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ead1e424 ILT |
1 | // common.cc -- handle common symbols for gold |
2 | ||
1f3212db ILT |
3 | // Copyright 2006, 2007, 2008, 2009, 2010, 2011, 2012 |
4 | // Free Software Foundation, Inc. | |
6cb15b7f ILT |
5 | // Written by Ian Lance Taylor <iant@google.com>. |
6 | ||
7 | // This file is part of gold. | |
8 | ||
9 | // This program is free software; you can redistribute it and/or modify | |
10 | // it under the terms of the GNU General Public License as published by | |
11 | // the Free Software Foundation; either version 3 of the License, or | |
12 | // (at your option) any later version. | |
13 | ||
14 | // This program is distributed in the hope that it will be useful, | |
15 | // but WITHOUT ANY WARRANTY; without even the implied warranty of | |
16 | // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
17 | // GNU General Public License for more details. | |
18 | ||
19 | // You should have received a copy of the GNU General Public License | |
20 | // along with this program; if not, write to the Free Software | |
21 | // Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston, | |
22 | // MA 02110-1301, USA. | |
23 | ||
ead1e424 ILT |
24 | #include "gold.h" |
25 | ||
26 | #include <algorithm> | |
27 | ||
28 | #include "workqueue.h" | |
7d9e3d98 | 29 | #include "mapfile.h" |
ead1e424 ILT |
30 | #include "layout.h" |
31 | #include "output.h" | |
f6ce93d6 | 32 | #include "symtab.h" |
ead1e424 ILT |
33 | #include "common.h" |
34 | ||
35 | namespace gold | |
36 | { | |
37 | ||
38 | // Allocate_commons_task methods. | |
39 | ||
93ceb764 ILT |
40 | // This task allocates the common symbols. We arrange to run it |
41 | // before anything else which needs to access the symbol table. | |
ead1e424 | 42 | |
17a1d0a9 ILT |
43 | Task_token* |
44 | Allocate_commons_task::is_runnable() | |
ead1e424 | 45 | { |
17a1d0a9 | 46 | return NULL; |
ead1e424 ILT |
47 | } |
48 | ||
93ceb764 | 49 | // Release a blocker. |
ead1e424 | 50 | |
17a1d0a9 ILT |
51 | void |
52 | Allocate_commons_task::locks(Task_locker* tl) | |
ead1e424 | 53 | { |
17a1d0a9 | 54 | tl->add(this, this->blocker_); |
ead1e424 ILT |
55 | } |
56 | ||
57 | // Allocate the common symbols. | |
58 | ||
59 | void | |
60 | Allocate_commons_task::run(Workqueue*) | |
61 | { | |
7d9e3d98 | 62 | this->symtab_->allocate_commons(this->layout_, this->mapfile_); |
ead1e424 ILT |
63 | } |
64 | ||
fc59c572 ILT |
65 | // This class is used to sort the common symbol. We normally put the |
66 | // larger common symbols first. This can be changed by using | |
67 | // --sort-commons, which tells the linker to sort by alignment. | |
ead1e424 ILT |
68 | |
69 | template<int size> | |
70 | class Sort_commons | |
71 | { | |
72 | public: | |
fc59c572 ILT |
73 | Sort_commons(const Symbol_table* symtab, |
74 | Symbol_table::Sort_commons_order sort_order) | |
75 | : symtab_(symtab), sort_order_(sort_order) | |
ead1e424 ILT |
76 | { } |
77 | ||
78 | bool operator()(const Symbol* a, const Symbol* b) const; | |
79 | ||
80 | private: | |
fc59c572 | 81 | // The symbol table. |
ead1e424 | 82 | const Symbol_table* symtab_; |
fc59c572 ILT |
83 | // How to sort. |
84 | Symbol_table::Sort_commons_order sort_order_; | |
ead1e424 ILT |
85 | }; |
86 | ||
87 | template<int size> | |
88 | bool | |
89 | Sort_commons<size>::operator()(const Symbol* pa, const Symbol* pb) const | |
90 | { | |
