr in that case.
210  bool isLoopLatch(const BlockT *BB) const {
211  assert(!isInvalid() && "Loop not in a valid state!");
212  assert(contains(BB) && "block does not belong to the loop");
213 
214  BlockT *Header = getHeader();
215  auto PredBegin = GraphTraits<Inverse<BlockT *>>::child_begin(Header);
216  auto PredEnd = GraphTraits<Inverse<BlockT *>>::child_end(Header);
217  return std::find(PredBegin, PredEnd, BB) != PredEnd;
218  }
219 
220  /// Calculate the number of back edges to the loop header.
221  unsigned getNumBackEdges() const {
222  assert(!isInvalid() && "Loop not in a valid state!");
223  unsigned NumBackEdges = 0;
224  BlockT *H = getHeader();
225 
226  for (const auto Pred : children<Inverse<BlockT *>>(H))
227  if (contains(Pred))
228  ++NumBackEdges;
229 
230  return NumBackEdges;
231  }
232 
233  //===--------------------------------------------------------------------===//
234  // APIs for simple analysis of the loop.
235  //
236  // Note that all of these methods can fail on general loops (ie, there may not
237  // be a preheader, etc). For best success, the loop simplification and
238  // induction variable canonicalization pass should be used to normalize loops
239  // for easy analysis. These methods assume canonical loops.
240 
241  /// Return all blocks inside the loop that have successors outside of the
242  /// loop. These are the blocks _inside of the current loop_ which branch out.
243  /// The returned list is always unique.
244  void getExitingBlocks(SmallVectorImpl<BlockT *> &ExitingBlocks) const;
245 
246  /// If getExitingBlocks would return exactly one block, return that block.
247  /// Otherwise return null.
248  BlockT *getExitingBlock() const;
249 
250  /// Return all of the successor blocks of this loop. These are the blocks
251  /// _outside of the current loop_ which are branched to.
252  void getExitBlocks(SmallVectorImpl<BlockT *> &ExitBlocks) const;
253 
254  /// If getExitBlocks would return exactly one block, return that block.
255  /// Otherwise return null.
256  BlockT *getExitBlock() const;
257 
258  /// Edge type.
259  typedef std::pair<const BlockT *, const BlockT *> Edge;
260 
261  /// Return all pairs of (_inside_block_,_outside_block_).
262  void getExitEdges(SmallVectorImpl<Edge> &ExitEdges) const;
263 
264  /// If there is a preheader for this loop, return it. A loop has a preheader
265  /// if there is only one edge to the header of the loop from outside of the
266  /// loop. If this is the case, the block branching to the header of the loop
267  /// is the preheader node.
268  ///
269  /// This method returns null if there is no preheader for the loop.
270  BlockT *getLoopPreheader() const;
271 
272  /// If the given loop's header has exactly one unique predecessor outside the
273  /// loop, return it. Otherwise return null.
274  /// This is less strict that the loop "preheader" concept, which requires
275  /// the predecessor to have exactly one successor.
276  BlockT *getLoopPredecessor() const;
277 
278  /// If there is a single latch block for this loop, return it.
279  /// A latch block is a block that contains a branch back to the header.
280  BlockT *getLoopLatch() const;
281 
282  /// Return all loop latch blocks of this loop. A latch block is a block that
283  /// contains a branch back to the header.
284  void getLoopLatches(SmallVectorImpl<BlockT *> &LoopLatches) const {
285  assert(!isInvalid() && "Loop not in a valid state!");
286  BlockT *H = getHeader();
287  for (const auto Pred : children<Inverse<BlockT *>>(H))
288  if (contains(Pred))
289  LoopLatches.push_back(Pred);
290  }
291 
292  //===--------------------------------------------------------------------===//
293  // APIs for updating loop information after changing the CFG
294  //
295 
296  /// This method is used by other analyses to update loop information.
297  /// NewBB is set to be a new member of the current loop.
298  /// Because of this, it is added as a member of all parent loops, and is added
299  /// to the specified LoopInfo object as being in the current basic block. It
300  /// is not valid to replace the loop header with this method.
301  void addBasicBlockToLoop(BlockT *NewBB, LoopInfoBase<BlockT, LoopT> &LI);
302 
303  /// This is used when splitting loops up. It replaces the OldChild entry in
304  /// our children list with NewChild, and updates the parent pointer of
305  /// OldChild to be null and the NewChild to be this loop.
306  /// This updates the loop depth of the new child.
307  void replaceChildLoopWith(LoopT *OldChild, LoopT *NewChild);
308 
309  /// Add the specified loop to be a child of this loop.
