1 //===- lld/Core/LinkingContext.h - Linker Target Info Interface -*- C++ -*-===//
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 #ifndef LLD_CORE_LINKING_CONTEXT_H
11 #define LLD_CORE_LINKING_CONTEXT_H
13 #include "lld/Core/Node.h"
14 #include "lld/Core/Reader.h"
15 #include "llvm/ADT/ArrayRef.h"
16 #include "llvm/ADT/StringRef.h"
17 #include "llvm/Support/Allocator.h"
18 #include "llvm/Support/Error.h"
31 class SharedLibraryFile;
33 /// The LinkingContext class encapsulates "what and how" to link.
35 /// The base class LinkingContext contains the options needed by core linking.
36 /// Subclasses of LinkingContext have additional options needed by specific
38 class LinkingContext {
40 virtual ~LinkingContext();
42 /// \name Methods needed by core linking
45 /// Name of symbol linker should use as "entry point" to program,
46 /// usually "main" or "start".
47 virtual StringRef entrySymbolName() const { return _entrySymbolName; }
49 /// Whether core linking should remove Atoms not reachable by following
50 /// References from the entry point Atom or from all global scope Atoms
51 /// if globalsAreDeadStripRoots() is true.
52 bool deadStrip() const { return _deadStrip; }
54 /// Only used if deadStrip() returns true. Means all global scope Atoms
55 /// should be marked live (along with all Atoms they reference). Usually
56 /// this method returns false for main executables, but true for dynamic
58 bool globalsAreDeadStripRoots() const { return _globalsAreDeadStripRoots; }
60 /// Only used if deadStrip() returns true. This method returns the names
61 /// of DefinedAtoms that should be marked live (along with all Atoms they
62 /// reference). Only Atoms with scope scopeLinkageUnit or scopeGlobal can
63 /// be kept live using this method.
64 ArrayRef<StringRef> deadStripRoots() const {
65 return _deadStripRoots;
68 /// Add the given symbol name to the dead strip root set. Only used if
69 /// deadStrip() returns true.
70 void addDeadStripRoot(StringRef symbolName) {
71 assert(!symbolName.empty() && "Empty symbol cannot be a dead strip root");
72 _deadStripRoots.push_back(symbolName);
75 /// Normally, every UndefinedAtom must be replaced by a DefinedAtom or a
76 /// SharedLibraryAtom for the link to be successful. This method controls
77 /// whether core linking prints out a list of remaining UndefinedAtoms.
79 /// \todo This should be a method core linking calls with a list of the
80 /// UndefinedAtoms so that different drivers can format the error message
82 bool printRemainingUndefines() const { return _printRemainingUndefines; }
84 /// Normally, every UndefinedAtom must be replaced by a DefinedAtom or a
85 /// SharedLibraryAtom for the link to be successful. This method controls
86 /// whether core linking considers remaining undefines to be an error.
87 bool allowRemainingUndefines() const { return _allowRemainingUndefines; }
89 /// Normally, every UndefinedAtom must be replaced by a DefinedAtom or a
90 /// SharedLibraryAtom for the link to be successful. This method controls
91 /// whether core linking considers remaining undefines from the shared library
93 bool allowShlibUndefines() const { return _allowShlibUndefines; }
95 /// If true, core linking will write the path to each input file to stdout
96 /// (i.e. llvm::outs()) as it is used. This is used to implement the -t
99 /// \todo This should be a method core linking calls so that drivers can
100 /// format the line as needed.
101 bool logInputFiles() const { return _logInputFiles; }
103 /// Parts of LLVM use global variables which are bound to command line
104 /// options (see llvm::cl::Options). This method returns "command line"
105 /// options which are used to configure LLVM's command line settings.
106 /// For instance the -debug-only XXX option can be used to dynamically
107 /// trace different parts of LLVM and lld.
108 ArrayRef<const char *> llvmOptions() const { return _llvmOptions; }
110 /// \name Methods used by Drivers to configure TargetInfo
112 void setOutputPath(StringRef str) { _outputPath = str; }
114 // Set the entry symbol name. You may also need to call addDeadStripRoot() for
115 // the symbol if your platform supports dead-stripping, so that the symbol
116 // will not be removed from the output.
117 void setEntrySymbolName(StringRef name) {
118 _entrySymbolName = name;
121 void setDeadStripping(bool enable) { _deadStrip = enable; }
122 void setGlobalsAreDeadStripRoots(bool v) { _globalsAreDeadStripRoots = v; }
124 void setPrintRemainingUndefines(bool print) {
125 _printRemainingUndefines = print;
128 void setAllowRemainingUndefines(bool allow) {
129 _allowRemainingUndefines = allow;
132 void setAllowShlibUndefines(bool allow) { _allowShlibUndefines = allow; }
133 void setLogInputFiles(bool log) { _logInputFiles = log; }
135 void appendLLVMOption(const char *opt) { _llvmOptions.push_back(opt); }
137 std::vector<std::unique_ptr<Node>> &getNodes() { return _nodes; }
138 const std::vector<std::unique_ptr<Node>> &getNodes() const { return _nodes; }
140 /// This method adds undefined symbols specified by the -u option to the to
141 /// the list of undefined symbols known to the linker. This option essentially
142 /// forces an undefined symbol to be created. You may also need to call
143 /// addDeadStripRoot() for the symbol if your platform supports dead
144 /// stripping, so that the symbol will not be removed from the output.
