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