310  /// This updates the loop depth of the new child.
311  void addChildLoop(LoopT *NewChild) {
312  assert(!isInvalid() && "Loop not in a valid state!");
313  assert(!NewChild->ParentLoop && "NewChild already has a parent!");
314  NewChild->ParentLoop = static_cast<LoopT *>(this);
315  SubLoops.push_back(NewChild);
316  }
317 
318  /// This removes the specified child from being a subloop of this loop. The
319  /// loop is not deleted, as it will presumably be inserted into another loop.
320  LoopT *removeChildLoop(iterator I) {
321  assert(!isInvalid() && "Loop not in a valid state!");
322  assert(I != SubLoops.end() && "Cannot remove end iterator!");
323  LoopT *Child = *I;
324  assert(Child->ParentLoop == this && "Child is not a child of this loop!");
325  SubLoops.erase(SubLoops.begin() + (I - begin()));
326  Child->ParentLoop = nullptr;
327  return Child;
328  }
329 
330  /// This removes the specified child from being a subloop of this loop. The
331  /// loop is not deleted, as it will presumably be inserted into another loop.
332  LoopT *removeChildLoop(LoopT *Child) {
333  return removeChildLoop(llvm::find(*this, Child));
334  }
335 
336  /// This adds a basic block directly to the basic block list.
337  /// This should only be used by transformations that create new loops. Other
338  /// transformations should use addBasicBlockToLoop.
339  void addBlockEntry(BlockT *BB) {
340  assert(!isInvalid() && "Loop not in a valid state!");
341  Blocks.push_back(BB);
342  DenseBlockSet.insert(BB);
343  }
344 
345  /// interface to reverse Blocks[from, end of loop] in this loop
346  void reverseBlock(unsigned from) {
347  assert(!isInvalid() && "Loop not in a valid state!");
348  std::reverse(Blocks.begin() + from, Blocks.end());
349  }
350 
351  /// interface to do reserve() for Blocks
352  void reserveBlocks(unsigned size) {
353  assert(!isInvalid() && "Loop not in a valid state!");
354  Blocks.reserve(size);
355  }
356 
357  /// This method is used to move BB (which must be part of this loop) to be the
358  /// loop header of the loop (the block that dominates all others).
359  void moveToHeader(BlockT *BB) {
360  assert(!isInvalid() && "Loop not in a valid state!");
361  if (Blocks[0] == BB)
362  return;
363  for (unsigned i = 0;; ++i) {
364  assert(i != Blocks.size() && "Loop does not contain BB!");
365  if (Blocks[i] == BB) {
366  Blocks[i] = Blocks[0];
367  Blocks[0] = BB;
368  return;
369  }
370  }
371  }
372 
373  /// This removes the specified basic block from the current loop, updating the
374  /// Blocks as appropriate. This does not update the mapping in the LoopInfo
375  /// class.
376  void removeBlockFromLoop(BlockT *BB) {
377  assert(!isInvalid() && "Loop not in a valid state!");
378  auto I = find(Blocks, BB);
379  assert(I != Blocks.end() && "N is not in this list!");
380  Blocks.erase(I);
381 
382  DenseBlockSet.erase(BB);
383  }
384 
385  /// Verify loop structure
386  void verifyLoop() const;
387 
388  /// Verify loop structure of this loop and all nested loops.
390 
391  /// Print loop with all the BBs inside it.
392  void print(raw_ostream &OS, unsigned Depth = 0, bool Verbose = false) const;
393 
394 protected:
395  friend class LoopInfoBase<BlockT, LoopT>;
396 
397  /// This creates an empty loop.
398  LoopBase() : ParentLoop(nullptr) {}
399 
400  explicit LoopBase(BlockT *BB) : ParentLoop(nullptr) {
401  Blocks.push_back(BB);
402  DenseBlockSet.insert(BB);
403  }
404 
405  // Since loop passes like SCEV are allowed to key analysis results off of
406  // `Loop` pointers, we cannot re-use pointers within a loop pass manager.
407  // This means loop passes should not be `delete` ing `Loop` objects directly
408  // (and risk a later `Loop` allocation re-using the address of a previous one)
409  // but should be using LoopInfo::markAsRemoved, which keeps around the `Loop`
410  // pointer till the end of the lifetime of the `LoopInfo` object.
411  //
412  // To make it easier to follow this rule, we mark the destructor as
413  // non-public.