145 void addInitialUndefinedSymbol(StringRef symbolName) {
146 _initialUndefinedSymbols.push_back(symbolName);
149 /// Iterators for symbols that appear on the command line.
150 typedef std::vector<StringRef> StringRefVector;
151 typedef StringRefVector::iterator StringRefVectorIter;
152 typedef StringRefVector::const_iterator StringRefVectorConstIter;
154 /// Create linker internal files containing atoms for the linker to include
155 /// during link. Flavors can override this function in their LinkingContext
156 /// to add more internal files. These internal files are positioned before
157 /// the actual input files.
158 virtual void createInternalFiles(std::vector<std::unique_ptr<File>> &) const;
160 /// Return the list of undefined symbols that are specified in the
161 /// linker command line, using the -u option.
162 ArrayRef<StringRef> initialUndefinedSymbols() const {
163 return _initialUndefinedSymbols;
166 /// After all set* methods are called, the Driver calls this method
167 /// to validate that there are no missing options or invalid combinations
168 /// of options. If there is a problem, a description of the problem
169 /// is written to the global error handler.
171 /// \returns true if there is an error with the current settings.
174 /// Formats symbol name for use in error messages.
175 virtual std::string demangle(StringRef symbolName) const = 0;
178 /// \name Methods used by Driver::link()
181 /// Returns the file system path to which the linked output should be written.
183 /// \todo To support in-memory linking, we need an abstraction that allows
184 /// the linker to write to an in-memory buffer.
185 StringRef outputPath() const { return _outputPath; }
187 /// Accessor for Register object embedded in LinkingContext.
188 const Registry ®istry() const { return _registry; }
189 Registry ®istry() { return _registry; }
191 /// This method is called by core linking to give the Writer a chance
192 /// to add file format specific "files" to set of files to be linked. This is
193 /// how file format specific atoms can be added to the link.
194 virtual void createImplicitFiles(std::vector<std::unique_ptr<File>> &) = 0;
196 /// This method is called by core linking to build the list of Passes to be
197 /// run on the merged/linked graph of all input files.
198 virtual void addPasses(PassManager &pm) = 0;
200 /// Calls through to the writeFile() method on the specified Writer.
202 /// \param linkedFile This is the merged/linked graph of all input file Atoms.
203 virtual llvm::Error writeFile(const File &linkedFile) const;
205 /// Return the next ordinal and Increment it.
206 virtual uint64_t getNextOrdinalAndIncrement() const { return _nextOrdinal++; }
208 // This function is called just before the Resolver kicks in.
209 // Derived classes may use it to change the list of input files.
210 virtual void finalizeInputFiles() = 0;
212 /// Callback invoked for each file the Resolver decides we are going to load.
213 /// This can be used to update context state based on the file, and emit
214 /// errors for any differences between the context state and a loaded file.
215 /// For example, we can error if we try to load a file which is a different
216 /// arch from that being linked.
217 virtual llvm::Error handleLoadedFile(File &file) = 0;
221 LinkingContext(); // Must be subclassed
223 /// Abstract method to lazily instantiate the Writer.
224 virtual Writer &writer() const = 0;
226 /// Method to create an internal file for the entry symbol
227 virtual std::unique_ptr<File> createEntrySymbolFile() const;
228 std::unique_ptr<File> createEntrySymbolFile(StringRef filename) const;
230 /// Method to create an internal file for an undefined symbol
231 virtual std::unique_ptr<File> createUndefinedSymbolFile() const;
232 std::unique_ptr<File> createUndefinedSymbolFile(StringRef filename) const;
234 StringRef _outputPath;
235 StringRef _entrySymbolName;
236 bool _deadStrip = false;
237 bool _globalsAreDeadStripRoots = false;
238 bool _printRemainingUndefines = true;
239 bool _allowRemainingUndefines = false;
240 bool _logInputFiles = false;
241 bool _allowShlibUndefines = false;
242 std::vector<StringRef> _deadStripRoots;
243 std::vector<const char *> _llvmOptions;
244 StringRefVector _initialUndefinedSymbols;
245 std::vector<std::unique_ptr<Node>> _nodes;
246 mutable llvm::BumpPtrAllocator _allocator;
247 mutable uint64_t _nextOrdinal = 0;
251 /// Validate the subclass bits. Only called by validate.
252 virtual bool validateImpl() = 0;
255 } // end namespace lld
257 #endif // LLD_CORE_LINKING_CONTEXT_H