LLVM API Documentation
00001 //===-- Reader.h - Interface To Bytecode Reading ----------------*- C++ -*-===// 00002 // 00003 // The LLVM Compiler Infrastructure 00004 // 00005 // This file was developed by Reid Spencer and is distributed under the 00006 // University of Illinois Open Source License. See LICENSE.TXT for details. 00007 // 00008 //===----------------------------------------------------------------------===// 00009 // 00010 // This header file defines the interface to the Bytecode Reader which is 00011 // responsible for correctly interpreting bytecode files (backwards compatible) 00012 // and materializing a module from the bytecode read. 00013 // 00014 //===----------------------------------------------------------------------===// 00015 00016 #ifndef BYTECODE_PARSER_H 00017 #define BYTECODE_PARSER_H 00018 00019 #include "llvm/Constants.h" 00020 #include "llvm/DerivedTypes.h" 00021 #include "llvm/GlobalValue.h" 00022 #include "llvm/Function.h" 00023 #include "llvm/ModuleProvider.h" 00024 #include "llvm/Bytecode/Analyzer.h" 00025 #include <utility> 00026 #include <map> 00027 00028 namespace llvm { 00029 00030 class BytecodeHandler; ///< Forward declare the handler interface 00031 00032 /// This class defines the interface for parsing a buffer of bytecode. The 00033 /// parser itself takes no action except to call the various functions of 00034 /// the handler interface. The parser's sole responsibility is the correct 00035 /// interpretation of the bytecode buffer. The handler is responsible for 00036 /// instantiating and keeping track of all values. As a convenience, the parser 00037 /// is responsible for materializing types and will pass them through the 00038 /// handler interface as necessary. 00039 /// @see BytecodeHandler 00040 /// @brief Bytecode Reader interface 00041 class BytecodeReader : public ModuleProvider { 00042 00043 /// @name Constructors 00044 /// @{ 00045 public: 00046 /// @brief Default constructor. By default, no handler is used. 00047 BytecodeReader(BytecodeHandler* h = 0) { 00048 decompressedBlock = 0; 00049 Handler = h; 00050 } 00051 00052 ~BytecodeReader() { 00053 freeState(); 00054 if (decompressedBlock) { 00055 ::free(decompressedBlock); 00056 decompressedBlock = 0; 00057 } 00058 } 00059 00060 /// @} 00061 /// @name Types 00062 /// @{ 00063 public: 00064 00065 /// @brief A convenience type for the buffer pointer 00066 typedef const unsigned char* BufPtr; 00067 00068 /// @brief The type used for a vector of potentially abstract types 00069 typedef std::vector<PATypeHolder> TypeListTy; 00070 00071 /// This type provides a vector of Value* via the User class for 00072 /// storage of Values that have been constructed when reading the 00073 /// bytecode. Because of forward referencing, constant replacement 00074 /// can occur so we ensure that our list of Value* is updated 00075 /// properly through those transitions. This ensures that the 00076 /// correct Value* is in our list when it comes time to associate 00077 /// constants with global variables at the end of reading the 00078 /// globals section. 00079 /// @brief A list of values as a User of those Values. 00080 class ValueList : public User { 00081 std::vector<Use> Uses; 00082 public: 00083 ValueList() : User(Type::VoidTy, Value::ArgumentVal, 0, 0) {} 00084 00085 // vector compatibility methods 00086 unsigned size() const { return getNumOperands(); } 00087 void push_back(Value *V) { 00088 Uses.push_back(Use(V, this)); 00089 OperandList = &Uses[0]; 00090 ++NumOperands; 00091 } 00092 Value *back() const { return Uses.back(); } 00093 void pop_back() { Uses.pop_back(); --NumOperands; } 00094 bool empty() const { return NumOperands == 0; } 00095 virtual void print(std::ostream& os) const { 00096 for (unsigned i = 0; i < size(); ++i) { 00097 os << i << " "; 00098 getOperand(i)->print(os); 00099 os << "\n"; 00100 } 00101 } 00102 }; 00103 00104 /// @brief A 2 dimensional table of values 00105 typedef std::vector<ValueList*> ValueTable; 00106 00107 /// This map is needed so that forward references to constants can be looked 00108 /// up by Type and slot number when resolving those references. 