415  for (auto *SubLoop : SubLoops)
416  SubLoop->~LoopT();
417 
418 #if LLVM_ENABLE_ABI_BREAKING_CHECKS
419  IsInvalid = true;
420 #endif
421  SubLoops.clear();
422  Blocks.clear();
423  DenseBlockSet.clear();
424  ParentLoop = nullptr;
425  }
426 };
427 
428 template <class BlockT, class LoopT>
429 raw_ostream &operator<<(raw_ostream &OS, const LoopBase<BlockT, LoopT> &Loop) {
430  Loop.print(OS);
431  return OS;
432 }
433 
434 // Implementation in LoopInfoImpl.h
435 extern template class LoopBase<BasicBlock, Loop>;
436 
437 /// Represents a single loop in the control flow graph. Note that not all SCCs
438 /// in the CFG are necessarily loops.
440 public:
441  /// \brief A range representing the start and end location of a loop.
442  class LocRange {
443  DebugLoc Start;
444  DebugLoc End;
445 
446  public:
447  LocRange() {}
448  LocRange(DebugLoc Start) : Start(std::move(Start)), End(std::move(Start)) {}
450  : Start(std::move(Start)), End(std::move(End)) {}
451 
452  const DebugLoc &getStart() const { return Start; }
453  const DebugLoc &getEnd() const { return End; }
454 
455  /// \brief Check for null.
456  ///
457  explicit operator bool() const { return Start && End; }
458  };
459 
460  /// Return true if the specified value is loop invariant.
461  bool isLoopInvariant(const Value *V) const;
462 
463  /// Return true if all the operands of the specified instruction are loop
464  /// invariant.
465  bool hasLoopInvariantOperands(const Instruction *I) const;
466 
467  /// If the given value is an instruction inside of the loop and it can be
468  /// hoisted, do so to make it trivially loop-invariant.
469  /// Return true if the value after any hoisting is loop invariant. This
470  /// function can be used as a slightly more aggressive replacement for
471  /// isLoopInvariant.
472  ///
473  /// If InsertPt is specified, it is the point to hoist instructions to.
474  /// If null, the terminator of the loop preheader is used.
475  bool makeLoopInvariant(Value *V, bool &Changed,
476  Instruction *InsertPt = nullptr) const;
477 
478  /// If the given instruction is inside of the loop and it can be hoisted, do
479  /// so to make it trivially loop-invariant.
480  /// Return true if the instruction after any hoisting is loop invariant. This
481  /// function can be used as a slightly more aggressive replacement for
482  /// isLoopInvariant.
483  ///
484  /// If InsertPt is specified, it is the point to hoist instructions to.
485  /// If null, the terminator of the loop preheader is used.
486  ///
487  bool makeLoopInvariant(Instruction *I, bool &Changed,
488  Instruction *InsertPt = nullptr) const;
489 
490  /// Check to see if the loop has a canonical induction variable: an integer
491  /// recurrence that starts at 0 and increments by one each time through the
492  /// loop. If so, return the phi node that corresponds to it.
493  ///
494  /// The IndVarSimplify pass transforms loops to have a canonical induction
495  /// variable.
496  ///
497  PHINode *getCanonicalInductionVariable() const;
498 
499  /// Return true if the Loop is in LCSSA form.
500  bool isLCSSAForm(DominatorTree &DT) const;
501 
502  /// Return true if this Loop and all inner subloops are in LCSSA form.
503  bool isRecursivelyLCSSAForm(DominatorTree &DT, const LoopInfo &LI) const;
504 
505  /// Return true if the Loop is in the form that the LoopSimplify form
506  /// transforms loops to, which is sometimes called normal form.
507  bool isLoopSimplifyForm() const;
508 
509  /// Return true if the loop body is safe to clone in practice.
510  bool isSafeToClone() const;
511 
512  /// Returns true if the loop is annotated parallel.
513  ///
514  /// A parallel loop can be assumed to not contain any dependencies between
515  /// iterations by the compiler. That is, any loop-carried dependency checking
516  /// can be skipped completely when parallelizing the loop on the target
517  /// machine. Thus, if the parallel loop information originates from the
518  /// programmer, e.g. via the OpenMP parallel for pragma, it is the
519  /// programmer's responsibility to ensure there are no loop-carried
520  /// dependencies. The final execution order of the instructions across
521  /// iterations is not guaranteed, thus, the end result might or might not
522  /// implement actual concurrent execution of instructions across multiple
523  /// iterations.
524  bool isAnnotatedParallel() const;
525 
526  /// Return the llvm.loop loop id metadata node for this loop if it is present.
