1 //===- llvm/Pass.h - Base class for Passes ----------------------*- 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 a base class that indicates that a specified class is a 11 // transformation pass implementation. 12 // 13 // Passes are designed this way so that it is possible to run passes in a cache 14 // and organizationally optimal order without having to specify it at the front 15 // end. This allows arbitrary passes to be strung together and have them 16 // executed as efficiently as possible. 17 // 18 // Passes should extend one of the classes below, depending on the guarantees 19 // that it can make about what will be modified as it is run. For example, most 20 // global optimizations should derive from FunctionPass, because they do not add 21 // or delete functions, they operate on the internals of the function. 22 // 23 // Note that this file #includes PassSupport.h and PassAnalysisSupport.h (at the 24 // bottom), so the APIs exposed by these files are also automatically available 25 // to all users of this file. 26 // 27 //===----------------------------------------------------------------------===// 28 29 #ifndef LLVM_PASS_H 30 #define LLVM_PASS_H 31 32 #include "llvm/ADT/StringRef.h" 33 #include <string> 34 35 namespace llvm { 36 37 class AnalysisResolver; 38 class AnalysisUsage; 39 class BasicBlock; 40 class Function; 41 class ImmutablePass; 42 class Module; 43 class PassInfo; 44 class PMDataManager; 45 class PMStack; 46 class raw_ostream; 47 48 // AnalysisID - Use the PassInfo to identify a pass... 49 using AnalysisID = const void *; 50 51 /// Different types of internal pass managers. External pass managers 52 /// (PassManager and FunctionPassManager) are not represented here. 53 /// Ordering of pass manager types is important here. 54 enum PassManagerType { 55 PMT_Unknown = 0, 56 PMT_ModulePassManager = 1, ///< MPPassManager 57 PMT_CallGraphPassManager, ///< CGPassManager 58 PMT_FunctionPassManager, ///< FPPassManager 59 PMT_LoopPassManager, ///< LPPassManager 60 PMT_RegionPassManager, ///< RGPassManager 61 PMT_BasicBlockPassManager, ///< BBPassManager 62 PMT_Last 63 }; 64 65 // Different types of passes. 66 enum PassKind { 67 PT_BasicBlock, 68 PT_Region, 69 PT_Loop, 70 PT_Function, 71 PT_CallGraphSCC, 72 PT_Module, 73 PT_PassManager 74 }; 75 76 //===----------------------------------------------------------------------===// 77 /// Pass interface - Implemented by all 'passes'. Subclass this if you are an 78 /// interprocedural optimization or you do not fit into any of the more 79 /// constrained passes described below. 80 /// 81 class Pass { 82 AnalysisResolver *Resolver = nullptr; // Used to resolve analysis 83 const void *PassID; 84 PassKind Kind; 85 86 public: 87 explicit Pass(PassKind K, char &pid) : PassID(&pid), Kind(K) {} 88 Pass(const Pass &) = delete; 89 Pass &operator=(const Pass &) = delete; 90 virtual ~Pass(); 91 92 PassKind getPassKind() const { return Kind; } 93 94 /// getPassName - Return a nice clean name for a pass. This usually 95 /// implemented in terms of the name that is registered by one of the 96 /// Registration templates, but can be overloaded directly. 97 virtual StringRef getPassName() const; 98 99 /// getPassID - Return the PassID number that corresponds to this pass. 100 AnalysisID getPassID() const { 101 return PassID; 102 } 103 104 /// doInitialization - Virtual method overridden by subclasses to do 105 /// any necessary initialization before any pass is run. 106 virtual bool doInitialization(Module &) { return false; } 107 108 /// doFinalization - Virtual method overriden by subclasses to do any 109 /// necessary clean up after all passes have run. 110 virtual bool doFinalization(Module &) { return false; } 111 112 /// print - Print out the internal state of the pass. This is called by 113 /// Analyze to print out the contents of an analysis. Otherwise it is not 114 /// necessary to implement this method. Beware that the module pointer MAY be 115 /// null. This automatically forwards to a virtual function that does not 116 /// provide the Module* in case the analysis doesn't need it it can just be 117 /// ignored. 118 virtual void print(raw_ostream &OS, const Module *M) const; 119 120 void dump() const; // dump - Print to stderr. 121 122 /// createPrinterPass - Get a Pass appropriate to print the IR this 123 /// pass operates on (Module, Function or MachineFunction). 124 virtual Pass *createPrinterPass(raw_ostream &OS, 125 const std::string &Banner) const = 0; 126 127 /// Each pass is responsible for assigning a pass manager to itself. 128 /// PMS is the stack of available pass manager. 129 virtual void assignPassManager(PMStack &, 130 PassManagerType) {} 131 132 /// Check if available pass managers are suitable for this pass or not. 133 virtual void preparePassManager(PMStack &); 134 135 /// Return what kind of Pass Manager can manage this pass. 136 virtual PassManagerType getPotentialPassManagerType() const; 137 138 // Access AnalysisResolver 139 void setResolver(AnalysisResolver *AR); 140 AnalysisResolver *getResolver() const { return Resolver; } 141 142 /// getAnalysisUsage - This function should be overriden by passes that need 143 /// analysis information to do their job. If a pass specifies that it uses a 144 /// particular analysis result to this function, it can then use the 145 /// getAnalysis<AnalysisType>() function, below. 