00109 /// @brief A mapping of a Type/slot pair to a Constant*. 00110 typedef std::map<std::pair<unsigned,unsigned>, Constant*> ConstantRefsType; 00111 00112 /// For lazy read-in of functions, we need to save the location in the 00113 /// data stream where the function is located. This structure provides that 00114 /// information. Lazy read-in is used mostly by the JIT which only wants to 00115 /// resolve functions as it needs them. 00116 /// @brief Keeps pointers to function contents for later use. 00117 struct LazyFunctionInfo { 00118 const unsigned char *Buf, *EndBuf; 00119 LazyFunctionInfo(const unsigned char *B = 0, const unsigned char *EB = 0) 00120 : Buf(B), EndBuf(EB) {} 00121 }; 00122 00123 /// @brief A mapping of functions to their LazyFunctionInfo for lazy reading. 00124 typedef std::map<Function*, LazyFunctionInfo> LazyFunctionMap; 00125 00126 /// @brief A list of global variables and the slot number that initializes 00127 /// them. 00128 typedef std::vector<std::pair<GlobalVariable*, unsigned> > GlobalInitsList; 00129 00130 /// This type maps a typeslot/valueslot pair to the corresponding Value*. 00131 /// It is used for dealing with forward references as values are read in. 00132 /// @brief A map for dealing with forward references of values. 00133 typedef std::map<std::pair<unsigned,unsigned>,Value*> ForwardReferenceMap; 00134 00135 /// @} 00136 /// @name Methods 00137 /// @{ 00138 public: 00139 /// @brief Main interface to parsing a bytecode buffer. 00140 void ParseBytecode( 00141 const unsigned char *Buf, ///< Beginning of the bytecode buffer 00142 unsigned Length, ///< Length of the bytecode buffer 00143 const std::string &ModuleID ///< An identifier for the module constructed. 00144 ); 00145 00146 /// @brief Parse all function bodies 00147 void ParseAllFunctionBodies(); 00148 00149 /// @brief Parse the next function of specific type 00150 void ParseFunction(Function* Func) ; 00151 00152 /// This method is abstract in the parent ModuleProvider class. Its 00153 /// implementation is identical to the ParseFunction method. 00154 /// @see ParseFunction 00155 /// @brief Make a specific function materialize. 00156 virtual void materializeFunction(Function *F) { 00157 LazyFunctionMap::iterator Fi = LazyFunctionLoadMap.find(F); 00158 if (Fi == LazyFunctionLoadMap.end()) return; 00159 ParseFunction(F); 00160 } 00161 00162 /// This method is abstract in the parent ModuleProvider class. Its 00163 /// implementation is identical to ParseAllFunctionBodies. 00164 /// @see ParseAllFunctionBodies 00165 /// @brief Make the whole module materialize 00166 virtual Module* materializeModule() { 00167 ParseAllFunctionBodies(); 00168 return TheModule; 00169 } 00170 00171 /// This method is provided by the parent ModuleProvde class and overriden 00172 /// here. It simply releases the module from its provided and frees up our 00173 /// state. 00174 /// @brief Release our hold on the generated module 00175 Module* releaseModule() { 00176 // Since we're losing control of this Module, we must hand it back complete 00177 Module *M = ModuleProvider::releaseModule(); 00178 freeState(); 00179 return M; 00180 } 00181 00182 /// @} 00183 /// @name Parsing Units For Subclasses 00184 /// @{ 00185 protected: 00186 /// @brief Parse whole module scope 00187 void ParseModule(); 00188 00189 /// @brief Parse the version information block 00190 void ParseVersionInfo(); 00191 00192 /// @brief Parse the ModuleGlobalInfo block 00193 void ParseModuleGlobalInfo(); 00194 00195 /// @brief Parse a symbol table 00196 void ParseSymbolTable( Function* Func, SymbolTable *ST); 00197 00198 /// @brief Parse functions lazily. 