527  ///
528  /// If this loop contains the same llvm.loop metadata on each branch to the
529  /// header then the node is returned. If any latch instruction does not
530  /// contain llvm.loop or or if multiple latches contain different nodes then
531  /// 0 is returned.
532  MDNode *getLoopID() const;
533  /// Set the llvm.loop loop id metadata for this loop.
534  ///
535  /// The LoopID metadata node will be added to each terminator instruction in
536  /// the loop that branches to the loop header.
537  ///
538  /// The LoopID metadata node should have one or more operands and the first
539  /// operand should be the node itself.
540  void setLoopID(MDNode *LoopID) const;
541 
542  /// Add llvm.loop.unroll.disable to this loop's loop id metadata.
543  ///
544  /// Remove existing unroll metadata and add unroll disable metadata to
545  /// indicate the loop has already been unrolled. This prevents a loop
546  /// from being unrolled more than is directed by a pragma if the loop
547  /// unrolling pass is run more than once (which it generally is).
548  void setLoopAlreadyUnrolled();
549 
550  /// Return true if no exit block for the loop has a predecessor that is
551  /// outside the loop.
552  bool hasDedicatedExits() const;
553 
554  /// Return all unique successor blocks of this loop.
555  /// These are the blocks _outside of the current loop_ which are branched to.
556  /// This assumes that loop exits are in canonical form, i.e. all exits are
557  /// dedicated exits.
558  void getUniqueExitBlocks(SmallVectorImpl<BasicBlock *> &ExitBlocks) const;
559 
560  /// If getUniqueExitBlocks would return exactly one block, return that block.
561  /// Otherwise return null.
562  BasicBlock *getUniqueExitBlock() const;
563 
564  void dump() const;
565  void dumpVerbose() const;
566 
567  /// Return the debug location of the start of this loop.
568  /// This looks for a BB terminating instruction with a known debug
569  /// location by looking at the preheader and header blocks. If it
570  /// cannot find a terminating instruction with location information,
571  /// it returns an unknown location.
572  DebugLoc getStartLoc() const;
573 
574  /// Return the source code span of the loop.
575  LocRange getLocRange() const;
576 
577  StringRef getName() const {
578  if (BasicBlock *Header = getHeader())
579  if (Header->hasName())
580  return Header->getName();
581  return "<unnamed loop>";
582  }
583 
584 private:
585  Loop() = default;
586 
589  explicit Loop(BasicBlock *BB) : LoopBase<BasicBlock, Loop>(BB) {}
590  ~Loop() = default;
591 };
592 
593 //===----------------------------------------------------------------------===//
594 /// This class builds and contains all of the top-level loop
595 /// structures in the specified function.
596 ///
597 
598 template <class BlockT, class LoopT> class LoopInfoBase {
599  // BBMap - Mapping of basic blocks to the inner most loop they occur in
601  std::vector<LoopT *> TopLevelLoops;
602  BumpPtrAllocator LoopAllocator;
603 
605  friend class LoopInfo;
606 
607  void operator=(const LoopInfoBase &) = delete;
608  LoopInfoBase(const LoopInfoBase &) = delete;
609 
610 public:
612  ~LoopInfoBase() { releaseMemory(); }
613 
615  : BBMap(std::move(Arg.BBMap)),
616  TopLevelLoops(std::move(Arg.TopLevelLoops)),
617  LoopAllocator(std::move(Arg.LoopAllocator)) {
618  // We have to clear the arguments top level loops as we've taken ownership.
619  Arg.TopLevelLoops.clear();
620  }
622  BBMap = std::move(RHS.BBMap);
623 
624  for (auto *L : TopLevelLoops)
625  L->~LoopT();
626 
627  TopLevelLoops = std::move(RHS.TopLevelLoops);
628  LoopAllocator = std::move(RHS.LoopAllocator);
629  RHS.TopLevelLoops.clear();
630  return *this;
631  }
632 
633  void releaseMemory() {
634  BBMap.clear();
635 
636  for (auto *L : TopLevelLoops)
637  L->~LoopT();
638  TopLevelLoops.clear();
639  LoopAllocator.Reset();
640  }
641 
642  template <typename... ArgsTy> LoopT *AllocateLoop(ArgsTy &&... Args) {
643  LoopT *Storage = LoopAllocator.Allocate<LoopT>();
644  return new (Storage) LoopT(std::forward<ArgsTy>(Args)...);
645  }
646 
647  /// iterator/begin/end - The interface to the top-level loops in the current
648  /// function.