91 | if (pa == NULL) | |
55455f89 | 92 | return false; |
ead1e424 ILT |
93 | if (pb == NULL) |
94 | return true; | |
95 | ||
96 | const Symbol_table* symtab = this->symtab_; | |
7d1a9ebb ILT |
97 | const Sized_symbol<size>* psa = symtab->get_sized_symbol<size>(pa); |
98 | const Sized_symbol<size>* psb = symtab->get_sized_symbol<size>(pb); | |
ead1e424 | 99 | |
fc59c572 | 100 | // The size. |
ead1e424 ILT |
101 | typename Sized_symbol<size>::Size_type sa = psa->symsize(); |
102 | typename Sized_symbol<size>::Size_type sb = psb->symsize(); | |
fc59c572 ILT |
103 | |
104 | // The alignment. | |
105 | typename Sized_symbol<size>::Value_type aa = psa->value(); | |
106 | typename Sized_symbol<size>::Value_type ab = psb->value(); | |
107 | ||
108 | if (this->sort_order_ == Symbol_table::SORT_COMMONS_BY_ALIGNMENT_DESCENDING) | |
109 | { | |
110 | if (aa < ab) | |
111 | return false; | |
112 | else if (ab < aa) | |
113 | return true; | |
114 | } | |
115 | else if (this->sort_order_ | |
116 | == Symbol_table::SORT_COMMONS_BY_ALIGNMENT_ASCENDING) | |
117 | { | |
118 | if (aa < ab) | |
119 | return true; | |
120 | else if (ab < aa) | |
121 | return false; | |
122 | } | |
123 | else | |
124 | gold_assert(this->sort_order_ | |
125 | == Symbol_table::SORT_COMMONS_BY_SIZE_DESCENDING); | |
126 | ||
127 | // Sort by descending size. | |
ead1e424 ILT |
128 | if (sa < sb) |
129 | return false; | |
49bdd526 | 130 | else if (sb < sa) |
ead1e424 ILT |
131 | return true; |
132 | ||
fc59c572 ILT |
133 | if (this->sort_order_ == Symbol_table::SORT_COMMONS_BY_SIZE_DESCENDING) |
134 | { | |
135 | // When the symbols are the same size, we sort them by | |
136 | // alignment, largest alignment first. | |
137 | if (aa < ab) | |
138 | return false; | |
139 | else if (ab < aa) | |
140 | return true; | |
141 | } | |
ead1e424 ILT |
142 | |
143 | // Otherwise we stabilize the sort by sorting by name. | |
144 | return strcmp(psa->name(), psb->name()) < 0; | |
145 | } | |
146 | ||
147 | // Allocate the common symbols. | |
148 | ||
149 | void | |
7d9e3d98 | 150 | Symbol_table::allocate_commons(Layout* layout, Mapfile* mapfile) |
ead1e424 | 151 | { |
fc59c572 ILT |
152 | Sort_commons_order sort_order; |
153 | if (!parameters->options().user_set_sort_common()) | |
154 | sort_order = SORT_COMMONS_BY_SIZE_DESCENDING; | |
155 | else | |
156 | { | |
157 | const char* order = parameters->options().sort_common(); | |
158 | if (*order == '\0' || strcmp(order, "descending") == 0) | |
159 | sort_order = SORT_COMMONS_BY_ALIGNMENT_DESCENDING; | |
160 | else if (strcmp(order, "ascending") == 0) | |
161 | sort_order = SORT_COMMONS_BY_ALIGNMENT_ASCENDING; | |
162 | else | |
163 | { | |
164 | gold_error("invalid --sort-common argument: %s", order); | |
165 | sort_order = SORT_COMMONS_BY_SIZE_DESCENDING; | |
166 | } | |
167 | } | |
168 | ||
8851ecca | 169 | if (parameters->target().get_size() == 32) |
8ae3da90 ILT |
170 | { |
171 | #if defined(HAVE_TARGET_32_LITTLE) || defined(HAVE_TARGET_32_BIG) | |
fc59c572 | 172 | this->do_allocate_commons<32>(layout, mapfile, sort_order); |
8ae3da90 ILT |
173 | #else |
174 | gold_unreachable(); | |
175 | #endif | |
176 | } | |
8851ecca | 177 | else if (parameters->target().get_size() == 64) |
8ae3da90 ILT |
178 | { |
179 | #if defined(HAVE_TARGET_64_LITTLE) || defined(HAVE_TARGET_64_BIG) | |
fc59c572 | 180 | this->do_allocate_commons<64>(layout, mapfile, sort_order); |
8ae3da90 ILT |
