2010-12-21 Kai Tietz <kai.tietz@onevision.com>
[deliverable/binutils-gdb.git] / gold / merge.cc
1 // merge.cc -- handle section merging for gold
2
3 // Copyright 2006, 2007, 2008, 2010 Free Software Foundation, Inc.
4 // Written by Ian Lance Taylor <iant@google.com>.
5
6 // This file is part of gold.
7
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.
12
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.
17
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.
22
23 #include "gold.h"
24
25 #include <cstdlib>
26 #include <algorithm>
27
28 #include "merge.h"
29 #include "compressed_output.h"
30
31 namespace gold
32 {
33
34 // Class Object_merge_map.
35
36 // Destructor.
37
38 Object_merge_map::~Object_merge_map()
39 {
40 for (Section_merge_maps::iterator p = this->section_merge_maps_.begin();
41 p != this->section_merge_maps_.end();
42 ++p)
43 delete p->second;
44 }
45
46 // Get the Input_merge_map to use for an input section, or NULL.
47
48 Object_merge_map::Input_merge_map*
49 Object_merge_map::get_input_merge_map(unsigned int shndx)
50 {
51 gold_assert(shndx != -1U);
52 if (shndx == this->first_shnum_)
53 return &this->first_map_;
54 if (shndx == this->second_shnum_)
55 return &this->second_map_;
56 Section_merge_maps::const_iterator p = this->section_merge_maps_.find(shndx);
57 if (p != this->section_merge_maps_.end())
58 return p->second;
59 return NULL;
60 }
61
62 // Get or create the Input_merge_map to use for an input section.
63
64 Object_merge_map::Input_merge_map*
65 Object_merge_map::get_or_make_input_merge_map(const Merge_map* merge_map,
66 unsigned int shndx)
67 {
68 Input_merge_map* map = this->get_input_merge_map(shndx);
69 if (map != NULL)
70 {
71 // For a given input section in a given object, every mapping
72 // must be done with the same Merge_map.
73 gold_assert(map->merge_map == merge_map);
74 return map;
75 }
76
77 // We need to create a new entry.
78 if (this->first_shnum_ == -1U)
79 {
80 this->first_shnum_ = shndx;
81 this->first_map_.merge_map = merge_map;
82 return &this->first_map_;
83 }
84 if (this->second_shnum_ == -1U)
85 {
86 this->second_shnum_ = shndx;
87 this->second_map_.merge_map = merge_map;
88 return &this->second_map_;
89 }
90
91 Input_merge_map* new_map = new Input_merge_map;
92 new_map->merge_map = merge_map;
93 this->section_merge_maps_[shndx] = new_map;
94 return new_map;
95 }
96
97 // Add a mapping.
98
99 void
100 Object_merge_map::add_mapping(const Merge_map* merge_map, unsigned int shndx,
101 section_offset_type input_offset,
102 section_size_type length,
103 section_offset_type output_offset)
104 {
105 Input_merge_map* map = this->get_or_make_input_merge_map(merge_map, shndx);
106
107 // Try to merge the new entry in the last one we saw.
108 if (!map->entries.empty())
109 {
110 Input_merge_entry& entry(map->entries.back());
111
112 // Use section_size_type to avoid signed/unsigned warnings.
113 section_size_type input_offset_u = input_offset;
114 section_size_type output_offset_u = output_offset;
115
116 // If this entry is not in order, we need to sort the vector
117 // before looking anything up.
118 if (input_offset_u < entry.input_offset + entry.length)
119 {
120 gold_assert(input_offset < entry.input_offset);
121 gold_assert(input_offset_u + length
122 <= static_cast<section_size_type>(entry.input_offset));
123 map->sorted = false;
124 }
125 else if (entry.input_offset + entry.length == input_offset_u
126 && (output_offset == -1
127 ? entry.output_offset == -1
128 : entry.output_offset + entry.length == output_offset_u))
129 {
130 entry.length += length;
131 return;
132 }
133 }
134
135 Input_merge_entry entry;
136 entry.input_offset = input_offset;
137 entry.length = length;
138 entry.output_offset = output_offset;
139 map->entries.push_back(entry);
140 }
141
142 // Get the output offset for an input address.
