1 //===- llvm/Pass.h - Base class for Passes ----------------------*- C++ -*-===// 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 a base class that indicates that a specified class is a 10 // transformation pass implementation. 11 // 12 // Passes are designed this way so that it is possible to run passes in a cache 13 // and organizationally optimal order without having to specify it at the front 14 // end. This allows arbitrary passes to be strung together and have them 15 // executed as efficiently as possible. 16 // 17 // Passes should extend one of the classes below, depending on the guarantees 18 // that it can make about what will be modified as it is run. For example, most 19 // global optimizations should derive from FunctionPass, because they do not add 20 // or delete functions, they operate on the internals of the function. 21 // 22 // Note that this file #includes PassSupport.h and PassAnalysisSupport.h (at the 23 // bottom), so the APIs exposed by these files are also automatically available 24 // to all users of this file. 25 // 26 //===----------------------------------------------------------------------===// 27 28 #ifndef LLVM_PASS_H 29 #define LLVM_PASS_H 30 31 #ifdef EXPENSIVE_CHECKS 32 #include <cstdint> 33 #endif 34 #include "llvm/Support/Compiler.h" 35 #include <string> 36 37 namespace llvm { 38 39 class AnalysisResolver; 40 class AnalysisUsage; 41 class Function; 42 class ImmutablePass; 43 class Module; 44 class PassInfo; 45 class PMDataManager; 46 class PMStack; 47 class raw_ostream; 48 class StringRef; 49 50 // AnalysisID - Use the PassInfo to identify a pass... 51 using AnalysisID = const void *; 52 53 /// Different types of internal pass managers. External pass managers 54 /// (PassManager and FunctionPassManager) are not represented here. 55 /// Ordering of pass manager types is important here. 56 enum PassManagerType { 57 PMT_Unknown = 0, 58 PMT_ModulePassManager = 1, ///< MPPassManager 59 PMT_CallGraphPassManager, ///< CGPassManager 60 PMT_FunctionPassManager, ///< FPPassManager 61 PMT_LoopPassManager, ///< LPPassManager 62 PMT_RegionPassManager, ///< RGPassManager 63 PMT_Last 64 }; 65 66 // Different types of passes. 67 enum PassKind { 68 PT_Region, 69 PT_Loop, 70 PT_Function, 71 PT_CallGraphSCC, 72 PT_Module, 73 PT_PassManager 74 }; 75 76 /// This enumerates the LLVM full LTO or ThinLTO optimization phases. 77 enum class ThinOrFullLTOPhase { 78 /// No LTO/ThinLTO behavior needed. 79 None, 80 /// ThinLTO prelink (summary) phase. 81 ThinLTOPreLink, 82 /// ThinLTO postlink (backend compile) phase. 83 ThinLTOPostLink, 84 /// Full LTO prelink phase. 85 FullLTOPreLink, 86 /// Full LTO postlink (backend compile) phase. 87 FullLTOPostLink 88 }; 89 90 #ifndef NDEBUG 91 const char *to_string(ThinOrFullLTOPhase Phase); 92 #endif 93 94 //===----------------------------------------------------------------------===// 95 /// Pass interface - Implemented by all 'passes'. Subclass this if you are an 96 /// interprocedural optimization or you do not fit into any of the more 97 /// constrained passes described below. 98 /// 99 class LLVM_ABI Pass { 100 AnalysisResolver *Resolver = nullptr; // Used to resolve analysis 101 const void *PassID; 102 PassKind Kind; 103 104 public: Pass(PassKind K,char & pid)105 explicit Pass(PassKind K, char &pid) : PassID(&pid), Kind(K) {} 106 Pass(const Pass &) = delete; 107 Pass &operator=(const Pass &) = delete; 108 virtual ~Pass(); 109 getPassKind()110 PassKind getPassKind() const { return Kind; } 111 112 /// getPassName - Return a nice clean name for a pass. This usually 113 /// implemented in terms of the name that is registered by one of the 114 /// Registration templates, but can be overloaded directly. 115 virtual StringRef getPassName() const; 116 117 /// getPassID - Return the PassID number that corresponds to this pass. getPassID()118 AnalysisID getPassID() const { 119 return PassID; 120 } 121 122 /// doInitialization - Virtual method overridden by subclasses to do 123 /// any necessary initialization before any pass is run. doInitialization(Module &)124 virtual bool doInitialization(Module &) { return false; } 125 126 /// doFinalization - Virtual method overriden by subclasses to do any 127 /// necessary clean up after all passes have run. doFinalization(Module &)128 virtual bool doFinalization(Module &) { return false; } 129 130 /// print - Print out the internal state of the pass. This is called by 131 /// Analyze to print out the contents of an analysis. Otherwise it is not 132 /// necessary to implement this method. Beware that the module pointer MAY be 133 /// null. This automatically forwards to a virtual function that does not 134 /// provide the Module* in case the analysis doesn't need it it can just be 135 /// ignored. 