649  ///
650  typedef typename std::vector<LoopT *>::const_iterator iterator;
651  typedef
652  typename std::vector<LoopT *>::const_reverse_iterator reverse_iterator;
653  iterator begin() const { return TopLevelLoops.begin(); }
654  iterator end() const { return TopLevelLoops.end(); }
655  reverse_iterator rbegin() const { return TopLevelLoops.rbegin(); }
656  reverse_iterator rend() const { return TopLevelLoops.rend(); }
657  bool empty() const { return TopLevelLoops.empty(); }
658 
659  /// Return all of the loops in the function in preorder across the loop
660  /// nests, with siblings in forward program order.
661  ///
662  /// Note that because loops form a forest of trees, preorder is equivalent to
663  /// reverse postorder.
664  SmallVector<LoopT *, 4> getLoopsInPreorder();
665 
666  /// Return all of the loops in the function in preorder across the loop
667  /// nests, with siblings in *reverse* program order.
668  ///
669  /// Note that because loops form a forest of trees, preorder is equivalent to
670  /// reverse postorder.
671  ///
672  /// Also note that this is *not* a reverse preorder. Only the siblings are in
673  /// reverse program order.
674  SmallVector<LoopT *, 4> getLoopsInReverseSiblingPreorder();
675 
676  /// Return the inner most loop that BB lives in. If a basic block is in no
677  /// loop (for example the entry node), null is returned.
678  LoopT *getLoopFor(const BlockT *BB) const { return BBMap.lookup(BB); }
679 
680  /// Same as getLoopFor.
681  const LoopT *operator[](const BlockT *BB) const { return getLoopFor(BB); }
682 
683  /// Return the loop nesting level of the specified block. A depth of 0 means
684  /// the block is not inside any loop.
685  unsigned getLoopDepth(const BlockT *BB) const {
686  const LoopT *L = getLoopFor(BB);
687  return L ? L->getLoopDepth() : 0;
688  }
689 
690  // True if the block is a loop header node
691  bool isLoopHeader(const BlockT *BB) const {
692  const LoopT *L = getLoopFor(BB);
693  return L && L->getHeader() == BB;
694  }
695 
696  /// This removes the specified top-level loop from this loop info object.
697  /// The loop is not deleted, as it will presumably be inserted into
698  /// another loop.
699  LoopT *removeLoop(iterator I) {
700  assert(I != end() && "Cannot remove end iterator!");
701  LoopT *L = *I;
702  assert(!L->getParentLoop() && "Not a top-level loop!");
703  TopLevelLoops.erase(TopLevelLoops.begin() + (I - begin()));
704  return L;
705  }
706 
707  /// Change the top-level loop that contains BB to the specified loop.
708  /// This should be used by transformations that restructure the loop hierarchy
709  /// tree.
710  void changeLoopFor(BlockT *BB, LoopT *L) {
711  if (!L) {
712  BBMap.erase(BB);
713  return;
714  }
715  BBMap[BB] = L;
716  }
717 
718  /// Replace the specified loop in the top-level loops list with the indicated
719  /// loop.
720  void changeTopLevelLoop(LoopT *OldLoop, LoopT *NewLoop) {
721  auto I = find(TopLevelLoops, OldLoop);
722  assert(I != TopLevelLoops.end() && "Old loop not at top level!");
723  *I = NewLoop;
724  assert(!NewLoop->ParentLoop && !OldLoop->ParentLoop &&
725  "Loops already embedded into a subloop!");
726  }
727 
728  /// This adds the specified loop to the collection of top-level loops.
729  void addTopLevelLoop(LoopT *New) {
730  assert(!New->getParentLoop() && "Loop already in subloop!");
731  TopLevelLoops.push_back(New);
732  }
733 
734  /// This method completely removes BB from all data structures,
735  /// including all of the Loop objects it is nested in and our mapping from
736  /// BasicBlocks to loops.
737  void removeBlock(BlockT *BB) {
738  auto I = BBMap.find(BB);
739  if (I != BBMap.end()) {
740  for (LoopT *L = I->second; L; L = L->getParentLoop())
741  L->removeBlockFromLoop(BB);
742 
743  BBMap.erase(I);
744  }
745  }
746 
747  // Internals
748 
749  static bool isNotAlreadyContainedIn(const LoopT *SubLoop,
750  const LoopT *ParentLoop) {
751  if (!SubLoop)
752  return true;
753  if (SubLoop == ParentLoop)
754  return false;
755  return isNotAlreadyContainedIn(SubLoop->getParentLoop(), ParentLoop);
756  }
757 
758  /// Create the loop forest using a stable algorithm.
