2009-06-25 Kai Tietz <kai.tietz@onevision.com>
[binutils.git] / gold / common.cc
blobf90ae40e1b56d826819629d6f84d163210fce20e
1 // common.cc -- handle common symbols for gold
3 // Copyright 2006, 2007, 2008 Free Software Foundation, Inc.
4 // Written by Ian Lance Taylor <iant@google.com>.
6 // This file is part of gold.
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.
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.
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.
23 #include "gold.h"
25 #include <algorithm>
27 #include "workqueue.h"
28 #include "mapfile.h"
29 #include "layout.h"
30 #include "output.h"
31 #include "symtab.h"
32 #include "common.h"
34 namespace gold
37 // Allocate_commons_task methods.
39 // This task allocates the common symbols. We need a lock on the
40 // symbol table.
42 Task_token*
43 Allocate_commons_task::is_runnable()
45 if (!this->symtab_lock_->is_writable())
46 return this->symtab_lock_;
47 return NULL;
50 // Return the locks we hold: one on the symbol table, and one blocker.
52 void
53 Allocate_commons_task::locks(Task_locker* tl)
55 tl->add(this, this->blocker_);
56 tl->add(this, this->symtab_lock_);
59 // Allocate the common symbols.
61 void
62 Allocate_commons_task::run(Workqueue*)
64 this->symtab_->allocate_commons(this->layout_, this->mapfile_);
67 // This class is used to sort the common symbol by size. We put the
68 // larger common symbols first.
70 template<int size>
71 class Sort_commons
73 public:
74 Sort_commons(const Symbol_table* symtab)
75 : symtab_(symtab)
76 { }
78 bool operator()(const Symbol* a, const Symbol* b) const;
80 private:
81 const Symbol_table* symtab_;
84 template<int size>
85 bool
86 Sort_commons<size>::operator()(const Symbol* pa, const Symbol* pb) const
88 if (pa == NULL)
89 return false;
90 if (pb == NULL)
91 return true;
93 const Symbol_table* symtab = this->symtab_;
94 const Sized_symbol<size>* psa = symtab->get_sized_symbol<size>(pa);
95 const Sized_symbol<size>* psb = symtab->get_sized_symbol<size>(pb);
97 // Sort by largest size first.
98 typename Sized_symbol<size>::Size_type sa = psa->symsize();
99 typename Sized_symbol<size>::Size_type sb = psb->symsize();
100 if (sa < sb)
101 return false;
102 else if (sb < sa)
103 return true;
105 // When the symbols are the same size, we sort them by alignment,
106 // largest alignment first.
107 typename Sized_symbol<size>::Value_type va = psa->value();
108 typename Sized_symbol<size>::Value_type vb = psb->value();
109 if (va < vb)
110 return false;
111 else if (vb < va)
112 return true;
114 // Otherwise we stabilize the sort by sorting by name.
115 return strcmp(psa->name(), psb->name()) < 0;
118 // Allocate the common symbols.
120 void
121 Symbol_table::allocate_commons(Layout* layout, Mapfile* mapfile)
123 if (parameters->target().get_size() == 32)
125 #if defined(HAVE_TARGET_32_LITTLE) || defined(HAVE_TARGET_32_BIG)
126 this->do_allocate_commons<32>(layout, mapfile);
127 #else
128 gold_unreachable();
129 #endif
131 else if (parameters->target().get_size() == 64)
133 #if defined(HAVE_TARGET_64_LITTLE) || defined(HAVE_TARGET_64_BIG)
134 this->do_allocate_commons<64>(layout, mapfile);
135 #else
136 gold_unreachable();
137 #endif
139 else
140 gold_unreachable();
143 // Allocated the common symbols, sized version.
