Merge branch 'vendor/GCC44'
[dragonfly.git] / contrib / binutils-2.22 / gold / merge.cc
1 // merge.cc -- handle section merging for gold
2
3 // Copyright 2006, 2007, 2008, 2009, 2010, 2011 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   gold_assert(object != NULL);
246   Object_merge_map* object_merge_map = object->merge_map();
247   if (object_merge_map == NULL)
248     {
249       object_merge_map = new Object_merge_map();
250       object->set_merge_map(object_merge_map);
251     }
252
253   object_merge_map->add_mapping(this, shndx, offset, length, output_offset);
254 }
255
256 // Return the output offset for an input address.  The input address
257 // is at offset OFFSET in section SHNDX in OBJECT.  This sets
258 // *OUTPUT_OFFSET to the offset in the merged data in the output
259 // section.  This returns true if the mapping is known, false
260 // otherwise.
261
262 bool
263 Merge_map::get_output_offset(const Relobj* object, unsigned int shndx,
264                              section_offset_type offset,
265                              section_offset_type* output_offset) const
266 {
267   Object_merge_map* object_merge_map = object->merge_map();
268   if (object_merge_map == NULL)
269     return false;
270   return object_merge_map->get_output_offset(this, shndx, offset,
271                                              output_offset);
272 }
273
274 // Return whether this is the merge section for SHNDX in OBJECT.
275
276 bool
277 Merge_map::is_merge_section_for(const Relobj* object, unsigned int shndx) const
278 {
279   Object_merge_map* object_merge_map = object->merge_map();
280   if (object_merge_map == NULL)
281     return false;
282   return object_merge_map->is_merge_section_for(this, shndx);
283 }
284
285 // Class Output_merge_base.
286
287 // Return the output offset for an input offset.  The input address is
288 // at offset OFFSET in section SHNDX in OBJECT.  If we know the
289 // offset, set *POUTPUT and return true.  Otherwise return false.
290
291 bool
292 Output_merge_base::do_output_offset(const Relobj* object,
293                                     unsigned int shndx,
294                                     section_offset_type offset,
295                                     section_offset_type* poutput) const
296 {
297   return this->merge_map_.get_output_offset(object, shndx, offset, poutput);
298 }
299
300 // Return whether this is the merge section for SHNDX in OBJECT.
301
302 bool
303 Output_merge_base::do_is_merge_section_for(const Relobj* object,
304                                            unsigned int shndx) const
305 {
306   return this->merge_map_.is_merge_section_for(object, shndx);
307 }
308
309 // Record a merged input section for script processing.
310
311 void
312 Output_merge_base::record_input_section(Relobj* relobj, unsigned int shndx)
313 {
314   gold_assert(this->keeps_input_sections_ && relobj != NULL);
315   // If this is the first input section, record it.  We need do this because
316   // this->input_sections_ is unordered.
317   if (this->first_relobj_ == NULL)
318     {
319       this->first_relobj_ = relobj;
320       this->first_shndx_ = shndx;
321     }
322
323   std::pair<Input_sections::iterator, bool> result =
324     this->input_sections_.insert(Section_id(relobj, shndx));
325   // We should insert a merge section once only.
326   gold_assert(result.second);
327 }
328
329 // Class Output_merge_data.
330
331 // Compute the hash code for a fixed-size constant.
332
333 size_t
334 Output_merge_data::Merge_data_hash::operator()(Merge_data_key k) const
335 {
336   const unsigned char* p = this->pomd_->constant(k);
337   section_size_type entsize =
338     convert_to_section_size_type(this->pomd_->entsize());
339
340   // Fowler/Noll/Vo (FNV) hash (type FNV-1a).
341   if (sizeof(size_t) == 8)
342     {
343       size_t result = static_cast<size_t>(14695981039346656037ULL);
344       for (section_size_type i = 0; i < entsize; ++i)
345         {
346           result &= (size_t) *p++;
347           result *= 1099511628211ULL;
348         }
349       return result;
350     }
351   else
352     {
353       size_t result = 2166136261UL;
354       for (section_size_type i = 0; i < entsize; ++i)
355         {
356           result ^= (size_t) *p++;
357           result *= 16777619UL;
358         }
359       return result;
360     }
361 }
362
363 // Return whether one hash table key equals another.
