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[/] [openrisc/] [trunk/] [gnu-src/] [binutils-2.20.1/] [gold/] [merge.h] - Blame information for rev 438

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// merge.h -- handle section merging for gold  -*- C++ -*-
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// Copyright 2006, 2007, 2008 Free Software Foundation, Inc.
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// Written by Ian Lance Taylor <iant@google.com>.
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6
// This file is part of gold.
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8
// This program is free software; you can redistribute it and/or modify
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// it under the terms of the GNU General Public License as published by
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// the Free Software Foundation; either version 3 of the License, or
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// (at your option) any later version.
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13
// This program is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
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// GNU General Public License for more details.
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18
// You should have received a copy of the GNU General Public License
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// along with this program; if not, write to the Free Software
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// Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,
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// MA 02110-1301, USA.
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23
#ifndef GOLD_MERGE_H
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#define GOLD_MERGE_H
25
 
26
#include <climits>
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#include <map>
28
#include <vector>
29
 
30
#include "stringpool.h"
31
#include "output.h"
32
 
33
namespace gold
34
{
35
 
36
class Merge_map;
37
 
38
// For each object with merge sections, we store an Object_merge_map.
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// This is used to map locations in input sections to a merged output
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// section.  The output section itself is not recorded here--it can be
41
// found in the output_sections_ field of the Object.
42
 
43
class Object_merge_map
44
{
45
 public:
46
  Object_merge_map()
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    : first_shnum_(-1U), first_map_(),
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      second_shnum_(-1U), second_map_(),
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      section_merge_maps_()
50
  { }
51
 
52
  ~Object_merge_map();
53
 
54
  // Add a mapping for MERGE_MAP, for the bytes from OFFSET to OFFSET
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  // + LENGTH in the input section SHNDX to OUTPUT_OFFSET in the
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  // output section.  An OUTPUT_OFFSET of -1 means that the bytes are
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  // discarded.  OUTPUT_OFFSET is relative to the start of the merged
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  // data in the output section.
59
  void
60
  add_mapping(const Merge_map*, unsigned int shndx, section_offset_type offset,
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              section_size_type length, section_offset_type output_offset);
62
 
63
  // Get the output offset for an input address.  MERGE_MAP is the map
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  // we are looking for, or NULL if we don't care.  The input address
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  // is at offset OFFSET in section SHNDX.  This sets *OUTPUT_OFFSET
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  // to the offset in the output section; this will be -1 if the bytes
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  // are not being copied to the output.  This returns true if the
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  // mapping is known, false otherwise.  *OUTPUT_OFFSET is relative to
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  // the start of the merged data in the output section.
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  bool
71
  get_output_offset(const Merge_map*, unsigned int shndx,
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                    section_offset_type offset,
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                    section_offset_type *output_offset);
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75
  // Return whether this is the merge map for section SHNDX.
76
  bool
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  is_merge_section_for(const Merge_map*, unsigned int shndx);
78
 
79
  // Initialize an mapping from input offsets to output addresses for
80
  // section SHNDX.  STARTING_ADDRESS is the output address of the
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  // merged section.
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  template<int size>
83
  void
84
  initialize_input_to_output_map(
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      unsigned int shndx,
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      typename elfcpp::Elf_types<size>::Elf_Addr starting_address,
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      Unordered_map<section_offset_type,
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                    typename elfcpp::Elf_types<size>::Elf_Addr>*);
89
 
90
 private:
91
  // Map input section offsets to a length and an output section
92
  // offset.  An output section offset of -1 means that this part of
93
  // the input section is being discarded.
94
  struct Input_merge_entry
95
  {
96
    // The offset in the input section.
97
    section_offset_type input_offset;
98
    // The length.
99
    section_size_type length;
100
    // The offset in the output section.
101
    section_offset_type output_offset;
102
  };
103
 
104
  // A less-than comparison routine for Input_merge_entry.
105
  struct Input_merge_compare
106
  {
107
    bool
108
    operator()(const Input_merge_entry& i1, const Input_merge_entry& i2) const
109
    { return i1.input_offset < i2.input_offset; }
110
  };
111
 
112
  // A list of entries for a particular input section.
113
  struct Input_merge_map
114
  {
115
    typedef std::vector<Input_merge_entry> Entries;
116
 
