1 // merge.cc -- handle section merging for gold
3 // Copyright 2006, 2007 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.
32 // Sort the entries in a merge mapping. The key is an input object, a
33 // section index in that object, and an offset in that section.
36 Output_merge_base::Merge_key_less::operator()(const Merge_key& mk1,
37 const Merge_key& mk2) const
39 // The order of different objects and different sections doesn't
40 // matter. We want to get consistent results across links so we
41 // don't use pointer comparison.
42 if (mk1.object != mk2.object)
43 return mk1.object->name() < mk2.object->name();
44 if (mk1.shndx != mk2.shndx)
45 return mk1.shndx < mk2.shndx;
46 return mk1.offset < mk2.offset;
49 // Add a mapping from an OFFSET in input section SHNDX in object
50 // OBJECT to an OUTPUT_OFFSET in a merged output section. This
51 // manages the mapping used to resolve relocations against merged
55 Output_merge_base::add_mapping(Relobj* object, unsigned int shndx,
56 off_t offset, off_t output_offset)
62 std::pair<Merge_map::iterator, bool> ins =
63 this->merge_map_.insert(std::make_pair(mk, output_offset));
64 gold_assert(ins.second);
67 // Return the output address for an input address. The input address
68 // is at offset OFFSET in section SHNDX in OBJECT.
69 // OUTPUT_SECTION_ADDRESS is the address of the output section. If we
70 // know the address, set *POUTPUT and return true. Otherwise return
74 Output_merge_base::do_output_address(const Relobj* object, unsigned int shndx,
76 uint64_t output_section_address,
77 uint64_t* poutput) const
79 gold_assert(output_section_address == this->address());
85 Merge_map::const_iterator p = this->merge_map_.lower_bound(mk);
87 // If MK is not in the map, lower_bound returns the next iterator
89 if (p->first.object != object
90 || p->first.shndx != shndx
91 || p->first.offset != offset)
93 if (p == this->merge_map_.begin())
98 if (p->first.object != object || p->first.shndx != shndx)
101 // Any input section is fully mapped: we don't need to know the size
102 // of the range starting at P->FIRST.OFFSET.
103 *poutput = output_section_address + p->second + (offset - p->first.offset);
107 // Compute the hash code for a fixed-size constant.
110 Output_merge_data::Merge_data_hash::operator()(Merge_data_key k) const
112 const unsigned char* p = this->pomd_->constant(k);
113 uint64_t entsize = this->pomd_->entsize();
115 // Fowler/Noll/Vo (FNV) hash (type FNV-1a).
116 if (sizeof(size_t) == 8)
118 size_t result = static_cast<size_t>(14695981039346656037ULL);
119 for (uint64_t i = 0; i < entsize; ++i)
121 result &= (size_t) *p++;
122 result *= 1099511628211ULL;
128 size_t result = 2166136261UL;
129 for (uint64_t i = 0; i < entsize; ++i)
131 result ^= (size_t) *p++;
132 result *= 16777619UL;
138 // Return whether one hash table key equals another.
141 Output_merge_data::Merge_data_eq::operator()(Merge_data_key k1,
142 Merge_data_key k2) const
144 const unsigned char* p1 = this->pomd_->constant(k1);
145 const unsigned char* p2 = this->pomd_->constant(k2);
146 return memcmp(p1, p2, this->pomd_->entsize()) == 0;
149 // Add a constant to the end of the section contents.
152 Output_merge_data::add_constant(const unsigned char* p)
154 uint64_t entsize = this->entsize();
155 if (this->len_ + entsize > this->alc_)
158 this->alc_ = 128 * entsize;
161 this->p_ = static_cast<unsigned char*>(realloc(this->p_, this->alc_));
162 if (this->p_ == NULL)
163 gold_fatal("out of memory", true);
166 memcpy(this->p_ + this->len_, p, entsize);
167 this->len_ += entsize;
170 // Add the input section SHNDX in OBJECT to a merged output section
171 // which holds fixed length constants. Return whether we were able to
172 // handle the section; if not, it will be linked as usual without
176 Output_merge_data::do_add_input_section(Relobj* object, unsigned int shndx)
179 const unsigned char* p = object->section_contents(shndx, &len);
181 uint64_t entsize = this->entsize();
183 if (len % entsize != 0)
186 for (off_t i = 0; i < len; i += entsize, p += entsize)
188 // Add the constant to the section contents. If we find that it
189 // is already in the hash table, we will remove it again.
190 Merge_data_key k = this->len_;
191 this->add_constant(p);
193 std::pair<Merge_data_hashtable::iterator, bool> ins =
194 this->hashtable_.insert(k);
198 // Key was already present. Remove the copy we just added.
199 this->len_ -= entsize;
203 // Record the offset of this constant in the output section.
204 this->add_mapping(object, shndx, i, k);
210 // Set the final data size in a merged output section with fixed size
214 Output_merge_data::do_set_address(uint64_t, off_t)
216 // Release the memory we don't need.
217 this->p_ = static_cast<unsigned char*>(realloc(this->p_, this->len_));
218 gold_assert(this->p_ != NULL);
219 this->set_data_size(this->len_);
222 // Write the data of a merged output section with fixed size constants
226 Output_merge_data::do_write(Output_file* of)
228 of->write(this->offset(), this->p_, this->len_);
231 // Add an input section to a merged string section.
233 template<typename Char_type>
235 Output_merge_string<Char_type>::do_add_input_section(Relobj* object,
239 const unsigned char* pdata = object->section_contents(shndx, &len);
241 const Char_type* p = reinterpret_cast<const Char_type*>(pdata);
243 if (len % sizeof(Char_type) != 0)
246 _("%s: %s: mergeable string section length not multiple of "
248 program_name, object->name().c_str());
251 len /= sizeof(Char_type);
257 for (const Char_type* pl = p; *pl != 0; ++pl)
263 _("%s: %s: entry in mergeable string section "
264 "not null terminated\n"),
265 program_name, object->name().c_str());
270 const Char_type* str = this->stringpool_.add(p, NULL);
272 this->merged_strings_.push_back(Merged_string(object, shndx, i, str));
281 // Set the final data size of a merged string section. This is where
282 // we finalize the mappings from the input sections to the output
285 template<typename Char_type>
287 Output_merge_string<Char_type>::do_set_address(uint64_t, off_t)
289 this->stringpool_.set_string_offsets();
291 for (typename Merged_strings::const_iterator p =
292 this->merged_strings_.begin();
293 p != this->merged_strings_.end();
295 this->add_mapping(p->object, p->shndx, p->offset,
296 this->stringpool_.get_offset(p->string));
298 this->set_data_size(this->stringpool_.get_strtab_size());
301 this->merged_strings_.clear();
304 // Write out a merged string section.
306 template<typename Char_type>
308 Output_merge_string<Char_type>::do_write(Output_file* of)
310 this->stringpool_.write(of, this->offset());
313 // Instantiate the templates we need.
316 class Output_merge_string<char>;
319 class Output_merge_string<uint16_t>;
322 class Output_merge_string<uint32_t>;
324 } // End namespace gold.