1 //===-- Reader.h - Interface To Bytecode Reading ----------------*- C++ -*-===//
3 // The LLVM Compiler Infrastructure
5 // This file was developed by Reid Spencer and is distributed under the
6 // University of Illinois Open Source License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This header file defines the interface to the Bytecode Reader which is
11 // responsible for correctly interpreting bytecode files (backwards compatible)
12 // and materializing a module from the bytecode read.
14 //===----------------------------------------------------------------------===//
16 #ifndef BYTECODE_PARSER_H
17 #define BYTECODE_PARSER_H
19 #include "llvm/Constants.h"
20 #include "llvm/DerivedTypes.h"
21 #include "llvm/GlobalValue.h"
22 #include "llvm/Function.h"
23 #include "llvm/ModuleProvider.h"
24 #include "llvm/Bytecode/Analyzer.h"
30 class BytecodeHandler; ///< Forward declare the handler interface
32 /// This class defines the interface for parsing a buffer of bytecode. The
33 /// parser itself takes no action except to call the various functions of
34 /// the handler interface. The parser's sole responsibility is the correct
35 /// interpretation of the bytecode buffer. The handler is responsible for
36 /// instantiating and keeping track of all values. As a convenience, the parser
37 /// is responsible for materializing types and will pass them through the
38 /// handler interface as necessary.
39 /// @see BytecodeHandler
40 /// @brief Bytecode Reader interface
41 class BytecodeReader : public ModuleProvider {
43 /// @name Constructors
46 /// @brief Default constructor. By default, no handler is used.
48 BytecodeHandler* h = 0
64 /// @brief A convenience type for the buffer pointer
65 typedef const unsigned char* BufPtr;
67 /// @brief The type used for a vector of potentially abstract types
68 typedef std::vector<PATypeHolder> TypeListTy;
70 /// @brief An internal buffer object used for handling decompression
74 BufferInfo() { buff = 0; size = 0; }
77 /// This type provides a vector of Value* via the User class for
78 /// storage of Values that have been constructed when reading the
79 /// bytecode. Because of forward referencing, constant replacement
80 /// can occur so we ensure that our list of Value* is updated
81 /// properly through those transitions. This ensures that the
82 /// correct Value* is in our list when it comes time to associate
83 /// constants with global variables at the end of reading the
85 /// @brief A list of values as a User of those Values.
86 struct ValueList : public User {
87 ValueList() : User(Type::VoidTy, Value::ValueListVal) {}
89 // vector compatibility methods
90 unsigned size() const { return getNumOperands(); }
91 void push_back(Value *V) { Operands.push_back(Use(V, this)); }
92 Value *back() const { return Operands.back(); }
93 void pop_back() { Operands.pop_back(); }
94 bool empty() const { return Operands.empty(); }
96 virtual void print(std::ostream& os) const {
97 for ( unsigned i = 0; i < size(); i++ ) {
99 getOperand(i)->print(os);
105 /// @brief A 2 dimensional table of values
106 typedef std::vector<ValueList*> ValueTable;
108 /// This map is needed so that forward references to constants can be looked
109 /// up by Type and slot number when resolving those references.
110 /// @brief A mapping of a Type/slot pair to a Constant*.
111 typedef std::map<std::pair<const Type*,unsigned>, Constant*> ConstantRefsType;
113 /// For lazy read-in of functions, we need to save the location in the
114 /// data stream where the function is located. This structure provides that
115 /// information. Lazy read-in is used mostly by the JIT which only wants to
116 /// resolve functions as it needs them.
117 /// @brief Keeps pointers to function contents for later use.
118 struct LazyFunctionInfo {
119 const unsigned char *Buf, *EndBuf;
120 LazyFunctionInfo(const unsigned char *B = 0, const unsigned char *EB = 0)
121 : Buf(B), EndBuf(EB) {}
124 /// @brief A mapping of functions to their LazyFunctionInfo for lazy reading.