00199 void ParseFunctionLazily(); 00200 00201 /// @brief Parse a function body 00202 void ParseFunctionBody(Function* Func); 00203 00204 /// @brief Parse the type list portion of a compaction table 00205 void ParseCompactionTypes(unsigned NumEntries); 00206 00207 /// @brief Parse a compaction table 00208 void ParseCompactionTable(); 00209 00210 /// @brief Parse global types 00211 void ParseGlobalTypes(); 00212 00213 /// @brief Parse a basic block (for LLVM 1.0 basic block blocks) 00214 BasicBlock* ParseBasicBlock(unsigned BlockNo); 00215 00216 /// @brief parse an instruction list (for post LLVM 1.0 instruction lists 00217 /// with blocks differentiated by terminating instructions. 00218 unsigned ParseInstructionList( 00219 Function* F ///< The function into which BBs will be inserted 00220 ); 00221 00222 /// @brief Parse a single instruction. 00223 void ParseInstruction( 00224 std::vector<unsigned>& Args, ///< The arguments to be filled in 00225 BasicBlock* BB ///< The BB the instruction goes in 00226 ); 00227 00228 /// @brief Parse the whole constant pool 00229 void ParseConstantPool(ValueTable& Values, TypeListTy& Types, 00230 bool isFunction); 00231 00232 /// @brief Parse a single constant pool value 00233 Value *ParseConstantPoolValue(unsigned TypeID); 00234 00235 /// @brief Parse a block of types constants 00236 void ParseTypes(TypeListTy &Tab, unsigned NumEntries); 00237 00238 /// @brief Parse a single type constant 00239 const Type *ParseType(); 00240 00241 /// @brief Parse a string constants block 00242 void ParseStringConstants(unsigned NumEntries, ValueTable &Tab); 00243 00244 /// @} 00245 /// @name Data 00246 /// @{ 00247 private: 00248 char* decompressedBlock; ///< Result of decompression 00249 BufPtr MemStart; ///< Start of the memory buffer 00250 BufPtr MemEnd; ///< End of the memory buffer 00251 BufPtr BlockStart; ///< Start of current block being parsed 00252 BufPtr BlockEnd; ///< End of current block being parsed 00253 BufPtr At; ///< Where we're currently parsing at 00254 00255 /// Information about the module, extracted from the bytecode revision number. 00256 /// 00257 unsigned char RevisionNum; // The rev # itself 00258 00259 /// Flags to distinguish LLVM 1.0 & 1.1 bytecode formats (revision #0) 00260 00261 /// Revision #0 had an explicit alignment of data only for the 00262 /// ModuleGlobalInfo block. This was fixed to be like all other blocks in 1.2 00263 bool hasInconsistentModuleGlobalInfo; 00264 00265 /// Revision #0 also explicitly encoded zero values for primitive types like 00266 /// int/sbyte/etc. 00267 bool hasExplicitPrimitiveZeros; 00268 00269 // Flags to control features specific the LLVM 1.2 and before (revision #1) 00270 00271 /// LLVM 1.2 and earlier required that getelementptr structure indices were 00272 /// ubyte constants and that sequential type indices were longs. 00273 bool hasRestrictedGEPTypes; 00274 00275 /// LLVM 1.2 and earlier had class Type deriving from Value and the Type 00276 /// objects were located in the "Type Type" plane of various lists in read 00277 /// by the bytecode reader. In LLVM 1.3 this is no longer the case. Types are 00278 /// completely distinct from Values. Consequently, Types are written in fixed 00279 /// locations in LLVM 1.3. This flag indicates that the older Type derived 00280 /// from Value style of bytecode file is being read. 00281 bool hasTypeDerivedFromValue; 00282 00283 /// LLVM 