LLVM  6.0.0svn
PassAnalysisSupport.h
Go to the documentation of this file.
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 
26 namespace llvm {
27 class 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 ///
38 public:
40 
41 private:
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.
47  SmallVector<AnalysisID, 2> RequiredTransitive;
50  bool PreservesAll;
51 
52 public:
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>
62  }
63 
65  template<class PassClass>
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  }
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>
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..
93  Used.push_back(ID);
94  return *this;
95  }
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>
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!
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 ///
143 class PMDataManager;
145 private:
146  AnalysisResolver() = delete;
147 
148 public:
149  explicit AnalysisResolver(PMDataManager &P) : PM(P) { }
150 
151  inline PMDataManager &getPMDataManager() { return PM; }
152 
153  /// Find pass that is implementing 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 
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).
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 
183 private:
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 ///
200 template<typename AnalysisType>
201 AnalysisType *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 ///
220 template<typename AnalysisType>
221 AnalysisType &Pass::getAnalysis() const {
222  assert(Resolver && "Pass has not been inserted into a PassManager object!");
223  return getAnalysisID<AnalysisType>(&AnalysisType::ID);
224 }
225 
226 template<typename AnalysisType>
227 AnalysisType &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 ///
249 template<typename AnalysisType>
250 AnalysisType &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 
256 template<typename AnalysisType>
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
Pass interface - Implemented by all &#39;passes&#39;.
Definition: Pass.h:81
void push_back(const T &Elt)
Definition: SmallVector.h:212
AnalysisUsage & addPreserved()
Add the specified Pass class to the set of analyses preserved by this pass.
Compute iterated dominance frontiers using a linear time algorithm.
Definition: AllocatorList.h:24
const VectorType & getUsedSet() const
const VectorType & getRequiredSet() const
AnalysisUsage & addRequired()
SmallVectorImpl< AnalysisID > VectorType
AnalysisUsage & addPreservedID(char &ID)
const VectorType & getPreservedSet() const
AnalysisUsage & addUsedIfAvailableID(char &ID)
#define F(x, y, z)
Definition: MD5.cpp:55
AnalysisUsage & addPreservedID(const void *ID)
AnalysisType & getAnalysis() const
getAnalysis<AnalysisType>() - This function is used by subclasses to get to the analysis information ...
AnalysisResolver(PMDataManager &P)
AnalysisType & getAnalysisID(AnalysisID PI) const
#define P(N)
Represent the analysis usage information of a pass.
AnalysisUsage & addUsedIfAvailableID(const void *ID)
AnalysisUsage & addRequiredID(const void *ID)
Definition: Pass.cpp:291
void addAnalysisImplsPair(AnalysisID PI, Pass *P)
void setPreservesCFG()
This function should be called by the pass, iff they do not:
Definition: Pass.cpp:278
void clearAnalysisImpls()
Clear cache that is used to connect a pass to the the analysis (PassInfo).
Pass * findImplPass(AnalysisID PI)
Find pass that is implementing PI.
void setPreservesAll()
Set by analyses that do not transform their input at all.
const VectorType & getRequiredTransitiveSet() const
PMDataManager & getPMDataManager()
AnalysisUsage & addRequiredTransitiveID(char &ID)
Definition: Pass.cpp:301
AnalysisUsage & addRequiredTransitive()
const void * AnalysisID
Definition: Pass.h:46
PMDataManager provides the common place to manage the analysis data used by pass managers.
assert(ImpDefSCC.getReg()==AMDGPU::SCC &&ImpDefSCC.isDef())
AnalysisUsage & addUsedIfAvailable()
Add the specified Pass class to the set of analyses used by this pass.
AnalysisType * getAnalysisIfAvailable() const
getAnalysisIfAvailable<AnalysisType>() - Subclasses use this function to get analysis information tha...
virtual void * getAdjustedAnalysisPointer(AnalysisID ID)
getAdjustedAnalysisPointer - This method is used when a pass implements an analysis interface through...
Definition: Pass.cpp:96
StringRef - Represent a constant reference to a string, i.e.
Definition: StringRef.h:49
bool getPreservesAll() const
Determine whether a pass said it does not transform its input at all.