aboutsummaryrefslogtreecommitdiffstats
path: root/contrib/libs/llvm16/include/llvm/Transforms/Scalar/LoopPassManager.h
blob: c2e8954f395077e6dd34d1255890206ac91fe1eb (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
#pragma once

#ifdef __GNUC__
#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wunused-parameter"
#endif

//===- LoopPassManager.h - Loop pass management -----------------*- C++ -*-===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
/// \file
///
/// This header provides classes for managing a pipeline of passes over loops
/// in LLVM IR.
///
/// The primary loop pass pipeline is managed in a very particular way to
/// provide a set of core guarantees:
/// 1) Loops are, where possible, in simplified form.
/// 2) Loops are *always* in LCSSA form.
/// 3) A collection of Loop-specific analysis results are available:
///    - LoopInfo
///    - DominatorTree
///    - ScalarEvolution
///    - AAManager
/// 4) All loop passes preserve #1 (where possible), #2, and #3.
/// 5) Loop passes run over each loop in the loop nest from the innermost to
///    the outermost. Specifically, all inner loops are processed before
///    passes run over outer loops. When running the pipeline across an inner
///    loop creates new inner loops, those are added and processed in this
///    order as well.
///
/// This process is designed to facilitate transformations which simplify,
/// reduce, and remove loops. For passes which are more oriented towards
/// optimizing loops, especially optimizing loop *nests* instead of single
/// loops in isolation, this framework is less interesting.
///
//===----------------------------------------------------------------------===//

#ifndef LLVM_TRANSFORMS_SCALAR_LOOPPASSMANAGER_H
#define LLVM_TRANSFORMS_SCALAR_LOOPPASSMANAGER_H

#include "llvm/ADT/PriorityWorklist.h"
#include "llvm/Analysis/LoopAnalysisManager.h"
#include "llvm/Analysis/LoopInfo.h"
#include "llvm/Analysis/LoopNestAnalysis.h"
#include "llvm/IR/PassManager.h"
#include "llvm/Transforms/Utils/LCSSA.h"
#include "llvm/Transforms/Utils/LoopSimplify.h"
#include "llvm/Transforms/Utils/LoopUtils.h"
#include <memory>

namespace llvm {

// Forward declarations of an update tracking API used in the pass manager.
class LPMUpdater;
class PassInstrumentation;

namespace {

template <typename PassT>
using HasRunOnLoopT = decltype(std::declval<PassT>().run(
    std::declval<Loop &>(), std::declval<LoopAnalysisManager &>(),
    std::declval<LoopStandardAnalysisResults &>(),
    std::declval<LPMUpdater &>()));

} // namespace

// Explicit specialization and instantiation declarations for the pass manager.
// See the comments on the definition of the specialization for details on how
// it differs from the primary template.
template <>
class PassManager<Loop, LoopAnalysisManager, LoopStandardAnalysisResults &,
                  LPMUpdater &>
    : public PassInfoMixin<
          PassManager<Loop, LoopAnalysisManager, LoopStandardAnalysisResults &,
                      LPMUpdater &>> {
public:
  explicit PassManager() = default;

  // FIXME: These are equivalent to the default move constructor/move
  // assignment. However, using = default triggers linker errors due to the
  // explicit instantiations below. Find a way to use the default and remove the
  // duplicated code here.
  PassManager(PassManager &&Arg)
      : IsLoopNestPass(std::move(Arg.IsLoopNestPass)),
        LoopPasses(std::move(Arg.LoopPasses)),
        LoopNestPasses(std::move(Arg.LoopNestPasses)) {}

  PassManager &operator=(PassManager &&RHS) {
    IsLoopNestPass = std::move(RHS.IsLoopNestPass);
    LoopPasses = std::move(RHS.LoopPasses);
    LoopNestPasses = std::move(RHS.LoopNestPasses);
    return *this;
  }