1.2 and earlier encoded block headers as two uint (8 bytes), one for 00284 /// the size and one for the type. This is a bit wasteful, especially for 00285 /// small files where the 8 bytes per block is a large fraction of the total 00286 /// block size. In LLVM 1.3, the block type and length are encoded into a 00287 /// single uint32 by restricting the number of block types (limit 31) and the 00288 /// maximum size of a block (limit 2^27-1=134,217,727). Note that the module 00289 /// block still uses the 8-byte format so the maximum size of a file can be 00290 /// 2^32-1 bytes long. 00291 bool hasLongBlockHeaders; 00292 00293 /// LLVM 1.2 and earlier wrote type slot numbers as vbr_uint32. In LLVM 1.3 00294 /// this has been reduced to vbr_uint24. It shouldn't make much difference 00295 /// since we haven't run into a module with > 24 million types, but for safety 00296 /// the 24-bit restriction has been enforced in 1.3 to free some bits in 00297 /// various places and to ensure consistency. In particular, global vars are 00298 /// restricted to 24-bits. 00299 bool has32BitTypes; 00300 00301 /// LLVM 1.2 and earlier did not provide a target triple nor a list of 00302 /// libraries on which the bytecode is dependent. LLVM 1.3 provides these 00303 /// features, for use in future versions of LLVM. 00304 bool hasNoDependentLibraries; 00305 00306 /// LLVM 1.3 and earlier caused blocks and other fields to start on 32-bit 00307 /// aligned boundaries. This can lead to as much as 30% bytecode size overhead 00308 /// in various corner cases (lots of long instructions). In LLVM 1.4, 00309 /// alignment of bytecode fields was done away with completely. 00310 bool hasAlignment; 00311 00312 // In version 4 and earlier, the bytecode format did not support the 'undef' 00313 // constant. 00314 bool hasNoUndefValue; 00315 00316 // In version 4 and earlier, the bytecode format did not save space for flags 00317 // in the global info block for functions. 00318 bool hasNoFlagsForFunctions; 00319 00320 // In version 4 and earlier, there was no opcode space reserved for the 00321 // unreachable instruction. 00322 bool hasNoUnreachableInst; 00323 00324 /// In release 1.7 we changed intrinsic functions to not be overloaded. There 00325 /// is no bytecode change for this, but to optimize the auto-upgrade of calls 00326 /// to intrinsic functions, we save a mapping of old function definitions to 00327 /// the new ones so call instructions can be upgraded efficiently. 00328 std::map<Function*,Function*> upgradedFunctions; 00329 00330 /// CompactionTypes - If a compaction table is active in the current function, 00331 /// this is the mapping that it contains. We keep track of what resolved type 00332 /// it is as well as what global type entry it is. 00333 std::vector<std::pair<const Type*, unsigned> > CompactionTypes; 00334 00335 /// @brief If a compaction table is active in the current function, 00336 /// this is the mapping that it contains. 00337 std::vector<std::vector<Value*> > CompactionValues; 00338 00339 /// @brief This vector is used to deal with forward references to types in 00340 /// a module. 00341 TypeListTy ModuleTypes; 00342 00343 /// @brief This is an inverse mapping of ModuleTypes from the type to an 00344 /// index. Because refining types causes the index of this map to be 00345 /// invalidated, any time we refine a type, we clear this cache and recompute 00346 /// it next time we need it. These entries are ordered by the pointer value. 00347 std::vector<std::pair<const Type*, unsigned> > ModuleTypeIDCache; 00348 00349 /// @brief This vector is used to deal with forward references to types in 00350 /// a function. 