Pass.h revision ce20771ec2fd95cf3a7f9d0ad95717c2e83b5324
1//===- llvm/Pass.h - Base class for Passes ----------------------*- C++ -*-===// 2// 3// The LLVM Compiler Infrastructure 4// 5// This file was developed by the LLVM research group and is distributed under 6// the University of Illinois Open Source 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// Pass's 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 effeciently 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 <vector> 33#include <map> 34#include <iosfwd> 35#include <typeinfo> 36#include <cassert> 37 38namespace llvm { 39 40class Value; 41class BasicBlock; 42class Function; 43class Module; 44class AnalysisUsage; 45class PassInfo; 46class ImmutablePass; 47template<class UnitType> class PassManagerT; 48struct AnalysisResolver; 49 50// AnalysisID - Use the PassInfo to identify a pass... 51typedef const PassInfo* AnalysisID; 52 53//===----------------------------------------------------------------------===// 54/// Pass interface - Implemented by all 'passes'. Subclass this if you are an 55/// interprocedural optimization or you do not fit into any of the more 56/// constrained passes described below. 57/// 58class Pass { 59 friend struct AnalysisResolver; 60 AnalysisResolver *Resolver; // AnalysisResolver this pass is owned by... 61 const PassInfo *PassInfoCache; 62 63 // AnalysisImpls - This keeps track of which passes implement the interfaces 64 // that are required by the current pass (to implement getAnalysis()). 65 // 66 std::vector<std::pair<const PassInfo*, Pass*> > AnalysisImpls; 67 68 void operator=(const Pass&); // DO NOT IMPLEMENT 69 Pass(const Pass &); // DO NOT IMPLEMENT 70public: 71 Pass() : Resolver(0), PassInfoCache(0) {} 72 virtual ~Pass() {} // Destructor is virtual so we can be subclassed 73 74 /// getPassName - Return a nice clean name for a pass. This usually 75 /// implemented in terms of the name that is registered by one of the 76 /// Registration templates, but can be overloaded directly, and if nothing 77 /// else is available, C++ RTTI will be consulted to get a SOMEWHAT 78 /// intelligible name for the pass. 79 /// 80 virtual const char *getPassName() const; 81 82 /// getPassInfo - Return the PassInfo data structure that corresponds to this 83 /// pass... If the pass has not been registered, this will return null. 84 /// 85 const PassInfo *getPassInfo() const; 86 87 /// runPass - Run this pass, returning true if a modification was made to the 88 /// module argument. This should be implemented by all concrete subclasses. 89 /// 90 virtual bool runPass(Module &M) { return false; } 91 virtual bool runPass(BasicBlock&) { return false; } 92 93 /// print - Print out the internal state of the pass. This is called by 94 /// Analyze to print out the contents of an analysis. Otherwise it is not 95 /// necessary to implement this method. Beware that the module pointer MAY be 96 /// null. This automatically forwards to a virtual function that does not 97 /// provide the Module* in case the analysis doesn't need it it can just be 98 /// ignored. 99 /// 100 virtual void print(std::ostream &O, const Module *M) const; 101 void dump() const; // dump - call print(std::cerr, 0); 102 103 104 /// getAnalysisUsage - This function should be overriden by passes that need 105 /// analysis information to do their job. If a pass specifies that it uses a 106 /// particular analysis result to this function, it can then use the 107 /// getAnalysis<AnalysisType>() function, below. 108 /// 109 virtual void getAnalysisUsage(AnalysisUsage &Info) const { 110 // By default, no analysis results are used, all are invalidated. 111 } 112 113 /// releaseMemory() - This member can be implemented by a pass if it wants to 114 /// be able to release its memory when it is no longer needed. The default 115 /// behavior of passes is to hold onto memory for the entire duration of their 116 /// lifetime (which is the entire compile time). For pipelined passes, this 117 /// is not a big deal because that memory gets recycled every time the pass is 118 /// invoked on another program unit. For IP passes, it is more important to 119 /// free memory when it is unused. 120 /// 121 /// Optionally implement this function to release pass memory when it is no 122 /// longer used. 123 /// 124 virtual void releaseMemory() {} 125 126 // dumpPassStructure - Implement the -debug-passes=PassStructure option 127 virtual void dumpPassStructure(unsigned Offset = 0); 128 129 130 // getPassInfo - Static method to get the pass information from a class name. 131 template<typename AnalysisClass> 132 static const PassInfo *getClassPassInfo() { 133 return lookupPassInfo(typeid(AnalysisClass)); 134 } 135 136 // lookupPassInfo - Return the pass info object for the specified pass class, 137 // or null if it is not known. 