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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/GVMaterializer.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:
BitcodeReaderValueList(LLVMContext & C)49   BitcodeReaderValueList(LLVMContext &C) : Context(C) {}
~BitcodeReaderValueList()50   ~BitcodeReaderValueList() {
51     assert(ResolveConstants.empty() && "Constants not resolved?");
52   }
53 
54   // vector compatibility methods
size()55   unsigned size() const { return ValuePtrs.size(); }
resize(unsigned N)56   void resize(unsigned N) { ValuePtrs.resize(N); }
push_back(Value * V)57   void push_back(Value *V) {
58     ValuePtrs.push_back(V);
59   }
60 
clear()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 
back()71   Value *back() const { return ValuePtrs.back(); }
pop_back()72     void pop_back() { ValuePtrs.pop_back(); }
empty()73   bool empty() const { return ValuePtrs.empty(); }
shrinkTo(unsigned N)74   void shrinkTo(unsigned N) {
75     assert(N <= size() && "Invalid shrinkTo request!");
76     ValuePtrs.resize(N);
77   }
78 
79   Constant *getConstantFwdRef(unsigned Idx, Type *Ty);
80   Value *getValueFwdRef(unsigned Idx, 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:
BitcodeReaderMDValueList(LLVMContext & C)99   BitcodeReaderMDValueList(LLVMContext& C) : Context(C) {}
100 
101   // vector compatibility methods
size()102   unsigned size() const       { return MDValuePtrs.size(); }
resize(unsigned N)103   void resize(unsigned N)     { MDValuePtrs.resize(N); }
push_back(Value * V)104   void push_back(Value *V)    { MDValuePtrs.push_back(V);  }
clear()105   void clear()                { MDValuePtrs.clear();  }
back()106   Value *back() const         { return MDValuePtrs.back(); }
pop_back()107   void pop_back()             { MDValuePtrs.pop_back(); }
empty()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 
shrinkTo(unsigned N)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 GVMaterializer {
125   LLVMContext &Context;
126   Module *TheModule;
127   MemoryBuffer *Buffer;
128   bool BufferOwned;
129   BitstreamReader StreamFile;
130   BitstreamCursor Stream;
131 
132   const char *ErrorString;
133 
134   std::vector<Type*> TypeList;
135   BitcodeReaderValueList ValueList;
136   BitcodeReaderMDValueList MDValueList;
137   SmallVector<Instruction *, 64> InstructionList;
138 
139   std::vector<std::pair<GlobalVariable*, unsigned> > GlobalInits;
140   std::vector<std::pair<GlobalAlias*, unsigned> > AliasInits;
141 
142   /// MAttributes - The set of attributes by index.  Index zero in the
143   /// file is for null, and is thus not represented here.  As such all indices
144   /// are off by one.
145   std::vector<AttrListPtr> MAttributes;
146 
147   /// FunctionBBs - While parsing a function body, this is a list of the basic
148   /// blocks for the function.
149   std::vector<BasicBlock*> FunctionBBs;
150 
151   // When reading the module header, this list is populated with functions that
152   // have bodies later in the file.
153   std::vector<Function*> FunctionsWithBodies;
154 
155   // When intrinsic functions are encountered which require upgrading they are
156   // stored here with their replacement function.
157   typedef std::vector<std::pair<Function*, Function*> > UpgradedIntrinsicMap;
158   UpgradedIntrinsicMap UpgradedIntrinsics;
159 
160   // Map the bitcode's custom MDKind ID to the Module's MDKind ID.
161   DenseMap<unsigned, unsigned> MDKindMap;
162 
163   // After the module header has been read, the FunctionsWithBodies list is
164   // reversed.  This keeps track of whether we've done this yet.
165   bool HasReversedFunctionsWithBodies;
166 
167   /// DeferredFunctionInfo - When function bodies are initially scanned, this
168   /// map contains info about where to find deferred function body in the
169   /// stream.
170   DenseMap<Function*, uint64_t> DeferredFunctionInfo;
171 
172   /// BlockAddrFwdRefs - These are blockaddr references to basic blocks.  These
173   /// are resolved lazily when functions are loaded.
