1//===- llvm/PassAnalysisSupport.h - Analysis Pass Support code --*- 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 stuff that is used to define and "use" Analysis Passes.
11// This file is automatically #included by Pass.h, so:
12//
13//           NO .CPP FILES SHOULD INCLUDE THIS FILE DIRECTLY
14//
15// Instead, #include Pass.h
16//
17//===----------------------------------------------------------------------===//
18
19#ifndef LLVM_PASSANALYSISSUPPORT_H
20#define LLVM_PASSANALYSISSUPPORT_H
21
22#include "llvm/ADT/SmallVector.h"
23#include "llvm/Pass.h"
24#include <vector>
25
26namespace llvm {
27class StringRef;
28
29//===----------------------------------------------------------------------===//
30/// Represent the analysis usage information of a pass.  This tracks analyses
31/// that the pass REQUIRES (must be available when the pass runs), REQUIRES
32/// TRANSITIVE (must be available throughout the lifetime of the pass), and
33/// analyses that the pass PRESERVES (the pass does not invalidate the results
34/// of these analyses).  This information is provided by a pass to the Pass
35/// infrastructure through the getAnalysisUsage virtual function.
36///
37class AnalysisUsage {
38public:
39  typedef SmallVectorImpl<AnalysisID> VectorType;
40
41private:
42  /// Sets of analyses required and preserved by a pass
43  // TODO: It's not clear that SmallVector is an appropriate data structure for
44  // this usecase.  The sizes were picked to minimize wasted space, but are
45  // otherwise fairly meaningless.
46  SmallVector<AnalysisID, 8> Required;
47  SmallVector<AnalysisID, 2> RequiredTransitive;
48  SmallVector<AnalysisID, 2> Preserved;
49  SmallVector<AnalysisID, 0> Used;
50  bool PreservesAll;
51
52public:
53  AnalysisUsage() : PreservesAll(false) {}
54
55  ///@{
56  /// Add the specified ID to the required set of the usage info for a pass.
57  AnalysisUsage &addRequiredID(const void *ID);
58  AnalysisUsage &addRequiredID(char &ID);
59  template<class PassClass>
60  AnalysisUsage &addRequired() {
61    return addRequiredID(PassClass::ID);
62  }
63
64  AnalysisUsage &addRequiredTransitiveID(char &ID);
65  template<class PassClass>
66  AnalysisUsage &addRequiredTransitive() {
67    return addRequiredTransitiveID(PassClass::ID);
68  }
69  ///@}
70
71  ///@{
72  /// Add the specified ID to the set of analyses preserved by this pass.
73  AnalysisUsage &addPreservedID(const void *ID) {
74    Preserved.push_back(ID);
75    return *this;
76  }
77  AnalysisUsage &addPreservedID(char &ID) {
78    Preserved.push_back(&ID);
79    return *this;
80  }
81  /// Add the specified Pass class to the set of analyses preserved by this pass.
82  template<class PassClass>
83  AnalysisUsage &addPreserved() {
84    Preserved.push_back(&PassClass::ID);
85    return *this;
86  }
87  ///@}
88
89  ///@{
90  /// Add the specified ID to the set of analyses used by this pass if they are
91  /// available..
92  AnalysisUsage &addUsedIfAvailableID(const void *ID) {
93    Used.push_back(ID);
94    return *this;
95  }
96  AnalysisUsage &addUsedIfAvailableID(char &ID) {
97    Used.push_back(&ID);
98    return *this;
99  }
100  /// Add the specified Pass class to the set of analyses used by this pass.
101  template<class PassClass>
102  AnalysisUsage &addUsedIfAvailable() {
103    Used.push_back(&PassClass::ID);
104    return *this;
105  }
106  ///@}
107
108  /// Add the Pass with the specified argument string to the set of analyses
109  /// preserved by this pass. If no such Pass exists, do nothing. This can be
110  /// useful when a pass is trivially preserved, but may not be linked in. Be
111  /// careful about spelling!
112  AnalysisUsage &addPreserved(StringRef Arg);
113
114  /// Set by analyses that do not transform their input at all
115  void setPreservesAll() { PreservesAll = true; }
116
117  /// Determine whether a pass said it does not transform its input at all
118  bool getPreservesAll() const { return PreservesAll; }
119
120  /// This function should be called by the pass, iff they do not:
121  ///
122  ///  1. Add or remove basic blocks from the function
123  ///  2. Modify terminator instructions in any way.
124  ///
125  /// This function annotates the AnalysisUsage info object to say that analyses
126  /// that only depend on the CFG are preserved by this pass.
127  ///
128  void setPreservesCFG();
129
130  const VectorType &getRequiredSet() const { return Required; }
131  const VectorType &getRequiredTransitiveSet() const {
132    return RequiredTransitive;
133  }
134  const VectorType &getPreservedSet() const { return Preserved; }
135  const VectorType &getUsedSet() const { return Used; }
136};
137
138//===----------------------------------------------------------------------===//
139/// AnalysisResolver - Simple interface used by Pass objects to pull all
140/// analysis information out of pass manager that is responsible to manage
141/// the pass.
142///
143class PMDataManager;
144class AnalysisResolver {
145private:
146  AnalysisResolver() = delete;
147
148public:
149  explicit AnalysisResolver(PMDataManager &P) : PM(P) { }
150
151  inline PMDataManager &getPMDataManager() { return PM; }
152
153  /// Find pass that is implementing PI.