143
144 bool
145 Object_merge_map::get_output_offset(const Merge_map* merge_map,
146 unsigned int shndx,
147 section_offset_type input_offset,
148 section_offset_type* output_offset)
149 {
150 Input_merge_map* map = this->get_input_merge_map(shndx);
151 if (map == NULL
152 || (merge_map != NULL && map->merge_map != merge_map))
153 return false;
154
155 if (!map->sorted)
156 {
157 std::sort(map->entries.begin(), map->entries.end(),
158 Input_merge_compare());
159 map->sorted = true;
160 }
161
162 Input_merge_entry entry;
163 entry.input_offset = input_offset;
164 std::vector<Input_merge_entry>::const_iterator p =
165 std::lower_bound(map->entries.begin(), map->entries.end(),
166 entry, Input_merge_compare());
167 if (p == map->entries.end() || p->input_offset > input_offset)
168 {
169 if (p == map->entries.begin())
170 return false;
171 --p;
172 gold_assert(p->input_offset <= input_offset);
173 }
174
175 if (input_offset - p->input_offset
176 >= static_cast<section_offset_type>(p->length))
177 return false;
178
179 *output_offset = p->output_offset;
180 if (*output_offset != -1)
181 *output_offset += (input_offset - p->input_offset);
182 return true;
183 }
184
185 // Return whether this is the merge map for section SHNDX.
186
187 inline bool
188 Object_merge_map::is_merge_section_for(const Merge_map* merge_map,
189 unsigned int shndx)
190 {
191 Input_merge_map* map = this->get_input_merge_map(shndx);
192 return map != NULL && map->merge_map == merge_map;
193 }
194
195 // Initialize a mapping from input offsets to output addresses.
196
197 template<int size>
198 void
199 Object_merge_map::initialize_input_to_output_map(
200 unsigned int shndx,
201 typename elfcpp::Elf_types<size>::Elf_Addr starting_address,
202 Unordered_map<section_offset_type,
203 typename elfcpp::Elf_types<size>::Elf_Addr>* initialize_map)
204 {
205 Input_merge_map* map = this->get_input_merge_map(shndx);
206 gold_assert(map != NULL);
207
208 gold_assert(initialize_map->empty());
209 // We know how many entries we are going to add.
210 // reserve_unordered_map takes an expected count of buckets, not a
211 // count of elements, so double it to try to reduce collisions.
212 reserve_unordered_map(initialize_map, map->entries.size() * 2);
213
214 for (Input_merge_map::Entries::const_iterator p = map->entries.begin();
215 p != map->entries.end();
216 ++p)
217 {
218 section_offset_type output_offset = p->output_offset;
219 if (output_offset != -1)
220 output_offset += starting_address;
221 else
222 {
223 // If we see a relocation against an address we have chosen
224 // to discard, we relocate to zero. FIXME: We could also
225 // issue a warning in this case; that would require
226 // reporting this somehow and checking it in the routines in
227 // reloc.h.
228 output_offset = 0;
229 }
230 initialize_map->insert(std::make_pair(p->input_offset, output_offset));
231 }
232 }
233
234 // Class Merge_map.
235
236 // Add a mapping for the bytes from OFFSET to OFFSET + LENGTH in input
237 // section SHNDX in object OBJECT to an OUTPUT_OFFSET in merged data
238 // in an output section.
239
240 void
241 Merge_map::add_mapping(Relobj* object, unsigned int shndx,
242 section_offset_type offset, section_size_type length,
243 section_offset_type output_offset)
244 {
245 Object_merge_map* object_merge_map = object->merge_map();
246 if (object_merge_map == NULL)
247 {
248 object_merge_map = new Object_merge_map();
249 object->set_merge_map(object_merge_map);
250 }
251
252 object_merge_map->add_mapping(this, shndx, offset, length, output_offset);
253 }
254
255 // Return the output offset for an input address. The input address
256 // is at offset OFFSET in section SHNDX in OBJECT. This sets
257 // *OUTPUT_OFFSET to the offset in the merged data in the output
258 // section. This returns true if the mapping is known, false
259 // otherwise.