146 virtual void getAnalysisUsage(AnalysisUsage &) const; 147 148 /// releaseMemory() - This member can be implemented by a pass if it wants to 149 /// be able to release its memory when it is no longer needed. The default 150 /// behavior of passes is to hold onto memory for the entire duration of their 151 /// lifetime (which is the entire compile time). For pipelined passes, this 152 /// is not a big deal because that memory gets recycled every time the pass is 153 /// invoked on another program unit. For IP passes, it is more important to 154 /// free memory when it is unused. 155 /// 156 /// Optionally implement this function to release pass memory when it is no 157 /// longer used. 158 virtual void releaseMemory(); 159 160 /// getAdjustedAnalysisPointer - This method is used when a pass implements 161 /// an analysis interface through multiple inheritance. If needed, it should 162 /// override this to adjust the this pointer as needed for the specified pass 163 /// info. 164 virtual void *getAdjustedAnalysisPointer(AnalysisID ID); 165 virtual ImmutablePass *getAsImmutablePass(); 166 virtual PMDataManager *getAsPMDataManager(); 167 168 /// verifyAnalysis() - This member can be implemented by a analysis pass to 169 /// check state of analysis information. 170 virtual void verifyAnalysis() const; 171 172 // dumpPassStructure - Implement the -debug-passes=PassStructure option 173 virtual void dumpPassStructure(unsigned Offset = 0); 174 175 // lookupPassInfo - Return the pass info object for the specified pass class, 176 // or null if it is not known. 177 static const PassInfo *lookupPassInfo(const void *TI); 178 179 // lookupPassInfo - Return the pass info object for the pass with the given 180 // argument string, or null if it is not known. 181 static const PassInfo *lookupPassInfo(StringRef Arg); 182 183 // createPass - Create a object for the specified pass class, 184 // or null if it is not known. 185 static Pass *createPass(AnalysisID ID); 186 187 /// getAnalysisIfAvailable<AnalysisType>() - Subclasses use this function to 188 /// get analysis information that might be around, for example to update it. 189 /// This is different than getAnalysis in that it can fail (if the analysis 190 /// results haven't been computed), so should only be used if you can handle 191 /// the case when the analysis is not available. This method is often used by 192 /// transformation APIs to update analysis results for a pass automatically as 193 /// the transform is performed. 194 template<typename AnalysisType> AnalysisType * 195 getAnalysisIfAvailable() const; // Defined in PassAnalysisSupport.h 196 197 /// mustPreserveAnalysisID - This method serves the same function as 198 /// getAnalysisIfAvailable, but works if you just have an AnalysisID. This 199 /// obviously cannot give you a properly typed instance of the class if you 200 /// don't have the class name available (use getAnalysisIfAvailable if you 201 /// do), but it can tell you if you need to preserve the pass at least. 202 bool mustPreserveAnalysisID(char &AID) const; 203 204 /// getAnalysis<AnalysisType>() - This function is used by subclasses to get 205 /// to the analysis information that they claim to use by overriding the 206 /// getAnalysisUsage function. 207 template<typename AnalysisType> 208 AnalysisType &getAnalysis() const; // Defined in PassAnalysisSupport.h 209 210 template<typename AnalysisType> 211 AnalysisType &getAnalysis(Function &F); // Defined in PassAnalysisSupport.h 212 213 template<typename AnalysisType> 214 AnalysisType &getAnalysisID(AnalysisID PI) const; 215 216 template<typename AnalysisType> 217 AnalysisType &getAnalysisID(AnalysisID PI, Function &F); 218 }; 219 220 //===----------------------------------------------------------------------===// 221 /// ModulePass class - This class is used to implement unstructured 222 /// interprocedural optimizations and analyses. ModulePasses may do anything 223 /// they want to the program. 224 /// 225 class ModulePass : public Pass { 226 public: 227 explicit ModulePass(char &pid) : Pass(PT_Module, pid) {} 228 229 // Force out-of-line virtual method. 230 ~ModulePass() override; 231 232 /// createPrinterPass - Get a module printer pass. 233 Pass *createPrinterPass(raw_ostream &OS, 234 const std::string &Banner) const override; 235 236 /// runOnModule - Virtual method overriden by subclasses to process the module 237 /// being operated on. 238 virtual bool runOnModule(Module &M) = 0; 239 240 void assignPassManager(PMStack &PMS, PassManagerType T) override; 241 242 /// Return what kind of Pass Manager can manage this pass. 243 PassManagerType getPotentialPassManagerType() const override; 244 245 protected: 246 /// Optional passes call this function to check whether the pass should be 247 /// skipped. This is the case when optimization bisect is over the limit. 248 bool skipModule(Module &M) const; 249 }; 250 251 //===----------------------------------------------------------------------===// 252 /// ImmutablePass class - This class is used to provide information that does 253 /// not need to be run. This is useful for things like target information and 254 /// "basic" versions of AnalysisGroups. 