BitcodeReader.h revision e54abc90fe9942ef3902040a7ac475ce0c369dc9 
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
27namespace llvm {
28  class MemoryBuffer;
29  class LLVMContext;
30
31//===----------------------------------------------------------------------===//
32//                          BitcodeReaderValueList Class
33//===----------------------------------------------------------------------===//
34
35class 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;
48public:
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
89class BitcodeReader : public ModuleProvider {
90  LLVMContext& Context;
91  MemoryBuffer *Buffer;
92  BitstreamReader StreamFile;
93  BitstreamCursor Stream;
94
95  const char *ErrorString;
96
97  std::vector<PATypeHolder> TypeList;
98  BitcodeReaderValueList ValueList;
99  std::vector<std::pair<GlobalVariable*, unsigned> > GlobalInits;
100  std::vector<std::pair<GlobalAlias*, unsigned> > AliasInits;
101
102  /// MAttributes - The set of attributes by index.  Index zero in the
103  /// file is for null, and is thus not represented here.  As such all indices
104  /// are off by one.
105  std::vector<AttrListPtr> MAttributes;
106
107  /// FunctionBBs - While parsing a function body, this is a list of the basic
108  /// blocks for the function.
109  std::vector<BasicBlock*> FunctionBBs;
110
111  // When reading the module header, this list is populated with functions that
112  // have bodies later in the file.
113  std::vector<Function*> FunctionsWithBodies;
114
115  // When intrinsic functions are encountered which require upgrading they are
116  // stored here with their replacement function.
117  typedef std::vector<std::pair<Function*, Function*> > UpgradedIntrinsicMap;
118  UpgradedIntrinsicMap UpgradedIntrinsics;
119
120  // After the module header has been read, the FunctionsWithBodies list is
121  // reversed.  This keeps track of whether we've done this yet.
122  bool HasReversedFunctionsWithBodies;
123
124  /// DeferredFunctionInfo - When function bodies are initially scanned, this
125  /// map contains info about where to find deferred function body (in the
126  /// stream) and what linkage the original function had.
127  DenseMap<Function*, std::pair<uint64_t, unsigned> > DeferredFunctionInfo;
128public:
129  explicit BitcodeReader(MemoryBuffer *buffer, LLVMContext& C)
130      : Context(C), Buffer(buffer), ErrorString(0), ValueList(C) {
131    HasReversedFunctionsWithBodies = false;
132  }
133  ~BitcodeReader() {
134    FreeState();
135  }
136
137  void FreeState();
138
139  /// releaseMemoryBuffer - This causes the reader to completely forget about
140  /// the memory buffer it contains, which prevents the buffer from being
141  /// destroyed when it is deleted.
142  void releaseMemoryBuffer() {
143    Buffer = 0;
144  }
145
146  virtual bool materializeFunction(Function *F, std::string *ErrInfo = 0);
147  virtual Module *materializeModule(std::string *ErrInfo = 0);
148  virtual void dematerializeFunction(Function *F);
149  virtual Module *releaseModule(std::string *ErrInfo = 0);
150
151  bool Error(const char *Str) {
152    ErrorString = Str;
153    return true;
154  }
155  const char *getErrorString() const { return ErrorString; }
156
157  /// @brief Main interface to parsing a bitcode buffer.
158  /// @returns true if an error occurred.
159  bool ParseBitcode();
160private:
161  const Type *getTypeByID(unsigned ID, bool isTypeTable = false);
162  Value *getFnValueByID(unsigned ID, const Type *Ty) {
163    return ValueList.getValueFwdRef(ID, Ty);
164  }
165  BasicBlock *getBasicBlock(unsigned ID) const {
166    if (ID >= FunctionBBs.size()) return 0; // Invalid ID
167    return FunctionBBs[ID];
168  }
169  AttrListPtr getAttributes(unsigned i) const {
170    if (i-1 < MAttributes.size())
171      return MAttributes[i-1];
172    return AttrListPtr();
173  }
174
175  /// getValueTypePair - Read a value/type pair out of the specified record from
176  /// slot 'Slot'.  Increment Slot past the number of slots used in the record.
177  /// Return true on failure.
178  bool getValueTypePair(SmallVector<uint64_t, 64> &Record, unsigned &Slot,
179                        unsigned InstNum, Value *&ResVal) {
180    if (Slot == Record.size()) return true;
181    unsigned ValNo = (unsigned)Record[Slot++];
182    if (ValNo < InstNum) {
183      // If this is not a forward reference, just return the value we already
184      // have.
185      ResVal = getFnValueByID(ValNo, 0);
186      return ResVal == 0;
187    } else if (Slot == Record.size()) {
188      return true;
189    }
190
191    unsigned TypeNo = (unsigned)Record[Slot++];
192    ResVal = getFnValueByID(ValNo, getTypeByID(TypeNo));
193    return ResVal == 0;
194  }
195  bool getValue(SmallVector<uint64_t, 64> &Record, unsigned &Slot,
196                const Type *Ty, Value *&ResVal) {
197    if (Slot == Record.size()) return true;
198    unsigned ValNo = (unsigned)Record[Slot++];
199    ResVal = getFnValueByID(ValNo, Ty);
200    return ResVal == 0;
201  }
202
203
204  bool ParseModule(const std::string &ModuleID);
205  bool ParseAttributeBlock();
206  bool ParseTypeTable();
207  bool ParseTypeSymbolTable();
208  bool ParseValueSymbolTable();
209  bool ParseConstants();
210  bool RememberAndSkipFunctionBody();
211  bool ParseFunctionBody(Function *F);
212  bool ResolveGlobalAndAliasInits();
213  bool ParseMetadata();
214};
215
216} // End llvm namespace
217
218#endif
219