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.
33 // Class Merge_map::Merge_key_less.
35 // Sort the entries in a merge mapping. The key is an input object, a
36 // section index in that object, and an offset in that section.
39 Merge_map::Merge_key_less::operator()(const Merge_key
& mk1
,
40 const Merge_key
& mk2
) const
42 // The order of different objects and different sections doesn't
43 // matter. We want to get consistent results across links so we
44 // don't use pointer comparison.
45 if (mk1
.object
!= mk2
.object
)
47 // Two different object files can have the same name: if foo.a
48 // includes both bar/qux.o and baz/qux.o, then both end up with
49 // the name foo.a(qux.o). But it's impossible for two different
50 // object files to have both the same name and the same offset.
51 if (mk1
.object
->offset() != mk2
.object
->offset())
52 return mk1
.object
->offset() < mk2
.object
->offset();
53 return mk1
.object
->name() < mk2
.object
->name();
55 if (mk1
.shndx
!= mk2
.shndx
)
56 return mk1
.shndx
< mk2
.shndx
;
57 return mk1
.offset
< mk2
.offset
;
62 // Add a mapping for the bytes from OFFSET to OFFSET + LENGTH in input
63 // section SHNDX in object OBJECT to an OUTPUT_OFFSET in a merged
67 Merge_map::add_mapping(Relobj
* object
, unsigned int shndx
,
68 off_t offset
, off_t length
, off_t output_offset
)
77 mv
.output_offset
= output_offset
;
79 std::pair
<Merge_mapping::iterator
, bool> ins
=
80 this->merge_map_
.insert(std::make_pair(mk
, mv
));
81 gold_assert(ins
.second
);
84 // Return the output offset for an input address. The input address
85 // is at offset OFFSET in section SHNDX in OBJECT. This sets
86 // *OUTPUT_OFFSET to the offset in the output section. This returns
87 // true if the mapping is known, false otherwise.
90 Merge_map::get_output_offset(const Relobj
* object
, unsigned int shndx
,
91 off_t offset
, off_t
* output_offset
) const
97 Merge_mapping::const_iterator p
= this->merge_map_
.lower_bound(mk
);
99 // If MK is not in the map, lower_bound returns the next iterator
101 if (p
== this->merge_map_
.end()
102 || p
->first
.object
!= object
103 || p
->first
.shndx
!= shndx
104 || p
->first
.offset
!= offset
)
106 if (p
== this->merge_map_
.begin())
111 if (p
->first
.object
!= object
|| p
->first
.shndx
!= shndx
)
114 if (offset
- p
->first
.offset
>= p
->second
.length
)
117 *output_offset
= p
->second
.output_offset
;
118 if (*output_offset
!= -1)
119 *output_offset
+= (offset
- p
->first
.offset
);
123 // Class Output_merge_base.
125 // Return the output offset for an input offset. The input address is
126 // at offset OFFSET in section SHNDX in OBJECT. If we know the
127 // offset, set *POUTPUT and return true. Otherwise return false.
130 Output_merge_base::do_output_offset(const Relobj
* object
,
133 off_t
* poutput
) const
135 return this->merge_map_
.get_output_offset(object
, shndx
, offset
, poutput
);
138 // Class Output_merge_data.
140 // Compute the hash code for a fixed-size constant.
143 Output_merge_data::Merge_data_hash::operator()(Merge_data_key k
) const
145 const unsigned char* p
= this->pomd_
->constant(k
);
146 uint64_t entsize
= this->pomd_
->entsize();
148 // Fowler/Noll/Vo (FNV) hash (type FNV-1a).
149 if (sizeof(size_t) == 8)
151 size_t result
= static_cast<size_t>(14695981039346656037ULL);
152 for (uint64_t i
= 0; i
< entsize
; ++i
)
154 result
&= (size_t) *p
++;
155 result
*= 1099511628211ULL;
161 size_t result
= 2166136261UL;
162 for (uint64_t i
= 0; i
< entsize
; ++i
)
164 result
^= (size_t) *p
++;
165 result
*= 16777619UL;
171 // Return whether one hash table key equals another.
174 Output_merge_data::Merge_data_eq::operator()(Merge_data_key k1
,
175 Merge_data_key k2
) const
177 const unsigned char* p1
= this->pomd_
->constant(k1
);
178 const unsigned char* p2
= this->pomd_
->constant(k2
);
179 return memcmp(p1
, p2
, this->pomd_
->entsize()) == 0;
182 // Add a constant to the end of the section contents.
