lib/Bitcode/Reader/BitcodeReader.h

   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/ModuleProvider.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
  30 //===----------------------------------------------------------------------===//
  31 //                          BitcodeReaderValueList Class
  32 //===----------------------------------------------------------------------===//
  33
  34 class BitcodeReaderValueList {
  35   std::vector<WeakVH> ValuePtrs;
  36
  37   /// ResolveConstants - As we resolve forward-referenced constants, we add
  38   /// information about them to this vector.  This allows us to resolve them in
  39   /// bulk instead of resolving each reference at a time.  See the code in
  40   /// ResolveConstantForwardRefs for more information about this.
  41   ///
  42   /// The key of this vector is the placeholder constant, the value is the slot
  43   /// number that holds the resolved value.
  44   typedef std::vector<std::pair<Constant*, unsigned> > ResolveConstantsTy;
  45   ResolveConstantsTy ResolveConstants;
  46 public:
  47   BitcodeReaderValueList() {}
  48   ~BitcodeReaderValueList() {
  49     assert(ResolveConstants.empty() && "Constants not resolved?");
  50   }
  51
  52   // vector compatibility methods
  53   unsigned size() const { return ValuePtrs.size(); }
  54   void resize(unsigned N) { ValuePtrs.resize(N); }
  55   void push_back(Value *V) {
  56     ValuePtrs.push_back(V);
  57   }
  58
  59   void clear() {
  60     assert(ResolveConstants.empty() && "Constants not resolved?");
  61     ValuePtrs.clear();
  62   }
  63
  64   Value *operator[](unsigned i) const {
  65     assert(i < ValuePtrs.size());
  66     return ValuePtrs[i];
  67   }
  68
  69   Value *back() const { return ValuePtrs.back(); }
  70     void pop_back() { ValuePtrs.pop_back(); }
  71   bool empty() const { return ValuePtrs.empty(); }
  72   void shrinkTo(unsigned N) {
  73     assert(N <= size() && "Invalid shrinkTo request!");
  74     ValuePtrs.resize(N);
  75   }
  76
  77   Constant *getConstantFwdRef(unsigned Idx, const Type *Ty);
  78   Value *getValueFwdRef(unsigned Idx, const Type *Ty);
  79
  80   void AssignValue(Value *V, unsigned Idx);
  81
  82   /// ResolveConstantForwardRefs - Once all constants are read, this method bulk
  83   /// resolves any forward references.
  84   void ResolveConstantForwardRefs();
  85 };
  86
  87 class BitcodeReader : public ModuleProvider {
  88   MemoryBuffer *Buffer;
  89   BitstreamReader StreamFile;
  90   BitstreamCursor Stream;
  91
  92   const char *ErrorString;
  93
  94   std::vector<PATypeHolder> TypeList;
  95   BitcodeReaderValueList ValueList;
  96   std::vector<std::pair<GlobalVariable*, unsigned> > GlobalInits;
  97   std::vector<std::pair<GlobalAlias*, unsigned> > AliasInits;
  98
  99   /// MAttributes - The set of attributes by index.  Index zero in the
 100   /// file is for null, and is thus not represented here.  As such all indices
 101   /// are off by one.
 102   std::vector<AttrListPtr> MAttributes;
 103
 104   /// FunctionBBs - While parsing a function body, this is a list of the basic
 105   /// blocks for the function.
 106   std::vector<BasicBlock*> FunctionBBs;
 107
 108   // When reading the module header, this list is populated with functions that
 109   // have bodies later in the file.
 110   std::vector<Function*> FunctionsWithBodies;
 111
 112   // When intrinsic functions are encountered which require upgrading they are
 113   // stored here with their replacement function.
 114   typedef std::vector<std::pair<Function*, Function*> > UpgradedIntrinsicMap;
 115   UpgradedIntrinsicMap UpgradedIntrinsics;
 116
 117   // After the module header has been read, the FunctionsWithBodies list is
 118   // reversed.  This keeps track of whether we've done this yet.