364
365 bool
366 Output_merge_data::Merge_data_eq::operator()(Merge_data_key k1,
367                                              Merge_data_key k2) const
368 {
369   const unsigned char* p1 = this->pomd_->constant(k1);
370   const unsigned char* p2 = this->pomd_->constant(k2);
371   return memcmp(p1, p2, this->pomd_->entsize()) == 0;
372 }
373
374 // Add a constant to the end of the section contents.
375
376 void
377 Output_merge_data::add_constant(const unsigned char* p)
378 {
379   section_size_type entsize = convert_to_section_size_type(this->entsize());
380   section_size_type addralign =
381     convert_to_section_size_type(this->addralign());
382   section_size_type addsize = std::max(entsize, addralign);
383   if (this->len_ + addsize > this->alc_)
384     {
385       if (this->alc_ == 0)
386         this->alc_ = 128 * addsize;
387       else
388         this->alc_ *= 2;
389       this->p_ = static_cast<unsigned char*>(realloc(this->p_, this->alc_));
390       if (this->p_ == NULL)
391         gold_nomem();
392     }
393
394   memcpy(this->p_ + this->len_, p, entsize);
395   if (addsize > entsize)
396     memset(this->p_ + this->len_ + entsize, 0, addsize - entsize);
397   this->len_ += addsize;
398 }
399
400 // Add the input section SHNDX in OBJECT to a merged output section
401 // which holds fixed length constants.  Return whether we were able to
402 // handle the section; if not, it will be linked as usual without
403 // constant merging.
404
405 bool
406 Output_merge_data::do_add_input_section(Relobj* object, unsigned int shndx)
407 {
408   section_size_type len;
409   section_size_type uncompressed_size = 0;
410   unsigned char* uncompressed_data = NULL;
411   const unsigned char* p = object->section_contents(shndx, &len, false);
412
413   if (object->section_is_compressed(shndx, &uncompressed_size))
414     {
415       uncompressed_data = new unsigned char[uncompressed_size];
416       if (!decompress_input_section(p, len, uncompressed_data,
417                                     uncompressed_size))
418         object->error(_("could not decompress section %s"),
419                       object->section_name(shndx).c_str());
420       p = uncompressed_data;
421       len = uncompressed_size;
422     }
423
424   section_size_type entsize = convert_to_section_size_type(this->entsize());
425
426   if (len % entsize != 0)
427     {
428       if (uncompressed_data != NULL)
429         delete[] uncompressed_data;
430       return false;
431     }
432
433   this->input_count_ += len / entsize;
434
435   for (section_size_type i = 0; i < len; i += entsize, p += entsize)
436     {
437       // Add the constant to the section contents.  If we find that it
438       // is already in the hash table, we will remove it again.
439       Merge_data_key k = this->len_;
440       this->add_constant(p);
441
442       std::pair<Merge_data_hashtable::iterator, bool> ins =
443         this->hashtable_.insert(k);
444
445       if (!ins.second)
446         {
447           // Key was already present.  Remove the copy we just added.
448           this->len_ -= entsize;
449           k = *ins.first;
450         }
451
452       // Record the offset of this constant in the output section.
453       this->add_mapping(object, shndx, i, entsize, k);
454     }
455
456   // For script processing, we keep the input sections.
457   if (this->keeps_input_sections())
458     record_input_section(object, shndx);
459
460   if (uncompressed_data != NULL)
461     delete[] uncompressed_data;
462
463   return true;
464 }
465
466 // Set the final data size in a merged output section with fixed size
467 // constants.
468
469 void
470 Output_merge_data::set_final_data_size()
471 {
472   // Release the memory we don't need.
473   this->p_ = static_cast<unsigned char*>(realloc(this->p_, this->len_));
474   // An Output_merge_data object may be empty and realloc is allowed
475   // to return a NULL pointer in this case.  An Output_merge_data is empty
476   // if all its input sections have sizes that are not multiples of entsize.
477   gold_assert(this->p_ != NULL || this->len_ == 0);
478   this->set_data_size(this->len_);
479 }
480
481 // Write the data of a merged output section with fixed size constants
482 // to the file.
483
484 void
485 Output_merge_data::do_write(Output_file* of)
486 {
487   of->write(this->offset(), this->p_, this->len_);
488 }
489
490 // Write the data to a buffer.
