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_LEGACY_LTOMODULE_H
14 #define LLVM_LTO_LEGACY_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::unique_ptr<Module> Mod;
52   MemoryBufferRef MBRef;
53   ModuleSymbolTable SymTab;
54   std::unique_ptr<TargetMachine> _target;
55   std::vector<NameAndAttributes> _symbols;
56 
57   // _defines and _undefines only needed to disambiguate tentative definitions
58   StringSet<>                             _defines;
59   StringMap<NameAndAttributes> _undefines;
60   std::vector<StringRef> _asm_undefines;
61 
62   LTOModule(std::unique_ptr<Module> M, MemoryBufferRef MBRef,
63             TargetMachine *TM);
64 
65 public:
66   ~LTOModule();
67 
68   /// Returns 'true' if the file or memory contents is LLVM bitcode.
69   static bool isBitcodeFile(const void *mem, size_t length);
70   static bool isBitcodeFile(StringRef path);
71 
72   /// Returns 'true' if the Module is produced for ThinLTO.
73   bool isThinLTO();
74 
75   /// Returns 'true' if the memory buffer is LLVM bitcode for the specified
76   /// triple.
77   static bool isBitcodeForTarget(MemoryBuffer *memBuffer,
78                                  StringRef triplePrefix);
79 
80   /// Returns a string representing the producer identification stored in the
81   /// bitcode, or "" if the bitcode does not contains any.
82   ///
83   static std::string getProducerString(MemoryBuffer *Buffer);
84 
85   /// Create a MemoryBuffer from a memory range with an optional name.
86   static std::unique_ptr<MemoryBuffer>
87   makeBuffer(const void *mem, size_t length, StringRef name = "");
88 
89   /// Create an LTOModule. N.B. These methods take ownership of the buffer. The
90   /// caller must have initialized the Targets, the TargetMCs, the AsmPrinters,
91   /// and the AsmParsers by calling:
92   ///
93   /// InitializeAllTargets();
94   /// InitializeAllTargetMCs();
95   /// InitializeAllAsmPrinters();
96   /// InitializeAllAsmParsers();
97   static ErrorOr<std::unique_ptr<LTOModule>>
98   createFromFile(LLVMContext &Context, StringRef path,
99                  const TargetOptions &options);
100   static ErrorOr<std::unique_ptr<LTOModule>>
101   createFromOpenFile(LLVMContext &Context, int fd, StringRef path, size_t size,
102                      const TargetOptions &options);
103   static ErrorOr<std::unique_ptr<LTOModule>>
104   createFromOpenFileSlice(LLVMContext &Context, int fd, StringRef path,
105                           size_t map_size, off_t offset,
106                           const TargetOptions &options);
107   static ErrorOr<std::unique_ptr<LTOModule>>
108   createFromBuffer(LLVMContext &Context, const void *mem, size_t length,
109                    const TargetOptions &options, StringRef path = "");
110   static ErrorOr<std::unique_ptr<LTOModule>>
111   createInLocalContext(std::unique_ptr<LLVMContext> Context, const void *mem,
112                        size_t length, const TargetOptions &options,
113                        StringRef path);
114 
115   const Module &getModule() const { return *Mod; }
116   Module &getModule() { return *Mod; }
117 
118   std::unique_ptr<Module> takeModule() { return std::move(Mod); }
119 
120   /// Return the Module's target triple.
121   const std::string &getTargetTriple() {
122     return getModule().getTargetTriple();
123   }
124 
125   /// Set the Module's target triple.
126   void setTargetTriple(StringRef Triple) {
127     getModule().setTargetTriple(Triple);
128   }
129 
130   /// Get the number of symbols
131   uint32_t getSymbolCount() {
132     return _symbols.size();
133   }
134 
135   /// Get the attributes for a symbol at the specified index.
136   lto_symbol_attributes getSymbolAttributes(uint32_t index) {
137     if (index < _symbols.size())
138       return lto_symbol_attributes(_symbols[index].attributes);
139     return lto_symbol_attributes(0);
140   }
141 
142   /// Get the name of the symbol at the specified index.
143   StringRef getSymbolName(uint32_t index) {
144     if (index < _symbols.size())
145       return _symbols[index].name;
146     return StringRef();
147   }
148 
149   const GlobalValue *getSymbolGV(uint32_t index) {
150     if (index < _symbols.size())
151       return _symbols[index].symbol;
152     return nullptr;
153   }
154 
155   StringRef getLinkerOpts() { return LinkerOpts; }
156 
157   const std::vector<StringRef> &getAsmUndefinedRefs() { return _asm_undefines; }
158 
159   static lto::InputFile *createInputFile(const void *buffer, size_t buffer_size,
160                                          const char *path, std::string &out_error);
161 
162   static size_t getDependentLibraryCount(lto::InputFile *input);
163 
164   static const char *getDependentLibrary(lto::InputFile *input, size_t index, size_t *size);
165 
166   Expected<uint32_t> getMachOCPUType() const;
167 
168   Expected<uint32_t> getMachOCPUSubType() const;
169 
170 private:
171   /// Parse metadata from the module
172   // FIXME: it only parses "llvm.linker.options" metadata at the moment
173   // FIXME: can't access metadata in lazily loaded modules
174   void parseMetadata();
175 
176   /// Parse the symbols from the module and model-level ASM and add them to
177   /// either the defined or undefined lists.
178   void parseSymbols();
179 
180   /// Add a symbol which isn't defined just yet to a list to be resolved later.
181   void addPotentialUndefinedSymbol(ModuleSymbolTable::Symbol Sym,
182                                    bool isFunc);
183 
184   /// Add a defined symbol to the list.
185   void addDefinedSymbol(StringRef Name, const GlobalValue *def,
186                         bool isFunction);
187 
188   /// Add a data symbol as defined to the list.
189   void addDefinedDataSymbol(ModuleSymbolTable::Symbol Sym);
190   void addDefinedDataSymbol(StringRef Name, const GlobalValue *v);
191 
192   /// Add a function symbol as defined to the list.
193   void addDefinedFunctionSymbol(ModuleSymbolTable::Symbol Sym);
194   void addDefinedFunctionSymbol(StringRef Name, const Function *F);
195 
196   /// Add a global symbol from module-level ASM to the defined list.
197   void addAsmGlobalSymbol(StringRef, lto_symbol_attributes scope);
198 
199   /// Add a global symbol from module-level ASM to the undefined list.
200   void addAsmGlobalSymbolUndef(StringRef);
201 
202   /// Parse i386/ppc ObjC class data structure.
203   void addObjCClass(const GlobalVariable *clgv);
204 
205   /// Parse i386/ppc ObjC category data structure.
206   void addObjCCategory(const GlobalVariable *clgv);
207 
208   /// Parse i386/ppc ObjC class list data structure.
209   void addObjCClassRef(const GlobalVariable *clgv);
210 
211   /// Get string that the data pointer points to.
212   bool objcClassNameFromExpression(const Constant *c, std::string &name);
213 
214   /// Create an LTOModule (private version).
215   static ErrorOr<std::unique_ptr<LTOModule>>
216   makeLTOModule(MemoryBufferRef Buffer, const TargetOptions &options,
217                 LLVMContext &Context, bool ShouldBeLazy);
218 };
219 }
220 #endif
221