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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 namespace llvm_2_7 {
33 
34 using namespace llvm;
35 
36 //===----------------------------------------------------------------------===//
37 //                          BitcodeReaderValueList Class
38 //===----------------------------------------------------------------------===//
39 
40 class BitcodeReaderValueList {
41   std::vector<WeakVH> ValuePtrs;
42 
43   /// ResolveConstants - As we resolve forward-referenced constants, we add
44   /// information about them to this vector.  This allows us to resolve them in
45   /// bulk instead of resolving each reference at a time.  See the code in
46   /// ResolveConstantForwardRefs for more information about this.
47   ///
48   /// The key of this vector is the placeholder constant, the value is the slot
49   /// number that holds the resolved value.
50   typedef std::vector<std::pair<Constant*, unsigned> > ResolveConstantsTy;
51   ResolveConstantsTy ResolveConstants;
52   LLVMContext &Context;
53 public:
BitcodeReaderValueList(LLVMContext & C)54   BitcodeReaderValueList(LLVMContext &C) : Context(C) {}
~BitcodeReaderValueList()55   ~BitcodeReaderValueList() {
56     assert(ResolveConstants.empty() && "Constants not resolved?");
57   }
58 
59   // vector compatibility methods
size()60   unsigned size() const { return ValuePtrs.size(); }
resize(unsigned N)61   void resize(unsigned N) { ValuePtrs.resize(N); }
push_back(Value * V)62   void push_back(Value *V) {
63     ValuePtrs.push_back(V);
64   }
65 
clear()66   void clear() {
67     assert(ResolveConstants.empty() && "Constants not resolved?");
68     ValuePtrs.clear();
69   }
70 
71   Value *operator[](unsigned i) const {
72     assert(i < ValuePtrs.size());
73     return ValuePtrs[i];
74   }
75 
back()76   Value *back() const { return ValuePtrs.back(); }
pop_back()77     void pop_back() { ValuePtrs.pop_back(); }
empty()78   bool empty() const { return ValuePtrs.empty(); }
shrinkTo(unsigned N)79   void shrinkTo(unsigned N) {
80     assert(N <= size() && "Invalid shrinkTo request!");
81     ValuePtrs.resize(N);
82   }
83 
84   Constant *getConstantFwdRef(unsigned Idx, Type *Ty);
85   Value *getValueFwdRef(unsigned Idx, Type *Ty);
86 
87   void AssignValue(Value *V, unsigned Idx);
88 
89   /// ResolveConstantForwardRefs - Once all constants are read, this method bulk
90   /// resolves any forward references.
91   void ResolveConstantForwardRefs();
92 };
93 
94 
95 //===----------------------------------------------------------------------===//
96 //                          BitcodeReaderMDValueList Class
97 //===----------------------------------------------------------------------===//
98 
99 class BitcodeReaderMDValueList {
100   std::vector<WeakVH> MDValuePtrs;
101 
102   LLVMContext &Context;
103 public:
BitcodeReaderMDValueList(LLVMContext & C)104   BitcodeReaderMDValueList(LLVMContext& C) : Context(C) {}
105 
106   // vector compatibility methods
size()107   unsigned size() const       { return MDValuePtrs.size(); }
resize(unsigned N)108   void resize(unsigned N)     { MDValuePtrs.resize(N); }
push_back(Value * V)109   void push_back(Value *V)    { MDValuePtrs.push_back(V);  }
clear()110   void clear()                { MDValuePtrs.clear();  }
back()111   Value *back() const         { return MDValuePtrs.back(); }
pop_back()112   void pop_back()             { MDValuePtrs.pop_back(); }
empty()113   bool empty() const          { return MDValuePtrs.empty(); }
114 
115   Value *operator[](unsigned i) const {
116     assert(i < MDValuePtrs.size());
117     return MDValuePtrs[i];
118   }
119 
shrinkTo(unsigned N)120   void shrinkTo(unsigned N) {
121     assert(N <= size() && "Invalid shrinkTo request!");
122     MDValuePtrs.resize(N);
123   }
124 
125   Value *getValueFwdRef(unsigned Idx);
126   void AssignValue(Value *V, unsigned Idx);
127 };
128 
129 class BitcodeReader : public GVMaterializer {
130   LLVMContext &Context;
131   Module *TheModule;
132   MemoryBuffer *Buffer;
133   bool BufferOwned;
134   BitstreamReader StreamFile;
135   BitstreamCursor Stream;
136 
137   const char *ErrorString;
138 
139   std::vector<Type*> TypeList;
140   BitcodeReaderValueList ValueList;
141   BitcodeReaderMDValueList MDValueList;
142   SmallVector<Instruction *, 64> InstructionList;
143 
144   std::vector<std::pair<GlobalVariable*, unsigned> > GlobalInits;
145   std::vector<std::pair<GlobalAlias*, unsigned> > AliasInits;
146 
147   /// MAttributes - The set of attributes by index.  Index zero in the
148   /// file is for null, and is thus not represented here.  As such all indices
149   /// are off by one.