260
261 bool
262 Merge_map::get_output_offset(const Relobj* object, unsigned int shndx,
263 section_offset_type offset,
264 section_offset_type* output_offset) const
265 {
266 Object_merge_map* object_merge_map = object->merge_map();
267 if (object_merge_map == NULL)
268 return false;
269 return object_merge_map->get_output_offset(this, shndx, offset,
270 output_offset);
271 }
272
273 // Return whether this is the merge section for SHNDX in OBJECT.
274
275 bool
276 Merge_map::is_merge_section_for(const Relobj* object, unsigned int shndx) const
277 {
278 Object_merge_map* object_merge_map = object->merge_map();
279 if (object_merge_map == NULL)
280 return false;
281 return object_merge_map->is_merge_section_for(this, shndx);
282 }
283
284 // Class Output_merge_base.
285
286 // Return the output offset for an input offset. The input address is
287 // at offset OFFSET in section SHNDX in OBJECT. If we know the
288 // offset, set *POUTPUT and return true. Otherwise return false.
289
290 bool
291 Output_merge_base::do_output_offset(const Relobj* object,
292 unsigned int shndx,
293 section_offset_type offset,
294 section_offset_type* poutput) const
295 {
296 return this->merge_map_.get_output_offset(object, shndx, offset, poutput);
297 }
298
299 // Return whether this is the merge section for SHNDX in OBJECT.
300
301 bool
302 Output_merge_base::do_is_merge_section_for(const Relobj* object,
303 unsigned int shndx) const
304 {
305 return this->merge_map_.is_merge_section_for(object, shndx);
306 }
307
308 // Record a merged input section for script processing.
309
310 void
311 Output_merge_base::record_input_section(Relobj* relobj, unsigned int shndx)
312 {
313 gold_assert(this->keeps_input_sections_ && relobj != NULL);
314 // If this is the first input section, record it. We need do this because
315 // this->input_sections_ is unordered.
316 if (this->first_relobj_ == NULL)
317 {
318 this->first_relobj_ = relobj;
319 this->first_shndx_ = shndx;
320 }
321
322 std::pair<Input_sections::iterator, bool> result =
323 this->input_sections_.insert(Section_id(relobj, shndx));
324 // We should insert a merge section once only.
325 gold_assert(result.second);
326 }
327
328 // Class Output_merge_data.
329
330 // Compute the hash code for a fixed-size constant.
331
332 size_t
333 Output_merge_data::Merge_data_hash::operator()(Merge_data_key k) const
334 {
335 const unsigned char* p = this->pomd_->constant(k);
336 section_size_type entsize =
337 convert_to_section_size_type(this->pomd_->entsize());
338
339 // Fowler/Noll/Vo (FNV) hash (type FNV-1a).
340 if (sizeof(size_t) == 8)
341 {
342 size_t result = static_cast<size_t>(14695981039346656037ULL);
343 for (section_size_type i = 0; i < entsize; ++i)
344 {
345 result &= (size_t) *p++;
346 result *= 1099511628211ULL;
347 }
348 return result;
349 }
350 else
351 {
352 size_t result = 2166136261UL;
353 for (section_size_type i = 0; i < entsize; ++i)
354 {
355 result ^= (size_t) *p++;
356 result *= 16777619UL;
357 }
358 return result;
359 }
360 }
361
362 // Return whether one hash table key equals another.
363
364 bool
365 Output_merge_data::Merge_data_eq::operator()(Merge_data_key k1,
366 Merge_data_key k2) const
367 {
368 const unsigned char* p1 = this->pomd_->constant(k1);
369 const unsigned char* p2 = this->pomd_->constant(k2);
370 return memcmp(p1, p2, this->pomd_->entsize()) == 0;
371 }
372
373 // Add a constant to the end of the section contents.
