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      1 //===- BitcodeReader.h - Internal BitcodeReader impl ------------*- C++ -*-===//
      2 //
      3 //                     The LLVM Compiler Infrastructure
      4 //
      5 // This file is distributed under the University of Illinois Open Source
      6 // License. See LICENSE.TXT for details.
      7 //
      8 //===----------------------------------------------------------------------===//
      9 //
     10 // This header defines the BitcodeReader class.
     11 //
     12 //===----------------------------------------------------------------------===//
     13 
     14 #ifndef BITCODE_READER_H
     15 #define BITCODE_READER_H
     16 
     17 #include "llvm/GVMaterializer.h"
     18 #include "llvm/Attributes.h"
     19 #include "llvm/Type.h"
     20 #include "llvm/OperandTraits.h"
     21 #include "llvm/Bitcode/BitstreamReader.h"
     22 #include "llvm/Bitcode/LLVMBitCodes.h"
     23 #include "llvm/Support/ValueHandle.h"
     24 #include "llvm/ADT/DenseMap.h"
     25 #include <vector>
     26 
     27 namespace llvm {
     28   class MemoryBuffer;
     29   class LLVMContext;
     30 
     31 //===----------------------------------------------------------------------===//
     32 //                          BitcodeReaderValueList Class
     33 //===----------------------------------------------------------------------===//
     34 
     35 class BitcodeReaderValueList {
     36   std::vector<WeakVH> ValuePtrs;
     37 
     38   /// ResolveConstants - As we resolve forward-referenced constants, we add
     39   /// information about them to this vector.  This allows us to resolve them in
     40   /// bulk instead of resolving each reference at a time.  See the code in
     41   /// ResolveConstantForwardRefs for more information about this.
     42   ///
     43   /// The key of this vector is the placeholder constant, the value is the slot
     44   /// number that holds the resolved value.
     45   typedef std::vector<std::pair<Constant*, unsigned> > ResolveConstantsTy;
     46   ResolveConstantsTy ResolveConstants;
     47   LLVMContext &Context;
     48 public:
     49   BitcodeReaderValueList(LLVMContext &C) : Context(C) {}
     50   ~BitcodeReaderValueList() {
     51     assert(ResolveConstants.empty() && "Constants not resolved?");
     52   }
     53 
     54   // vector compatibility methods
     55   unsigned size() const { return ValuePtrs.size(); }
     56   void resize(unsigned N) { ValuePtrs.resize(N); }
     57   void push_back(Value *V) {
     58     ValuePtrs.push_back(V);
     59   }
     60 
     61   void clear() {
     62     assert(ResolveConstants.empty() && "Constants not resolved?");
     63     ValuePtrs.clear();
     64   }
     65 
     66   Value *operator[](unsigned i) const {
     67     assert(i < ValuePtrs.size());
     68     return ValuePtrs[i];
     69   }
     70 
     71   Value *back() const { return ValuePtrs.back(); }
     72     void pop_back() { ValuePtrs.pop_back(); }
     73   bool empty() const { return ValuePtrs.empty(); }
     74   void shrinkTo(unsigned N) {
     75     assert(N <= size() && "Invalid shrinkTo request!");
     76     ValuePtrs.resize(N);
     77   }
     78 
     79   Constant *getConstantFwdRef(unsigned Idx, Type *Ty);
     80   Value *getValueFwdRef(unsigned Idx, Type *Ty);
     81 
     82   void AssignValue(Value *V, unsigned Idx);
     83 
     84   /// ResolveConstantForwardRefs - Once all constants are read, this method bulk
     85   /// resolves any forward references.
