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6d03d481 ST |
1 | // gc.h -- garbage collection of unused sections |
2 | ||
3 | // Copyright 2009 Free Software Foundation, Inc. | |
4 | // Written by Sriraman Tallam <tmsriram@google.com>. | |
5 | ||
6 | // This file is part of gold. | |
7 | ||
8 | // This program is free software; you can redistribute it and/or modify | |
9 | // it under the terms of the GNU General Public License as published by | |
10 | // the Free Software Foundation; either version 3 of the License, or | |
11 | // (at your option) any later version. | |
12 | ||
13 | // This program is distributed in the hope that it will be useful, | |
14 | // but WITHOUT ANY WARRANTY; without even the implied warranty of | |
15 | // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
16 | // GNU General Public License for more details. | |
17 | ||
18 | // You should have received a copy of the GNU General Public License | |
19 | // along with this program; if not, write to the Free Software | |
20 | // Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston, | |
21 | // MA 02110-1301, USA. | |
22 | ||
23 | #ifndef GOLD_GC_H | |
24 | #define GOLD_GC_H | |
25 | ||
26 | #include <queue> | |
ef15dade | 27 | #include <vector> |
6d03d481 ST |
28 | |
29 | #include "elfcpp.h" | |
30 | #include "symtab.h" | |
f345227a | 31 | #include "icf.h" |
6d03d481 ST |
32 | |
33 | namespace gold | |
34 | { | |
35 | ||
36 | class Object; | |
37 | ||
38 | template<int size, bool big_endian> | |
39 | class Sized_relobj; | |
40 | ||
41 | template<int sh_type, int size, bool big_endian> | |
42 | class Reloc_types; | |
43 | ||
44 | class Output_section; | |
45 | class General_options; | |
46 | class Layout; | |
47 | ||
48 | typedef std::pair<Object *, unsigned int> Section_id; | |
49 | ||
50 | class Garbage_collection | |
51 | { | |
52 | struct Section_id_hash | |
53 | { | |
54 | size_t operator()(const Section_id& loc) const | |
55 | { return reinterpret_cast<uintptr_t>(loc.first) ^ loc.second; } | |
56 | }; | |
57 | ||
ef15dade ST |
58 | public: |
59 | ||
6d03d481 ST |
60 | typedef Unordered_set<Section_id, Section_id_hash> Sections_reachable; |
61 | typedef std::map<Section_id, Sections_reachable> Section_ref; | |
62 | typedef std::queue<Section_id> Worklist_type; | |
63 | ||
ef15dade ST |
64 | Garbage_collection() |
65 | : is_worklist_ready_(false) | |
66 | { } | |
67 | ||
68 | // Accessor methods for the private members. | |
69 | ||
70 | Sections_reachable& | |
71 | referenced_list() | |
72 | { return referenced_list_; } | |
73 | ||
74 | Section_ref& | |
75 | section_reloc_map() | |
76 | { return this->section_reloc_map_; } | |
77 | ||
78 | Worklist_type& | |
79 | worklist() | |
80 | { return this->work_list_; } | |
81 | ||
82 | bool | |
83 | is_worklist_ready() | |
84 | { return this->is_worklist_ready_; } | |
85 | ||
86 | void | |
87 | worklist_ready() | |
88 | { this->is_worklist_ready_ = true; } | |
89 | ||
90 | void | |
91 | do_transitive_closure(); | |
92 | ||
93 | bool | |
94 | is_section_garbage(Object* obj, unsigned int shndx) | |
95 | { return (this->referenced_list().find(Section_id(obj, shndx)) | |
96 | == this->referenced_list().end()); } | |
97 | private: | |
98 | ||
99 | Worklist_type work_list_; | |
100 | bool is_worklist_ready_; | |
101 | Section_ref section_reloc_map_; | |
102 | Sections_reachable referenced_list_; | |
6d03d481 ST |
103 | }; |
104 | ||
105 | // Data to pass between successive invocations of do_layout | |
106 | // in object.cc while garbage collecting. This data structure | |
107 | // is filled by using the data from Read_symbols_data. | |
108 | ||
109 | struct Symbols_data | |
110 | { | |
111 | // Section headers. | |
112 | unsigned char* section_headers_data; | |
113 | // Section names. | |
114 | unsigned char* section_names_data; | |
115 | // Size of section name data in bytes. | |
116 | section_size_type section_names_size; | |
117 | // Symbol data. | |
118 | unsigned char* symbols_data; | |
119 | // Size of symbol data in bytes. | |
120 | section_size_type symbols_size; | |
121 | // Offset of external symbols within symbol data. This structure | |
122 | // sometimes contains only external symbols, in which case this will | |
123 | // be zero. Sometimes it contains all symbols. | |
124 | section_offset_type external_symbols_offset; | |
125 | // Symbol names. | |
126 | unsigned char* symbol_names_data; | |
127 | // Size of symbol name data in bytes. | |
128 | section_size_type symbol_names_size; | |
129 | }; | |
130 | ||
ef15dade ST |
131 | // This function implements the generic part of reloc |
132 | // processing to map a section to all the sections it | |
133 | // references through relocs. It is called only during | |
134 | // garbage collection (--gc-sections) and identical code | |