145 template<int size>
146 void
147 Symbol_table::do_allocate_commons(Layout* layout, Mapfile* mapfile)
149 if (!this->commons_.empty())
150 this->do_allocate_commons_list<size>(layout, COMMONS_NORMAL,
151 &this->commons_, mapfile);
152 if (!this->tls_commons_.empty())
153 this->do_allocate_commons_list<size>(layout, COMMONS_TLS,
154 &this->tls_commons_, mapfile);
155 if (!this->small_commons_.empty())
156 this->do_allocate_commons_list<size>(layout, COMMONS_SMALL,
157 &this->small_commons_, mapfile);
158 if (!this->large_commons_.empty())
159 this->do_allocate_commons_list<size>(layout, COMMONS_LARGE,
160 &this->large_commons_, mapfile);
163 // Allocate the common symbols in a list. IS_TLS indicates whether
164 // these are TLS common symbols.
166 template<int size>
167 void
168 Symbol_table::do_allocate_commons_list(
169 Layout* layout,
170 Commons_section_type commons_section_type,
171 Commons_type* commons,
172 Mapfile* mapfile)
174 typedef typename Sized_symbol<size>::Value_type Value_type;
175 typedef typename Sized_symbol<size>::Size_type Size_type;
177 // We've kept a list of all the common symbols. But the symbol may
178 // have been resolved to a defined symbol by now. And it may be a
179 // forwarder. First remove all non-common symbols.
180 bool any = false;
181 uint64_t addralign = 0;
182 for (Commons_type::iterator p = commons->begin();
183 p != commons->end();
184 ++p)
186 Symbol* sym = *p;
187 if (sym->is_forwarder())
189 sym = this->resolve_forwards(sym);
190 *p = sym;
192 if (!sym->is_common())
193 *p = NULL;
194 else
196 any = true;
197 Sized_symbol<size>* ssym = this->get_sized_symbol<size>(sym);
198 if (ssym->value() > addralign)
199 addralign = ssym->value();
202 if (!any)
203 return;
205 // Sort the common symbols by size, so that they pack better into
206 // memory.
207 std::sort(commons->begin(), commons->end(),
208 Sort_commons<size>(this));
210 // Place them in a newly allocated BSS section.
211 elfcpp::Elf_Xword flags = elfcpp::SHF_WRITE | elfcpp::SHF_ALLOC;
212 const char* name;
213 const char* ds_name;
214 switch (commons_section_type)
216 case COMMONS_NORMAL:
217 name = ".bss";
218 ds_name = "** common";
219 break;
220 case COMMONS_TLS:
221 flags |= elfcpp::SHF_TLS;
222 name = ".tbss";
223 ds_name = "** tls common";
224 break;
225 case COMMONS_SMALL:
226 flags |= parameters->target().small_common_section_flags();
227 name = ".sbss";
228 ds_name = "** small common";
229 break;
230 case COMMONS_LARGE:
231 flags |= parameters->target().large_common_section_flags();
232 name = ".lbss";
233 ds_name = "** large common";
234 break;
235 default:
236 gold_unreachable();
239 Output_data_space *poc = new Output_data_space(addralign, ds_name);
240 Output_section *os = layout->add_output_section_data(name,
241 elfcpp::SHT_NOBITS,
242 flags, poc);
243 if (os != NULL)
245 if (commons_section_type == COMMONS_SMALL)
246 os->set_is_small_section();
247 else if (commons_section_type == COMMONS_LARGE)
248 os->set_is_large_section();
251 // Allocate them all.
253 off_t off = 0;
254 for (Commons_type::iterator p = commons->begin();
255 p != commons->end();
256 ++p)
258 Symbol* sym = *p;
259 if (sym == NULL)
260 break;
261 Sized_symbol<size>* ssym = this->get_sized_symbol<size>(sym);
263 // Record the symbol in the map file now, before we change its
264 // value. Pass the size in separately so that we don't have to
265 // templatize the map code, which is not performance sensitive.
266 if (mapfile != NULL)
267 mapfile->report_allocate_common(sym, ssym->symsize());
269 off = align_address(off, ssym->value());
270 ssym->allocate_common(poc, off);
271 off += ssym->symsize();
274 poc->set_current_data_size(off);
276 commons->clear();
279 } // End namespace gold.