     86   void ResolveConstantForwardRefs();
     87 };
     88 
     89 
     90 //===----------------------------------------------------------------------===//
     91 //                          BitcodeReaderMDValueList Class
     92 //===----------------------------------------------------------------------===//
     93 
     94 class BitcodeReaderMDValueList {
     95   std::vector<WeakVH> MDValuePtrs;
     96 
     97   LLVMContext &Context;
     98 public:
     99   BitcodeReaderMDValueList(LLVMContext& C) : Context(C) {}
    100 
    101   // vector compatibility methods
    102   unsigned size() const       { return MDValuePtrs.size(); }
    103   void resize(unsigned N)     { MDValuePtrs.resize(N); }
    104   void push_back(Value *V)    { MDValuePtrs.push_back(V);  }
    105   void clear()                { MDValuePtrs.clear();  }
    106   Value *back() const         { return MDValuePtrs.back(); }
    107   void pop_back()             { MDValuePtrs.pop_back(); }
    108   bool empty() const          { return MDValuePtrs.empty(); }
    109 
    110   Value *operator[](unsigned i) const {
    111     assert(i < MDValuePtrs.size());
    112     return MDValuePtrs[i];
    113   }
    114 
    115   void shrinkTo(unsigned N) {
    116     assert(N <= size() && "Invalid shrinkTo request!");
    117     MDValuePtrs.resize(N);
    118   }
    119 
    120   Value *getValueFwdRef(unsigned Idx);
    121   void AssignValue(Value *V, unsigned Idx);
    122 };
    123 
    124 class BitcodeReader : public GVMaterializer {
    125   LLVMContext &Context;
    126   Module *TheModule;
    127   MemoryBuffer *Buffer;
    128   bool BufferOwned;
    129   BitstreamReader StreamFile;
    130   BitstreamCursor Stream;
    131 
    132   const char *ErrorString;
    133 
    134   std::vector<Type*> TypeList;
    135   BitcodeReaderValueList ValueList;
    136   BitcodeReaderMDValueList MDValueList;
    137   SmallVector<Instruction *, 64> InstructionList;
    138 
    139   std::vector<std::pair<GlobalVariable*, unsigned> > GlobalInits;
    140   std::vector<std::pair<GlobalAlias*, unsigned> > AliasInits;
    141 
    142   /// MAttributes - The set of attributes by index.  Index zero in the
    143   /// file is for null, and is thus not represented here.  As such all indices
    144   /// are off by one.
    145   std::vector<AttrListPtr> MAttributes;
    146 
    147   /// FunctionBBs - While parsing a function body, this is a list of the basic
    148   /// blocks for the function.
    149   std::vector<BasicBlock*> FunctionBBs;
    150 
    151   // When reading the module header, this list is populated with functions that
    152   // have bodies later in the file.
    153   std::vector<Function*> FunctionsWithBodies;
    154 
    155   // When intrinsic functions are encountered which require upgrading they are
    156   // stored here with their replacement function.
    157   typedef std::vector<std::pair<Function*, Function*> > UpgradedIntrinsicMap;
    158   UpgradedIntrinsicMap UpgradedIntrinsics;
    159 
    160   // Map the bitcode's custom MDKind ID to the Module's MDKind ID.
    161   DenseMap<unsigned, unsigned> MDKindMap;
    162 
    163   // After the module header has been read, the FunctionsWithBodies list is
    164   // reversed.  This keeps track of whether we've done this yet.
    165   bool HasReversedFunctionsWithBodies;
    166 
    167   /// DeferredFunctionInfo - When function bodies are initially scanned, this
    168   /// map contains info about where to find deferred function body in the
    169   /// stream.
    170   DenseMap<Function*, uint64_t> DeferredFunctionInfo;
    171 
    172   /// BlockAddrFwdRefs - These are blockaddr references to basic blocks.  These
    173   /// are resolved lazily when functions are loaded.
    174   typedef std::pair<unsigned, GlobalVariable*> BlockAddrRefTy;
    175   DenseMap<Function*, std::vector<BlockAddrRefTy> > BlockAddrFwdRefs;
    176 
    177 public:
    178   explicit BitcodeReader(MemoryBuffer *buffer, LLVMContext &C)
    179     : Context(C), TheModule(0), Buffer(buffer), BufferOwned(false),
    180       ErrorString(0), ValueList(C), MDValueList(C) {
    181     HasReversedFunctionsWithBodies = false;
    182   }
    183   ~BitcodeReader() {
    184     FreeState();
    185   }
    186 
    187   void FreeState();
    188 
    189   /// setBufferOwned - If this is true, the reader will destroy the MemoryBuffer
    190   /// when the reader is destroyed.