759  void analyze(const DominatorTreeBase<BlockT, false> &DomTree);
760 
761  // Debugging
762  void print(raw_ostream &OS) const;
763 
764  void verify(const DominatorTreeBase<BlockT, false> &DomTree) const;
765 
766  /// Destroy a loop that has been removed from the `LoopInfo` nest.
767  ///
768  /// This runs the destructor of the loop object making it invalid to
769  /// reference afterward. The memory is retained so that the *pointer* to the
770  /// loop remains valid.
771  ///
772  /// The caller is responsible for removing this loop from the loop nest and
773  /// otherwise disconnecting it from the broader `LoopInfo` data structures.
774  /// Callers that don't naturally handle this themselves should probably call
775  /// `erase' instead.
776  void destroy(LoopT *L) {
777  L->~LoopT();
778 
779  // Since LoopAllocator is a BumpPtrAllocator, this Deallocate only poisons
780  // \c L, but the pointer remains valid for non-dereferencing uses.
781  LoopAllocator.Deallocate(L);
782  }
783 };
784 
785 // Implementation in LoopInfoImpl.h
786 extern template class LoopInfoBase<BasicBlock, Loop>;
787 
790 
792 
793  void operator=(const LoopInfo &) = delete;
794  LoopInfo(const LoopInfo &) = delete;
795 
796 public:
797  LoopInfo() {}
798  explicit LoopInfo(const DominatorTreeBase<BasicBlock, false> &DomTree);
799 
800  LoopInfo(LoopInfo &&Arg) : BaseT(std::move(static_cast<BaseT &>(Arg))) {}
802  BaseT::operator=(std::move(static_cast<BaseT &>(RHS)));
803  return *this;
804  }
805 
806  /// Handle invalidation explicitly.
807  bool invalidate(Function &F, const PreservedAnalyses &PA,
809 
810  // Most of the public interface is provided via LoopInfoBase.
811 
812  /// Update LoopInfo after removing the last backedge from a loop. This updates
813  /// the loop forest and parent loops for each block so that \c L is no longer
814  /// referenced, but does not actually delete \c L immediately. The pointer
815  /// will remain valid until this LoopInfo's memory is released.
816  void erase(Loop *L);
817 
818  /// Returns true if replacing From with To everywhere is guaranteed to
819  /// preserve LCSSA form.
821  // Preserving LCSSA form is only problematic if the replacing value is an
822  // instruction.
824  if (!I)
825  return true;
826  // If both instructions are defined in the same basic block then replacement
827  // cannot break LCSSA form.
828  if (I->getParent() == From->getParent())
829  return true;
830  // If the instruction is not defined in a loop then it can safely replace
831  // anything.
832  Loop *ToLoop = getLoopFor(I->getParent());
833  if (!ToLoop)
834  return true;
835  // If the replacing instruction is defined in the same loop as the original
836  // instruction, or in a loop that contains it as an inner loop, then using
837  // it as a replacement will not break LCSSA form.
838  return ToLoop->contains(getLoopFor(From->getParent()));
839  }
840 
841  /// Checks if moving a specific instruction can break LCSSA in any loop.
842  ///
843  /// Return true if moving \p Inst to before \p NewLoc will break LCSSA,
844  /// assuming that the function containing \p Inst and \p NewLoc is currently
845  /// in LCSSA form.
847  assert(Inst->getFunction() == NewLoc->getFunction() &&
848  "Can't reason about IPO!");
849 
850  auto *OldBB = Inst->getParent();
851  auto *NewBB = NewLoc->getParent();
852 
853  // Movement within the same loop does not break LCSSA (the equality check is
854  // to avoid doing a hashtable lookup in case of intra-block movement).
855  if (OldBB == NewBB)
856  return true;
857 
858  auto *OldLoop = getLoopFor(OldBB);
859  auto *NewLoop = getLoopFor(NewBB);
860 
861  if (OldLoop == NewLoop)
862  return true;
863 
864  // Check if Outer contains Inner; with the null loop counting as the
865  // "outermost" loop.
866  auto Contains = [](const Loop *Outer, const Loop *Inner) {
867  return !Outer || Outer->contains(Inner);
868  };
869 
870  // To check that the movement of Inst to before NewLoc does not break LCSSA,
871  // we need to check two sets of uses for possible LCSSA violations at
872  // NewLoc: the users of NewInst, and the operands of NewInst.
873 
874  // If we know we're hoisting Inst out of an inner loop to an outer loop,
875  // then the uses *of* Inst don't need to be checked.