  PreservedAnalyses run(Loop &L, LoopAnalysisManager &AM,
                        LoopStandardAnalysisResults &AR, LPMUpdater &U);

  void printPipeline(raw_ostream &OS,
                     function_ref<StringRef(StringRef)> MapClassName2PassName);
  /// Add either a loop pass or a loop-nest pass to the pass manager. Append \p
  /// Pass to the list of loop passes if it has a dedicated \fn run() method for
  /// loops and to the list of loop-nest passes if the \fn run() method is for
  /// loop-nests instead. Also append whether \p Pass is loop-nest pass or not
  /// to the end of \var IsLoopNestPass so we can easily identify the types of
  /// passes in the pass manager later.
  template <typename PassT>
  LLVM_ATTRIBUTE_MINSIZE
      std::enable_if_t<is_detected<HasRunOnLoopT, PassT>::value>
      addPass(PassT &&Pass) {
    using LoopPassModelT =
        detail::PassModel<Loop, PassT, PreservedAnalyses, LoopAnalysisManager,
                          LoopStandardAnalysisResults &, LPMUpdater &>;
    IsLoopNestPass.push_back(false);
    // Do not use make_unique or emplace_back, they cause too many template
    // instantiations, causing terrible compile times.
    LoopPasses.push_back(std::unique_ptr<LoopPassConceptT>(
        new LoopPassModelT(std::forward<PassT>(Pass))));
  }

  template <typename PassT>
  LLVM_ATTRIBUTE_MINSIZE
      std::enable_if_t<!is_detected<HasRunOnLoopT, PassT>::value>
      addPass(PassT &&Pass) {
    using LoopNestPassModelT =
        detail::PassModel<LoopNest, PassT, PreservedAnalyses,
                          LoopAnalysisManager, LoopStandardAnalysisResults &,
                          LPMUpdater &>;
    IsLoopNestPass.push_back(true);
    // Do not use make_unique or emplace_back, they cause too many template
    // instantiations, causing terrible compile times.
    LoopNestPasses.push_back(std::unique_ptr<LoopNestPassConceptT>(
        new LoopNestPassModelT(std::forward<PassT>(Pass))));
  }

  // Specializations of `addPass` for `RepeatedPass`. These are necessary since
  // `RepeatedPass` has a templated `run` method that will result in incorrect
  // detection of `HasRunOnLoopT`.
  template <typename PassT>
  LLVM_ATTRIBUTE_MINSIZE
      std::enable_if_t<is_detected<HasRunOnLoopT, PassT>::value>
      addPass(RepeatedPass<PassT> &&Pass) {
    using RepeatedLoopPassModelT =
        detail::PassModel<Loop, RepeatedPass<PassT>, PreservedAnalyses,
                          LoopAnalysisManager, LoopStandardAnalysisResults &,
                          LPMUpdater &>;
    IsLoopNestPass.push_back(false);
    // Do not use make_unique or emplace_back, they cause too many template
    // instantiations, causing terrible compile times.
    LoopPasses.push_back(std::unique_ptr<LoopPassConceptT>(
        new RepeatedLoopPassModelT(std::move(Pass))));
  }

  template <typename PassT>
  LLVM_ATTRIBUTE_MINSIZE
      std::enable_if_t<!is_detected<HasRunOnLoopT, PassT>::value>
      addPass(RepeatedPass<PassT> &&Pass) {
    using RepeatedLoopNestPassModelT =
        detail::PassModel<LoopNest, RepeatedPass<PassT>, PreservedAnalyses,
                          LoopAnalysisManager, LoopStandardAnalysisResults &,
                          LPMUpdater &>;
    IsLoopNestPass.push_back(true);
    // Do not use make_unique or emplace_back, they cause too many template
    // instantiations, causing terrible compile times.
    LoopNestPasses.push_back(std::unique_ptr<LoopNestPassConceptT>(
        new RepeatedLoopNestPassModelT(std::move(Pass))));
  }

  bool isEmpty() const { return LoopPasses.empty() && LoopNestPasses.empty(); }

  static bool isRequired() { return true; }

  size_t getNumLoopPasses() const { return LoopPasses.size(); }
  size_t getNumLoopNestPasses() const { return LoopNestPasses.size(); }

protected:
  using LoopPassConceptT =
      detail::PassConcept<Loop, LoopAnalysisManager,
                          LoopStandardAnalysisResults &, LPMUpdater &>;
  using LoopNestPassConceptT =
      detail::PassConcept<LoopNest, LoopAnalysisManager,
                          LoopStandardAnalysisResults &, LPMUpdater &>;

