1 //===-LTOModule.h - LLVM Link Time Optimizer ------------------------------===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 //
9 // This file declares the LTOModule class.
10 //
11 //===----------------------------------------------------------------------===//
12 
13 #ifndef LLVM_LTO_LTOMODULE_H
14 #define LLVM_LTO_LTOMODULE_H
15 
16 #include "llvm-c/lto.h"
17 #include "llvm/ADT/StringMap.h"
18 #include "llvm/ADT/StringSet.h"
19 #include "llvm/IR/Module.h"
20 #include "llvm/LTO/LTO.h"
21 #include "llvm/Object/IRObjectFile.h"
22 #include "llvm/Object/ModuleSymbolTable.h"
23 #include "llvm/Target/TargetMachine.h"
24 #include <string>
25 #include <vector>
26 
27 // Forward references to llvm classes.
28 namespace llvm {
29   class Function;
30   class GlobalValue;
31   class MemoryBuffer;
32   class TargetOptions;
33   class Value;
34 
35 //===----------------------------------------------------------------------===//
36 /// C++ class which implements the opaque lto_module_t type.
37 ///
38 struct LTOModule {
39 private:
40   struct NameAndAttributes {
41     StringRef name;
42     uint32_t           attributes = 0;
43     bool               isFunction = 0;
44     const GlobalValue *symbol = 0;
45   };
46 
47   std::unique_ptr<LLVMContext> OwnedContext;
48 
49   std::string LinkerOpts;
50 
51   std::string DependentLibraries;
52 
53   std::unique_ptr<Module> Mod;
54   MemoryBufferRef MBRef;
55   ModuleSymbolTable SymTab;
56   std::unique_ptr<TargetMachine> _target;
57   std::vector<NameAndAttributes> _symbols;
58 
59   // _defines and _undefines only needed to disambiguate tentative definitions
60   StringSet<>                             _defines;
61   StringMap<NameAndAttributes> _undefines;
62   std::vector<StringRef> _asm_undefines;
63 
64   LTOModule(std::unique_ptr<Module> M, MemoryBufferRef MBRef,
65             TargetMachine *TM);
66 
67 public:
68   ~LTOModule();
69 
70   /// Returns 'true' if the file or memory contents is LLVM bitcode.
71   static bool isBitcodeFile(const void *mem, size_t length);
72   static bool isBitcodeFile(StringRef path);
73 
74   /// Returns 'true' if the Module is produced for ThinLTO.
75   bool isThinLTO();
76 
77   /// Returns 'true' if the memory buffer is LLVM bitcode for the specified
78   /// triple.
79   static bool isBitcodeForTarget(MemoryBuffer *memBuffer,
80                                  StringRef triplePrefix);
81 
82   /// Returns a string representing the producer identification stored in the
83   /// bitcode, or "" if the bitcode does not contains any.
84   ///
85   static std::string getProducerString(MemoryBuffer *Buffer);
86 
87   /// Create a MemoryBuffer from a memory range with an optional name.
88   static std::unique_ptr<MemoryBuffer>
89   makeBuffer(const void *mem, size_t length, StringRef name = "");
90 
91   /// Create an LTOModule. N.B. These methods take ownership of the buffer. The
92   /// caller must have initialized the Targets, the TargetMCs, the AsmPrinters,
93   /// and the AsmParsers by calling:
94   ///
95   /// InitializeAllTargets();
96   /// InitializeAllTargetMCs();
97   /// InitializeAllAsmPrinters();
98   /// InitializeAllAsmParsers();
99   static ErrorOr<std::unique_ptr<LTOModule>>
100   createFromFile(LLVMContext &Context, StringRef path,
101                  const TargetOptions &options);
102   static ErrorOr<std::unique_ptr<LTOModule>>
103   createFromOpenFile(LLVMContext &Context, int fd, StringRef path, size_t size,
104                      const TargetOptions &options);
105   static ErrorOr<std::unique_ptr<LTOModule>>
106   createFromOpenFileSlice(LLVMContext &Context, int fd, StringRef path,
107                           size_t map_size, off_t offset,
108                           const TargetOptions &options);
109   static ErrorOr<std::unique_ptr<LTOModule>>
110   createFromBuffer(LLVMContext &Context, const void *mem, size_t length,
111                    const TargetOptions &options, StringRef path = "");
112   static ErrorOr<std::unique_ptr<LTOModule>>
113   createInLocalContext(std::unique_ptr<LLVMContext> Context, const void *mem,
114                        size_t length, const TargetOptions &options,
115                        StringRef path);
116 
117   const Module &getModule() const { return *Mod; }
118   Module &getModule() { return *Mod; }
119 
120   std::unique_ptr<Module> takeModule() { return std::move(Mod); }
121 
122   /// Return the Module's target triple.