154  Pass *findImplPass(AnalysisID PI) {
155    Pass *ResultPass = nullptr;
156    for (const auto &AnalysisImpl : AnalysisImpls) {
157      if (AnalysisImpl.first == PI) {
158        ResultPass = AnalysisImpl.second;
159        break;
160      }
161    }
162    return ResultPass;
163  }
164
165  /// Find pass that is implementing PI. Initialize pass for Function F.
166  Pass *findImplPass(Pass *P, AnalysisID PI, Function &F);
167
168  void addAnalysisImplsPair(AnalysisID PI, Pass *P) {
169    if (findImplPass(PI) == P)
170      return;
171    std::pair<AnalysisID, Pass*> pir = std::make_pair(PI,P);
172    AnalysisImpls.push_back(pir);
173  }
174
175  /// Clear cache that is used to connect a pass to the the analysis (PassInfo).
176  void clearAnalysisImpls() {
177    AnalysisImpls.clear();
178  }
179
180  /// Return analysis result or null if it doesn't exist.
181  Pass *getAnalysisIfAvailable(AnalysisID ID, bool Direction) const;
182
183private:
184  /// This keeps track of which passes implements the interfaces that are
185  /// required by the current pass (to implement getAnalysis()).
186  std::vector<std::pair<AnalysisID, Pass*> > AnalysisImpls;
187
188  /// PassManager that is used to resolve analysis info
189  PMDataManager &PM;
190};
191
192/// getAnalysisIfAvailable<AnalysisType>() - Subclasses use this function to
193/// get analysis information that might be around, for example to update it.
194/// This is different than getAnalysis in that it can fail (if the analysis
195/// results haven't been computed), so should only be used if you can handle
196/// the case when the analysis is not available.  This method is often used by
197/// transformation APIs to update analysis results for a pass automatically as
198/// the transform is performed.
199///
200template<typename AnalysisType>
201AnalysisType *Pass::getAnalysisIfAvailable() const {
202  assert(Resolver && "Pass not resident in a PassManager object!");
203
204  const void *PI = &AnalysisType::ID;
205
206  Pass *ResultPass = Resolver->getAnalysisIfAvailable(PI, true);
207  if (!ResultPass) return nullptr;
208
209  // Because the AnalysisType may not be a subclass of pass (for
210  // AnalysisGroups), we use getAdjustedAnalysisPointer here to potentially
211  // adjust the return pointer (because the class may multiply inherit, once
212  // from pass, once from AnalysisType).
213  return (AnalysisType*)ResultPass->getAdjustedAnalysisPointer(PI);
214}
215
216/// getAnalysis<AnalysisType>() - This function is used by subclasses to get
217/// to the analysis information that they claim to use by overriding the
218/// getAnalysisUsage function.
219///
220template<typename AnalysisType>
221AnalysisType &Pass::getAnalysis() const {
222  assert(Resolver && "Pass has not been inserted into a PassManager object!");
223  return getAnalysisID<AnalysisType>(&AnalysisType::ID);
224}
225
226template<typename AnalysisType>
227AnalysisType &Pass::getAnalysisID(AnalysisID PI) const {
228  assert(PI && "getAnalysis for unregistered pass!");
229  assert(Resolver&&"Pass has not been inserted into a PassManager object!");
230  // PI *must* appear in AnalysisImpls.  Because the number of passes used
231  // should be a small number, we just do a linear search over a (dense)
232  // vector.
233  Pass *ResultPass = Resolver->findImplPass(PI);
234  assert (ResultPass &&
235          "getAnalysis*() called on an analysis that was not "
236          "'required' by pass!");
237
238  // Because the AnalysisType may not be a subclass of pass (for
239  // AnalysisGroups), we use getAdjustedAnalysisPointer here to potentially
240  // adjust the return pointer (because the class may multiply inherit, once
241  // from pass, once from AnalysisType).
242  return *(AnalysisType*)ResultPass->getAdjustedAnalysisPointer(PI);
243}
244
245/// getAnalysis<AnalysisType>() - This function is used by subclasses to get
246/// to the analysis information that they claim to use by overriding the
247/// getAnalysisUsage function.
248///
249template<typename AnalysisType>
250AnalysisType &Pass::getAnalysis(Function &F) {
251  assert(Resolver &&"Pass has not been inserted into a PassManager object!");
252
253  return getAnalysisID<AnalysisType>(&AnalysisType::ID, F);
254}
255
256template<typename AnalysisType>
257AnalysisType &Pass::getAnalysisID(AnalysisID PI, Function &F) {
258  assert(PI && "getAnalysis for unregistered pass!");
259  assert(Resolver && "Pass has not been inserted into a PassManager object!");
260  // PI *must* appear in AnalysisImpls.  Because the number of passes used
261  // should be a small number, we just do a linear search over a (dense)
262  // vector.
263  Pass *ResultPass = Resolver->findImplPass(this, PI, F);
264  assert(ResultPass && "Unable to find requested analysis info");
265
266  // Because the AnalysisType may not be a subclass of pass (for
267  // AnalysisGroups), we use getAdjustedAnalysisPointer here to potentially
268  // adjust the return pointer (because the class may multiply inherit, once
269  // from pass, once from AnalysisType).
270  return *(AnalysisType*)ResultPass->getAdjustedAnalysisPointer(PI);
271}
272
273} // End llvm namespace
274
275#endif
276