491
492 void
493 Output_merge_data::do_write_to_buffer(unsigned char* buffer)
494 {
495   memcpy(buffer, this->p_, this->len_);
496 }
497
498 // Print merge stats to stderr.
499
500 void
501 Output_merge_data::do_print_merge_stats(const char* section_name)
502 {
503   fprintf(stderr,
504           _("%s: %s merged constants size: %lu; input: %zu; output: %zu\n"),
505           program_name, section_name,
506           static_cast<unsigned long>(this->entsize()),
507           this->input_count_, this->hashtable_.size());
508 }
509
510 // Class Output_merge_string.
511
512 // Add an input section to a merged string section.
513
514 template<typename Char_type>
515 bool
516 Output_merge_string<Char_type>::do_add_input_section(Relobj* object,
517                                                      unsigned int shndx)
518 {
519   section_size_type len;
520   section_size_type uncompressed_size = 0;
521   unsigned char* uncompressed_data = NULL;
522   const unsigned char* pdata = object->section_contents(shndx, &len, false);
523
524   if (object->section_is_compressed(shndx, &uncompressed_size))
525     {
526       uncompressed_data = new unsigned char[uncompressed_size];
527       if (!decompress_input_section(pdata, len, uncompressed_data,
528                                     uncompressed_size))
529         object->error(_("could not decompress section %s"),
530                       object->section_name(shndx).c_str());
531       pdata = uncompressed_data;
532       len = uncompressed_size;
533     }
534
535   const Char_type* p = reinterpret_cast<const Char_type*>(pdata);
536   const Char_type* pend = p + len / sizeof(Char_type);
537   const Char_type* pend0 = pend;
538
539   if (len % sizeof(Char_type) != 0)
540     {
541       object->error(_("mergeable string section length not multiple of "
542                       "character size"));
543       if (uncompressed_data != NULL)
544         delete[] uncompressed_data;
545       return false;
546     }
547
548   if (pend[-1] != 0)
549     {
550       gold_warning(_("%s: last entry in mergeable string section '%s' "
551                      "not null terminated"),
552                    object->name().c_str(),
553                    object->section_name(shndx).c_str());
554       // Find the end of the last NULL-terminated string in the buffer.
555       while (pend0 > p && pend0[-1] != 0)
556         --pend0;
557     }
558
559   Merged_strings_list* merged_strings_list =
560       new Merged_strings_list(object, shndx);
561   this->merged_strings_lists_.push_back(merged_strings_list);
562   Merged_strings& merged_strings = merged_strings_list->merged_strings;
563
564   // Count the number of strings in the section and size the list.
565   size_t count = 0;
566   for (const Char_type* pt = p; pt < pend0; pt += string_length(pt) + 1)
567     ++count;
568   if (pend0 < pend)
569     ++count;
570   merged_strings.reserve(count + 1);
571
572   // The index I is in bytes, not characters.
573   section_size_type i = 0;
574   while (p < pend0)
575     {
576       size_t len = string_length(p);
577
578       Stringpool::Key key;
579       this->stringpool_.add_with_length(p, len, true, &key);
580
581       merged_strings.push_back(Merged_string(i, key));
582
583       p += len + 1;
584       i += (len + 1) * sizeof(Char_type);
585     }
586   if (p < pend)
587     {
588       size_t len = pend - p;
589
590       Stringpool::Key key;
591       this->stringpool_.add_with_length(p, len, true, &key);
592
593       merged_strings.push_back(Merged_string(i, key));
594
595       i += (len + 1) * sizeof(Char_type);
596     }
597
598   // Record the last offset in the input section so that we can
599   // compute the length of the last string.
600   merged_strings.push_back(Merged_string(i, 0));
601
602   this->input_count_ += count;
603   this->input_size_ += len;
604
605   // For script processing, we keep the input sections.
606   if (this->keeps_input_sections())
607     record_input_section(object, shndx);
608
609   if (uncompressed_data != NULL)
610     delete[] uncompressed_data;
611
612   return true;
613 }
614
615 // Finalize the mappings from the input sections to the output
616 // section, and return the final data size.