  // BitVector that identifies whether the passes are loop passes or loop-nest
  // passes (true for loop-nest passes).
  BitVector IsLoopNestPass;
  std::vector<std::unique_ptr<LoopPassConceptT>> LoopPasses;
  std::vector<std::unique_ptr<LoopNestPassConceptT>> LoopNestPasses;

  /// Run either a loop pass or a loop-nest pass. Returns `std::nullopt` if
  /// PassInstrumentation's BeforePass returns false. Otherwise, returns the
  /// preserved analyses of the pass.
  template <typename IRUnitT, typename PassT>
  std::optional<PreservedAnalyses>
  runSinglePass(IRUnitT &IR, PassT &Pass, LoopAnalysisManager &AM,
                LoopStandardAnalysisResults &AR, LPMUpdater &U,
                PassInstrumentation &PI);

  PreservedAnalyses runWithLoopNestPasses(Loop &L, LoopAnalysisManager &AM,
                                          LoopStandardAnalysisResults &AR,
                                          LPMUpdater &U);
  PreservedAnalyses runWithoutLoopNestPasses(Loop &L, LoopAnalysisManager &AM,
                                             LoopStandardAnalysisResults &AR,
                                             LPMUpdater &U);

private:
  static const Loop &getLoopFromIR(Loop &L) { return L; }
  static const Loop &getLoopFromIR(LoopNest &LN) {
    return LN.getOutermostLoop();
  }
};

/// The Loop pass manager.
///
/// See the documentation for the PassManager template for details. It runs
/// a sequence of Loop passes over each Loop that the manager is run over. This
/// typedef serves as a convenient way to refer to this construct.
typedef PassManager<Loop, LoopAnalysisManager, LoopStandardAnalysisResults &,
                    LPMUpdater &>
    LoopPassManager;

/// A partial specialization of the require analysis template pass to forward
/// the extra parameters from a transformation's run method to the
/// AnalysisManager's getResult.
template <typename AnalysisT>
struct RequireAnalysisPass<AnalysisT, Loop, LoopAnalysisManager,
                           LoopStandardAnalysisResults &, LPMUpdater &>
    : PassInfoMixin<
          RequireAnalysisPass<AnalysisT, Loop, LoopAnalysisManager,
                              LoopStandardAnalysisResults &, LPMUpdater &>> {
  PreservedAnalyses run(Loop &L, LoopAnalysisManager &AM,
                        LoopStandardAnalysisResults &AR, LPMUpdater &) {
    (void)AM.template getResult<AnalysisT>(L, AR);
    return PreservedAnalyses::all();
  }
  void printPipeline(raw_ostream &OS,
                     function_ref<StringRef(StringRef)> MapClassName2PassName) {
    auto ClassName = AnalysisT::name();
    auto PassName = MapClassName2PassName(ClassName);
    OS << "require<" << PassName << ">";
  }
};

/// An alias template to easily name a require analysis loop pass.
template <typename AnalysisT>
using RequireAnalysisLoopPass =
    RequireAnalysisPass<AnalysisT, Loop, LoopAnalysisManager,
                        LoopStandardAnalysisResults &, LPMUpdater &>;

class FunctionToLoopPassAdaptor;

/// This class provides an interface for updating the loop pass manager based
/// on mutations to the loop nest.
///
/// A reference to an instance of this class is passed as an argument to each
/// Loop pass, and Loop passes should use it to update LPM infrastructure if
/// they modify the loop nest structure.
///
/// \c LPMUpdater comes with two modes: the loop mode and the loop-nest mode. In
/// loop mode, all the loops in the function will be pushed into the worklist
/// and when new loops are added to the pipeline, their subloops are also
/// inserted recursively. On the other hand, in loop-nest mode, only top-level
/// loops are contained in the worklist and the addition of new (top-level)
/// loops will not trigger the addition of their subloops.
class LPMUpdater {
public:
  /// This can be queried by loop passes which run other loop passes (like pass
  /// managers) to know whether the loop needs to be skipped due to updates to
  /// the loop nest.
  ///
  /// If this returns true, the loop object may have been deleted, so passes
  /// should take care not to touch the object.
  bool skipCurrentLoop() const { return SkipCurrentLoop; }