174   typedef std::pair<unsigned, GlobalVariable*> BlockAddrRefTy;
175   DenseMap<Function*, std::vector<BlockAddrRefTy> > BlockAddrFwdRefs;
176 
177 public:
BitcodeReader(MemoryBuffer * buffer,LLVMContext & C)178   explicit BitcodeReader(MemoryBuffer *buffer, LLVMContext &C)
179     : Context(C), TheModule(0), Buffer(buffer), BufferOwned(false),
180       ErrorString(0), ValueList(C), MDValueList(C) {
181     HasReversedFunctionsWithBodies = false;
182   }
~BitcodeReader()183   ~BitcodeReader() {
184     FreeState();
185   }
186 
187   void FreeState();
188 
189   /// setBufferOwned - If this is true, the reader will destroy the MemoryBuffer
190   /// when the reader is destroyed.
setBufferOwned(bool Owned)191   void setBufferOwned(bool Owned) { BufferOwned = Owned; }
192 
193   virtual bool isMaterializable(const GlobalValue *GV) const;
194   virtual bool isDematerializable(const GlobalValue *GV) const;
195   virtual bool Materialize(GlobalValue *GV, std::string *ErrInfo = 0);
196   virtual bool MaterializeModule(Module *M, std::string *ErrInfo = 0);
197   virtual void Dematerialize(GlobalValue *GV);
198 
Error(const char * Str)199   bool Error(const char *Str) {
200     ErrorString = Str;
201     return true;
202   }
getErrorString()203   const char *getErrorString() const { return ErrorString; }
204 
205   /// @brief Main interface to parsing a bitcode buffer.
206   /// @returns true if an error occurred.
207   bool ParseBitcodeInto(Module *M);
208 
209   /// @brief Cheap mechanism to just extract module triple
210   /// @returns true if an error occurred.
211   bool ParseTriple(std::string &Triple);
212 private:
213   Type *getTypeByID(unsigned ID);
214   Type *getTypeByIDOrNull(unsigned ID);
getFnValueByID(unsigned ID,Type * Ty)215   Value *getFnValueByID(unsigned ID, Type *Ty) {
216     if (Ty && Ty->isMetadataTy())
217       return MDValueList.getValueFwdRef(ID);
218     return ValueList.getValueFwdRef(ID, Ty);
219   }
getBasicBlock(unsigned ID)220   BasicBlock *getBasicBlock(unsigned ID) const {
221     if (ID >= FunctionBBs.size()) return 0; // Invalid ID
222     return FunctionBBs[ID];
223   }
getAttributes(unsigned i)224   AttrListPtr getAttributes(unsigned i) const {
225     if (i-1 < MAttributes.size())
226       return MAttributes[i-1];
227     return AttrListPtr();
228   }
229 
230   /// getValueTypePair - Read a value/type pair out of the specified record from
231   /// slot 'Slot'.  Increment Slot past the number of slots used in the record.
232   /// Return true on failure.
getValueTypePair(SmallVector<uint64_t,64> & Record,unsigned & Slot,unsigned InstNum,Value * & ResVal)233   bool getValueTypePair(SmallVector<uint64_t, 64> &Record, unsigned &Slot,
234                         unsigned InstNum, Value *&ResVal) {
235     if (Slot == Record.size()) return true;
236     unsigned ValNo = (unsigned)Record[Slot++];
237     if (ValNo < InstNum) {
238       // If this is not a forward reference, just return the value we already
239       // have.
240       ResVal = getFnValueByID(ValNo, 0);
241       return ResVal == 0;
242     } else if (Slot == Record.size()) {
243       return true;
244     }
245 
246     unsigned TypeNo = (unsigned)Record[Slot++];
247     ResVal = getFnValueByID(ValNo, getTypeByID(TypeNo));
248     return ResVal == 0;
249   }
getValue(SmallVector<uint64_t,64> & Record,unsigned & Slot,Type * Ty,Value * & ResVal)250   bool getValue(SmallVector<uint64_t, 64> &Record, unsigned &Slot,
251                 Type *Ty, Value *&ResVal) {
252     if (Slot == Record.size()) return true;
253     unsigned ValNo = (unsigned)Record[Slot++];
254     ResVal = getFnValueByID(ValNo, Ty);
255     return ResVal == 0;
256   }
257 
258 
259   bool ParseModule();
260   bool ParseAttributeBlock();
261   bool ParseTypeTable();
262   bool ParseOldTypeTable();         // FIXME: Remove in LLVM 3.1
263   bool ParseTypeTableBody();
264 
265   bool ParseOldTypeSymbolTable();   // FIXME: Remove in LLVM 3.1
266   bool ParseValueSymbolTable();
267   bool ParseConstants();
268   bool RememberAndSkipFunctionBody();
269   bool ParseFunctionBody(Function *F);
270   bool ResolveGlobalAndAliasInits();
271   bool ParseMetadata();
272   bool ParseMetadataAttachment();
273   bool ParseModuleTriple(std::string &Triple);
274 };
275 
276 } // End llvm namespace
277 
278 #endif
279