125 typedef std::map<Function*, LazyFunctionInfo> LazyFunctionMap;
127 /// @brief A list of global variables and the slot number that initializes
129 typedef std::vector<std::pair<GlobalVariable*, unsigned> > GlobalInitsList;
131 /// This type maps a typeslot/valueslot pair to the corresponding Value*.
132 /// It is used for dealing with forward references as values are read in.
133 /// @brief A map for dealing with forward references of values.
134 typedef std::map<std::pair<unsigned,unsigned>,Value*> ForwardReferenceMap;
140 /// @brief Main interface to parsing a bytecode buffer.
142 const unsigned char *Buf, ///< Beginning of the bytecode buffer
143 unsigned Length, ///< Length of the bytecode buffer
144 const std::string &ModuleID ///< An identifier for the module constructed.
147 /// @brief Parse all function bodies
148 void ParseAllFunctionBodies();
150 /// @brief Parse the next function of specific type
151 void ParseFunction(Function* Func) ;
153 /// This method is abstract in the parent ModuleProvider class. Its
154 /// implementation is identical to the ParseFunction method.
155 /// @see ParseFunction
156 /// @brief Make a specific function materialize.
157 virtual void materializeFunction(Function *F) {
158 LazyFunctionMap::iterator Fi = LazyFunctionLoadMap.find(F);
159 if (Fi == LazyFunctionLoadMap.end()) return;
163 /// This method is abstract in the parent ModuleProvider class. Its
164 /// implementation is identical to ParseAllFunctionBodies.
165 /// @see ParseAllFunctionBodies
166 /// @brief Make the whole module materialize
167 virtual Module* materializeModule() {
168 ParseAllFunctionBodies();
172 /// This method is provided by the parent ModuleProvde class and overriden
173 /// here. It simply releases the module from its provided and frees up our
175 /// @brief Release our hold on the generated module
176 Module* releaseModule() {
177 // Since we're losing control of this Module, we must hand it back complete
178 Module *M = ModuleProvider::releaseModule();
184 /// @name Parsing Units For Subclasses
187 /// @brief Parse whole module scope
190 /// @brief Parse the version information block
191 void ParseVersionInfo();
193 /// @brief Parse the ModuleGlobalInfo block
194 void ParseModuleGlobalInfo();
196 /// @brief Parse a symbol table
197 void ParseSymbolTable( Function* Func, SymbolTable *ST);
199 /// @brief Parse functions lazily.
200 void ParseFunctionLazily();
202 /// @brief Parse a function body
203 void ParseFunctionBody(Function* Func);
205 /// @brief Parse the type list portion of a compaction table
206 void ParseCompactionTypes(unsigned NumEntries);
208 /// @brief Parse a compaction table
209 void ParseCompactionTable();
211 /// @brief Parse global types
212 void ParseGlobalTypes();
214 /// @brief Parse a basic block (for LLVM 1.0 basic block blocks)
215 BasicBlock* ParseBasicBlock(unsigned BlockNo);
217 /// @brief parse an instruction list (for post LLVM 1.0 instruction lists
218 /// with blocks differentiated by terminating instructions.
219 unsigned ParseInstructionList(
220 Function* F ///< The function into which BBs will be inserted
223 /// @brief Parse a single instruction.
224 void ParseInstruction(
225 std::vector<unsigned>& Args, ///< The arguments to be filled in
226 BasicBlock* BB ///< The BB the instruction goes in
229 /// @brief Parse the whole constant pool
230 void ParseConstantPool(ValueTable& Values, TypeListTy& Types,
233 /// @brief Parse a single constant value
234 Constant* ParseConstantValue(unsigned TypeID);
236 /// @brief Parse a block of types constants
237 void ParseTypes(TypeListTy &Tab, unsigned NumEntries);
239 /// @brief Parse a single type constant
240 const Type *ParseType();
242 /// @brief Parse a string constants block
243 void ParseStringConstants(unsigned NumEntries, ValueTable &Tab);
249 BufferInfo bi; ///< Buffer info for decompression
251 BufPtr MemStart; ///< Start of the memory buffer
252 BufPtr MemEnd; ///< End of the memory buffer
253 BufPtr BlockStart; ///< Start of current block being parsed
254 BufPtr BlockEnd; ///< End of current block being parsed
255 BufPtr At; ///< Where we're currently parsing at
257 /// Information about the module, extracted from the bytecode revision number.