 119   bool HasReversedFunctionsWithBodies;
 120
 121   /// DeferredFunctionInfo - When function bodies are initially scanned, this
 122   /// map contains info about where to find deferred function body (in the
 123   /// stream) and what linkage the original function had.
 124   DenseMap<Function*, std::pair<uint64_t, unsigned> > DeferredFunctionInfo;
 125 public:
 126   explicit BitcodeReader(MemoryBuffer *buffer)
 127       : Buffer(buffer), ErrorString(0) {
 128     HasReversedFunctionsWithBodies = false;
 129   }
 130   ~BitcodeReader() {
 131     FreeState();
 132   }
 133
 134   void FreeState();
 135
 136   /// releaseMemoryBuffer - This causes the reader to completely forget about
 137   /// the memory buffer it contains, which prevents the buffer from being
 138   /// destroyed when it is deleted.
 139   void releaseMemoryBuffer() {
 140     Buffer = 0;
 141   }
 142
 143   virtual bool materializeFunction(Function *F, std::string *ErrInfo = 0);
 144   virtual Module *materializeModule(std::string *ErrInfo = 0);
 145   virtual void dematerializeFunction(Function *F);
 146   virtual Module *releaseModule(std::string *ErrInfo = 0);
 147
 148   bool Error(const char *Str) {
 149     ErrorString = Str;
 150     return true;
 151   }
 152   const char *getErrorString() const { return ErrorString; }
 153
 154   /// @brief Main interface to parsing a bitcode buffer.
 155   /// @returns true if an error occurred.
 156   bool ParseBitcode();
 157 private:
 158   const Type *getTypeByID(unsigned ID, bool isTypeTable = false);
 159   Value *getFnValueByID(unsigned ID, const Type *Ty) {
 160     return ValueList.getValueFwdRef(ID, Ty);
 161   }
 162   BasicBlock *getBasicBlock(unsigned ID) const {
 163     if (ID >= FunctionBBs.size()) return 0; // Invalid ID
 164     return FunctionBBs[ID];
 165   }
 166   AttrListPtr getAttributes(unsigned i) const {
 167     if (i-1 < MAttributes.size())
 168       return MAttributes[i-1];
 169     return AttrListPtr();
 170   }
 171
 172   /// getValueTypePair - Read a value/type pair out of the specified record from
 173   /// slot 'Slot'.  Increment Slot past the number of slots used in the record.
 174   /// Return true on failure.
 175   bool getValueTypePair(SmallVector<uint64_t, 64> &Record, unsigned &Slot,
 176                         unsigned InstNum, Value *&ResVal) {
 177     if (Slot == Record.size()) return true;
 178     unsigned ValNo = (unsigned)Record[Slot++];
 179     if (ValNo < InstNum) {
 180       // If this is not a forward reference, just return the value we already
 181       // have.
 182       ResVal = getFnValueByID(ValNo, 0);
 183       return ResVal == 0;
 184     } else if (Slot == Record.size()) {
 185       return true;
 186     }
 187
 188     unsigned TypeNo = (unsigned)Record[Slot++];
 189     ResVal = getFnValueByID(ValNo, getTypeByID(TypeNo));
 190     return ResVal == 0;
 191   }
 192   bool getValue(SmallVector<uint64_t, 64> &Record, unsigned &Slot,
 193                 const Type *Ty, Value *&ResVal) {
 194     if (Slot == Record.size()) return true;
 195     unsigned ValNo = (unsigned)Record[Slot++];
 196     ResVal = getFnValueByID(ValNo, Ty);
 197     return ResVal == 0;
 198   }
 199
 200
 201   bool ParseModule(const std::string &ModuleID);
 202   bool ParseAttributeBlock();
 203   bool ParseTypeTable();
 204   bool ParseTypeSymbolTable();
 205   bool ParseValueSymbolTable();
 206   bool ParseConstants();
 207   bool RememberAndSkipFunctionBody();
 208   bool ParseFunctionBody(Function *F);
 209   bool ResolveGlobalAndAliasInits();
 210 };
 211
 212 } // End llvm namespace
 213
 214 #endif