374
375 void
376 Output_merge_data::add_constant(const unsigned char* p)
377 {
378 section_size_type entsize = convert_to_section_size_type(this->entsize());
379 section_size_type addralign =
380 convert_to_section_size_type(this->addralign());
381 section_size_type addsize = std::max(entsize, addralign);
382 if (this->len_ + addsize > this->alc_)
383 {
384 if (this->alc_ == 0)
385 this->alc_ = 128 * addsize;
386 else
387 this->alc_ *= 2;
388 this->p_ = static_cast<unsigned char*>(realloc(this->p_, this->alc_));
389 if (this->p_ == NULL)
390 gold_nomem();
391 }
392
393 memcpy(this->p_ + this->len_, p, entsize);
394 if (addsize > entsize)
395 memset(this->p_ + this->len_ + entsize, 0, addsize - entsize);
396 this->len_ += addsize;
397 }
398
399 // Add the input section SHNDX in OBJECT to a merged output section
400 // which holds fixed length constants. Return whether we were able to
401 // handle the section; if not, it will be linked as usual without
402 // constant merging.
403
404 bool
405 Output_merge_data::do_add_input_section(Relobj* object, unsigned int shndx)
406 {
407 section_size_type len;
408 section_size_type uncompressed_size = 0;
409 unsigned char* uncompressed_data = NULL;
410 const unsigned char* p = object->section_contents(shndx, &len, false);
411
412 if (object->section_is_compressed(shndx, &uncompressed_size))
413 {
414 uncompressed_data = new unsigned char[uncompressed_size];
415 if (!decompress_input_section(p, len, uncompressed_data,
416 uncompressed_size))
417 object->error(_("could not decompress section %s"),
418 object->section_name(shndx).c_str());
419 p = uncompressed_data;
420 len = uncompressed_size;
421 }
422
423 section_size_type entsize = convert_to_section_size_type(this->entsize());
424
425 if (len % entsize != 0)
426 {
427 if (uncompressed_data != NULL)
428 delete[] uncompressed_data;
429 return false;
430 }
431
432 this->input_count_ += len / entsize;
433
434 for (section_size_type i = 0; i < len; i += entsize, p += entsize)
435 {
436 // Add the constant to the section contents. If we find that it
437 // is already in the hash table, we will remove it again.
438 Merge_data_key k = this->len_;
439 this->add_constant(p);
440
441 std::pair<Merge_data_hashtable::iterator, bool> ins =
442 this->hashtable_.insert(k);
443
444 if (!ins.second)
445 {
446 // Key was already present. Remove the copy we just added.
447 this->len_ -= entsize;
448 k = *ins.first;
449 }
450
451 // Record the offset of this constant in the output section.
452 this->add_mapping(object, shndx, i, entsize, k);
453 }
454
455 // For script processing, we keep the input sections.
456 if (this->keeps_input_sections())
457 record_input_section(object, shndx);
458
459 if (uncompressed_data != NULL)
460 delete[] uncompressed_data;
461
462 return true;
463 }
464
465 // Set the final data size in a merged output section with fixed size
466 // constants.
467
468 void
469 Output_merge_data::set_final_data_size()
470 {
471 // Release the memory we don't need.
472 this->p_ = static_cast<unsigned char*>(realloc(this->p_, this->len_));
473 // An Output_merge_data object may be empty and realloc is allowed
474 // to return a NULL pointer in this case. An Output_merge_data is empty
475 // if all its input sections have sizes that are not multiples of entsize.
476 gold_assert(this->p_ != NULL || this->len_ == 0);
477 this->set_data_size(this->len_);
478 }
479
480 // Write the data of a merged output section with fixed size constants
481 // to the file.
482
483 void
484 Output_merge_data::do_write(Output_file* of)
485 {
486 of->write(this->offset(), this->p_, this->len_);
487 }
488
489 // Write the data to a buffer.
490
491 void
492 Output_merge_data::do_write_to_buffer(unsigned char* buffer)
493 {
494 memcpy(buffer, this->p_, this->len_);
495 }
496
497 // Print merge stats to stderr.
