1 // layout.h -- lay out output file sections for gold -*- C++ -*-
12 #include "workqueue.h"
14 #include "stringpool.h"
22 class Output_section_symtab;
23 class Output_section_headers;
28 // This Task handles mapping the input sections to output sections and
29 // laying them out in memory.
31 class Layout_task : public Task
34 // OPTIONS is the command line options, INPUT_OBJECTS is the list of
35 // input objects, THIS_BLOCKER is a token which blocks this task
36 // from executing until all the input symbols have been read.
37 Layout_task(const General_options& options,
38 const Input_objects* input_objects,
41 Task_token* this_blocker)
42 : options_(options), input_objects_(input_objects), symtab_(symtab),
43 layout_(layout), this_blocker_(this_blocker)
48 // The standard Task methods.
51 is_runnable(Workqueue*);
60 Layout_task(const Layout_task&);
61 Layout_task& operator=(const Layout_task&);
63 const General_options& options_;
64 const Input_objects* input_objects_;
65 Symbol_table* symtab_;
67 Task_token* this_blocker_;
70 // This class handles the details of laying out input sections.
75 Layout(const General_options& options);
77 // Given an input section named NAME with data in SHDR from the
78 // object file OBJECT, return the output section where this input
79 // section should go. Set *OFFSET to the offset within the output
81 template<int size, bool big_endian>
83 layout(Object *object, const char* name,
84 const elfcpp::Shdr<size, big_endian>& shdr, off_t* offset);
86 // Return the Stringpool used for symbol names.
89 { return &this->sympool_; }
91 // Return whether a section is a .gnu.linkonce section, given the
94 is_linkonce(const char* name)
95 { return strncmp(name, ".gnu.linkonce", sizeof(".gnu.linkonce") - 1) == 0; }
97 // Record the signature of a comdat section, and return whether to
98 // include it in the link. The GROUP parameter is true for a
99 // section group signature, false for a signature derived from a
100 // .gnu.linkonce section.
102 add_comdat(const char*, bool group);
104 // Finalize the layout after all the input sections have been added.
106 finalize(const Input_objects*, Symbol_table*);
108 // Write out data not associated with an input file or the symbol
111 write_data(Output_file*) const;
113 // The list of segments.
115 typedef std::vector<Output_segment*> Segment_list;
117 // The list of sections not attached to a segment.
119 typedef std::list<Output_section*> Section_list;
121 // The list of information to write out which is not attached to
122 // either a section or a segment.
123 typedef std::list<Output_data*> Data_list;
126 Layout(const Layout&);
127 Layout& operator=(const Layout&);
129 // Mapping from .gnu.linkonce section names to output section names.
130 struct Linkonce_mapping
136 static const Linkonce_mapping linkonce_mapping[];
137 static const int linkonce_mapping_count;
139 // Find the first read-only PT_LOAD segment, creating one if
142 find_first_load_seg();
144 // Set the final file offsets of all the segments.
146 set_segment_offsets(const Target*, Output_segment*);
148 // Set the final file offsets of all the sections not associated
151 set_section_offsets(off_t);
153 // Create the output sections for the symbol table.
155 create_symtab_sections(int size, const Input_objects*, Symbol_table*, off_t*,
156 Output_section** osymtab,
157 Output_section** ostrtab);
159 // Create the .shstrtab section.
163 // Create the section header table.
164 Output_section_headers*
165 create_shdrs(int size, bool big_endian, off_t*);
167 // Return whether to include this section in the link.
168 template<int size, bool big_endian>
170 include_section(Object* object, const char* name,
171 const elfcpp::Shdr<size, big_endian>&);
173 // Return the output section name to use for a linkonce section
176 linkonce_output_name(const char* name);
178 // Create a new Output_section.
180 make_output_section(const char* name, elfcpp::Elf_Word type,
181 elfcpp::Elf_Xword flags);
183 // Return whether SEG1 comes before SEG2 in the output file.
185 segment_precedes(const Output_segment* seg1, const Output_segment* seg2);
187 // Map from section flags to segment flags.
188 static elfcpp::Elf_Word
189 section_flags_to_segment(elfcpp::Elf_Xword flags);
191 // A mapping used for group signatures.
192 typedef Unordered_map<std::string, bool> Signatures;
194 // Mapping from input section name/type/flags to output section. We
195 // use canonicalized strings here.
197 typedef std::pair<const char*,
198 std::pair<elfcpp::Elf_Word, elfcpp::Elf_Xword> > Key;
203 operator()(const Key& k) const;
206 typedef Unordered_map<Key, Output_section*, Hash_key> Section_name_map;
208 // A comparison class for segments.
210 struct Compare_segments
213 operator()(const Output_segment* seg1, const Output_segment* seg2)
214 { return Layout::segment_precedes(seg1, seg2); }
217 // A reference to the options on the command line.
218 const General_options& options_;
219 // The index of the last output section.
220 unsigned int last_shndx_;
221 // The output section names.
222 Stringpool namepool_;
223 // The output symbol names.
225 // The list of group sections and linkonce sections which we have seen.
226 Signatures signatures_;
227 // The mapping from input section name/type/flags to output sections.
228 Section_name_map section_name_map_;
229 // The list of output segments.
230 Segment_list segment_list_;
231 // The list of output sections which are not attached to any output
233 Section_list section_list_;
234 // The list of sections which require special output because they
235 // are not comprised of input sections.
236 Data_list special_output_list_;
239 // This task handles writing out data which is not part of a section
242 class Write_data_task : public Task
245 Write_data_task(const Layout* layout, Output_file* of,
246 Task_token* final_blocker)
247 : layout_(layout), of_(of), final_blocker_(final_blocker)
250 // The standard Task methods.
253 is_runnable(Workqueue*);
262 const Layout* layout_;
264 Task_token* final_blocker_;
267 // This task handles writing out the global symbols.
269 class Write_symbols_task : public Task
272 Write_symbols_task(const Symbol_table* symtab, const Target* target,
273 const Stringpool* sympool, Output_file* of,
274 Task_token* final_blocker)
275 : symtab_(symtab), target_(target), sympool_(sympool), of_(of),
276 final_blocker_(final_blocker)
279 // The standard Task methods.
282 is_runnable(Workqueue*);
291 const Symbol_table* symtab_;
292 const Target* target_;
293 const Stringpool* sympool_;
295 Task_token* final_blocker_;
298 // This task handles closing the file.
300 class Close_task : public Task
303 Close_task(Output_file* of, Task_token* final_blocker)
304 : of_(of), final_blocker_(final_blocker)
307 // The standard task methods.
310 is_runnable(Workqueue*);
320 Task_token* final_blocker_;
323 } // End namespace gold.
325 #endif // !defined(GOLD_LAYOUT_H)