136 virtual void print(raw_ostream &OS, const Module *M) const; 137 138 void dump() const; // dump - Print to stderr. 139 140 /// createPrinterPass - Get a Pass appropriate to print the IR this 141 /// pass operates on (Module, Function or MachineFunction). 142 virtual Pass *createPrinterPass(raw_ostream &OS, 143 const std::string &Banner) const = 0; 144 145 /// Each pass is responsible for assigning a pass manager to itself. 146 /// PMS is the stack of available pass manager. assignPassManager(PMStack &,PassManagerType)147 virtual void assignPassManager(PMStack &, 148 PassManagerType) {} 149 150 /// Check if available pass managers are suitable for this pass or not. 151 virtual void preparePassManager(PMStack &); 152 153 /// Return what kind of Pass Manager can manage this pass. 154 virtual PassManagerType getPotentialPassManagerType() const; 155 156 // Access AnalysisResolver 157 void setResolver(AnalysisResolver *AR); getResolver()158 AnalysisResolver *getResolver() const { return Resolver; } 159 160 /// getAnalysisUsage - This function should be overriden by passes that need 161 /// analysis information to do their job. If a pass specifies that it uses a 162 /// particular analysis result to this function, it can then use the 163 /// getAnalysis<AnalysisType>() function, below. 164 virtual void getAnalysisUsage(AnalysisUsage &) const; 165 166 /// releaseMemory() - This member can be implemented by a pass if it wants to 167 /// be able to release its memory when it is no longer needed. The default 168 /// behavior of passes is to hold onto memory for the entire duration of their 169 /// lifetime (which is the entire compile time). For pipelined passes, this 170 /// is not a big deal because that memory gets recycled every time the pass is 171 /// invoked on another program unit. For IP passes, it is more important to 172 /// free memory when it is unused. 173 /// 174 /// Optionally implement this function to release pass memory when it is no 175 /// longer used. 176 virtual void releaseMemory(); 177 178 virtual ImmutablePass *getAsImmutablePass(); 179 virtual PMDataManager *getAsPMDataManager(); 180 181 /// verifyAnalysis() - This member can be implemented by a analysis pass to 182 /// check state of analysis information. 183 virtual void verifyAnalysis() const; 184 185 // dumpPassStructure - Implement the -debug-passes=PassStructure option 186 virtual void dumpPassStructure(unsigned Offset = 0); 187 188 // lookupPassInfo - Return the pass info object for the specified pass class, 189 // or null if it is not known. 190 static const PassInfo *lookupPassInfo(const void *TI); 191 192 // lookupPassInfo - Return the pass info object for the pass with the given 193 // argument string, or null if it is not known. 194 static const PassInfo *lookupPassInfo(StringRef Arg); 195 196 // createPass - Create a object for the specified pass class, 197 // or null if it is not known. 198 static Pass *createPass(AnalysisID ID); 199 200 /// getAnalysisIfAvailable<AnalysisType>() - Subclasses use this function to 201 /// get analysis information that might be around, for example to update it. 202 /// This is different than getAnalysis in that it can fail (if the analysis 203 /// results haven't been computed), so should only be used if you can handle 204 /// the case when the analysis is not available. This method is often used by 205 /// transformation APIs to update analysis results for a pass automatically as 206 /// the transform is performed. 207 template<typename AnalysisType> AnalysisType * 208 getAnalysisIfAvailable() const; // Defined in PassAnalysisSupport.h 209 210 /// mustPreserveAnalysisID - This method serves the same function as 211 /// getAnalysisIfAvailable, but works if you just have an AnalysisID. This 212 /// obviously cannot give you a properly typed instance of the class if you 213 /// don't have the class name available (use getAnalysisIfAvailable if you 214 /// do), but it can tell you if you need to preserve the pass at least. 215 bool mustPreserveAnalysisID(char &AID) const; 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 &getAnalysis() const; // Defined in PassAnalysisSupport.h 222 223 template <typename AnalysisType> 224 AnalysisType & 225 getAnalysis(Function &F, 226 bool *Changed = nullptr); // Defined in PassAnalysisSupport.h 227 228 template<typename AnalysisType> 229 AnalysisType &getAnalysisID(AnalysisID PI) const; 230 231 template <typename AnalysisType> 232 AnalysisType &getAnalysisID(AnalysisID PI, Function &F, 233 bool *Changed = nullptr); 234 235 #ifdef EXPENSIVE_CHECKS 236 /// Hash a module in order to detect when a module (or more specific) pass has 237 /// modified it. 238 uint64_t structuralHash(Module &M) const; 239 240 /// Hash a function in order to detect when a function (or more specific) pass 241 /// has modified it. 242 virtual uint64_t structuralHash(Function &F) const; 243 #endif 244 }; 245 246 //===----------------------------------------------------------------------===// 247 /// ModulePass class - This class is used to implement unstructured 248 /// interprocedural optimizations and analyses. ModulePasses may do anything 249 /// they want to the program. 