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 <string> 35 36 namespace llvm { 37 38 class AnalysisResolver; 39 class AnalysisUsage; 40 class Function; 41 class ImmutablePass; 42 class Module; 43 class PassInfo; 44 class PMDataManager; 45 class PMStack; 46 class raw_ostream; 47 class StringRef; 48 49 // AnalysisID - Use the PassInfo to identify a pass... 50 using AnalysisID = const void *; 51 52 /// Different types of internal pass managers. External pass managers 53 /// (PassManager and FunctionPassManager) are not represented here. 54 /// Ordering of pass manager types is important here. 55 enum PassManagerType { 56 PMT_Unknown = 0, 57 PMT_ModulePassManager = 1, ///< MPPassManager 58 PMT_CallGraphPassManager, ///< CGPassManager 59 PMT_FunctionPassManager, ///< FPPassManager 60 PMT_LoopPassManager, ///< LPPassManager 61 PMT_RegionPassManager, ///< RGPassManager 62 PMT_Last 63 }; 64 65 // Different types of passes. 66 enum PassKind { 67 PT_Region, 68 PT_Loop, 69 PT_Function, 70 PT_CallGraphSCC, 71 PT_Module, 72 PT_PassManager 73 }; 74 75 /// This enumerates the LLVM full LTO or ThinLTO optimization phases. 76 enum class ThinOrFullLTOPhase { 77 /// No LTO/ThinLTO behavior needed. 78 None, 79 /// ThinLTO prelink (summary) phase. 80 ThinLTOPreLink, 81 /// ThinLTO postlink (backend compile) phase. 82 ThinLTOPostLink, 83 /// Full LTO prelink phase. 84 FullLTOPreLink, 85 /// Full LTO postlink (backend compile) phase. 86 FullLTOPostLink 87 }; 88 89 //===----------------------------------------------------------------------===// 90 /// Pass interface - Implemented by all 'passes'. Subclass this if you are an 91 /// interprocedural optimization or you do not fit into any of the more 92 /// constrained passes described below. 93 /// 94 class Pass { 95 AnalysisResolver *Resolver = nullptr; // Used to resolve analysis 96 const void *PassID; 97 PassKind Kind; 98 99 public: Pass(PassKind K,char & pid)100 explicit Pass(PassKind K, char &pid) : PassID(&pid), Kind(K) {} 101 Pass(const Pass &) = delete; 102 Pass &operator=(const Pass &) = delete; 103 virtual ~Pass(); 104 getPassKind()105 PassKind getPassKind() const { return Kind; } 106 107 /// getPassName - Return a nice clean name for a pass. This usually 108 /// implemented in terms of the name that is registered by one of the 109 /// Registration templates, but can be overloaded directly. 110 virtual StringRef getPassName() const; 111 112 /// getPassID - Return the PassID number that corresponds to this pass. getPassID()113 AnalysisID getPassID() const { 114 return PassID; 115 } 116 117 /// doInitialization - Virtual method overridden by subclasses to do 118 /// any necessary initialization before any pass is run. doInitialization(Module &)119 virtual bool doInitialization(Module &) { return false; } 120 121 /// doFinalization - Virtual method overriden by subclasses to do any 122 /// necessary clean up after all passes have run. doFinalization(Module &)123 virtual bool doFinalization(Module &) { return false; } 124 125 /// print - Print out the internal state of the pass. This is called by 126 /// Analyze to print out the contents of an analysis. Otherwise it is not 127 /// necessary to implement this method. Beware that the module pointer MAY be 128 /// null. This automatically forwards to a virtual function that does not 129 /// provide the Module* in case the analysis doesn't need it it can just be 130 /// ignored. 131 virtual void print(raw_ostream &OS, const Module *M) const; 132 133 void dump() const; // dump - Print to stderr. 134 135 /// createPrinterPass - Get a Pass appropriate to print the IR this 136 /// pass operates on (Module, Function or MachineFunction). 137 virtual Pass *createPrinterPass(raw_ostream &OS, 138 const std::string &Banner) const = 0; 139 140 /// Each pass is responsible for assigning a pass manager to itself. 141 /// PMS is the stack of available pass manager. assignPassManager(PMStack &,PassManagerType)142 virtual void assignPassManager(PMStack &, 143 PassManagerType) {} 144 145 /// Check if available pass managers are suitable for this pass or not. 146 virtual void preparePassManager(PMStack &); 147 148 /// Return what kind of Pass Manager can manage this pass. 149 virtual PassManagerType getPotentialPassManagerType() const; 150 151 // Access AnalysisResolver 152 void setResolver(AnalysisResolver *AR); getResolver()153 AnalysisResolver *getResolver() const { return Resolver; } 154 155 /// getAnalysisUsage - This function should be overriden by passes that need 156 /// analysis information to do their job. If a pass specifies that it uses a 157 /// particular analysis result to this function, it can then use the 158 /// getAnalysis<AnalysisType>() function, below. 