00351 TypeListTy FunctionTypes; 00352 00353 /// When the ModuleGlobalInfo section is read, we create a Function object 00354 /// for each function in the module. When the function is loaded, after the 00355 /// module global info is read, this Function is populated. Until then, the 00356 /// functions in this vector just hold the function signature. 00357 std::vector<Function*> FunctionSignatureList; 00358 00359 /// @brief This is the table of values belonging to the current function 00360 ValueTable FunctionValues; 00361 00362 /// @brief This is the table of values belonging to the module (global) 00363 ValueTable ModuleValues; 00364 00365 /// @brief This keeps track of function level forward references. 00366 ForwardReferenceMap ForwardReferences; 00367 00368 /// @brief The basic blocks we've parsed, while parsing a function. 00369 std::vector<BasicBlock*> ParsedBasicBlocks; 00370 00371 /// This maintains a mapping between <Type, Slot #>'s and forward references 00372 /// to constants. Such values may be referenced before they are defined, and 00373 /// if so, the temporary object that they represent is held here. @brief 00374 /// Temporary place for forward references to constants. 00375 ConstantRefsType ConstantFwdRefs; 00376 00377 /// Constant values are read in after global variables. Because of this, we 00378 /// must defer setting the initializers on global variables until after module 00379 /// level constants have been read. In the mean time, this list keeps track 00380 /// of what we must do. 00381 GlobalInitsList GlobalInits; 00382 00383 // For lazy reading-in of functions, we need to save away several pieces of 00384 // information about each function: its begin and end pointer in the buffer 00385 // and its FunctionSlot. 00386 LazyFunctionMap LazyFunctionLoadMap; 00387 00388 /// This stores the parser's handler which is used for handling tasks other 00389 /// just than reading bytecode into the IR. If this is non-null, calls on 00390 /// the (polymorphic) BytecodeHandler interface (see llvm/Bytecode/Handler.h) 00391 /// will be made to report the logical structure of the bytecode file. What 00392 /// the handler does with the events it receives is completely orthogonal to 00393 /// the business of parsing the bytecode and building the IR. This is used, 00394 /// for example, by the llvm-abcd tool for analysis of byte code. 00395 /// @brief Handler for parsing events. 00396 BytecodeHandler* Handler; 00397 00398 00399 /// @} 00400 /// @name Implementation Details 00401 /// @{ 00402 private: 00403 /// @brief Determines if this module has a function or not. 00404 bool hasFunctions() { return ! FunctionSignatureList.empty(); } 00405 00406 /// @brief Determines if the type id has an implicit null value. 00407 bool hasImplicitNull(unsigned TyID ); 00408 00409 /// @brief Converts a type slot number to its Type* 00410 const Type *getType(unsigned ID); 00411 00412 /// @brief Converts a pre-sanitized type slot number to its Type* and 00413 /// sanitizes the type id. 00414 inline const Type* getSanitizedType(unsigned& ID ); 00415 00416 /// @brief Read in and get a sanitized type id 00417 inline const Type* readSanitizedType(); 00418 00419 /// @brief Converts a Type* to its type slot number 00420 unsigned getTypeSlot(const Type *Ty); 00421 00422 /// @brief Converts a normal type slot number to a compacted type slot num. 00423 unsigned getCompactionTypeSlot(unsigned type); 00424 00425 /// @brief Gets the global type corresponding to the TypeId 00426 const Type *getGlobalTableType(unsigned TypeId); 00427 00428 /// This is just like getTypeSlot, but when a compaction table is in use, 00429 /// it is ignored. 