876 
877  if (!Contains(NewLoop, OldLoop)) {
878  for (Use &U : Inst->uses()) {
879  auto *UI = cast<Instruction>(U.getUser());
880  auto *UBB = isa<PHINode>(UI) ? cast<PHINode>(UI)->getIncomingBlock(U)
881  : UI->getParent();
882  if (UBB != NewBB && getLoopFor(UBB) != NewLoop)
883  return false;
884  }
885  }
886 
887  // If we know we're sinking Inst from an outer loop into an inner loop, then
888  // the *operands* of Inst don't need to be checked.
889 
890  if (!Contains(OldLoop, NewLoop)) {
891  // See below on why we can't handle phi nodes here.
892  if (isa<PHINode>(Inst))
893  return false;
894 
895  for (Use &U : Inst->operands()) {
896  auto *DefI = dyn_cast<Instruction>(U.get());
897  if (!DefI)
898  return false;
899 
900  // This would need adjustment if we allow Inst to be a phi node -- the
901  // new use block won't simply be NewBB.
902 
903  auto *DefBlock = DefI->getParent();
904  if (DefBlock != NewBB && getLoopFor(DefBlock) != NewLoop)
905  return false;
906  }
907  }
908 
909  return true;
910  }
911 };
912 
913 // Allow clients to walk the list of nested loops...
914 template <> struct GraphTraits<const Loop *> {
915  typedef const Loop *NodeRef;
917 
918  static NodeRef getEntryNode(const Loop *L) { return L; }
919  static ChildIteratorType child_begin(NodeRef N) { return N->begin(); }
920  static ChildIteratorType child_end(NodeRef N) { return N->end(); }
921 };
922 
923 template <> struct GraphTraits<Loop *> {
924  typedef Loop *NodeRef;
926 
927  static NodeRef getEntryNode(Loop *L) { return L; }
928  static ChildIteratorType child_begin(NodeRef N) { return N->begin(); }
929  static ChildIteratorType child_end(NodeRef N) { return N->end(); }
930 };
931 
932 /// \brief Analysis pass that exposes the \c LoopInfo for a function.
933 class LoopAnalysis : public AnalysisInfoMixin<LoopAnalysis> {
935  static AnalysisKey Key;
936 
937 public:
938  typedef LoopInfo Result;
939 
941 };
942 
943 /// \brief Printer pass for the \c LoopAnalysis results.
944 class LoopPrinterPass : public PassInfoMixin<LoopPrinterPass> {
945  raw_ostream &OS;
946 
947 public:
948  explicit LoopPrinterPass(raw_ostream &OS) : OS(OS) {}
950 };
951 
952 /// \brief Verifier pass for the \c LoopAnalysis results.
953 struct LoopVerifierPass : public PassInfoMixin<LoopVerifierPass> {
955 };
956 
957 /// \brief The legacy pass manager's analysis pass to compute loop information.
959  LoopInfo LI;
960 
961 public:
962  static char ID; // Pass identification, replacement for typeid
963 
966  }
967 
968  LoopInfo &getLoopInfo() { return LI; }
969  const LoopInfo &getLoopInfo() const { return LI; }
970 
971  /// \brief Calculate the natural loop information for a given function.
972  bool runOnFunction(Function &F) override;
973 
974  void verifyAnalysis() const override;
975 
976  void releaseMemory() override { LI.releaseMemory(); }
977 
978  void print(raw_ostream &O, const Module *M = nullptr) const override;
979 
980  void getAnalysisUsage(AnalysisUsage &AU) const override;
981 };
982 
983 /// Function to print a loop's contents as LLVM's text IR assembly.
984 void printLoop(Loop &L, raw_ostream &OS, const std::string &Banner = "");
985 
986 } // End llvm namespace
987 
988 #endif
LoopInfo::iterator ChildIteratorType
Definition: LoopInfo.h:916
void destroy(LoopT *L)
Destroy a loop that has been removed from the LoopInfo nest.
Definition: LoopInfo.h:776
void push_back(const T &Elt)
Definition: SmallVector.h:212
LoopInfo Result
Definition: LoopInfo.h:938
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:360
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...
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:657
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:63
unsigned getLoopDepth(const BlockT *BB) const
Return the loop nesting level of the specified block.
Definition: LoopInfo.h:685
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:359
void reserveBlocks(unsigned size)
interface to do reserve() for Blocks
Definition: LoopInfo.h:352
LoopT * removeChildLoop(iterator I)
This removes the specified child from being a subloop of this loop.
Definition: LoopInfo.h:320
std::pair< const BlockT *, const BlockT * > Edge
Edge type.