185 Output_merge_data::add_constant(const unsigned char* p
)
187 uint64_t entsize
= this->entsize();
188 uint64_t addsize
= std::max(entsize
, this->addralign());
189 if (this->len_
+ addsize
> this->alc_
)
192 this->alc_
= 128 * addsize
;
195 this->p_
= static_cast<unsigned char*>(realloc(this->p_
, this->alc_
));
196 if (this->p_
== NULL
)
200 memcpy(this->p_
+ this->len_
, p
, entsize
);
201 if (addsize
> entsize
)
202 memset(this->p_
+ this->len_
+ entsize
, 0, addsize
- entsize
);
203 this->len_
+= addsize
;
206 // Add the input section SHNDX in OBJECT to a merged output section
207 // which holds fixed length constants. Return whether we were able to
208 // handle the section; if not, it will be linked as usual without
212 Output_merge_data::do_add_input_section(Relobj
* object
, unsigned int shndx
)
215 const unsigned char* p
= object
->section_contents(shndx
, &len
, false);
217 uint64_t entsize
= this->entsize();
219 if (len
% entsize
!= 0)
222 for (off_t i
= 0; i
< len
; i
+= entsize
, p
+= entsize
)
224 // Add the constant to the section contents. If we find that it
225 // is already in the hash table, we will remove it again.
226 Merge_data_key k
= this->len_
;
227 this->add_constant(p
);
229 std::pair
<Merge_data_hashtable::iterator
, bool> ins
=
230 this->hashtable_
.insert(k
);
234 // Key was already present. Remove the copy we just added.
235 this->len_
-= entsize
;
239 // Record the offset of this constant in the output section.
240 this->add_mapping(object
, shndx
, i
, entsize
, k
);
246 // Set the final data size in a merged output section with fixed size
250 Output_merge_data::do_set_address(uint64_t, off_t
)
252 // Release the memory we don't need.
253 this->p_
= static_cast<unsigned char*>(realloc(this->p_
, this->len_
));
254 gold_assert(this->p_
!= NULL
);
255 this->set_data_size(this->len_
);
258 // Write the data of a merged output section with fixed size constants
262 Output_merge_data::do_write(Output_file
* of
)
264 of
->write(this->offset(), this->p_
, this->len_
);
267 // Class Output_merge_string.
269 // Add an input section to a merged string section.
271 template<typename Char_type
>
273 Output_merge_string
<Char_type
>::do_add_input_section(Relobj
* object
,
277 const unsigned char* pdata
= object
->section_contents(shndx
, &len
, false);
279 const Char_type
* p
= reinterpret_cast<const Char_type
*>(pdata
);
281 if (len
% sizeof(Char_type
) != 0)
283 object
->error(_("mergeable string section length not multiple of "
288 // The index I is in bytes, not characters.
293 for (const Char_type
* pl
= p
; *pl
!= 0; ++pl
)
295 // The length PLEN is in characters, not bytes.
297 if (i
+ plen
* static_cast<off_t
>(sizeof(Char_type
)) >= len
)
299 object
->error(_("entry in mergeable string section "
300 "not null terminated"));
305 const Char_type
* str
= this->stringpool_
.add(p
, true, NULL
);
307 off_t bytelen_with_null
= (plen
+ 1) * sizeof(Char_type
);
308 this->merged_strings_
.push_back(Merged_string(object
, shndx
, i
, str
,
312 i
+= bytelen_with_null
;
318 // Set the final data size of a merged string section. This is where
319 // we finalize the mappings from the input sections to the output
322 template<typename Char_type
>
324 Output_merge_string
<Char_type
>::do_set_address(uint64_t, off_t
)
326 this->stringpool_
.set_string_offsets();
328 for (typename
Merged_strings::const_iterator p
=
329 this->merged_strings_
.begin();
330 p
!= this->merged_strings_
.end();
332 this->add_mapping(p
->object
, p
->shndx
, p
->offset
, p
->length
,
333 this->stringpool_
.get_offset(p
->string
));
335 this->set_data_size(this->stringpool_
.get_strtab_size());
338 this->merged_strings_
.clear();
341 // Write out a merged string section.
343 template<typename Char_type
>
345 Output_merge_string
<Char_type
>::do_write(Output_file
* of
)
347 this->stringpool_
.write(of
, this->offset());
350 // Instantiate the templates we need.
353 class Output_merge_string
<char>;
356 class Output_merge_string
<uint16_t>;
359 class Output_merge_string
<uint32_t>;
361 } // End namespace gold.
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