259 unsigned char RevisionNum; // The rev # itself
261 /// Flags to distinguish LLVM 1.0 & 1.1 bytecode formats (revision #0)
263 /// Revision #0 had an explicit alignment of data only for the
264 /// ModuleGlobalInfo block. This was fixed to be like all other blocks in 1.2
265 bool hasInconsistentModuleGlobalInfo;
267 /// Revision #0 also explicitly encoded zero values for primitive types like
269 bool hasExplicitPrimitiveZeros;
271 // Flags to control features specific the LLVM 1.2 and before (revision #1)
273 /// LLVM 1.2 and earlier required that getelementptr structure indices were
274 /// ubyte constants and that sequential type indices were longs.
275 bool hasRestrictedGEPTypes;
277 /// LLVM 1.2 and earlier had class Type deriving from Value and the Type
278 /// objects were located in the "Type Type" plane of various lists in read
279 /// by the bytecode reader. In LLVM 1.3 this is no longer the case. Types are
280 /// completely distinct from Values. Consequently, Types are written in fixed
281 /// locations in LLVM 1.3. This flag indicates that the older Type derived
282 /// from Value style of bytecode file is being read.
283 bool hasTypeDerivedFromValue;
285 /// LLVM 1.2 and earlier encoded block headers as two uint (8 bytes), one for
286 /// the size and one for the type. This is a bit wasteful, especially for
287 /// small files where the 8 bytes per block is a large fraction of the total
288 /// block size. In LLVM 1.3, the block type and length are encoded into a
289 /// single uint32 by restricting the number of block types (limit 31) and the
290 /// maximum size of a block (limit 2^27-1=134,217,727). Note that the module
291 /// block still uses the 8-byte format so the maximum size of a file can be
292 /// 2^32-1 bytes long.
293 bool hasLongBlockHeaders;
295 /// LLVM 1.2 and earlier wrote type slot numbers as vbr_uint32. In LLVM 1.3
296 /// this has been reduced to vbr_uint24. It shouldn't make much difference
297 /// since we haven't run into a module with > 24 million types, but for safety
298 /// the 24-bit restriction has been enforced in 1.3 to free some bits in
299 /// various places and to ensure consistency. In particular, global vars are
300 /// restricted to 24-bits.
303 /// LLVM 1.2 and earlier did not provide a target triple nor a list of
304 /// libraries on which the bytecode is dependent. LLVM 1.3 provides these
305 /// features, for use in future versions of LLVM.
306 bool hasNoDependentLibraries;
308 /// LLVM 1.3 and earlier caused blocks and other fields to start on 32-bit
309 /// aligned boundaries. This can lead to as much as 30% bytecode size overhead
310 /// in various corner cases (lots of long instructions). In LLVM 1.4,
311 /// alignment of bytecode fields was done away with completely.
314 // In version 4 and earlier, the bytecode format did not support the 'undef'
316 bool hasNoUndefValue;
318 // In version 4 and earlier, the bytecode format did not save space for flags
319 // in the global info block for functions.
320 bool hasNoFlagsForFunctions;
322 // In version 4 and earlier, there was no opcode space reserved for the
323 // unreachable instruction.
324 bool hasNoUnreachableInst;
326 // In version 5, basic blocks have a minimum index of 0 whereas all the
327 // other primitives have a minimum index of 1 (because 0 is the "null"
328 // value. In version 5, we made this consistent.
