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a2fb1b05 ILT |
1 | // layout.h -- lay out output file sections for gold -*- C++ -*- |
2 | ||
3 | #ifndef GOLD_LAYOUT_H | |
4 | #define GOLD_LAYOUT_H | |
5 | ||
6 | #include <list> | |
7 | #include <string> | |
8 | #include <utility> | |
9 | #include <vector> | |
10 | ||
11 | #include "options.h" | |
12 | #include "workqueue.h" | |
13 | #include "object.h" | |
14 | #include "stringpool.h" | |
15 | ||
16 | namespace gold | |
17 | { | |
18 | ||
19 | class Output_section; | |
20 | class Output_segment; | |
21 | ||
22 | // This Task handles mapping the input sections to output sections and | |
23 | // laying them out in memory. | |
24 | ||
25 | class Layout_task : public Task | |
26 | { | |
27 | public: | |
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) | |
35 | { } | |
36 | ||
37 | ~Layout_task(); | |
38 | ||
39 | // The standard Task methods. | |
40 | ||
41 | Is_runnable_type | |
42 | is_runnable(Workqueue*); | |
43 | ||
44 | Task_locker* | |
45 | locks(Workqueue*); | |
46 | ||
47 | void | |
48 | run(Workqueue*); | |
49 | ||
50 | private: | |
51 | Layout_task(const Layout_task&); | |
52 | Layout_task& operator=(const Layout_task&); | |
53 | ||
54 | const General_options& options_; | |
55 | const Object_list* input_objects_; | |
56 | Task_token* this_blocker_; | |
57 | }; | |
58 | ||
59 | // This class handles the details of laying out input sections. | |
60 | ||
61 | class Layout | |
62 | { | |
63 | public: | |
64 | Layout(const General_options& options) | |
65 | : options_(options), namepool_(), signatures_(), | |
66 | section_name_map_(), segment_list_() | |
67 | { } | |
68 | ||
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 | |
72 | // section. | |
73 | template<int size, bool big_endian> | |
74 | Output_section* | |
75 | layout(Object *object, const char* name, | |
76 | const elfcpp::Shdr<size, big_endian>& shdr, off_t* offset); | |
77 | ||
78 | // Return whether a section is a .gnu.linkonce section, given the | |
79 | // section name. | |
80 | static inline bool | |
81 | is_linkonce(const char* name) | |
82 | { return strncmp(name, ".gnu.linkonce", sizeof(".gnu.linkonce") - 1) == 0; } | |
83 | ||
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. | |
88 | bool | |
89 | add_comdat(const char*, bool group); | |
90 | ||
91 | private: | |
92 | Layout(const Layout&); | |
93 | Layout& operator=(const Layout&); | |
94 | ||
95 | // Mapping from .gnu.linkonce section names to output section names. | |
96 | struct Linkonce_mapping | |
97 | { | |
98 | const char* from; | |
99 | int fromlen; | |
100 | const char* to; | |
101 | }; | |
102 | static const Linkonce_mapping linkonce_mapping[]; | |
103 | static const int linkonce_mapping_count; | |
104 | ||
105 | // Return whether to include this section in the link. | |
106 | template<int size, bool big_endian> | |
107 | bool | |
108 | include_section(Object* object, const char* name, | |
109 | const elfcpp::Shdr<size, big_endian>&); | |
110 | ||
111 | // Return the output section name to use for a linkonce section | |
112 | // name. | |
113 | static const char* | |
114 | linkonce_output_name(const char* name); | |
115 | ||
116 | // Create a new Output_section. | |
117 | Output_section* | |
118 | make_output_section(const char* name, elfcpp::Elf_Word type, | |
119 | elfcpp::Elf_Xword flags); | |
120 | ||
121 | // Return whether SEG1 comes before SEG2 in the output file. | |
122 | static bool | |
123 | Layout::segment_precedes(const Output_segment* seg1, | |
124 | const Output_segment* seg2); | |
125 | ||
126 | // Map from section flags to segment flags. | |
127 | static elfcpp::Elf_Word | |
128 | section_flags_to_segment(elfcpp::Elf_Xword flags); | |
129 | ||
130 | // A mapping used for group signatures. | |
131 | typedef Unordered_map<std::string, bool> Signatures; | |
132 | ||
133 | // Mapping from input section name/type/flags to output section. We | |
134 | // use canonicalized strings here. | |
135 | ||
136 | typedef std::pair<const char*, | |
137 | std::pair<elfcpp::Elf_Word, elfcpp::Elf_Xword> > Key; | |
138 | ||
139 | struct Hash_key | |
140 | { | |
141 | size_t | |
142 | operator()(const Key& k) const; | |
143 | }; | |
144 | ||
145 | typedef Unordered_map<Key, Output_section*, Hash_key> Section_name_map; | |
146 | ||
147 | // A comparison class for segments. | |
148 | ||
149 | struct Compare_segments | |
150 | { | |
151 | bool | |
152 | operator()(const Output_segment* seg1, const Output_segment* seg2) | |
153 | { return Layout::segment_precedes(seg1, seg2); } | |
154 | }; | |
155 | ||
156 | // The list of segments. | |
157 | ||
158 | typedef std::list<Output_segment*> Segment_list; | |
159 | ||
160 | // The list of sections not attached to a segment. | |
161 | ||
162 | typedef std::list<Output_section*> Section_list; | |
163 | ||
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 | |
175 | // segment. | |
176 | Section_list section_list_; | |
177 | }; | |
178 | ||
179 | } // End namespace gold. | |
180 | ||
181 | #endif // !defined(GOLD_LAYOUT_H) |