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