329 bool hasInconsistentBBSlotNums;
331 // In version 5, the types SByte and UByte were encoded as vbr_uint so that
332 // signed values > 63 and unsigned values >127 would be encoded as two
333 // bytes. In version 5, they are encoded directly in a single byte.
334 bool hasVBRByteTypes;
336 // In version 5, modules begin with a "Module Block" which encodes a 4-byte
337 // integer value 0x01 to identify the module block. This is unnecessary and
338 // removed in version 5.
339 bool hasUnnecessaryModuleBlockId;
341 /// CompactionTypes - If a compaction table is active in the current function,
342 /// this is the mapping that it contains. We keep track of what resolved type
343 /// it is as well as what global type entry it is.
344 std::vector<std::pair<const Type*, unsigned> > CompactionTypes;
346 /// @brief If a compaction table is active in the current function,
347 /// this is the mapping that it contains.
348 std::vector<std::vector<Value*> > CompactionValues;
350 /// @brief This vector is used to deal with forward references to types in
352 TypeListTy ModuleTypes;
354 /// @brief This vector is used to deal with forward references to types in
356 TypeListTy FunctionTypes;
358 /// When the ModuleGlobalInfo section is read, we create a Function object
359 /// for each function in the module. When the function is loaded, after the
360 /// module global info is read, this Function is populated. Until then, the
361 /// functions in this vector just hold the function signature.
362 std::vector<Function*> FunctionSignatureList;
364 /// @brief This is the table of values belonging to the current function
365 ValueTable FunctionValues;
367 /// @brief This is the table of values belonging to the module (global)
368 ValueTable ModuleValues;
370 /// @brief This keeps track of function level forward references.
371 ForwardReferenceMap ForwardReferences;
373 /// @brief The basic blocks we've parsed, while parsing a function.
374 std::vector<BasicBlock*> ParsedBasicBlocks;
376 /// This maintains a mapping between <Type, Slot #>'s and forward references
377 /// to constants. Such values may be referenced before they are defined, and
378 /// if so, the temporary object that they represent is held here. @brief
379 /// Temporary place for forward references to constants.
380 ConstantRefsType ConstantFwdRefs;
382 /// Constant values are read in after global variables. Because of this, we
383 /// must defer setting the initializers on global variables until after module
384 /// level constants have been read. In the mean time, this list keeps track
385 /// of what we must do.
386 GlobalInitsList GlobalInits;
388 // For lazy reading-in of functions, we need to save away several pieces of
389 // information about each function: its begin and end pointer in the buffer
390 // and its FunctionSlot.
391 LazyFunctionMap LazyFunctionLoadMap;
393 /// This stores the parser's handler which is used for handling tasks other
394 /// just than reading bytecode into the IR. If this is non-null, calls on
395 /// the (polymorphic) BytecodeHandler interface (see llvm/Bytecode/Handler.h)
396 /// will be made to report the logical structure of the bytecode file. What
397 /// the handler does with the events it receives is completely orthogonal to
398 /// the business of parsing the bytecode and building the IR. This is used,
399 /// for example, by the llvm-abcd tool for analysis of byte code.
400 /// @brief Handler for parsing events.
401 BytecodeHandler* Handler;
404 /// @name Implementation Details
407 /// @brief Determines if this module has a function or not.
408 bool hasFunctions() { return ! FunctionSignatureList.empty(); }
410 /// @brief Determines if the type id has an implicit null value.
411 bool hasImplicitNull(unsigned TyID );
413 /// @brief Converts a type slot number to its Type*
414 const Type *getType(unsigned ID);
416 /// @brief Converts a pre-sanitized type slot number to its Type* and
417 /// sanitizes the type id.
418 inline const Type* getSanitizedType(unsigned& ID );
420 /// @brief Read in and get a sanitized type id
421 inline const Type* BytecodeReader::readSanitizedType();
423 /// @brief Converts a Type* to its type slot number
424 unsigned getTypeSlot(const Type *Ty);
426 /// @brief Converts a normal type slot number to a compacted type slot num.
