Merge branch 'vendor/GCC44'
[dragonfly.git] / contrib / binutils-2.21 / 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.