Definition: LoopInfo.h:259
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:398
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:187
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:221
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:678
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:339
static bool isNotAlreadyContainedIn(const LoopT *SubLoop, const LoopT *ParentLoop)
Definition: LoopInfo.h:749
std::vector< LoopT * >::const_iterator iterator
iterator/begin/end - The interface to the top-level loops in the current function.
Definition: LoopInfo.h:650
void getLoopLatches(SmallVectorImpl< BlockT *> &LoopLatches) const
Return all loop latch blocks of this loop.
Definition: LoopInfo.h:284
Printer pass for the LoopAnalysis results.
Definition: LoopInfo.h:944
Analysis pass that exposes the LoopInfo for a function.
Definition: LoopInfo.h:933
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:969
auto reverse(ContainerTy &&C, typename std::enable_if< has_rbegin< ContainerTy >::value >::type *=nullptr) -> decltype(make_range(C.rbegin(), C.rend()))
Definition: STLExtras.h:233
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:729
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:801
LocRange(DebugLoc Start, DebugLoc End)
Definition: LoopInfo.h:449
const DebugLoc & getEnd() const
Definition: LoopInfo.h:453
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:976
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:197
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:919
iterator end() const
Definition: LoopInfo.h:654
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:948
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
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
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:59
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:442
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:835
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:621
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
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:846
reverse_iterator rend() const
Definition: LoopInfo.h:656
Verifier pass for the LoopAnalysis results.
Definition: LoopInfo.h:953
This is a &#39;vector&#39; (really, a variable-sized array), optimized for the case when the array is small...
Definition: SmallVector.h:862
const T * const_iterator
Definition: ArrayRef.h:45
iterator begin() const
Definition: LoopInfo.h:142
LoopInfo & getLoopInfo()
Definition: LoopInfo.h:968
LoopT * removeLoop(iterator I)
This removes the specified top-level loop from this loop info object.
Definition: LoopInfo.h:699
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:918
LoopT * AllocateLoop(ArgsTy &&... Args)
Definition: LoopInfo.h:642
LoopInfo(LoopInfo &&Arg)
Definition: LoopInfo.h:800
static ChildIteratorType child_end(NodeRef N)
Definition: LoopInfo.h:920
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:210
iterator begin() const
Definition: LoopInfo.h:653
A range adaptor for a pair of iterators.
LoopInfo::iterator ChildIteratorType
Definition: LoopInfo.h:925
bool isLoopHeader(const BlockT *BB) const
Definition: LoopInfo.h:691
reverse_iterator rbegin() const
Definition: LoopInfo.h:655
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:927
const DebugLoc & getStart() const
Definition: LoopInfo.h:452
void addChildLoop(LoopT *NewChild)
Add the specified loop to be a child of this loop.
Definition: LoopInfo.h:311
StringRef getName() const
Definition: LoopInfo.h:577
Represents a single loop in the control flow graph.
Definition: LoopInfo.h:439
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:929
void changeTopLevelLoop(LoopT *OldLoop, LoopT *NewLoop)
Replace the specified loop in the top-level loops list with the indicated loop.
Definition: LoopInfo.h:720
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:710
friend class LoopInfo
Definition: LoopInfo.h:605
void removeBlockFromLoop(BlockT *BB)
This removes the specified basic block from the current loop, updating the Blocks as appropriate...
Definition: LoopInfo.h:376
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
LoopT * removeChildLoop(LoopT *Child)
This removes the specified child from being a subloop of this loop.
Definition: LoopInfo.h:332
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:681
void reverseBlock(unsigned from)
interface to reverse Blocks[from, end of loop] in this loop
Definition: LoopInfo.h:346
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:958
void verifyLoop() const
Verify loop structure.
Definition: LoopInfoImpl.h:227
LoopInfoBase(LoopInfoBase &&Arg)
Definition: LoopInfo.h:614
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:633
std::vector< LoopT * >::const_reverse_iterator reverse_iterator
Definition: LoopInfo.h:652
bool replacementPreservesLCSSAForm(Instruction *From, Value *To)
Returns true if replacing From with To everywhere is guaranteed to preserve LCSSA form...
Definition: LoopInfo.h:820
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:928
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:737
constexpr char Args[]
Key for Kernel::Metadata::mArgs.
const BasicBlock * getParent() const
Definition: Instruction.h:67
LoopBase(BlockT *BB)
Definition: LoopInfo.h:400
LocRange(DebugLoc Start)
Definition: LoopInfo.h:448
This class builds and contains all of the top-level loop structures in the specified function...
Definition: LoopInfo.h:62