427 unsigned getCompactionTypeSlot(unsigned type);
429 /// @brief Gets the global type corresponding to the TypeId
430 const Type *getGlobalTableType(unsigned TypeId);
432 /// This is just like getTypeSlot, but when a compaction table is in use,
434 unsigned getGlobalTableTypeSlot(const Type *Ty);
436 /// @brief Get a value from its typeid and slot number
437 Value* getValue(unsigned TypeID, unsigned num, bool Create = true);
439 /// @brief Get a value from its type and slot number, ignoring compaction
441 Value *getGlobalTableValue(unsigned TyID, unsigned SlotNo);
443 /// @brief Get a basic block for current function
444 BasicBlock *getBasicBlock(unsigned ID);
446 /// @brief Get a constant value from its typeid and value slot.
447 Constant* getConstantValue(unsigned typeSlot, unsigned valSlot);
449 /// @brief Convenience function for getting a constant value when
450 /// the Type has already been resolved.
451 Constant* getConstantValue(const Type *Ty, unsigned valSlot) {
452 return getConstantValue(getTypeSlot(Ty), valSlot);
455 /// @brief Insert a newly created value
456 unsigned insertValue(Value *V, unsigned Type, ValueTable &Table);
458 /// @brief Insert the arguments of a function.
459 void insertArguments(Function* F );
461 /// @brief Resolve all references to the placeholder (if any) for the
463 void ResolveReferencesToConstant(Constant *C, unsigned Slot);
465 /// @brief Release our memory.
467 freeTable(FunctionValues);
468 freeTable(ModuleValues);
471 /// @brief Free a table, making sure to free the ValueList in the table.
472 void freeTable(ValueTable &Tab) {
473 while (!Tab.empty()) {
479 inline void error(std::string errmsg);
481 BytecodeReader(const BytecodeReader &); // DO NOT IMPLEMENT
482 void operator=(const BytecodeReader &); // DO NOT IMPLEMENT
485 /// @name Reader Primitives
489 /// @brief Is there more to parse in the current block?
490 inline bool moreInBlock();
492 /// @brief Have we read past the end of the block
493 inline void checkPastBlockEnd(const char * block_name);
495 /// @brief Align to 32 bits
496 inline void align32();
498 /// @brief Read an unsigned integer as 32-bits
499 inline unsigned read_uint();
501 /// @brief Read an unsigned integer with variable bit rate encoding
502 inline unsigned read_vbr_uint();
504 /// @brief Read an unsigned integer of no more than 24-bits with variable
505 /// bit rate encoding.
506 inline unsigned read_vbr_uint24();
508 /// @brief Read an unsigned 64-bit integer with variable bit rate encoding.
509 inline uint64_t read_vbr_uint64();
511 /// @brief Read a signed 64-bit integer with variable bit rate encoding.
512 inline int64_t read_vbr_int64();
514 /// @brief Read a string
515 inline std::string read_str();
517 /// @brief Read a float value
518 inline void read_float(float& FloatVal);
520 /// @brief Read a double value
521 inline void read_double(double& DoubleVal);
523 /// @brief Read an arbitrary data chunk of fixed length
524 inline void read_data(void *Ptr, void *End);
526 /// @brief Read a bytecode block header
527 inline void read_block(unsigned &Type, unsigned &Size);
529 /// @brief Read a type identifier and sanitize it.
530 inline bool read_typeid(unsigned &TypeId);
532 /// @brief Recalculate type ID for pre 1.3 bytecode files.
533 inline bool sanitizeTypeId(unsigned &TypeId );
537 /// @brief A function for creating a BytecodeAnalzer as a handler
538 /// for the Bytecode reader.
539 BytecodeHandler* createBytecodeAnalyzerHandler(BytecodeAnalysis& bca,
540 std::ostream* output );
543 } // End llvm namespace