498
499 void
500 Output_merge_data::do_print_merge_stats(const char* section_name)
501 {
502 fprintf(stderr,
503 _("%s: %s merged constants size: %lu; input: %zu; output: %zu\n"),
504 program_name, section_name,
505 static_cast<unsigned long>(this->entsize()),
506 this->input_count_, this->hashtable_.size());
507 }
508
509 // Class Output_merge_string.
510
511 // Add an input section to a merged string section.
512
513 template<typename Char_type>
514 bool
515 Output_merge_string<Char_type>::do_add_input_section(Relobj* object,
516 unsigned int shndx)
517 {
518 section_size_type len;
519 section_size_type uncompressed_size = 0;
520 unsigned char* uncompressed_data = NULL;
521 const unsigned char* pdata = object->section_contents(shndx, &len, false);
522
523 if (object->section_is_compressed(shndx, &uncompressed_size))
524 {
525 uncompressed_data = new unsigned char[uncompressed_size];
526 if (!decompress_input_section(pdata, len, uncompressed_data,
527 uncompressed_size))
528 object->error(_("could not decompress section %s"),
529 object->section_name(shndx).c_str());
530 pdata = uncompressed_data;
531 len = uncompressed_size;
532 }
533
534 const Char_type* p = reinterpret_cast<const Char_type*>(pdata);
535 const Char_type* pend = p + len / sizeof(Char_type);
536 const Char_type* pend0 = pend;
537
538 if (len % sizeof(Char_type) != 0)
539 {
540 object->error(_("mergeable string section length not multiple of "
541 "character size"));
542 if (uncompressed_data != NULL)
543 delete[] uncompressed_data;
544 return false;
545 }
546
547 if (pend[-1] != 0)
548 {
549 gold_warning(_("%s: last entry in mergeable string section '%s' "
550 "not null terminated"),
551 object->name().c_str(),
552 object->section_name(shndx).c_str());
553 // Find the end of the last NULL-terminated string in the buffer.
554 while (pend0 > p && pend0[-1] != 0)
555 --pend0;
556 }
557
558 Merged_strings_list* merged_strings_list =
559 new Merged_strings_list(object, shndx);
560 this->merged_strings_lists_.push_back(merged_strings_list);
561 Merged_strings& merged_strings = merged_strings_list->merged_strings;
562
563 // Count the number of strings in the section and size the list.
564 size_t count = 0;
565 for (const Char_type* pt = p; pt < pend0; pt += string_length(pt) + 1)
566 ++count;
567 if (pend0 < pend)
568 ++count;
569 merged_strings.reserve(count + 1);
570
571 // The index I is in bytes, not characters.
572 section_size_type i = 0;
573 while (p < pend0)
574 {
575 size_t len = string_length(p);
576
577 Stringpool::Key key;
578 this->stringpool_.add_with_length(p, len, true, &key);
579
580 merged_strings.push_back(Merged_string(i, key));
581
582 p += len + 1;
583 i += (len + 1) * sizeof(Char_type);
584 }
585 if (p < pend)
586 {
587 size_t len = pend - p;
588
589 Stringpool::Key key;
590 this->stringpool_.add_with_length(p, len, true, &key);
591
592 merged_strings.push_back(Merged_string(i, key));
593
594 i += (len + 1) * sizeof(Char_type);
595 }
596
597 // Record the last offset in the input section so that we can
598 // compute the length of the last string.
599 merged_strings.push_back(Merged_string(i, 0));
600
601 this->input_count_ += count;
602 this->input_size_ += len;
603
604 // For script processing, we keep the input sections.
605 if (this->keeps_input_sections())
606 record_input_section(object, shndx);
607
608 if (uncompressed_data != NULL)
609 delete[] uncompressed_data;
610
611 return true;
612 }
613
614 // Finalize the mappings from the input sections to the output
615 // section, and return the final data size.