  /// Loop passes should use this method to indicate they have deleted a loop
  /// from the nest.
  ///
  /// Note that this loop must either be the current loop or a subloop of the
  /// current loop. This routine must be called prior to removing the loop from
  /// the loop nest.
  ///
  /// If this is called for the current loop, in addition to clearing any
  /// state, this routine will mark that the current loop should be skipped by
  /// the rest of the pass management infrastructure.
  void markLoopAsDeleted(Loop &L, llvm::StringRef Name) {
    LAM.clear(L, Name);
    assert((&L == CurrentL || CurrentL->contains(&L)) &&
           "Cannot delete a loop outside of the "
           "subloop tree currently being processed.");
    if (&L == CurrentL)
      SkipCurrentLoop = true;
  }

  void setParentLoop(Loop *L) {
#ifdef LLVM_ENABLE_ABI_BREAKING_CHECKS
    ParentL = L;
#endif
  }

  /// Loop passes should use this method to indicate they have added new child
  /// loops of the current loop.
  ///
  /// \p NewChildLoops must contain only the immediate children. Any nested
  /// loops within them will be visited in postorder as usual for the loop pass
  /// manager.
  void addChildLoops(ArrayRef<Loop *> NewChildLoops) {
    assert(!LoopNestMode &&
           "Child loops should not be pushed in loop-nest mode.");
    // Insert ourselves back into the worklist first, as this loop should be
    // revisited after all the children have been processed.
    Worklist.insert(CurrentL);

#ifndef NDEBUG
    for (Loop *NewL : NewChildLoops)
      assert(NewL->getParentLoop() == CurrentL && "All of the new loops must "
                                                  "be immediate children of "
                                                  "the current loop!");
#endif

    appendLoopsToWorklist(NewChildLoops, Worklist);

    // Also skip further processing of the current loop--it will be revisited
    // after all of its newly added children are accounted for.
    SkipCurrentLoop = true;
  }

  /// Loop passes should use this method to indicate they have added new
  /// sibling loops to the current loop.
  ///
  /// \p NewSibLoops must only contain the immediate sibling loops. Any nested
  /// loops within them will be visited in postorder as usual for the loop pass
  /// manager.
  void addSiblingLoops(ArrayRef<Loop *> NewSibLoops) {
#if defined(LLVM_ENABLE_ABI_BREAKING_CHECKS) && !defined(NDEBUG)
    for (Loop *NewL : NewSibLoops)
      assert(NewL->getParentLoop() == ParentL &&
             "All of the new loops must be siblings of the current loop!");
#endif

    if (LoopNestMode)
      Worklist.insert(NewSibLoops);
    else
      appendLoopsToWorklist(NewSibLoops, Worklist);

    // No need to skip the current loop or revisit it, as sibling loops
    // shouldn't impact anything.
  }

  /// Restart the current loop.
  ///
  /// Loop passes should call this method to indicate the current loop has been
  /// sufficiently changed that it should be re-visited from the begining of
  /// the loop pass pipeline rather than continuing.
  void revisitCurrentLoop() {
    // Tell the currently in-flight pipeline to stop running.
    SkipCurrentLoop = true;

    // And insert ourselves back into the worklist.
    Worklist.insert(CurrentL);
  }

  bool isLoopNestChanged() const {
    return LoopNestChanged;
  }

  /// Loopnest passes should use this method to indicate if the
  /// loopnest has been modified.
  void markLoopNestChanged(bool Changed) {
    LoopNestChanged = Changed;
  }

private:
  friend class llvm::FunctionToLoopPassAdaptor;

  /// The \c FunctionToLoopPassAdaptor's worklist of loops to process.
  SmallPriorityWorklist<Loop *, 4> &Worklist;

  /// The analysis manager for use in the current loop nest.
  LoopAnalysisManager &LAM;

  Loop *CurrentL;
  bool SkipCurrentLoop;
  const bool LoopNestMode;
  bool LoopNestChanged;

#ifdef LLVM_ENABLE_ABI_BREAKING_CHECKS
  // In debug builds we also track the parent loop to implement asserts even in
  // the face of loop deletion.
  Loop *ParentL;
#endif