117
    // We store these with the Relobj, and we look them up by input
118
    // section.  It is possible to have two different merge maps
119
    // associated with a single output section.  For example, this
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    // happens routinely with .rodata, when merged string constants
121
    // and merged fixed size constants are both put into .rodata.  The
122
    // output offset that we store is not the offset from the start of
123
    // the output section; it is the offset from the start of the
124
    // merged data in the output section.  That means that the caller
125
    // is going to add the offset of the merged data within the output
126
    // section, which means that the caller needs to know which set of
127
    // merged data it found the entry in.  So it's not enough to find
128
    // this data based on the input section and the output section; we
129
    // also have to find it based on a set of merged data in the
130
    // output section.  In order to verify that we are looking at the
131
    // right data, we store a pointer to the Merge_map here, and we
132
    // pass in a pointer when looking at the data.  If we are asked to
133
    // look up information for a different Merge_map, we report that
134
    // we don't have it, rather than trying a lookup and returning an
135
    // answer which will receive the wrong offset.
136
    const Merge_map* merge_map;
137
    // The list of mappings.
138
    Entries entries;
139
    // Whether the ENTRIES field is sorted by input_offset.
140
    bool sorted;
141
 
142
    Input_merge_map()
143
      : merge_map(NULL), entries(), sorted(true)
144
    { }
145
  };
146
 
147
  // Map input section indices to merge maps.
148
  typedef std::map<unsigned int, Input_merge_map*> Section_merge_maps;
149
 
150
  // Return a pointer to the Input_merge_map to use for the input
151
  // section SHNDX, or NULL.
152
  Input_merge_map*
153
  get_input_merge_map(unsigned int shndx);
154
 
155
  // Get or make the the Input_merge_map to use for the section SHNDX
156
  // with MERGE_MAP.
157
  Input_merge_map*
158
  get_or_make_input_merge_map(const Merge_map* merge_map, unsigned int shndx);
159
 
160
  // Any given object file will normally only have a couple of input
161
  // sections with mergeable contents.  So we keep the first two input
162
  // section numbers inline, and push any further ones into a map.  A
163
  // value of -1U in first_shnum_ or second_shnum_ means that we don't
164
  // have a corresponding entry.
165
  unsigned int first_shnum_;
166
  Input_merge_map first_map_;
167
  unsigned int second_shnum_;
168
  Input_merge_map second_map_;
169
  Section_merge_maps section_merge_maps_;
170
};
171
 
172
// This class manages mappings from input sections to offsets in an
173
// output section.  This is used where input sections are merged.  The
174
// actual data is stored in fields in Object.
175
 
176
class Merge_map
177
{
178
 public:
179
  Merge_map()
180
  { }
181
 
182
  // Add a mapping for the bytes from OFFSET to OFFSET + LENGTH in the
183
  // input section SHNDX in object OBJECT to OUTPUT_OFFSET in the
184
  // output section.  An OUTPUT_OFFSET of -1 means that the bytes are
185
  // discarded.  OUTPUT_OFFSET is not the offset from the start of the
186
  // output section, it is the offset from the start of the merged
187
  // data within the output section.
188
  void
189
  add_mapping(Relobj* object, unsigned int shndx,
190
              section_offset_type offset, section_size_type length,
191
              section_offset_type output_offset);
192
 
193
  // Return the output offset for an input address.  The input address
194
  // is at offset OFFSET in section SHNDX in OBJECT.  This sets
195
  // *OUTPUT_OFFSET to the offset in the output section; this will be
196
  // -1 if the bytes are not being copied to the output.  This returns
197
  // true if the mapping is known, false otherwise.  This returns the
198
  // value stored by add_mapping, namely the offset from the start of
199
  // the merged data within the output section.
200
  bool
201
  get_output_offset(const Relobj* object, unsigned int shndx,
202
                    section_offset_type offset,
203
                    section_offset_type *output_offset) const;
204
 
205
  // Return whether this is the merge mapping for section SHNDX in
206
  // OBJECT.  This should return true when get_output_offset would
207
  // return true for some input offset.
208
  bool
209
  is_merge_section_for(const Relobj* object, unsigned int shndx) const;
210
};
211
 
212
// A general class for SHF_MERGE data, to hold functions shared by
213
// fixed-size constant data and string data.
214
 
215
class Output_merge_base : public Output_section_data
216
{
217
 public:
218
  Output_merge_base(uint64_t entsize, uint64_t addralign)
219
    : Output_section_data(addralign), merge_map_(), entsize_(entsize)
220
  { }
221
 