616
617 template<typename Char_type>
618 section_size_type
619 Output_merge_string<Char_type>::finalize_merged_data()
620 {
621 this->stringpool_.set_string_offsets();
622
623 for (typename Merged_strings_lists::const_iterator l =
624 this->merged_strings_lists_.begin();
625 l != this->merged_strings_lists_.end();
626 ++l)
627 {
628 section_offset_type last_input_offset = 0;
629 section_offset_type last_output_offset = 0;
630 for (typename Merged_strings::const_iterator p =
631 (*l)->merged_strings.begin();
632 p != (*l)->merged_strings.end();
633 ++p)
634 {
635 section_size_type length = p->offset - last_input_offset;
636 if (length > 0)
637 this->add_mapping((*l)->object, (*l)->shndx, last_input_offset,
638 length, last_output_offset);
639 last_input_offset = p->offset;
640 if (p->stringpool_key != 0)
641 last_output_offset =
642 this->stringpool_.get_offset_from_key(p->stringpool_key);
643 }
644 delete *l;
645 }
646
647 // Save some memory. This also ensures that this function will work
648 // if called twice, as may happen if Layout::set_segment_offsets
649 // finds a better alignment.
650 this->merged_strings_lists_.clear();
651
652 return this->stringpool_.get_strtab_size();
653 }
654
655 template<typename Char_type>
656 void
657 Output_merge_string<Char_type>::set_final_data_size()
658 {
659 const off_t final_data_size = this->finalize_merged_data();
660 this->set_data_size(final_data_size);
661 }
662
663 // Write out a merged string section.
664
665 template<typename Char_type>
666 void
667 Output_merge_string<Char_type>::do_write(Output_file* of)
668 {
669 this->stringpool_.write(of, this->offset());
670 }
671
672 // Write a merged string section to a buffer.
673
674 template<typename Char_type>
675 void
676 Output_merge_string<Char_type>::do_write_to_buffer(unsigned char* buffer)
677 {
678 this->stringpool_.write_to_buffer(buffer, this->data_size());
679 }
680
681 // Return the name of the types of string to use with
682 // do_print_merge_stats.
683
684 template<typename Char_type>
685 const char*
686 Output_merge_string<Char_type>::string_name()
687 {
688 gold_unreachable();
689 return NULL;
690 }
691
692 template<>
693 const char*
694 Output_merge_string<char>::string_name()
695 {
696 return "strings";
697 }
698
699 template<>
700 const char*
701 Output_merge_string<uint16_t>::string_name()
702 {
703 return "16-bit strings";
704 }
705
706 template<>
707 const char*
708 Output_merge_string<uint32_t>::string_name()
709 {
710 return "32-bit strings";
711 }
712
713 // Print merge stats to stderr.
714
715 template<typename Char_type>
716 void
717 Output_merge_string<Char_type>::do_print_merge_stats(const char* section_name)
718 {
719 char buf[200];
720 snprintf(buf, sizeof buf, "%s merged %s", section_name, this->string_name());
721 fprintf(stderr, _("%s: %s input bytes: %zu\n"),
722 program_name, buf, this->input_size_);
723 fprintf(stderr, _("%s: %s input strings: %zu\n"),
724 program_name, buf, this->input_count_);
725 this->stringpool_.print_stats(buf);
726 }
727
728 // Instantiate the templates we need.
729
730 template
731 class Output_merge_string<char>;
732
733 template
734 class Output_merge_string<uint16_t>;
735
736 template
737 class Output_merge_string<uint32_t>;
738
739 #if defined(HAVE_TARGET_32_LITTLE) || defined(HAVE_TARGET_32_BIG)
740 template
741 void
742 Object_merge_map::initialize_input_to_output_map<32>(
743 unsigned int shndx,
744 elfcpp::Elf_types<32>::Elf_Addr starting_address,
745 Unordered_map<section_offset_type, elfcpp::Elf_types<32>::Elf_Addr>*);
746 #endif
747
748 #if defined(HAVE_TARGET_64_LITTLE) || defined(HAVE_TARGET_64_BIG)
749 template
750 void
751 Object_merge_map::initialize_input_to_output_map<64>(
752 unsigned int shndx,
753 elfcpp::Elf_types<64>::Elf_Addr starting_address,
754 Unordered_map<section_offset_type, elfcpp::Elf_types<64>::Elf_Addr>*);
755 #endif
756
757 } // End namespace gold.
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