150   std::vector<AttrListPtr> MAttributes;
151 
152   /// FunctionBBs - While parsing a function body, this is a list of the basic
153   /// blocks for the function.
154   std::vector<BasicBlock*> FunctionBBs;
155 
156   // When reading the module header, this list is populated with functions that
157   // have bodies later in the file.
158   std::vector<Function*> FunctionsWithBodies;
159 
160   // When intrinsic functions are encountered which require upgrading they are
161   // stored here with their replacement function.
162   typedef std::vector<std::pair<Function*, Function*> > UpgradedIntrinsicMap;
163   UpgradedIntrinsicMap UpgradedIntrinsics;
164 
165   // Map the bitcode's custom MDKind ID to the Module's MDKind ID.
166   DenseMap<unsigned, unsigned> MDKindMap;
167 
168   // After the module header has been read, the FunctionsWithBodies list is
169   // reversed.  This keeps track of whether we've done this yet.
170   bool HasReversedFunctionsWithBodies;
171 
172   /// DeferredFunctionInfo - When function bodies are initially scanned, this
173   /// map contains info about where to find deferred function body in the
174   /// stream.
175   DenseMap<Function*, uint64_t> DeferredFunctionInfo;
176 
177   /// BlockAddrFwdRefs - These are blockaddr references to basic blocks.  These
178   /// are resolved lazily when functions are loaded.
179   typedef std::pair<unsigned, GlobalVariable*> BlockAddrRefTy;
180   DenseMap<Function*, std::vector<BlockAddrRefTy> > BlockAddrFwdRefs;
181 
182   /// LLVM2_7MetadataDetected - True if metadata produced by LLVM 2.7 or
183   /// earlier was detected, in which case we behave slightly differently,
184   /// for compatibility.
185   /// FIXME: Remove in LLVM 3.0.
186   bool LLVM2_7MetadataDetected;
187 
188 public:
BitcodeReader(MemoryBuffer * buffer,LLVMContext & C)189   explicit BitcodeReader(MemoryBuffer *buffer, LLVMContext &C)
190     : Context(C), TheModule(0), Buffer(buffer), BufferOwned(false),
191       ErrorString(0), ValueList(C), MDValueList(C),
192       LLVM2_7MetadataDetected(false) {
193     HasReversedFunctionsWithBodies = false;
194   }
~BitcodeReader()195   ~BitcodeReader() {
196     FreeState();
197   }
198 
199   void FreeState();
200 
201   /// setBufferOwned - If this is true, the reader will destroy the MemoryBuffer
202   /// when the reader is destroyed.
setBufferOwned(bool Owned)203   void setBufferOwned(bool Owned) { BufferOwned = Owned; }
204 
205   virtual bool isMaterializable(const GlobalValue *GV) const;
206   virtual bool isDematerializable(const GlobalValue *GV) const;
207   virtual bool Materialize(GlobalValue *GV, std::string *ErrInfo = 0);
208   virtual bool MaterializeModule(Module *M, std::string *ErrInfo = 0);
209   virtual void Dematerialize(GlobalValue *GV);
210 
Error(const char * Str)211   bool Error(const char *Str) {
212     ErrorString = Str;
213     return true;
214   }
getErrorString()215   const char *getErrorString() const { return ErrorString; }
216 
217   /// @brief Main interface to parsing a bitcode buffer.