  LPMUpdater(SmallPriorityWorklist<Loop *, 4> &Worklist,
             LoopAnalysisManager &LAM, bool LoopNestMode = false,
             bool LoopNestChanged = false)
      : Worklist(Worklist), LAM(LAM), LoopNestMode(LoopNestMode),
        LoopNestChanged(LoopNestChanged) {}
};

template <typename IRUnitT, typename PassT>
std::optional<PreservedAnalyses> LoopPassManager::runSinglePass(
    IRUnitT &IR, PassT &Pass, LoopAnalysisManager &AM,
    LoopStandardAnalysisResults &AR, LPMUpdater &U, PassInstrumentation &PI) {
  // Get the loop in case of Loop pass and outermost loop in case of LoopNest
  // pass which is to be passed to BeforePass and AfterPass call backs.
  const Loop &L = getLoopFromIR(IR);
  // Check the PassInstrumentation's BeforePass callbacks before running the
  // pass, skip its execution completely if asked to (callback returns false).
  if (!PI.runBeforePass<Loop>(*Pass, L))
    return std::nullopt;

  PreservedAnalyses PA = Pass->run(IR, AM, AR, U);

  // do not pass deleted Loop into the instrumentation
  if (U.skipCurrentLoop())
    PI.runAfterPassInvalidated<IRUnitT>(*Pass, PA);
  else
    PI.runAfterPass<Loop>(*Pass, L, PA);
  return PA;
}

/// Adaptor that maps from a function to its loops.
///
/// Designed to allow composition of a LoopPass(Manager) and a
/// FunctionPassManager. Note that if this pass is constructed with a \c
/// FunctionAnalysisManager it will run the \c LoopAnalysisManagerFunctionProxy
/// analysis prior to running the loop passes over the function to enable a \c
/// LoopAnalysisManager to be used within this run safely.
///
/// The adaptor comes with two modes: the loop mode and the loop-nest mode, and
/// the worklist updater lived inside will be in the same mode as the adaptor
/// (refer to the documentation of \c LPMUpdater for more detailed explanation).
/// Specifically, in loop mode, all loops in the funciton will be pushed into
/// the worklist and processed by \p Pass, while only top-level loops are
/// processed in loop-nest mode. Please refer to the various specializations of
/// \fn createLoopFunctionToLoopPassAdaptor to see when loop mode and loop-nest
/// mode are used.
class FunctionToLoopPassAdaptor
    : public PassInfoMixin<FunctionToLoopPassAdaptor> {
public:
  using PassConceptT =
      detail::PassConcept<Loop, LoopAnalysisManager,
                          LoopStandardAnalysisResults &, LPMUpdater &>;

  explicit FunctionToLoopPassAdaptor(std::unique_ptr<PassConceptT> Pass,
                                     bool UseMemorySSA = false,
                                     bool UseBlockFrequencyInfo = false,
                                     bool UseBranchProbabilityInfo = false,
                                     bool LoopNestMode = false)
      : Pass(std::move(Pass)), UseMemorySSA(UseMemorySSA),
        UseBlockFrequencyInfo(UseBlockFrequencyInfo),
        UseBranchProbabilityInfo(UseBranchProbabilityInfo),
        LoopNestMode(LoopNestMode) {
    LoopCanonicalizationFPM.addPass(LoopSimplifyPass());
    LoopCanonicalizationFPM.addPass(LCSSAPass());
  }

  /// Runs the loop passes across every loop in the function.
  PreservedAnalyses run(Function &F, FunctionAnalysisManager &AM);
  void printPipeline(raw_ostream &OS,
                     function_ref<StringRef(StringRef)> MapClassName2PassName);

  static bool isRequired() { return true; }

  bool isLoopNestMode() const { return LoopNestMode; }

private:
  std::unique_ptr<PassConceptT> Pass;

  FunctionPassManager LoopCanonicalizationFPM;

  bool UseMemorySSA = false;
  bool UseBlockFrequencyInfo = false;
  bool UseBranchProbabilityInfo = false;
  const bool LoopNestMode;
};

