1//===- LoopPass.h - LoopPass class ----------------------------------------===//
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 LoopPass class. All loop optimization
11// and transformation passes are derived from LoopPass.
12//
13//===----------------------------------------------------------------------===//
14
15#ifndef LLVM_ANALYSIS_LOOPPASS_H
16#define LLVM_ANALYSIS_LOOPPASS_H
17
18#include "llvm/Analysis/LoopInfo.h"
19#include "llvm/IR/LegacyPassManagers.h"
20#include "llvm/Pass.h"
21#include <deque>
22
23namespace llvm {
24
25class LPPassManager;
26class Function;
27class PMStack;
28
29class LoopPass : public Pass {
30public:
31  explicit LoopPass(char &pid) : Pass(PT_Loop, pid) {}
32
33  /// getPrinterPass - Get a pass to print the function corresponding
34  /// to a Loop.
35  Pass *createPrinterPass(raw_ostream &O,
36                          const std::string &Banner) const override;
37
38  // runOnLoop - This method should be implemented by the subclass to perform
39  // whatever action is necessary for the specified Loop.
40  virtual bool runOnLoop(Loop *L, LPPassManager &LPM) = 0;
41
42  using llvm::Pass::doInitialization;
43  using llvm::Pass::doFinalization;
44
45  // Initialization and finalization hooks.
46  virtual bool doInitialization(Loop *L, LPPassManager &LPM) {
47    return false;
48  }
49
50  // Finalization hook does not supply Loop because at this time
51  // loop nest is completely different.
52  virtual bool doFinalization() { return false; }
53
54  // Check if this pass is suitable for the current LPPassManager, if
55  // available. This pass P is not suitable for a LPPassManager if P
56  // is not preserving higher level analysis info used by other
57  // LPPassManager passes. In such case, pop LPPassManager from the
58  // stack. This will force assignPassManager() to create new
59  // LPPassManger as expected.
60  void preparePassManager(PMStack &PMS) override;
61
62  /// Assign pass manager to manage this pass
63  void assignPassManager(PMStack &PMS, PassManagerType PMT) override;
64
65  ///  Return what kind of Pass Manager can manage this pass.
66  PassManagerType getPotentialPassManagerType() const override {
67    return PMT_LoopPassManager;
68  }
69
70  //===--------------------------------------------------------------------===//
71  /// SimpleAnalysis - Provides simple interface to update analysis info
72  /// maintained by various passes. Note, if required this interface can
73  /// be extracted into a separate abstract class but it would require
74  /// additional use of multiple inheritance in Pass class hierarchy, something
75  /// we are trying to avoid.
76
77  /// Each loop pass can override these simple analysis hooks to update
78  /// desired analysis information.
79  /// cloneBasicBlockAnalysis - Clone analysis info associated with basic block.
80  virtual void cloneBasicBlockAnalysis(BasicBlock *F, BasicBlock *T, Loop *L) {}
81
82  /// deleteAnalysisValue - Delete analysis info associated with value V.
83  virtual void deleteAnalysisValue(Value *V, Loop *L) {}
84
85protected:
86  /// skipOptnoneFunction - Containing function has Attribute::OptimizeNone
87  /// and most transformation passes should skip it.
88  bool skipOptnoneFunction(const Loop *L) const;
89};
90
91class LPPassManager : public FunctionPass, public PMDataManager {
92public:
93  static char ID;
94  explicit LPPassManager();
95
96  /// run - Execute all of the passes scheduled for execution.  Keep track of
97  /// whether any of the passes modifies the module, and if so, return true.
98  bool runOnFunction(Function &F) override;
99
100  /// Pass Manager itself does not invalidate any analysis info.
101  // LPPassManager needs LoopInfo.
102  void getAnalysisUsage(AnalysisUsage &Info) const override;
103
104  const char *getPassName() const override {
105    return "Loop Pass Manager";
106  }
107
108  PMDataManager *getAsPMDataManager() override { return this; }
109  Pass *getAsPass() override { return this; }
110
111  /// Print passes managed by this manager
112  void dumpPassStructure(unsigned Offset) override;
113
114  LoopPass *getContainedPass(unsigned N) {
115    assert(N < PassVector.size() && "Pass number out of range!");
116    LoopPass *LP = static_cast<LoopPass *>(PassVector[N]);
117    return LP;
118  }
119
120  PassManagerType getPassManagerType() const override {
121    return PMT_LoopPassManager;
122  }
123
124public:
125  // Delete loop from the loop queue and loop nest (LoopInfo).
126  void deleteLoopFromQueue(Loop *L);
127
128  // Insert loop into the loop queue and add it as a child of the
129  // given parent.
130  void insertLoop(Loop *L, Loop *ParentLoop);
131
132  // Insert a loop into the loop queue.
133  void insertLoopIntoQueue(Loop *L);
134
135  // Reoptimize this loop. LPPassManager will re-insert this loop into the
136  // queue. This allows LoopPass to change loop nest for the loop. This
137  // utility may send LPPassManager into infinite loops so use caution.
138  void redoLoop(Loop *L);
139
140  //===--------------------------------------------------------------------===//
141  /// SimpleAnalysis - Provides simple interface to update analysis info
142  /// maintained by various passes. Note, if required this interface can
143  /// be extracted into a separate abstract class but it would require
144  /// additional use of multiple inheritance in Pass class hierarchy, something
145  /// we are trying to avoid.
146
147  /// cloneBasicBlockSimpleAnalysis - Invoke cloneBasicBlockAnalysis hook for
148  /// all passes that implement simple analysis interface.
149  void cloneBasicBlockSimpleAnalysis(BasicBlock *From, BasicBlock *To, Loop *L);
150
151  /// deleteSimpleAnalysisValue - Invoke deleteAnalysisValue hook for all passes
152  /// that implement simple analysis interface.
153  void deleteSimpleAnalysisValue(Value *V, Loop *L);
154
155private:
156  std::deque<Loop *> LQ;
157  bool skipThisLoop;
158  bool redoThisLoop;
159  LoopInfo *LI;
160  Loop *CurrentLoop;
161};
162
163} // End llvm namespace
164
165#endif
166