BitcodeReader.h revision 4434ed44c45c87a72b7a0bf2f91211f895022b91 
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;
47public:
48  BitcodeReaderValueList() {}
49  ~BitcodeReaderValueList() {
50    assert(ResolveConstants.empty() && "Constants not resolved?");
51  }
52
53  // vector compatibility methods
54  unsigned size() const { return ValuePtrs.size(); }
55  void resize(unsigned N) { ValuePtrs.resize(N); }
56  void push_back(Value *V) {
57    ValuePtrs.push_back(V);
58  }
59
60  void clear() {
61    assert(ResolveConstants.empty() && "Constants not resolved?");
62    ValuePtrs.clear();
63  }
64
65  Value *operator[](unsigned i) const {
66    assert(i < ValuePtrs.size());
67    return ValuePtrs[i];
68  }
69
70  Value *back() const { return ValuePtrs.back(); }
71    void pop_back() { ValuePtrs.pop_back(); }
72  bool empty() const { return ValuePtrs.empty(); }
73  void shrinkTo(unsigned N) {
74    assert(N <= size() && "Invalid shrinkTo request!");
75    ValuePtrs.resize(N);
76  }
77
78  Constant *getConstantFwdRef(unsigned Idx, const Type *Ty);
79  Value *getValueFwdRef(unsigned Idx, const Type *Ty);
80
81  void AssignValue(Value *V, unsigned Idx);
82
83  /// ResolveConstantForwardRefs - Once all constants are read, this method bulk
84  /// resolves any forward references.
85  void ResolveConstantForwardRefs();
86};
87
88class BitcodeReader : public ModuleProvider {
89  LLVMContext& Context;
90  MemoryBuffer *Buffer;
91  BitstreamReader StreamFile;
92  BitstreamCursor Stream;
93
94  const char *ErrorString;
95
96  std::vector<PATypeHolder> TypeList;
97  BitcodeReaderValueList ValueList;
98  std::vector<std::pair<GlobalVariable*, unsigned> > GlobalInits;
99  std::vector<std::pair<GlobalAlias*, unsigned> > AliasInits;
100
101  /// MAttributes - The set of attributes by index.  Index zero in the
102  /// file is for null, and is thus not represented here.  As such all indices
103  /// are off by one.
104  std::vector<AttrListPtr> MAttributes;
105
106  /// FunctionBBs - While parsing a function body, this is a list of the basic
107  /// blocks for the function.
108  std::vector<BasicBlock*> FunctionBBs;
109
110  // When reading the module header, this list is populated with functions that
111  // have bodies later in the file.
112  std::vector<Function*> FunctionsWithBodies;
113
114  // When intrinsic functions are encountered which require upgrading they are
115  // stored here with their replacement function.
116  typedef std::vector<std::pair<Function*, Function*> > UpgradedIntrinsicMap;
117  UpgradedIntrinsicMap UpgradedIntrinsics;
118
119  // After the module header has been read, the FunctionsWithBodies list is
120  // reversed.  This keeps track of whether we've done this yet.
121  bool HasReversedFunctionsWithBodies;
122
123  /// DeferredFunctionInfo - When function bodies are initially scanned, this
124  /// map contains info about where to find deferred function body (in the
125  /// stream) and what linkage the original function had.
126  DenseMap<Function*, std::pair<uint64_t, unsigned> > DeferredFunctionInfo;
127public:
128  explicit BitcodeReader(MemoryBuffer *buffer, LLVMContext& C)
129      : Context(C), Buffer(buffer), ErrorString(0) {
130    HasReversedFunctionsWithBodies = false;
131  }
132  ~BitcodeReader() {
133    FreeState();
134  }
135
136  void FreeState();
137
138  /// releaseMemoryBuffer - This causes the reader to completely forget about
139  /// the memory buffer it contains, which prevents the buffer from being
140  /// destroyed when it is deleted.
141  void releaseMemoryBuffer() {
142    Buffer = 0;
143  }
144
145  virtual bool materializeFunction(Function *F, std::string *ErrInfo = 0);
146  virtual Module *materializeModule(std::string *ErrInfo = 0);
147  virtual void dematerializeFunction(Function *F);
148  virtual Module *releaseModule(std::string *ErrInfo = 0);
149
150  bool Error(const char *Str) {
151    ErrorString = Str;
152    return true;
153  }
154  const char *getErrorString() const { return ErrorString; }
155
156  /// @brief Main interface to parsing a bitcode buffer.
157  /// @returns true if an error occurred.
158  bool ParseBitcode();
159private:
160  const Type *getTypeByID(unsigned ID, bool isTypeTable = false);
161  Value *getFnValueByID(unsigned ID, const Type *Ty) {
162    return ValueList.getValueFwdRef(ID, Ty);
163  }
164  BasicBlock *getBasicBlock(unsigned ID) const {
165    if (ID >= FunctionBBs.size()) return 0; // Invalid ID
166    return FunctionBBs[ID];
167  }
168  AttrListPtr getAttributes(unsigned i) const {
169    if (i-1 < MAttributes.size())
170      return MAttributes[i-1];
171    return AttrListPtr();
172  }
173
174  /// getValueTypePair - Read a value/type pair out of the specified record from
175  /// slot 'Slot'.  Increment Slot past the number of slots used in the record.
176  /// Return true on failure.
177  bool getValueTypePair(SmallVector<uint64_t, 64> &Record, unsigned &Slot,
178                        unsigned InstNum, Value *&ResVal) {
179    if (Slot == Record.size()) return true;
180    unsigned ValNo = (unsigned)Record[Slot++];
181    if (ValNo < InstNum) {
182      // If this is not a forward reference, just return the value we already
183      // have.
184      ResVal = getFnValueByID(ValNo, 0);
185      return ResVal == 0;
186    } else if (Slot == Record.size()) {
187      return true;
188    }
189
190    unsigned TypeNo = (unsigned)Record[Slot++];
191    ResVal = getFnValueByID(ValNo, getTypeByID(TypeNo));
192    return ResVal == 0;
193  }
194  bool getValue(SmallVector<uint64_t, 64> &Record, unsigned &Slot,
195                const Type *Ty, Value *&ResVal) {
196    if (Slot == Record.size()) return true;
197    unsigned ValNo = (unsigned)Record[Slot++];
198    ResVal = getFnValueByID(ValNo, Ty);
199    return ResVal == 0;
200  }
201
202
203  bool ParseModule(const std::string &ModuleID);
204  bool ParseAttributeBlock();
205  bool ParseTypeTable();
206  bool ParseTypeSymbolTable();
207  bool ParseValueSymbolTable();
208  bool ParseConstants();
209  bool RememberAndSkipFunctionBody();
210  bool ParseFunctionBody(Function *F);
211  bool ResolveGlobalAndAliasInits();
212};
213
214} // End llvm namespace
215
216#endif
217