250 /// 251 class LLVM_ABI ModulePass : public Pass { 252 public: ModulePass(char & pid)253 explicit ModulePass(char &pid) : Pass(PT_Module, pid) {} 254 255 // Force out-of-line virtual method. 256 ~ModulePass() override; 257 258 /// createPrinterPass - Get a module printer pass. 259 Pass *createPrinterPass(raw_ostream &OS, 260 const std::string &Banner) const override; 261 262 /// runOnModule - Virtual method overriden by subclasses to process the module 263 /// being operated on. 264 virtual bool runOnModule(Module &M) = 0; 265 266 void assignPassManager(PMStack &PMS, PassManagerType T) override; 267 268 /// Return what kind of Pass Manager can manage this pass. 269 PassManagerType getPotentialPassManagerType() const override; 270 271 protected: 272 /// Optional passes call this function to check whether the pass should be 273 /// skipped. This is the case when optimization bisect is over the limit. 274 bool skipModule(const Module &M) const; 275 }; 276 277 //===----------------------------------------------------------------------===// 278 /// ImmutablePass class - This class is used to provide information that does 279 /// not need to be run. This is useful for things like target information. 280 /// 281 class LLVM_ABI ImmutablePass : public ModulePass { 282 public: ImmutablePass(char & pid)283 explicit ImmutablePass(char &pid) : ModulePass(pid) {} 284 285 // Force out-of-line virtual method. 286 ~ImmutablePass() override; 287 288 /// initializePass - This method may be overriden by immutable passes to allow 289 /// them to perform various initialization actions they require. This is 290 /// primarily because an ImmutablePass can "require" another ImmutablePass, 291 /// and if it does, the overloaded version of initializePass may get access to 292 /// these passes with getAnalysis<>. 293 virtual void initializePass(); 294 getAsImmutablePass()295 ImmutablePass *getAsImmutablePass() override { return this; } 296 297 /// ImmutablePasses are never run. runOnModule(Module &)298 bool runOnModule(Module &) override { return false; } 299 }; 300 301 //===----------------------------------------------------------------------===// 302 /// FunctionPass class - This class is used to implement most global 303 /// optimizations. Optimizations should subclass this class if they meet the 304 /// following constraints: 305 /// 306 /// 1. Optimizations are organized globally, i.e., a function at a time 307 /// 2. Optimizing a function does not cause the addition or removal of any 308 /// functions in the module 309 /// 310 class LLVM_ABI FunctionPass : public Pass { 311 public: FunctionPass(char & pid)312 explicit FunctionPass(char &pid) : Pass(PT_Function, pid) {} 313 314 /// createPrinterPass - Get a function printer pass. 315 Pass *createPrinterPass(raw_ostream &OS, 316 const std::string &Banner) const override; 317 318 /// runOnFunction - Virtual method overriden by subclasses to do the 319 /// per-function processing of the pass. 320 virtual bool runOnFunction(Function &F) = 0; 321 322 void assignPassManager(PMStack &PMS, PassManagerType T) override; 323 324 /// Return what kind of Pass Manager can manage this pass. 325 PassManagerType getPotentialPassManagerType() const override; 326 327 protected: 328 /// Optional passes call this function to check whether the pass should be 329 /// skipped. This is the case when Attribute::OptimizeNone is set or when 330 /// optimization bisect is over the limit. 331 bool skipFunction(const Function &F) const; 332 }; 333 334 /// If the user specifies the -time-passes argument on an LLVM tool command line 335 /// then the value of this boolean will be true, otherwise false. 336 /// This is the storage for the -time-passes option. 337 LLVM_ABI extern bool TimePassesIsEnabled; 338 /// If TimePassesPerRun is true, there would be one line of report for 339 /// each pass invocation. 340 /// If TimePassesPerRun is false, there would be only one line of 341 /// report for each pass (even there are more than one pass objects). 342 /// (For new pass manager only) 343 LLVM_ABI extern bool TimePassesPerRun; 344 345 } // end namespace llvm 346 347 // Include support files that contain important APIs commonly used by Passes, 348 // but that we want to separate out to make it easier to read the header files. 349 #include "llvm/PassAnalysisSupport.h" 350 #include "llvm/PassSupport.h" 351 352 #endif // LLVM_PASS_H 353