1 // layout.h -- lay out output file sections for gold -*- C++ -*-
12 #include "workqueue.h"
14 #include "stringpool.h"
22 // This Task handles mapping the input sections to output sections and
23 // laying them out in memory.
25 class Layout_task : public Task
28 // OPTIONS is the command line options, INPUT_OBJECTS is the list of
29 // input objects, THIS_BLOCKER is a token which blocks this task
30 // from executing until all the input symbols have been read.
31 Layout_task(const General_options& options, const Object_list* input_objects,
32 Task_token* this_blocker)
33 : options_(options), input_objects_(input_objects),
34 this_blocker_(this_blocker)
39 // The standard Task methods.
42 is_runnable(Workqueue*);
51 Layout_task(const Layout_task&);
52 Layout_task& operator=(const Layout_task&);
54 const General_options& options_;
55 const Object_list* input_objects_;
56 Task_token* this_blocker_;
59 // This class handles the details of laying out input sections.
64 Layout(const General_options& options)
65 : options_(options), namepool_(), signatures_(),
66 section_name_map_(), segment_list_()
69 // Given an input section named NAME with data in SHDR from the
70 // object file OBJECT, return the output section where this input
71 // section should go. Set *OFFSET to the offset within the output
73 template<int size, bool big_endian>
75 layout(Object *object, const char* name,
76 const elfcpp::Shdr<size, big_endian>& shdr, off_t* offset);
78 // Return whether a section is a .gnu.linkonce section, given the
81 is_linkonce(const char* name)
82 { return strncmp(name, ".gnu.linkonce", sizeof(".gnu.linkonce") - 1) == 0; }
84 // Record the signature of a comdat section, and return whether to
85 // include it in the link. The GROUP parameter is true for a
86 // section group signature, false for a signature derived from a
87 // .gnu.linkonce section.
89 add_comdat(const char*, bool group);
92 Layout(const Layout&);
93 Layout& operator=(const Layout&);
95 // Mapping from .gnu.linkonce section names to output section names.
96 struct Linkonce_mapping
102 static const Linkonce_mapping linkonce_mapping[];
103 static const int linkonce_mapping_count;
105 // Return whether to include this section in the link.
106 template<int size, bool big_endian>
108 include_section(Object* object, const char* name,
109 const elfcpp::Shdr<size, big_endian>&);
111 // Return the output section name to use for a linkonce section
114 linkonce_output_name(const char* name);
116 // Create a new Output_section.
118 make_output_section(const char* name, elfcpp::Elf_Word type,
119 elfcpp::Elf_Xword flags);
121 // Return whether SEG1 comes before SEG2 in the output file.
123 Layout::segment_precedes(const Output_segment* seg1,
124 const Output_segment* seg2);
126 // Map from section flags to segment flags.
127 static elfcpp::Elf_Word
128 section_flags_to_segment(elfcpp::Elf_Xword flags);
130 // A mapping used for group signatures.
131 typedef Unordered_map<std::string, bool> Signatures;
133 // Mapping from input section name/type/flags to output section. We
134 // use canonicalized strings here.
136 typedef std::pair<const char*,
137 std::pair<elfcpp::Elf_Word, elfcpp::Elf_Xword> > Key;
142 operator()(const Key& k) const;
145 typedef Unordered_map<Key, Output_section*, Hash_key> Section_name_map;
147 // A comparison class for segments.
149 struct Compare_segments
152 operator()(const Output_segment* seg1, const Output_segment* seg2)
153 { return Layout::segment_precedes(seg1, seg2); }
156 // The list of segments.
158 typedef std::list<Output_segment*> Segment_list;
160 // The list of sections not attached to a segment.
162 typedef std::list<Output_section*> Section_list;
164 // A reference to the options on the command line.
165 const General_options& options_;
166 // The output section names.
167 Stringpool namepool_;
168 // The list of group sections and linkonce sections which we have seen.
169 Signatures signatures_;
170 // The mapping from input section name/type/flags to output sections.
171 Section_name_map section_name_map_;
172 // The list of output segments.
173 Segment_list segment_list_;
174 // The list of output sections which are not attached to any output
176 Section_list section_list_;
179 } // End namespace gold.
181 #endif // !defined(GOLD_LAYOUT_H)