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
)
44 // Two different object files can have the same name: if foo.a
45 // includes both bar/qux.o and baz/qux.o, then both end up with
46 // the name foo.a(qux.o). But it's impossible for two different
47 // object files to have both the same name and the same offset.
48 if (mk1
.object
->offset() != mk2
.object
->offset())
49 return mk1
.object
->offset() < mk2
.object
->offset();
50 return mk1
.object
->name() < mk2
.object
->name();
52 if (mk1
.shndx
!= mk2
.shndx
)
53 return mk1
.shndx
< mk2
.shndx
;
54 return mk1
.offset
< mk2
.offset
;
57 // Add a mapping from an OFFSET in input section SHNDX in object
58 // OBJECT to an OUTPUT_OFFSET in a merged output section. This
59 // manages the mapping used to resolve relocations against merged
63 Output_merge_base::add_mapping(Relobj
* object
, unsigned int shndx
,
64 off_t offset
, off_t output_offset
)
70 std::pair
<Merge_map::iterator
, bool> ins
=
71 this->merge_map_
.insert(std::make_pair(mk
, output_offset
));
72 gold_assert(ins
.second
);
75 // Return the output address for an input address. The input address
76 // is at offset OFFSET in section SHNDX in OBJECT.
77 // OUTPUT_SECTION_ADDRESS is the address of the output section. If we
78 // know the address, set *POUTPUT and return true. Otherwise return
82 Output_merge_base::do_output_address(const Relobj
* object
, unsigned int shndx
,
84 uint64_t output_section_address
,
85 uint64_t* poutput
) const
87 gold_assert(output_section_address
== this->address());
93 Merge_map::const_iterator p
= this->merge_map_
.lower_bound(mk
);
95 // If MK is not in the map, lower_bound returns the next iterator
97 if (p
== this->merge_map_
.end()
98 || p
->first
.object
!= object
99 || p
->first
.shndx
!= shndx
100 || p
->first
.offset
!= offset
)
102 if (p
== this->merge_map_
.begin())
107 if (p
->first
.object
!= object
|| p
->first
.shndx
!= shndx
)
110 // Any input section is fully mapped: we don't need to know the size
111 // of the range starting at P->FIRST.OFFSET.
112 *poutput
= output_section_address
+ p
->second
+ (offset
- p
->first
.offset
);
116 // Compute the hash code for a fixed-size constant.
119 Output_merge_data::Merge_data_hash::operator()(Merge_data_key k
) const
121 const unsigned char* p
= this->pomd_
->constant(k
);
122 uint64_t entsize
= this->pomd_
->entsize();
124 // Fowler/Noll/Vo (FNV) hash (type FNV-1a).
125 if (sizeof(size_t) == 8)
127 size_t result
= static_cast<size_t>(14695981039346656037ULL);
128 for (uint64_t i
= 0; i
< entsize
; ++i
)
130 result
&= (size_t) *p
++;
131 result
*= 1099511628211ULL;
137 size_t result
= 2166136261UL;
138 for (uint64_t i
= 0; i
< entsize
; ++i
)
140 result
^= (size_t) *p
++;
141 result
*= 16777619UL;
147 // Return whether one hash table key equals another.
150 Output_merge_data::Merge_data_eq::operator()(Merge_data_key k1
,
151 Merge_data_key k2
) const
153 const unsigned char* p1
= this->pomd_
->constant(k1
);
154 const unsigned char* p2
= this->pomd_
->constant(k2
);
155 return memcmp(p1
, p2
, this->pomd_
->entsize()) == 0;
158 // Add a constant to the end of the section contents.
161 Output_merge_data::add_constant(const unsigned char* p
)
163 uint64_t entsize
= this->entsize();
164 if (this->len_
+ entsize
> this->alc_
)
167 this->alc_
= 128 * entsize
;
170 this->p_
= static_cast<unsigned char*>(realloc(this->p_
, this->alc_
));
171 if (this->p_
== NULL
)
175 memcpy(this->p_
+ this->len_
, p
, entsize
);
176 this->len_
+= entsize
;
179 // Add the input section SHNDX in OBJECT to a merged output section
180 // which holds fixed length constants. Return whether we were able to
181 // handle the section; if not, it will be linked as usual without
185 Output_merge_data::do_add_input_section(Relobj
* object
, unsigned int shndx
)
188 const unsigned char* p
= object
->section_contents(shndx
, &len
, false);
190 uint64_t entsize
= this->entsize();
192 if (len
% entsize
!= 0)
195 for (off_t i
= 0; i
< len
; i
+= entsize
, p
+= entsize
)
197 // Add the constant to the section contents. If we find that it
198 // is already in the hash table, we will remove it again.
199 Merge_data_key k
= this->len_
;
200 this->add_constant(p
);
202 std::pair
<Merge_data_hashtable::iterator
, bool> ins
=
203 this->hashtable_
.insert(k
);
207 // Key was already present. Remove the copy we just added.
208 this->len_
-= entsize
;
212 // Record the offset of this constant in the output section.
213 this->add_mapping(object
, shndx
, i
, k
);
219 // Set the final data size in a merged output section with fixed size
223 Output_merge_data::do_set_address(uint64_t, off_t
)
225 // Release the memory we don't need.
226 this->p_
= static_cast<unsigned char*>(realloc(this->p_
, this->len_
));
227 gold_assert(this->p_
!= NULL
);
228 this->set_data_size(this->len_
);
231 // Write the data of a merged output section with fixed size constants
235 Output_merge_data::do_write(Output_file
* of
)
237 of
->write(this->offset(), this->p_
, this->len_
);
240 // Add an input section to a merged string section.
242 template<typename Char_type
>
244 Output_merge_string
<Char_type
>::do_add_input_section(Relobj
* object
,
248 const unsigned char* pdata
= object
->section_contents(shndx
, &len
, false);
250 const Char_type
* p
= reinterpret_cast<const Char_type
*>(pdata
);
252 if (len
% sizeof(Char_type
) != 0)
254 object
->error(_("mergeable string section length not multiple of "
258 len
/= sizeof(Char_type
);
264 for (const Char_type
* pl
= p
; *pl
!= 0; ++pl
)
269 object
->error(_("entry in mergeable string section "
270 "not null terminated"));
275 const Char_type
* str
= this->stringpool_
.add(p
, true, NULL
);
277 this->merged_strings_
.push_back(Merged_string(object
, shndx
, i
, str
));
286 // Set the final data size of a merged string section. This is where
287 // we finalize the mappings from the input sections to the output
290 template<typename Char_type
>
292 Output_merge_string
<Char_type
>::do_set_address(uint64_t, off_t
)
294 this->stringpool_
.set_string_offsets();
296 for (typename
Merged_strings::const_iterator p
=
297 this->merged_strings_
.begin();
298 p
!= this->merged_strings_
.end();
300 this->add_mapping(p
->object
, p
->shndx
, p
->offset
,
301 this->stringpool_
.get_offset(p
->string
));
303 this->set_data_size(this->stringpool_
.get_strtab_size());
306 this->merged_strings_
.clear();
309 // Write out a merged string section.
311 template<typename Char_type
>
313 Output_merge_string
<Char_type
>::do_write(Output_file
* of
)
315 this->stringpool_
.write(of
, this->offset());
318 // Instantiate the templates we need.
321 class Output_merge_string
<char>;
324 class Output_merge_string
<uint16_t>;
327 class Output_merge_string
<uint32_t>;
329 } // End namespace gold.