/// A function to deduce a loop pass type and wrap it in the templated
/// adaptor.
///
/// If \p Pass is a loop pass, the returned adaptor will be in loop mode.
template <typename LoopPassT>
inline std::enable_if_t<is_detected<HasRunOnLoopT, LoopPassT>::value,
                        FunctionToLoopPassAdaptor>
createFunctionToLoopPassAdaptor(LoopPassT &&Pass, bool UseMemorySSA = false,
                                bool UseBlockFrequencyInfo = false,
                                bool UseBranchProbabilityInfo = false) {
  using PassModelT =
      detail::PassModel<Loop, LoopPassT, PreservedAnalyses, LoopAnalysisManager,
                        LoopStandardAnalysisResults &, LPMUpdater &>;
  // Do not use make_unique, it causes too many template instantiations,
  // causing terrible compile times.
  return FunctionToLoopPassAdaptor(
      std::unique_ptr<FunctionToLoopPassAdaptor::PassConceptT>(
          new PassModelT(std::forward<LoopPassT>(Pass))),
      UseMemorySSA, UseBlockFrequencyInfo, UseBranchProbabilityInfo, false);
}

/// If \p Pass is a loop-nest pass, \p Pass will first be wrapped into a
/// \c LoopPassManager and the returned adaptor will be in loop-nest mode.
template <typename LoopNestPassT>
inline std::enable_if_t<!is_detected<HasRunOnLoopT, LoopNestPassT>::value,
                        FunctionToLoopPassAdaptor>
createFunctionToLoopPassAdaptor(LoopNestPassT &&Pass, bool UseMemorySSA = false,
                                bool UseBlockFrequencyInfo = false,
                                bool UseBranchProbabilityInfo = false) {
  LoopPassManager LPM;
  LPM.addPass(std::forward<LoopNestPassT>(Pass));
  using PassModelT =
      detail::PassModel<Loop, LoopPassManager, PreservedAnalyses,
                        LoopAnalysisManager, LoopStandardAnalysisResults &,
                        LPMUpdater &>;
  // Do not use make_unique, it causes too many template instantiations,
  // causing terrible compile times.
  return FunctionToLoopPassAdaptor(
      std::unique_ptr<FunctionToLoopPassAdaptor::PassConceptT>(
          new PassModelT(std::move(LPM))),
      UseMemorySSA, UseBlockFrequencyInfo, UseBranchProbabilityInfo, true);
}

/// If \p Pass is an instance of \c LoopPassManager, the returned adaptor will
/// be in loop-nest mode if the pass manager contains only loop-nest passes.
template <>
inline FunctionToLoopPassAdaptor
createFunctionToLoopPassAdaptor<LoopPassManager>(
    LoopPassManager &&LPM, bool UseMemorySSA, bool UseBlockFrequencyInfo,
    bool UseBranchProbabilityInfo) {
  // Check if LPM contains any loop pass and if it does not, returns an adaptor
  // in loop-nest mode.
  using PassModelT =
      detail::PassModel<Loop, LoopPassManager, PreservedAnalyses,
                        LoopAnalysisManager, LoopStandardAnalysisResults &,
                        LPMUpdater &>;
  bool LoopNestMode = (LPM.getNumLoopPasses() == 0);
  // Do not use make_unique, it causes too many template instantiations,
  // causing terrible compile times.
  return FunctionToLoopPassAdaptor(
      std::unique_ptr<FunctionToLoopPassAdaptor::PassConceptT>(
          new PassModelT(std::move(LPM))),
      UseMemorySSA, UseBlockFrequencyInfo, UseBranchProbabilityInfo,
      LoopNestMode);
}

/// Pass for printing a loop's contents as textual IR.
class PrintLoopPass : public PassInfoMixin<PrintLoopPass> {
  raw_ostream &OS;
  std::string Banner;

public:
  PrintLoopPass();
  PrintLoopPass(raw_ostream &OS, const std::string &Banner = "");

  PreservedAnalyses run(Loop &L, LoopAnalysisManager &,
                        LoopStandardAnalysisResults &, LPMUpdater &);
};
}

#endif // LLVM_TRANSFORMS_SCALAR_LOOPPASSMANAGER_H

#ifdef __GNUC__
#pragma GCC diagnostic pop
#endif