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   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, const Type *Ty);
  80   Value *getValueFwdRef(unsigned Idx, const 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 ModuleProvider {
 125   LLVMContext& Context;
 126   MemoryBuffer *Buffer;
 127   BitstreamReader StreamFile;
 128   BitstreamCursor Stream;
 129
 130   const char *ErrorString;
 131
 132   std::vector<PATypeHolder> TypeList;
 133   BitcodeReaderValueList ValueList;
 134   BitcodeReaderMDValueList MDValueList;
 135   std::vector<std::pair<GlobalVariable*, unsigned> > GlobalInits;
 136   std::vector<std::pair<GlobalAlias*, unsigned> > AliasInits;
 137
 138   /// MAttributes - The set of attributes by index.  Index zero in the
 139   /// file is for null, and is thus not represented here.  As such all indices
 140   /// are off by one.
 141   std::vector<AttrListPtr> MAttributes;
 142
 143   /// FunctionBBs - While parsing a function body, this is a list of the basic
 144   /// blocks for the function.
 145   std::vector<BasicBlock*> FunctionBBs;
 146
 147   // When reading the module header, this list is populated with functions that
 148   // have bodies later in the file.
 149   std::vector<Function*> FunctionsWithBodies;
 150
 151   // When intrinsic functions are encountered which require upgrading they are
 152   // stored here with their replacement function.
 153   typedef std::vector<std::pair<Function*, Function*> > UpgradedIntrinsicMap;
 154   UpgradedIntrinsicMap UpgradedIntrinsics;
 155
 156   // After the module header has been read, the FunctionsWithBodies list is
 157   // reversed.  This keeps track of whether we've done this yet.
 158   bool HasReversedFunctionsWithBodies;
 159
 160   /// DeferredFunctionInfo - When function bodies are initially scanned, this
 161   /// map contains info about where to find deferred function body (in the
 162   /// stream) and what linkage the original function had.
 163   DenseMap<Function*, std::pair<uint64_t, unsigned> > DeferredFunctionInfo;
 164 public:
 165   explicit BitcodeReader(MemoryBuffer *buffer, LLVMContext& C)
 166     : Context(C), Buffer(buffer), ErrorString(0), ValueList(C), MDValueList(C) {
 167     HasReversedFunctionsWithBodies = false;
 168   }
 169   ~BitcodeReader() {
 170     FreeState();
 171   }
 172
 173   void FreeState();
 174
 175   /// releaseMemoryBuffer - This causes the reader to completely forget about
 176   /// the memory buffer it contains, which prevents the buffer from being
 177   /// destroyed when it is deleted.
 178   void releaseMemoryBuffer() {
 179     Buffer = 0;
 180   }
 181
 182   virtual bool materializeFunction(Function *F, std::string *ErrInfo = 0);
 183   virtual Module *materializeModule(std::string *ErrInfo = 0);
 184   virtual void dematerializeFunction(Function *F);
 185   virtual Module *releaseModule(std::string *ErrInfo = 0);
 186
 187   bool Error(const char *Str) {
 188     ErrorString = Str;
 189     return true;
 190   }
 191   const char *getErrorString() const { return ErrorString; }
 192
 193   /// @brief Main interface to parsing a bitcode buffer.
 194   /// @returns true if an error occurred.
 195   bool ParseBitcode();
 196 private:
 197   const Type *getTypeByID(unsigned ID, bool isTypeTable = false);
 198   Value *getFnValueByID(unsigned ID, const Type *Ty) {
 199     if (Ty == Type::getMetadataTy(Context))
 200       return MDValueList.getValueFwdRef(ID);
 201     else
 202       return ValueList.getValueFwdRef(ID, Ty);
 203   }
 204   BasicBlock *getBasicBlock(unsigned ID) const {
 205     if (ID >= FunctionBBs.size()) return 0; // Invalid ID
 206     return FunctionBBs[ID];
 207   }
 208   AttrListPtr getAttributes(unsigned i) const {
 209     if (i-1 < MAttributes.size())
 210       return MAttributes[i-1];
 211     return AttrListPtr();
 212   }
 213
 214   /// getValueTypePair - Read a value/type pair out of the specified record from
 215   /// slot 'Slot'.  Increment Slot past the number of slots used in the record.
 216   /// Return true on failure.
 217   bool getValueTypePair(SmallVector<uint64_t, 64> &Record, unsigned &Slot,
 218                         unsigned InstNum, Value *&ResVal) {
 219     if (Slot == Record.size()) return true;
 220     unsigned ValNo = (unsigned)Record[Slot++];
 221     if (ValNo < InstNum) {
 222       // If this is not a forward reference, just return the value we already
 223       // have.
 224       ResVal = getFnValueByID(ValNo, 0);
 225       return ResVal == 0;
 226     } else if (Slot == Record.size()) {
 227       return true;
 228     }
 229
 230     unsigned TypeNo = (unsigned)Record[Slot++];
 231     ResVal = getFnValueByID(ValNo, getTypeByID(TypeNo));
 232     return ResVal == 0;
 233   }
 234   bool getValue(SmallVector<uint64_t, 64> &Record, unsigned &Slot,
 235                 const Type *Ty, Value *&ResVal) {
 236     if (Slot == Record.size()) return true;
 237     unsigned ValNo = (unsigned)Record[Slot++];
 238     ResVal = getFnValueByID(ValNo, Ty);
 239     return ResVal == 0;
 240   }
 241
 242
 243   bool ParseModule(const std::string &ModuleID);
 244   bool ParseAttributeBlock();
 245   bool ParseTypeTable();
 246   bool ParseTypeSymbolTable();
 247   bool ParseValueSymbolTable();
 248   bool ParseConstants();
 249   bool RememberAndSkipFunctionBody();
 250   bool ParseFunctionBody(Function *F);
 251   bool ResolveGlobalAndAliasInits();
 252   bool ParseMetadata();
 253 };
 254
 255 } // End llvm namespace
 256
 257 #endif