include/llvm/PassAnalysisSupport.h

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