181 | #else |
182 | gold_unreachable(); | |
183 | #endif | |
184 | } | |
ead1e424 | 185 | else |
a3ad94ed | 186 | gold_unreachable(); |
ead1e424 ILT |
187 | } |
188 | ||
189 | // Allocated the common symbols, sized version. | |
190 | ||
191 | template<int size> | |
192 | void | |
fc59c572 ILT |
193 | Symbol_table::do_allocate_commons(Layout* layout, Mapfile* mapfile, |
194 | Sort_commons_order sort_order) | |
155a0dd7 | 195 | { |
8a5e3e08 ILT |
196 | if (!this->commons_.empty()) |
197 | this->do_allocate_commons_list<size>(layout, COMMONS_NORMAL, | |
fc59c572 ILT |
198 | &this->commons_, mapfile, |
199 | sort_order); | |
8a5e3e08 ILT |
200 | if (!this->tls_commons_.empty()) |
201 | this->do_allocate_commons_list<size>(layout, COMMONS_TLS, | |
fc59c572 ILT |
202 | &this->tls_commons_, mapfile, |
203 | sort_order); | |
8a5e3e08 ILT |
204 | if (!this->small_commons_.empty()) |
205 | this->do_allocate_commons_list<size>(layout, COMMONS_SMALL, | |
fc59c572 ILT |
206 | &this->small_commons_, mapfile, |
207 | sort_order); | |
8a5e3e08 ILT |
208 | if (!this->large_commons_.empty()) |
209 | this->do_allocate_commons_list<size>(layout, COMMONS_LARGE, | |
fc59c572 ILT |
210 | &this->large_commons_, mapfile, |
211 | sort_order); | |
155a0dd7 ILT |
212 | } |
213 | ||
214 | // Allocate the common symbols in a list. IS_TLS indicates whether | |
215 | // these are TLS common symbols. | |
216 | ||
217 | template<int size> | |
218 | void | |
8a5e3e08 ILT |
219 | Symbol_table::do_allocate_commons_list( |
220 | Layout* layout, | |
221 | Commons_section_type commons_section_type, | |
222 | Commons_type* commons, | |
fc59c572 ILT |
223 | Mapfile* mapfile, |
224 | Sort_commons_order sort_order) | |
ead1e424 | 225 | { |
ead1e424 ILT |
226 | // We've kept a list of all the common symbols. But the symbol may |
227 | // have been resolved to a defined symbol by now. And it may be a | |
228 | // forwarder. First remove all non-common symbols. | |
229 | bool any = false; | |
230 | uint64_t addralign = 0; | |
155a0dd7 ILT |
231 | for (Commons_type::iterator p = commons->begin(); |
232 | p != commons->end(); | |
ead1e424 ILT |
233 | ++p) |
234 | { | |
235 | Symbol* sym = *p; | |
236 | if (sym->is_forwarder()) | |
237 | { | |
238 | sym = this->resolve_forwards(sym); | |
239 | *p = sym; | |
240 | } | |
241 | if (!sym->is_common()) | |
242 | *p = NULL; | |
243 | else | |
244 | { | |
245 | any = true; | |
7d1a9ebb | 246 | Sized_symbol<size>* ssym = this->get_sized_symbol<size>(sym); |
ead1e424 ILT |
247 | if (ssym->value() > addralign) |
248 | addralign = ssym->value(); | |
249 | } | |
250 | } | |
251 | if (!any) | |
252 | return; | |
253 | ||
fc59c572 | 254 | // Sort the common symbols. |
155a0dd7 | 255 | std::sort(commons->begin(), commons->end(), |
fc59c572 | 256 | Sort_commons<size>(this, sort_order)); |
ead1e424 | 257 | |
155a0dd7 | 258 | // Place them in a newly allocated BSS section. |
155a0dd7 | 259 | elfcpp::Elf_Xword flags = elfcpp::SHF_WRITE | elfcpp::SHF_ALLOC; |
8a5e3e08 ILT |
260 | const char* name; |
261 | const char* ds_name; | |
262 | switch (commons_section_type) | |
155a0dd7 | 263 | { |
8a5e3e08 ILT |
264 | case COMMONS_NORMAL: |
265 | name = ".bss"; | |
266 | ds_name = "** common"; | |
267 | break; | |
268 | case COMMONS_TLS: | |
155a0dd7 | 269 | flags |= elfcpp::SHF_TLS; |
8a5e3e08 ILT |
270 | name = ".tbss"; |
271 | ds_name = "** tls common"; | |
272 | break; | |