    191   void setBufferOwned(bool Owned) { BufferOwned = Owned; }
    192 
    193   virtual bool isMaterializable(const GlobalValue *GV) const;
    194   virtual bool isDematerializable(const GlobalValue *GV) const;
    195   virtual bool Materialize(GlobalValue *GV, std::string *ErrInfo = 0);
    196   virtual bool MaterializeModule(Module *M, std::string *ErrInfo = 0);
    197   virtual void Dematerialize(GlobalValue *GV);
    198 
    199   bool Error(const char *Str) {
    200     ErrorString = Str;
    201     return true;
    202   }
    203   const char *getErrorString() const { return ErrorString; }
    204 
    205   /// @brief Main interface to parsing a bitcode buffer.
    206   /// @returns true if an error occurred.
    207   bool ParseBitcodeInto(Module *M);
    208 
    209   /// @brief Cheap mechanism to just extract module triple
    210   /// @returns true if an error occurred.
    211   bool ParseTriple(std::string &Triple);
    212 private:
    213   Type *getTypeByID(unsigned ID);
    214   Type *getTypeByIDOrNull(unsigned ID);
    215   Value *getFnValueByID(unsigned ID, Type *Ty) {
    216     if (Ty && Ty->isMetadataTy())
    217       return MDValueList.getValueFwdRef(ID);
    218     return ValueList.getValueFwdRef(ID, Ty);
    219   }
    220   BasicBlock *getBasicBlock(unsigned ID) const {
    221     if (ID >= FunctionBBs.size()) return 0; // Invalid ID
    222     return FunctionBBs[ID];
    223   }
    224   AttrListPtr getAttributes(unsigned i) const {
    225     if (i-1 < MAttributes.size())
    226       return MAttributes[i-1];
    227     return AttrListPtr();
    228   }
    229 
    230   /// getValueTypePair - Read a value/type pair out of the specified record from
    231   /// slot 'Slot'.  Increment Slot past the number of slots used in the record.
    232   /// Return true on failure.
    233   bool getValueTypePair(SmallVector<uint64_t, 64> &Record, unsigned &Slot,
    234                         unsigned InstNum, Value *&ResVal) {
    235     if (Slot == Record.size()) return true;
    236     unsigned ValNo = (unsigned)Record[Slot++];
    237     if (ValNo < InstNum) {
    238       // If this is not a forward reference, just return the value we already
    239       // have.
    240       ResVal = getFnValueByID(ValNo, 0);
    241       return ResVal == 0;
    242     } else if (Slot == Record.size()) {
    243       return true;
    244     }
    245 
    246     unsigned TypeNo = (unsigned)Record[Slot++];
    247     ResVal = getFnValueByID(ValNo, getTypeByID(TypeNo));
    248     return ResVal == 0;
    249   }
    250   bool getValue(SmallVector<uint64_t, 64> &Record, unsigned &Slot,
    251                 Type *Ty, Value *&ResVal) {
    252     if (Slot == Record.size()) return true;
    253     unsigned ValNo = (unsigned)Record[Slot++];
    254     ResVal = getFnValueByID(ValNo, Ty);
    255     return ResVal == 0;
    256   }
    257 
    258 
    259   bool ParseModule();
    260   bool ParseAttributeBlock();
    261   bool ParseTypeTable();
    262   bool ParseOldTypeTable();         // FIXME: Remove in LLVM 3.1
    263   bool ParseTypeTableBody();
    264 
    265   bool ParseOldTypeSymbolTable();   // FIXME: Remove in LLVM 3.1
    266   bool ParseValueSymbolTable();
    267   bool ParseConstants();
    268   bool RememberAndSkipFunctionBody();
    269   bool ParseFunctionBody(Function *F);
    270   bool ResolveGlobalAndAliasInits();
    271   bool ParseMetadata();
    272   bool ParseMetadataAttachment();
    273   bool ParseModuleTriple(std::string &Triple);
    274 };
    275 
    276 } // End llvm namespace
    277 
    278 #endif
    279