BitcodeReader.h revision 962dde3cef3184f1683d5070c298c9a29509d62e 
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
30//===----------------------------------------------------------------------===//
31//                          BitcodeReaderValueList Class
32//===----------------------------------------------------------------------===//
33
34class 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;
46public:
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
87class 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;
125public:
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();
157private:
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
215