123   const std::string &getTargetTriple() {
124     return getModule().getTargetTriple();
125   }
126 
127   /// Set the Module's target triple.
128   void setTargetTriple(StringRef Triple) {
129     getModule().setTargetTriple(Triple);
130   }
131 
132   /// Get the number of symbols
133   uint32_t getSymbolCount() {
134     return _symbols.size();
135   }
136 
137   /// Get the attributes for a symbol at the specified index.
138   lto_symbol_attributes getSymbolAttributes(uint32_t index) {
139     if (index < _symbols.size())
140       return lto_symbol_attributes(_symbols[index].attributes);
141     return lto_symbol_attributes(0);
142   }
143 
144   /// Get the name of the symbol at the specified index.
145   StringRef getSymbolName(uint32_t index) {
146     if (index < _symbols.size())
147       return _symbols[index].name;
148     return StringRef();
149   }
150 
151   const GlobalValue *getSymbolGV(uint32_t index) {
152     if (index < _symbols.size())
153       return _symbols[index].symbol;
154     return nullptr;
155   }
156 
157   StringRef getLinkerOpts() { return LinkerOpts; }
158 
159   const std::vector<StringRef> &getAsmUndefinedRefs() { return _asm_undefines; }
160 
161   static lto::InputFile *createInputFile(const void *buffer, size_t buffer_size,
162                                          const char *path, std::string &out_error);
163 
164   static size_t getDependentLibraryCount(lto::InputFile *input);
165 
166   static const char *getDependentLibrary(lto::InputFile *input, size_t index, size_t *size);
167 
168 private:
169   /// Parse metadata from the module
170   // FIXME: it only parses "llvm.linker.options" metadata at the moment
171   // FIXME: can't access metadata in lazily loaded modules
172   void parseMetadata();
173 
174   /// Parse the symbols from the module and model-level ASM and add them to
175   /// either the defined or undefined lists.
176   void parseSymbols();
177 
178   /// Add a symbol which isn't defined just yet to a list to be resolved later.
179   void addPotentialUndefinedSymbol(ModuleSymbolTable::Symbol Sym,
180                                    bool isFunc);
181 
182   /// Add a defined symbol to the list.
183   void addDefinedSymbol(StringRef Name, const GlobalValue *def,
184                         bool isFunction);
185 
186   /// Add a data symbol as defined to the list.
187   void addDefinedDataSymbol(ModuleSymbolTable::Symbol Sym);
188   void addDefinedDataSymbol(StringRef Name, const GlobalValue *v);
189 
190   /// Add a function symbol as defined to the list.
191   void addDefinedFunctionSymbol(ModuleSymbolTable::Symbol Sym);
192   void addDefinedFunctionSymbol(StringRef Name, const Function *F);
193 
194   /// Add a global symbol from module-level ASM to the defined list.
195   void addAsmGlobalSymbol(StringRef, lto_symbol_attributes scope);
196 
197   /// Add a global symbol from module-level ASM to the undefined list.
198   void addAsmGlobalSymbolUndef(StringRef);
199 
200   /// Parse i386/ppc ObjC class data structure.
201   void addObjCClass(const GlobalVariable *clgv);
202 
203   /// Parse i386/ppc ObjC category data structure.
204   void addObjCCategory(const GlobalVariable *clgv);
205 
206   /// Parse i386/ppc ObjC class list data structure.
207   void addObjCClassRef(const GlobalVariable *clgv);
208 
209   /// Get string that the data pointer points to.
210   bool objcClassNameFromExpression(const Constant *c, std::string &name);
211 
212   /// Create an LTOModule (private version).
213   static ErrorOr<std::unique_ptr<LTOModule>>
214   makeLTOModule(MemoryBufferRef Buffer, const TargetOptions &options,
215                 LLVMContext &Context, bool ShouldBeLazy);
216 };
217 }
218 #endif
219