617
618 template<typename Char_type>
619 section_size_type
620 Output_merge_string<Char_type>::finalize_merged_data()
621 {
622   this->stringpool_.set_string_offsets();
623
624   for (typename Merged_strings_lists::const_iterator l =
625          this->merged_strings_lists_.begin();
626        l != this->merged_strings_lists_.end();
627        ++l)
628     {
629       section_offset_type last_input_offset = 0;
630       section_offset_type last_output_offset = 0;
631       for (typename Merged_strings::const_iterator p =
632              (*l)->merged_strings.begin();
633            p != (*l)->merged_strings.end();
634            ++p)
635         {
636           section_size_type length = p->offset - last_input_offset;
637           if (length > 0)
638             this->add_mapping((*l)->object, (*l)->shndx, last_input_offset,
639                               length, last_output_offset);
640           last_input_offset = p->offset;
641           if (p->stringpool_key != 0)
642             last_output_offset =
643                 this->stringpool_.get_offset_from_key(p->stringpool_key);
644         }
645       delete *l;
646     }
647
648   // Save some memory.  This also ensures that this function will work
649   // if called twice, as may happen if Layout::set_segment_offsets
650   // finds a better alignment.
651   this->merged_strings_lists_.clear();
652
653   return this->stringpool_.get_strtab_size();
654 }
655
656 template<typename Char_type>
657 void
658 Output_merge_string<Char_type>::set_final_data_size()
659 {
660   const off_t final_data_size = this->finalize_merged_data();
661   this->set_data_size(final_data_size);
662 }
663
664 // Write out a merged string section.
665
666 template<typename Char_type>
667 void
668 Output_merge_string<Char_type>::do_write(Output_file* of)
669 {
670   this->stringpool_.write(of, this->offset());
671 }
672
673 // Write a merged string section to a buffer.
674
675 template<typename Char_type>
676 void
677 Output_merge_string<Char_type>::do_write_to_buffer(unsigned char* buffer)
678 {
679   this->stringpool_.write_to_buffer(buffer, this->data_size());
680 }
681
682 // Return the name of the types of string to use with
683 // do_print_merge_stats.
684
685 template<typename Char_type>
686 const char*
687 Output_merge_string<Char_type>::string_name()
688 {
689   gold_unreachable();
690   return NULL;
691 }
692
693 template<>
694 const char*
695 Output_merge_string<char>::string_name()
696 {
697   return "strings";
698 }
699
700 template<>
701 const char*
702 Output_merge_string<uint16_t>::string_name()
703 {
704   return "16-bit strings";
705 }
706
707 template<>
708 const char*
709 Output_merge_string<uint32_t>::string_name()
710 {
711   return "32-bit strings";
712 }
713
714 // Print merge stats to stderr.
715
716 template<typename Char_type>
717 void
718 Output_merge_string<Char_type>::do_print_merge_stats(const char* section_name)
719 {
720   char buf[200];
721   snprintf(buf, sizeof buf, "%s merged %s", section_name, this->string_name());
722   fprintf(stderr, _("%s: %s input bytes: %zu\n"),
723           program_name, buf, this->input_size_);
724   fprintf(stderr, _("%s: %s input strings: %zu\n"),
725           program_name, buf, this->input_count_);
726   this->stringpool_.print_stats(buf);
727 }
728
729 // Instantiate the templates we need.
730
731 template
732 class Output_merge_string<char>;
733
734 template
735 class Output_merge_string<uint16_t>;
736
737 template
738 class Output_merge_string<uint32_t>;
739
740 #if defined(HAVE_TARGET_32_LITTLE) || defined(HAVE_TARGET_32_BIG)
741 template
742 void
743 Object_merge_map::initialize_input_to_output_map<32>(
744     unsigned int shndx,
745     elfcpp::Elf_types<32>::Elf_Addr starting_address,
746     Unordered_map<section_offset_type, elfcpp::Elf_types<32>::Elf_Addr>*);
747 #endif
748
749 #if defined(HAVE_TARGET_64_LITTLE) || defined(HAVE_TARGET_64_BIG)
750 template
751 void
752 Object_merge_map::initialize_input_to_output_map<64>(
753     unsigned int shndx,
754     elfcpp::Elf_types<64>::Elf_Addr starting_address,
755     Unordered_map<section_offset_type, elfcpp::Elf_types<64>::Elf_Addr>*);
756 #endif
757
758 } // End namespace gold.