135 | // folding (--icf). | |
6d03d481 ST |
136 | |
137 | template<int size, bool big_endian, typename Target_type, int sh_type, | |
138 | typename Scan> | |
139 | inline void | |
140 | gc_process_relocs( | |
141 | const General_options& , | |
142 | Symbol_table* symtab, | |
143 | Layout*, | |
144 | Target_type* , | |
ef15dade ST |
145 | Sized_relobj<size, big_endian>* src_obj, |
146 | unsigned int src_indx, | |
6d03d481 ST |
147 | const unsigned char* prelocs, |
148 | size_t reloc_count, | |
149 | Output_section*, | |
150 | bool , | |
151 | size_t local_count, | |
152 | const unsigned char* plocal_syms) | |
153 | { | |
ef15dade ST |
154 | Object *dst_obj; |
155 | unsigned int dst_indx; | |
6d03d481 | 156 | |
6d03d481 ST |
157 | typedef typename Reloc_types<sh_type, size, big_endian>::Reloc Reltype; |
158 | const int reloc_size = Reloc_types<sh_type, size, big_endian>::reloc_size; | |
159 | const int sym_size = elfcpp::Elf_sizes<size>::sym_size; | |
160 | ||
ef15dade ST |
161 | std::vector<Section_id>* secvec = NULL; |
162 | std::vector<Symbol*>* symvec = NULL; | |
163 | std::vector<std::pair<long long, long long> >* addendvec = NULL; | |
164 | bool is_icf_tracked = false; | |
165 | ||
032ce4e9 | 166 | if (parameters->options().icf_enabled() |
ef15dade ST |
167 | && is_prefix_of(".text.", (src_obj)->section_name(src_indx).c_str())) |
168 | { | |
169 | is_icf_tracked = true; | |
170 | Section_id src_id(src_obj, src_indx); | |
171 | secvec = &symtab->icf()->section_reloc_list()[src_id]; | |
172 | symvec = &symtab->icf()->symbol_reloc_list()[src_id]; | |
173 | addendvec = &symtab->icf()->addend_reloc_list()[src_id]; | |
174 | } | |
175 | ||
6d03d481 ST |
176 | for (size_t i = 0; i < reloc_count; ++i, prelocs += reloc_size) |
177 | { | |
178 | Reltype reloc(prelocs); | |
179 | typename elfcpp::Elf_types<size>::Elf_WXword r_info = reloc.get_r_info(); | |
180 | unsigned int r_sym = elfcpp::elf_r_sym<size>(r_info); | |
ef15dade ST |
181 | typename elfcpp::Elf_types<size>::Elf_Swxword addend = |
182 | Reloc_types<sh_type, size, big_endian>::get_reloc_addend_noerror(&reloc); | |
183 | ||
6d03d481 ST |
184 | if (r_sym < local_count) |
185 | { | |
186 | gold_assert(plocal_syms != NULL); | |
187 | typename elfcpp::Sym<size, big_endian> lsym(plocal_syms | |
188 | + r_sym * sym_size); | |
189 | unsigned int shndx = lsym.get_st_shndx(); | |
190 | bool is_ordinary; | |
ef15dade ST |
191 | shndx = src_obj->adjust_sym_shndx(r_sym, shndx, &is_ordinary); |
192 | if (!is_ordinary) | |
6d03d481 ST |
193 | continue; |
194 | dst_obj = src_obj; | |
6d03d481 | 195 | dst_indx = shndx; |
ef15dade ST |
196 | Section_id dst_id(dst_obj, dst_indx); |
197 | if (is_icf_tracked) | |
198 | { | |
199 | (*secvec).push_back(dst_id); | |
200 | (*symvec).push_back(NULL); | |
201 | long long symvalue = static_cast<long long>(lsym.get_st_value()); | |
202 | (*addendvec).push_back(std::make_pair(symvalue, | |
203 | static_cast<long long>(addend))); | |
204 | } | |
205 | if (shndx == src_indx) | |
206 | continue; | |
6d03d481 ST |
207 | } |
208 | else | |
209 | { | |
ef15dade | 210 | Symbol* gsym = src_obj->global_symbol(r_sym); |
6d03d481 ST |
211 | gold_assert(gsym != NULL); |
212 | if (gsym->is_forwarder()) | |
213 | gsym = symtab->resolve_forwards(gsym); | |
214 | if (gsym->source() != Symbol::FROM_OBJECT) | |
215 | continue; | |
216 | bool is_ordinary; | |
217 | dst_obj = gsym->object(); | |
218 | dst_indx = gsym->shndx(&is_ordinary); | |
219 | if (!is_ordinary) | |
220 | continue; | |
ef15dade ST |
221 | Section_id dst_id(dst_obj, dst_indx); |
222 | if (is_icf_tracked) | |
223 | { | |
224 | (*secvec).push_back(dst_id); | |
225 | (*symvec).push_back(gsym); | |
226 | Sized_symbol<size>* sized_gsym = | |
227 | static_cast<Sized_symbol<size>* >(gsym); | |
228 | long long symvalue = | |
229 | static_cast<long long>(sized_gsym->value()); | |
230 | (*addendvec).push_back(std::make_pair(symvalue, | |
231 | static_cast<long long>(addend))); | |
232 | } | |
6d03d481 | 233 | } |
ef15dade | 234 | if (parameters->options().gc_sections()) |
6d03d481 | 235 | { |
ef15dade ST |
236 | Section_id src_id(src_obj, src_indx); |
237 | Section_id dst_id(dst_obj, dst_indx); | |
238 | Garbage_collection::Section_ref::iterator map_it; | |
239 | map_it = symtab->gc()->section_reloc_map().find(src_id); | |
240 | if (map_it == symtab->gc()->section_reloc_map().end()) | |
241 | { | |
242 | symtab->gc()->section_reloc_map()[src_id].insert(dst_id); | |
243 | } | |
244 | else | |
245 | { | |
246 | Garbage_collection::Sections_reachable& v(map_it->second); | |
247 | v.insert(dst_id); | |
248 | } | |
6d03d481 ST |
249 | } |
250 | } | |
251 | return; | |
252 | } | |
253 | ||
254 | } // End of namespace gold. | |
255 | ||
256 | #endif |