218   /// @returns true if an error occurred.
219   bool ParseBitcodeInto(Module *M);
220 
221   /// @brief Cheap mechanism to just extract module triple
222   /// @returns true if an error occurred.
223   bool ParseTriple(std::string &Triple);
224 private:
225   Type *getTypeByID(unsigned ID);
226   Type *getTypeByIDOrNull(unsigned ID);
getFnValueByID(unsigned ID,Type * Ty)227   Value *getFnValueByID(unsigned ID, Type *Ty) {
228     if (Ty && Ty->isMetadataTy())
229       return MDValueList.getValueFwdRef(ID);
230     return ValueList.getValueFwdRef(ID, Ty);
231   }
getBasicBlock(unsigned ID)232   BasicBlock *getBasicBlock(unsigned ID) const {
233     if (ID >= FunctionBBs.size()) return 0; // Invalid ID
234     return FunctionBBs[ID];
235   }
getAttributes(unsigned i)236   AttrListPtr getAttributes(unsigned i) const {
237     if (i-1 < MAttributes.size())
238       return MAttributes[i-1];
239     return AttrListPtr();
240   }
241 
242   /// getValueTypePair - Read a value/type pair out of the specified record from
243   /// slot 'Slot'.  Increment Slot past the number of slots used in the record.
244   /// Return true on failure.
getValueTypePair(SmallVector<uint64_t,64> & Record,unsigned & Slot,unsigned InstNum,Value * & ResVal)245   bool getValueTypePair(SmallVector<uint64_t, 64> &Record, unsigned &Slot,
246                         unsigned InstNum, Value *&ResVal) {
247     if (Slot == Record.size()) return true;
248     unsigned ValNo = (unsigned)Record[Slot++];
249     if (ValNo < InstNum) {
250       // If this is not a forward reference, just return the value we already
251       // have.
252       ResVal = getFnValueByID(ValNo, 0);
253       return ResVal == 0;
254     } else if (Slot == Record.size()) {
255       return true;
256     }
257 
258     unsigned TypeNo = (unsigned)Record[Slot++];
259     ResVal = getFnValueByID(ValNo, getTypeByID(TypeNo));
260     return ResVal == 0;
261   }
getValue(SmallVector<uint64_t,64> & Record,unsigned & Slot,Type * Ty,Value * & ResVal)262   bool getValue(SmallVector<uint64_t, 64> &Record, unsigned &Slot,
263                 Type *Ty, Value *&ResVal) {
264     if (Slot == Record.size()) return true;
265     unsigned ValNo = (unsigned)Record[Slot++];
266     ResVal = getFnValueByID(ValNo, Ty);
267     return ResVal == 0;
268   }
269 
270 
271   bool ParseModule();
272   bool ParseAttributeBlock();
273   bool ParseTypeTable();
274   bool ParseOldTypeTable();         // FIXME: Remove in LLVM 3.1
275   bool ParseTypeTableBody();
276 
277   bool ParseOldTypeSymbolTable();   // FIXME: Remove in LLVM 3.1
278   bool ParseValueSymbolTable();
279   bool ParseConstants();
280   bool RememberAndSkipFunctionBody();
281   bool ParseFunctionBody(Function *F);
282   bool ResolveGlobalAndAliasInits();
283   bool ParseMetadata();
284   bool ParseMetadataAttachment();
285   bool ParseModuleTriple(std::string &Triple);
286 };
287 
288 } // End llvm namespace
289 
290 #endif
291