255 /// 256 class ImmutablePass : public ModulePass { 257 public: 258 explicit ImmutablePass(char &pid) : ModulePass(pid) {} 259 260 // Force out-of-line virtual method. 261 ~ImmutablePass() override; 262 263 /// initializePass - This method may be overriden by immutable passes to allow 264 /// them to perform various initialization actions they require. This is 265 /// primarily because an ImmutablePass can "require" another ImmutablePass, 266 /// and if it does, the overloaded version of initializePass may get access to 267 /// these passes with getAnalysis<>. 268 virtual void initializePass(); 269 270 ImmutablePass *getAsImmutablePass() override { return this; } 271 272 /// ImmutablePasses are never run. 273 bool runOnModule(Module &) override { return false; } 274 }; 275 276 //===----------------------------------------------------------------------===// 277 /// FunctionPass class - This class is used to implement most global 278 /// optimizations. Optimizations should subclass this class if they meet the 279 /// following constraints: 280 /// 281 /// 1. Optimizations are organized globally, i.e., a function at a time 282 /// 2. Optimizing a function does not cause the addition or removal of any 283 /// functions in the module 284 /// 285 class FunctionPass : public Pass { 286 public: 287 explicit FunctionPass(char &pid) : Pass(PT_Function, pid) {} 288 289 /// createPrinterPass - Get a function printer pass. 290 Pass *createPrinterPass(raw_ostream &OS, 291 const std::string &Banner) const override; 292 293 /// runOnFunction - Virtual method overriden by subclasses to do the 294 /// per-function processing of the pass. 295 virtual bool runOnFunction(Function &F) = 0; 296 297 void assignPassManager(PMStack &PMS, PassManagerType T) override; 298 299 /// Return what kind of Pass Manager can manage this pass. 300 PassManagerType getPotentialPassManagerType() const override; 301 302 protected: 303 /// Optional passes call this function to check whether the pass should be 304 /// skipped. This is the case when Attribute::OptimizeNone is set or when 305 /// optimization bisect is over the limit. 306 bool skipFunction(const Function &F) const; 307 }; 308 309 //===----------------------------------------------------------------------===// 310 /// BasicBlockPass class - This class is used to implement most local 311 /// optimizations. Optimizations should subclass this class if they 312 /// meet the following constraints: 313 /// 1. Optimizations are local, operating on either a basic block or 314 /// instruction at a time. 315 /// 2. Optimizations do not modify the CFG of the contained function, or any 316 /// other basic block in the function. 317 /// 3. Optimizations conform to all of the constraints of FunctionPasses. 318 /// 319 class BasicBlockPass : public Pass { 320 public: 321 explicit BasicBlockPass(char &pid) : Pass(PT_BasicBlock, pid) {} 322 323 /// createPrinterPass - Get a basic block printer pass. 324 Pass *createPrinterPass(raw_ostream &OS, 325 const std::string &Banner) const override; 326 327 using llvm::Pass::doInitialization; 328 using llvm::Pass::doFinalization; 329 330 /// doInitialization - Virtual method overridden by BasicBlockPass subclasses 331 /// to do any necessary per-function initialization. 332 virtual bool doInitialization(Function &); 333 334 /// runOnBasicBlock - Virtual method overriden by subclasses to do the 335 /// per-basicblock processing of the pass. 336 virtual bool runOnBasicBlock(BasicBlock &BB) = 0; 337 338 /// doFinalization - Virtual method overriden by BasicBlockPass subclasses to 339 /// do any post processing needed after all passes have run. 340 virtual bool doFinalization(Function &); 341 342 void assignPassManager(PMStack &PMS, PassManagerType T) override; 343 344 /// Return what kind of Pass Manager can manage this pass. 345 PassManagerType getPotentialPassManagerType() const override; 346 347 protected: 348 /// Optional passes call this function to check whether the pass should be 349 /// skipped. This is the case when Attribute::OptimizeNone is set or when 350 /// optimization bisect is over the limit. 351 bool skipBasicBlock(const BasicBlock &BB) const; 352 }; 353 354 /// If the user specifies the -time-passes argument on an LLVM tool command line 355 /// then the value of this boolean will be true, otherwise false. 356 /// @brief This is the storage for the -time-passes option. 357 extern bool TimePassesIsEnabled; 358 359 /// isFunctionInPrintList - returns true if a function should be printed via 360 // debugging options like -print-after-all/-print-before-all. 361 // @brief Tells if the function IR should be printed by PrinterPass. 362 extern bool isFunctionInPrintList(StringRef FunctionName); 363 364 } // end namespace llvm 365 366 // Include support files that contain important APIs commonly used by Passes, 367 // but that we want to separate out to make it easier to read the header files. 368 #include "llvm/InitializePasses.h" 369 #include "llvm/PassAnalysisSupport.h" 370 #include "llvm/PassSupport.h" 371 372 #endif // LLVM_PASS_H 373