00430 unsigned getGlobalTableTypeSlot(const Type *Ty); 00431 00432 /// @brief Get a value from its typeid and slot number 00433 Value* getValue(unsigned TypeID, unsigned num, bool Create = true); 00434 00435 /// @brief Get a value from its type and slot number, ignoring compaction 00436 /// tables. 00437 Value *getGlobalTableValue(unsigned TyID, unsigned SlotNo); 00438 00439 /// @brief Get a basic block for current function 00440 BasicBlock *getBasicBlock(unsigned ID); 00441 00442 /// @brief Get a constant value from its typeid and value slot. 00443 Constant* getConstantValue(unsigned typeSlot, unsigned valSlot); 00444 00445 /// @brief Convenience function for getting a constant value when 00446 /// the Type has already been resolved. 00447 Constant* getConstantValue(const Type *Ty, unsigned valSlot) { 00448 return getConstantValue(getTypeSlot(Ty), valSlot); 00449 } 00450 00451 /// @brief Insert a newly created value 00452 unsigned insertValue(Value *V, unsigned Type, ValueTable &Table); 00453 00454 /// @brief Insert the arguments of a function. 00455 void insertArguments(Function* F ); 00456 00457 /// @brief Resolve all references to the placeholder (if any) for the 00458 /// given constant. 00459 void ResolveReferencesToConstant(Constant *C, unsigned Typ, unsigned Slot); 00460 00461 /// @brief Release our memory. 00462 void freeState() { 00463 freeTable(FunctionValues); 00464 freeTable(ModuleValues); 00465 } 00466 00467 /// @brief Free a table, making sure to free the ValueList in the table. 00468 void freeTable(ValueTable &Tab) { 00469 while (!Tab.empty()) { 00470 delete Tab.back(); 00471 Tab.pop_back(); 00472 } 00473 } 00474 00475 inline void error(std::string errmsg); 00476 00477 BytecodeReader(const BytecodeReader &); // DO NOT IMPLEMENT 00478 void operator=(const BytecodeReader &); // DO NOT IMPLEMENT 00479 00480 /// @} 00481 /// @name Reader Primitives 00482 /// @{ 00483 private: 00484 00485 /// @brief Is there more to parse in the current block? 00486 inline bool moreInBlock(); 00487 00488 /// @brief Have we read past the end of the block 00489 inline void checkPastBlockEnd(const char * block_name); 00490 00491 /// @brief Align to 32 bits 00492 inline void align32(); 00493 00494 /// @brief Read an unsigned integer as 32-bits 00495 inline unsigned read_uint(); 00496 00497 /// @brief Read an unsigned integer with variable bit rate encoding 00498 inline unsigned read_vbr_uint(); 00499 00500 /// @brief Read an unsigned integer of no more than 24-bits with variable 00501 /// bit rate encoding. 00502 inline unsigned read_vbr_uint24(); 00503 00504 /// @brief Read an unsigned 64-bit integer with variable bit rate encoding. 00505 inline uint64_t read_vbr_uint64(); 00506 00507 /// @brief Read a signed 64-bit integer with variable bit rate encoding. 00508 inline int64_t read_vbr_int64(); 00509 00510 /// @brief Read a string 00511 inline std::string read_str(); 00512 00513 /// @brief Read a float value 00514 inline void read_float(float& FloatVal); 00515 00516 /// @brief Read a double value 00517 inline void read_double(double& DoubleVal); 00518 00519 /// @brief Read an arbitrary data chunk of fixed length 00520 inline void read_data(void *Ptr, void *End); 00521 00522 /// @brief Read a bytecode block header 00523 inline void read_block(unsigned &Type, unsigned &Size); 00524 00525 /// @brief Read a type identifier and sanitize it. 00526 inline bool read_typeid(unsigned &TypeId); 00527 00528 /// @brief Recalculate type ID for pre 1.3 bytecode files. 00529 inline bool sanitizeTypeId(unsigned &TypeId ); 00530 /// @} 00531 }; 00532 00533 /// @brief A function for creating a BytecodeAnalzer as a handler 00534 /// for the Bytecode reader. 00535 BytecodeHandler* createBytecodeAnalyzerHandler(BytecodeAnalysis& bca, 00536 std::ostream* output ); 00537 00538 00539 } // End llvm namespace 00540 00541 // vim: sw=2 00542 #endif