222
  // Return the entry size.
223
  uint64_t
224
  entsize() const
225
  { return this->entsize_; }
226
 
227
  // Whether this is a merge string section.  This is only true of
228
  // Output_merge_string.
229
  bool
230
  is_string()
231
  { return this->do_is_string(); }
232
 
233
 protected:
234
  // Return the output offset for an input offset.
235
  bool
236
  do_output_offset(const Relobj* object, unsigned int shndx,
237
                   section_offset_type offset,
238
                   section_offset_type* poutput) const;
239
 
240
  // Return whether this is the merge section for an input section.
241
  bool
242
  do_is_merge_section_for(const Relobj*, unsigned int shndx) const;
243
 
244
  // Add a mapping from an OFFSET in input section SHNDX in object
245
  // OBJECT to an OUTPUT_OFFSET in the output section.  OUTPUT_OFFSET
246
  // is the offset from the start of the merged data in the output
247
  // section.
248
  void
249
  add_mapping(Relobj* object, unsigned int shndx, section_offset_type offset,
250
              section_size_type length, section_offset_type output_offset)
251
  {
252
    this->merge_map_.add_mapping(object, shndx, offset, length, output_offset);
253
  }
254
 
255
  // This may be overriden by the child class.
256
  virtual bool
257
  do_is_string()
258
  { return false; }
259
 
260
 private:
261
  // A mapping from input object/section/offset to offset in output
262
  // section.
263
  Merge_map merge_map_;
264
  // The entry size.  For fixed-size constants, this is the size of
265
  // the constants.  For strings, this is the size of a character.
266
  uint64_t entsize_;
267
};
268
 
269
// Handle SHF_MERGE sections with fixed-size constant data.
270
 
271
class Output_merge_data : public Output_merge_base
272
{
273
 public:
274
  Output_merge_data(uint64_t entsize, uint64_t addralign)
275
    : Output_merge_base(entsize, addralign), p_(NULL), len_(0), alc_(0),
276
      input_count_(0),
277
      hashtable_(128, Merge_data_hash(this), Merge_data_eq(this))
278
  { }
279
 
280
 protected:
281
  // Add an input section.
282
  bool
283
  do_add_input_section(Relobj* object, unsigned int shndx);
284
 
285
  // Set the final data size.
286
  void
287
  set_final_data_size();
288
 
289
  // Write the data to the file.
290
  void
291
  do_write(Output_file*);
292
 
293
  // Write the data to a buffer.
294
  void
295
  do_write_to_buffer(unsigned char*);
296
 
297
  // Write to a map file.
298
  void
299
  do_print_to_mapfile(Mapfile* mapfile) const
300
  { mapfile->print_output_data(this, _("** merge constants")); }
301
 
302
  // Print merge stats to stderr.
303
  void
304
  do_print_merge_stats(const char* section_name);
305
 
306
 private:
307
  // We build a hash table of the fixed-size constants.  Each constant
308
  // is stored as a pointer into the section data we are accumulating.
309
 
310
  // A key in the hash table.  This is an offset in the section
311
  // contents we are building.
312
  typedef section_offset_type Merge_data_key;
313
 
314
  // Compute the hash code.  To do this we need a pointer back to the
315
  // object holding the data.
316
  class Merge_data_hash
317
  {
318
   public:
319
    Merge_data_hash(const Output_merge_data* pomd)
320
      : pomd_(pomd)
321
    { }
322
 
323
    size_t
324
    operator()(Merge_data_key) const;
325
 
326
   private:
327
    const Output_merge_data* pomd_;
328
  };
329
 
330
  friend class Merge_data_hash;
331
 
332
  // Compare two entries in the hash table for equality.  To do this
333
  // we need a pointer back to the object holding the data.  Note that
334
  // we now have a pointer to the object stored in two places in the
335
  // hash table.  Fixing this would require specializing the hash
336
  // table, which would be hard to do portably.
337
  class Merge_data_eq
338
  {
339
   public:
340
    Merge_data_eq(const Output_merge_data* pomd)
341
      : pomd_(pomd)
342
    { }
343
 
344
    bool
345
    operator()(Merge_data_key k1, Merge_data_key k2) const;
346
 
347
   private:
348
    const Output_merge_data* pomd_;
349
  };
350
 
351
  friend class Merge_data_eq;
352
 
353
  // The type of the hash table.
354
  typedef Unordered_set<Merge_data_key, Merge_data_hash, Merge_data_eq>
355
    Merge_data_hashtable;
356
 