273 | case COMMONS_SMALL: | |
274 | flags |= parameters->target().small_common_section_flags(); | |
275 | name = ".sbss"; | |
276 | ds_name = "** small common"; | |
277 | break; | |
278 | case COMMONS_LARGE: | |
279 | flags |= parameters->target().large_common_section_flags(); | |
280 | name = ".lbss"; | |
281 | ds_name = "** large common"; | |
282 | break; | |
283 | default: | |
284 | gold_unreachable(); | |
285 | } | |
286 | ||
5146f448 CC |
287 | Output_data_space* poc; |
288 | Output_section* os; | |
289 | ||
290 | if (!parameters->incremental_update()) | |
291 | { | |
292 | poc = new Output_data_space(addralign, ds_name); | |
293 | os = layout->add_output_section_data(name, elfcpp::SHT_NOBITS, flags, | |
294 | poc, ORDER_INVALID, false); | |
295 | } | |
296 | else | |
297 | { | |
298 | // When doing an incremental update, we need to allocate each common | |
299 | // directly from the output section's free list. | |
300 | poc = NULL; | |
301 | os = layout->find_output_section(name); | |
302 | } | |
303 | ||
8a5e3e08 ILT |
304 | if (os != NULL) |
305 | { | |
306 | if (commons_section_type == COMMONS_SMALL) | |
307 | os->set_is_small_section(); | |
308 | else if (commons_section_type == COMMONS_LARGE) | |
309 | os->set_is_large_section(); | |
155a0dd7 | 310 | } |
ead1e424 ILT |
311 | |
312 | // Allocate them all. | |
313 | ||
314 | off_t off = 0; | |
155a0dd7 ILT |
315 | for (Commons_type::iterator p = commons->begin(); |
316 | p != commons->end(); | |
ead1e424 ILT |
317 | ++p) |
318 | { | |
319 | Symbol* sym = *p; | |
320 | if (sym == NULL) | |
321 | break; | |
eda294df ILT |
322 | |
323 | // Because we followed forwarding symbols above, but we didn't | |
324 | // do it reliably before adding symbols to the list, it is | |
325 | // possible for us to have the same symbol on the list twice. | |
326 | // This can happen in the horrible case where a program defines | |
327 | // a common symbol with the same name as a versioned libc | |
328 | // symbol. That will show up here as a symbol which has already | |
329 | // been allocated and is therefore no longer a common symbol. | |
330 | if (!sym->is_common()) | |
331 | continue; | |
332 | ||
7d1a9ebb | 333 | Sized_symbol<size>* ssym = this->get_sized_symbol<size>(sym); |
7d9e3d98 ILT |
334 | |
335 | // Record the symbol in the map file now, before we change its | |
336 | // value. Pass the size in separately so that we don't have to | |
337 | // templatize the map code, which is not performance sensitive. | |
338 | if (mapfile != NULL) | |
339 | mapfile->report_allocate_common(sym, ssym->symsize()); | |
340 | ||
5146f448 CC |
341 | if (poc != NULL) |
342 | { | |
343 | off = align_address(off, ssym->value()); | |
344 | ssym->allocate_common(poc, off); | |
345 | off += ssym->symsize(); | |
346 | } | |
347 | else | |
348 | { | |
349 | // For an incremental update, allocate from the free list. | |
350 | off = os->allocate(ssym->symsize(), ssym->value()); | |
351 | if (off == -1) | |
e6455dfb CC |
352 | gold_fallback(_("out of patch space in section %s; " |
353 | "relink with --incremental-full"), | |
354 | os->name()); | |
5146f448 CC |
355 | ssym->allocate_common(os, off); |
356 | } | |
ead1e424 ILT |
357 | } |
358 | ||
5146f448 CC |
359 | if (poc != NULL) |
360 | poc->set_current_data_size(off); | |
ead1e424 | 361 | |
155a0dd7 | 362 | commons->clear(); |
ead1e424 ILT |
363 | } |
364 | ||
365 | } // End namespace gold. |