138 static const PassInfo *lookupPassInfo(const std::type_info &TI); 139 140 /// getAnalysisToUpdate<AnalysisType>() - This function is used by subclasses 141 /// to get to the analysis information that might be around that needs to be 142 /// updated. This is different than getAnalysis in that it can fail (ie the 143 /// analysis results haven't been computed), so should only be used if you 144 /// provide the capability to update an analysis that exists. This method is 145 /// often used by transformation APIs to update analysis results for a pass 146 /// automatically as the transform is performed. 147 /// 148 template<typename AnalysisType> 149 AnalysisType *getAnalysisToUpdate() const; // Defined in PassAnalysisSupport.h 150 151 /// mustPreserveAnalysisID - This method serves the same function as 152 /// getAnalysisToUpdate, but works if you just have an AnalysisID. This 153 /// obviously cannot give you a properly typed instance of the class if you 154 /// don't have the class name available (use getAnalysisToUpdate if you do), 155 /// but it can tell you if you need to preserve the pass at least. 156 /// 157 bool mustPreserveAnalysisID(const PassInfo *AnalysisID) const; 158 159 /// getAnalysis<AnalysisType>() - This function is used by subclasses to get 160 /// to the analysis information that they claim to use by overriding the 161 /// getAnalysisUsage function. 162 /// 163 template<typename AnalysisType> 164 AnalysisType &getAnalysis() const { 165 assert(Resolver && "Pass has not been inserted into a PassManager object!"); 166 const PassInfo *PI = getClassPassInfo<AnalysisType>(); 167 return getAnalysisID<AnalysisType>(PI); 168 } 169 170 template<typename AnalysisType> 171 AnalysisType &getAnalysisID(const PassInfo *PI) const { 172 assert(Resolver && "Pass has not been inserted into a PassManager object!"); 173 assert(PI && "getAnalysis for unregistered pass!"); 174 175 // PI *must* appear in AnalysisImpls. Because the number of passes used 176 // should be a small number, we just do a linear search over a (dense) 177 // vector. 178 Pass *ResultPass = 0; 179 for (unsigned i = 0; ; ++i) { 180 assert(i != AnalysisImpls.size() && 181 "getAnalysis*() called on an analysis that was not " 182 "'required' by pass!"); 183 if (AnalysisImpls[i].first == PI) { 184 ResultPass = AnalysisImpls[i].second; 185 break; 186 } 187 } 188 189 // Because the AnalysisType may not be a subclass of pass (for 190 // AnalysisGroups), we must use dynamic_cast here to potentially adjust the 191 // return pointer (because the class may multiply inherit, once from pass, 192 // once from AnalysisType). 193 // 194 AnalysisType *Result = dynamic_cast<AnalysisType*>(ResultPass); 195 assert(Result && "Pass does not implement interface required!"); 196 return *Result; 197 } 198 199private: 200 friend class PassManagerT<Module>; 201 friend class PassManagerT<Function>; 202 friend class PassManagerT<BasicBlock>; 203}; 204 205inline std::ostream &operator<<(std::ostream &OS, const Pass &P) { 206 P.print(OS, 0); return OS; 207} 208 209//===----------------------------------------------------------------------===// 210/// ModulePass class - This class is used to implement unstructured 211/// interprocedural optimizations and analyses. ModulePass's may do anything 212/// they want to the program. 213/// 214class ModulePass : public Pass { 215public: 216 /// runOnModule - Virtual method overriden by subclasses to process the module 217 /// being operated on. 218 virtual bool runOnModule(Module &M) = 0; 219 220 virtual bool runPass(Module &M) { return runOnModule(M); } 221 virtual bool runPass(BasicBlock&) { return false; } 222 223 virtual void addToPassManager(PassManagerT<Module> *PM, AnalysisUsage &AU); 224}; 225 226 227//===----------------------------------------------------------------------===// 228/// ImmutablePass class - This class is used to provide information that does 229/// not need to be run. This is useful for things like target information and 230/// "basic" versions of AnalysisGroups. 231/// 232class ImmutablePass : public ModulePass { 233public: 234 /// initializePass - This method may be overriden by immutable passes to allow 235 /// them to perform various initialization actions they require. This is 236 /// primarily because an ImmutablePass can "require" another ImmutablePass, 237 /// and if it does, the overloaded version of initializePass may get access to 238 /// these passes with getAnalysis<>. 