357
  // Given a hash table key, which is just an offset into the section
358
  // data, return a pointer to the corresponding constant.
359
  const unsigned char*
360
  constant(Merge_data_key k) const
361
  {
362
    gold_assert(k >= 0 && k < static_cast<section_offset_type>(this->len_));
363
    return this->p_ + k;
364
  }
365
 
366
  // Add a constant to the output.
367
  void
368
  add_constant(const unsigned char*);
369
 
370
  // The accumulated data.
371
  unsigned char* p_;
372
  // The length of the accumulated data.
373
  section_size_type len_;
374
  // The size of the allocated buffer.
375
  section_size_type alc_;
376
  // The number of entries seen in input files.
377
  size_t input_count_;
378
  // The hash table.
379
  Merge_data_hashtable hashtable_;
380
};
381
 
382
// Handle SHF_MERGE sections with string data.  This is a template
383
// based on the type of the characters in the string.
384
 
385
template<typename Char_type>
386
class Output_merge_string : public Output_merge_base
387
{
388
 public:
389
  Output_merge_string(uint64_t addralign)
390
    : Output_merge_base(sizeof(Char_type), addralign), stringpool_(),
391
      merged_strings_(), input_count_(0)
392
  {
393
    gold_assert(addralign <= sizeof(Char_type));
394
    this->stringpool_.set_no_zero_null();
395
  }
396
 
397
 protected:
398
  // Add an input section.
399
  bool
400
  do_add_input_section(Relobj* object, unsigned int shndx);
401
 
402
  // Do all the final processing after the input sections are read in.
403
  // Returns the final data size.
404
  section_size_type
405
  finalize_merged_data();
406
 
407
  // Set the final data size.
408
  void
409
  set_final_data_size();
410
 
411
  // Write the data to the file.
412
  void
413
  do_write(Output_file*);
414
 
415
  // Write the data to a buffer.
416
  void
417
  do_write_to_buffer(unsigned char*);
418
 
419
  // Write to a map file.
420
  void
421
  do_print_to_mapfile(Mapfile* mapfile) const
422
  { mapfile->print_output_data(this, _("** merge strings")); }
423
 
424
  // Print merge stats to stderr.
425
  void
426
  do_print_merge_stats(const char* section_name);
427
 
428
  // Writes the stringpool to a buffer.
429
  void
430
  stringpool_to_buffer(unsigned char* buffer, section_size_type buffer_size)
431
  { this->stringpool_.write_to_buffer(buffer, buffer_size); }
432
 
433
  // Clears all the data in the stringpool, to save on memory.
434
  void
435
  clear_stringpool()
436
  { this->stringpool_.clear(); }
437
 
438
  // Whether this is a merge string section.
439
  virtual bool
440
  do_is_string()
441
  { return true; }
442
 
443
 private:
444
  // The name of the string type, for stats.
445
  const char*
446
  string_name();
447
 
448
  // As we see input sections, we build a mapping from object, section
449
  // index and offset to strings.
450
  struct Merged_string
451
  {
452
    // The input object where the string was found.
453
    Relobj* object;
454
    // The input section in the input object.
455
    unsigned int shndx;
456
    // The offset in the input section.
457
    section_offset_type offset;
458
    // The string itself, a pointer into a Stringpool.
459
    const Char_type* string;
460
    // The length of the string in bytes, including the null terminator.
461
    size_t length;
462
    // The key in the Stringpool.
463
    Stringpool::Key stringpool_key;
464
 
465
    Merged_string(Relobj *objecta, unsigned int shndxa,
466
                  section_offset_type offseta, const Char_type* stringa,
467
                  size_t lengtha, Stringpool::Key stringpool_keya)
468
      : object(objecta), shndx(shndxa), offset(offseta), string(stringa),
469
        length(lengtha), stringpool_key(stringpool_keya)
470
    { }
471
  };
472
 
473
  typedef std::vector<Merged_string> Merged_strings;
474
 
475
  // As we see the strings, we add them to a Stringpool.
476
  Stringpool_template<Char_type> stringpool_;
477
  // Map from a location in an input object to an entry in the
478
  // Stringpool.
479
  Merged_strings merged_strings_;
480
  // The number of entries seen in input files.
481
  size_t input_count_;
482
};
483
 
484
} // End namespace gold.
485
 
486
#endif // !defined(GOLD_MERGE_H)

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