1//===- LoopPass.h - LoopPass class ----------------------------------------===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8//
9// This file defines LoopPass class. All loop optimization
10// and transformation passes are derived from LoopPass.
11//
12//===----------------------------------------------------------------------===//
13
14#ifndef LLVM_ANALYSIS_LOOPPASS_H
15#define LLVM_ANALYSIS_LOOPPASS_H
16
17#include "llvm/Analysis/LoopInfo.h"
18#include "llvm/IR/LegacyPassManagers.h"
19#include "llvm/Pass.h"
20#include <deque>
21
22namespace llvm {
23
24class LPPassManager;
25class Function;
26
27class LoopPass : public Pass {
28public:
29  explicit LoopPass(char &pid) : Pass(PT_Loop, pid) {}
30
31  /// getPrinterPass - Get a pass to print the function corresponding
32  /// to a Loop.
33  Pass *createPrinterPass(raw_ostream &O,
34                          const std::string &Banner) const override;
35
36  // runOnLoop - This method should be implemented by the subclass to perform
37  // whatever action is necessary for the specified Loop.
38  virtual bool runOnLoop(Loop *L, LPPassManager &LPM) = 0;
39
40  using llvm::Pass::doInitialization;
41  using llvm::Pass::doFinalization;
42
43  // Initialization and finalization hooks.
44  virtual bool doInitialization(Loop *L, LPPassManager &LPM) {
45    return false;
46  }
47
48  // Finalization hook does not supply Loop because at this time
49  // loop nest is completely different.
50  virtual bool doFinalization() { return false; }
51
52  // Check if this pass is suitable for the current LPPassManager, if
53  // available. This pass P is not suitable for a LPPassManager if P
54  // is not preserving higher level analysis info used by other
55  // LPPassManager passes. In such case, pop LPPassManager from the
56  // stack. This will force assignPassManager() to create new
57  // LPPassManger as expected.
58  void preparePassManager(PMStack &PMS) override;
59
60  /// Assign pass manager to manage this pass
61  void assignPassManager(PMStack &PMS, PassManagerType PMT) override;
62
63  ///  Return what kind of Pass Manager can manage this pass.
64  PassManagerType getPotentialPassManagerType() const override {
65    return PMT_LoopPassManager;
66  }
67
68protected:
69  /// Optional passes call this function to check whether the pass should be
70  /// skipped. This is the case when Attribute::OptimizeNone is set or when
71  /// optimization bisect is over the limit.
72  bool skipLoop(const Loop *L) const;
73};
74
75class LPPassManager : public FunctionPass, public PMDataManager {
76public:
77  static char ID;
78  explicit LPPassManager();
79
80  /// run - Execute all of the passes scheduled for execution.  Keep track of
81  /// whether any of the passes modifies the module, and if so, return true.
82  bool runOnFunction(Function &F) override;
83
84  /// Pass Manager itself does not invalidate any analysis info.
85  // LPPassManager needs LoopInfo.
86  void getAnalysisUsage(AnalysisUsage &Info) const override;
87
88  StringRef getPassName() const override { return "Loop Pass Manager"; }
89
90  PMDataManager *getAsPMDataManager() override { return this; }
91  Pass *getAsPass() override { return this; }
92
93  /// Print passes managed by this manager
94  void dumpPassStructure(unsigned Offset) override;
95
96  LoopPass *getContainedPass(unsigned N) {
97    assert(N < PassVector.size() && "Pass number out of range!");
98    LoopPass *LP = static_cast<LoopPass *>(PassVector[N]);
99    return LP;
100  }
101
102  PassManagerType getPassManagerType() const override {
103    return PMT_LoopPassManager;
104  }
105
106public:
107  // Add a new loop into the loop queue.
108  void addLoop(Loop &L);
109
110  // Mark \p L as deleted.
111  void markLoopAsDeleted(Loop &L);
112
113private:
114  std::deque<Loop *> LQ;
115  LoopInfo *LI;
116  Loop *CurrentLoop;
117  bool CurrentLoopDeleted;
118};
119
120// This pass is required by the LCSSA transformation. It is used inside
121// LPPassManager to check if current pass preserves LCSSA form, and if it does
122// pass manager calls lcssa verification for the current loop.
123struct LCSSAVerificationPass : public FunctionPass {
124  static char ID;
125  LCSSAVerificationPass();
126
127  bool runOnFunction(Function &F) override { return false; }
128
129  void getAnalysisUsage(AnalysisUsage &AU) const override {
130    AU.setPreservesAll();
131  }
132};
133
134} // End llvm namespace
135
136#endif
137