239 /// 240 virtual void initializePass() {} 241 242 /// ImmutablePasses are never run. 243 /// 244 virtual bool runOnModule(Module &M) { return false; } 245 246private: 247 friend class PassManagerT<Module>; 248 virtual void addToPassManager(PassManagerT<Module> *PM, AnalysisUsage &AU); 249}; 250 251//===----------------------------------------------------------------------===// 252/// FunctionPass class - This class is used to implement most global 253/// optimizations. Optimizations should subclass this class if they meet the 254/// following constraints: 255/// 256/// 1. Optimizations are organized globally, i.e., a function at a time 257/// 2. Optimizing a function does not cause the addition or removal of any 258/// functions in the module 259/// 260class FunctionPass : public ModulePass { 261public: 262 /// doInitialization - Virtual method overridden by subclasses to do 263 /// any necessary per-module initialization. 264 /// 265 virtual bool doInitialization(Module &M) { return false; } 266 267 /// runOnFunction - Virtual method overriden by subclasses to do the 268 /// per-function processing of the pass. 269 /// 270 virtual bool runOnFunction(Function &F) = 0; 271 272 /// doFinalization - Virtual method overriden by subclasses to do any post 273 /// processing needed after all passes have run. 274 /// 275 virtual bool doFinalization(Module &M) { return false; } 276 277 /// runOnModule - On a module, we run this pass by initializing, 278 /// ronOnFunction'ing once for every function in the module, then by 279 /// finalizing. 280 /// 281 virtual bool runOnModule(Module &M); 282 283 /// run - On a function, we simply initialize, run the function, then 284 /// finalize. 285 /// 286 bool run(Function &F); 287 288private: 289 friend class PassManagerT<Module>; 290 friend class PassManagerT<Function>; 291 friend class PassManagerT<BasicBlock>; 292 virtual void addToPassManager(PassManagerT<Module> *PM, AnalysisUsage &AU); 293 virtual void addToPassManager(PassManagerT<Function> *PM, AnalysisUsage &AU); 294}; 295 296 297 298//===----------------------------------------------------------------------===// 299/// BasicBlockPass class - This class is used to implement most local 300/// optimizations. Optimizations should subclass this class if they 301/// meet the following constraints: 302/// 1. Optimizations are local, operating on either a basic block or 303/// instruction at a time. 304/// 2. Optimizations do not modify the CFG of the contained function, or any 305/// other basic block in the function. 306/// 3. Optimizations conform to all of the constraints of FunctionPass's. 307/// 308struct BasicBlockPass : public FunctionPass { 309 /// doInitialization - Virtual method overridden by subclasses to do 310 /// any necessary per-module initialization. 311 /// 312 virtual bool doInitialization(Module &M) { return false; } 313 314 /// doInitialization - Virtual method overridden by BasicBlockPass subclasses 315 /// to do any necessary per-function initialization. 316 /// 317 virtual bool doInitialization(Function &F) { return false; } 318 319 /// runOnBasicBlock - Virtual method overriden by subclasses to do the 320 /// per-basicblock processing of the pass. 321 /// 322 virtual bool runOnBasicBlock(BasicBlock &BB) = 0; 323 324 /// doFinalization - Virtual method overriden by BasicBlockPass subclasses to 325 /// do any post processing needed after all passes have run. 326 /// 327 virtual bool doFinalization(Function &F) { return false; } 328 329 /// doFinalization - Virtual method overriden by subclasses to do any post 330 /// processing needed after all passes have run. 331 /// 332 virtual bool doFinalization(Module &M) { return false; } 333 334 335 // To run this pass on a function, we simply call runOnBasicBlock once for 336 // each function. 337 // 338 bool runOnFunction(Function &F); 339 340 /// To run directly on the basic block, we initialize, runOnBasicBlock, then 341 /// finalize. 342 /// 343 virtual bool runPass(Module &M) { return false; } 344 virtual bool runPass(BasicBlock &BB); 345 346private: 347 friend class PassManagerT<Function>; 348 friend class PassManagerT<BasicBlock>; 349 virtual void addToPassManager(PassManagerT<Function> *PM, AnalysisUsage &AU); 350 virtual void addToPassManager(PassManagerT<BasicBlock> *PM,AnalysisUsage &AU); 351}; 352 353/// If the user specifies the -time-passes argument on an LLVM tool command line 354/// then the value of this boolean will be true, otherwise false. 355/// @brief This is the storage for the -time-passes option. 356extern bool TimePassesIsEnabled; 357 358} // End llvm namespace 359 360// Include support files that contain important APIs commonly used by Passes, 361// but that we want to separate out to make it easier to read the header files. 362// 363#include "llvm/PassSupport.h" 364#include "llvm/PassAnalysisSupport.h" 365 366#endif 367