159 virtual void getAnalysisUsage(AnalysisUsage &) const; 160 161 /// releaseMemory() - This member can be implemented by a pass if it wants to 162 /// be able to release its memory when it is no longer needed. The default 163 /// behavior of passes is to hold onto memory for the entire duration of their 164 /// lifetime (which is the entire compile time). For pipelined passes, this 165 /// is not a big deal because that memory gets recycled every time the pass is 166 /// invoked on another program unit. For IP passes, it is more important to 167 /// free memory when it is unused. 168 /// 169 /// Optionally implement this function to release pass memory when it is no 170 /// longer used. 171 virtual void releaseMemory(); 172 173 /// getAdjustedAnalysisPointer - This method is used when a pass implements 174 /// an analysis interface through multiple inheritance. If needed, it should 175 /// override this to adjust the this pointer as needed for the specified pass 176 /// info. 177 virtual void *getAdjustedAnalysisPointer(AnalysisID ID); 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 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(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 and 280 /// "basic" versions of AnalysisGroups. 281 /// 282 class ImmutablePass : public ModulePass { 283 public: ImmutablePass(char & pid)284 explicit ImmutablePass(char &pid) : ModulePass(pid) {} 285 286 // Force out-of-line virtual method. 287 ~ImmutablePass() override; 288 289 /// initializePass - This method may be overriden by immutable passes to allow 290 /// them to perform various initialization actions they require. This is 291 /// primarily because an ImmutablePass can "require" another ImmutablePass, 292 /// and if it does, the overloaded version of initializePass may get access to 293 /// these passes with getAnalysis<>. 294 virtual void initializePass(); 295 getAsImmutablePass()296 ImmutablePass *getAsImmutablePass() override { return this; } 297 298 /// ImmutablePasses are never run. runOnModule(Module &)299 bool runOnModule(Module &) override { return false; } 300 }; 301 302 //===----------------------------------------------------------------------===// 303 /// FunctionPass class - This class is used to implement most global 304 /// optimizations. Optimizations should subclass this class if they meet the 305 /// following constraints: 306 /// 307 /// 1. Optimizations are organized globally, i.e., a function at a time 308 /// 2. Optimizing a function does not cause the addition or removal of any 309 /// functions in the module 310 /// 311 class FunctionPass : public Pass { 312 public: FunctionPass(char & pid)313 explicit FunctionPass(char &pid) : Pass(PT_Function, pid) {} 314 315 /// createPrinterPass - Get a function printer pass. 316 Pass *createPrinterPass(raw_ostream &OS, 317 const std::string &Banner) const override; 318 319 /// runOnFunction - Virtual method overriden by subclasses to do the 320 /// per-function processing of the pass. 321 virtual bool runOnFunction(Function &F) = 0; 322 323 void assignPassManager(PMStack &PMS, PassManagerType T) override; 324 325 /// Return what kind of Pass Manager can manage this pass. 326 PassManagerType getPotentialPassManagerType() const override; 327 328 protected: 329 /// Optional passes call this function to check whether the pass should be 330 /// skipped. This is the case when Attribute::OptimizeNone is set or when 331 /// optimization bisect is over the limit. 332 bool skipFunction(const Function &F) const; 333 }; 334 335 /// If the user specifies the -time-passes argument on an LLVM tool command line 336 /// then the value of this boolean will be true, otherwise false. 337 /// This is the storage for the -time-passes option. 338 extern bool TimePassesIsEnabled; 339 /// If TimePassesPerRun is true, there would be one line of report for 340 /// each pass invocation. 341 /// If TimePassesPerRun is false, there would be only one line of 342 /// report for each pass (even there are more than one pass objects). 343 /// (For new pass manager only) 344 extern bool TimePassesPerRun; 345 346 } // end namespace llvm 347 348 // Include support files that contain important APIs commonly used by Passes, 349 // but that we want to separate out to make it easier to read the header files. 350 #include "llvm/PassAnalysisSupport.h" 351 #include "llvm/PassSupport.h" 352 353 #endif // LLVM_PASS_H 354