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[/] [open8_urisc/] [trunk/] [gnu/] [binutils/] [gold/] [dwarf_reader.cc] - Blame information for rev 98

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// dwarf_reader.cc -- parse dwarf2/3 debug information
2
 
3
// Copyright 2007, 2008, 2009, 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 <algorithm>
26
#include <vector>
27
 
28
#include "elfcpp_swap.h"
29
#include "dwarf.h"
30
#include "object.h"
31
#include "parameters.h"
32
#include "reloc.h"
33
#include "dwarf_reader.h"
34
#include "int_encoding.h"
35
#include "compressed_output.h"
36
 
37
namespace gold {
38
 
39
struct LineStateMachine
40
{
41
  int file_num;
42
  uint64_t address;
43
  int line_num;
44
  int column_num;
45
  unsigned int shndx;    // the section address refers to
46
  bool is_stmt;          // stmt means statement.
47
  bool basic_block;
48
  bool end_sequence;
49
};
50
 
51
static void
52
ResetLineStateMachine(struct LineStateMachine* lsm, bool default_is_stmt)
53
{
54
  lsm->file_num = 1;
55
  lsm->address = 0;
56
  lsm->line_num = 1;
57
  lsm->column_num = 0;
58
  lsm->shndx = -1U;
59
  lsm->is_stmt = default_is_stmt;
60
  lsm->basic_block = false;
61
  lsm->end_sequence = false;
62
}
63
 
64
template<int size, bool big_endian>
65
Sized_dwarf_line_info<size, big_endian>::Sized_dwarf_line_info(Object* object,
66
                                                               unsigned int read_shndx)
67
  : data_valid_(false), buffer_(NULL), symtab_buffer_(NULL),
68
    directories_(), files_(), current_header_index_(-1)
69
{
70
  unsigned int debug_shndx;
71
  for (debug_shndx = 1; debug_shndx < object->shnum(); ++debug_shndx)
72
    {
73
      // FIXME: do this more efficiently: section_name() isn't super-fast
74
      std::string name = object->section_name(debug_shndx);
75
      if (name == ".debug_line" || name == ".zdebug_line")
76
        {
77
          section_size_type buffer_size;
78
          this->buffer_ = object->section_contents(debug_shndx, &buffer_size,
79
                                                   false);
80
          this->buffer_end_ = this->buffer_ + buffer_size;
81
          break;
82
        }
83
    }
84
  if (this->buffer_ == NULL)
85
    return;
86
 
87
  section_size_type uncompressed_size = 0;
88
  unsigned char* uncompressed_data = NULL;
89
  if (object->section_is_compressed(debug_shndx, &uncompressed_size))
90
    {
91
      uncompressed_data = new unsigned char[uncompressed_size];
92
      if (!decompress_input_section(this->buffer_,
93
                                    this->buffer_end_ - this->buffer_,
94
                                    uncompressed_data,
95
                                    uncompressed_size))
96
        object->error(_("could not decompress section %s"),
97
                      object->section_name(debug_shndx).c_str());
98
      this->buffer_ = uncompressed_data;
99
      this->buffer_end_ = this->buffer_ + uncompressed_size;
100
    }
101
 
102
  // Find the relocation section for ".debug_line".
103
  // We expect these for relobjs (.o's) but not dynobjs (.so's).
104
  bool got_relocs = false;
105
  for (unsigned int reloc_shndx = 0;
106
       reloc_shndx < object->shnum();
107
       ++reloc_shndx)
108
    {
109
      unsigned int reloc_sh_type = object->section_type(reloc_shndx);
110
      if ((reloc_sh_type == elfcpp::SHT_REL
111
           || reloc_sh_type == elfcpp::SHT_RELA)
112
          && object->section_info(reloc_shndx) == debug_shndx)
113
        {
114
          got_relocs = this->track_relocs_.initialize(object, reloc_shndx,
115
                                                      reloc_sh_type);
116
          this->track_relocs_type_ = reloc_sh_type;
117
          break;
118
        }
119
    }
120
 
121
  // Finally, we need the symtab section to interpret the relocs.
122
  if (got_relocs)
123
    {
124
      unsigned int symtab_shndx;
125
      for (symtab_shndx = 0; symtab_shndx < object->shnum(); ++symtab_shndx)
126
        if (object->section_type(symtab_shndx) == elfcpp::SHT_SYMTAB)
127
          {
128
            this->symtab_buffer_ = object->section_contents(
129
                symtab_shndx, &this->symtab_buffer_size_, false);
130
            break;
131
          }
132
      if (this->symtab_buffer_ == NULL)
133
        return;
134
    }
135
 
136
  // Now that we have successfully read all the data, parse the debug
137
  // info.
138
  this->data_valid_ = true;
139
  this->read_line_mappings(object, read_shndx);
140
}
141
 
142
// Read the DWARF header.
143
 
144
template<int size, bool big_endian>
145
const unsigned char*
146
Sized_dwarf_line_info<size, big_endian>::read_header_prolog(
147
    const unsigned char* lineptr)
148
{
149
  uint32_t initial_length = elfcpp::Swap_unaligned<32, big_endian>::readval(lineptr);
150
  lineptr += 4;
151
 
152
  // In DWARF2/3, if the initial length is all 1 bits, then the offset
153
  // size is 8 and we need to read the next 8 bytes for the real length.
154
  if (initial_length == 0xffffffff)
155
    {
156
      header_.offset_size = 8;
157
      initial_length = elfcpp::Swap_unaligned<64, big_endian>::readval(lineptr);
158
      lineptr += 8;
159
    }
160
  else
161
    header_.offset_size = 4;
162
 
163
  header_.total_length = initial_length;
164
 
165
  gold_assert(lineptr + header_.total_length <= buffer_end_);
166
 
167
  header_.version = elfcpp::Swap_unaligned<16, big_endian>::readval(lineptr);
168
  lineptr += 2;
169
 
170
  if (header_.offset_size == 4)
171
    header_.prologue_length = elfcpp::Swap_unaligned<32, big_endian>::readval(lineptr);
172
  else
173
    header_.prologue_length = elfcpp::Swap_unaligned<64, big_endian>::readval(lineptr);
174
  lineptr += header_.offset_size;
175
 
176
  header_.min_insn_length = *lineptr;
177
  lineptr += 1;
178
 
179
  header_.default_is_stmt = *lineptr;
180
  lineptr += 1;
181
 
182
  header_.line_base = *reinterpret_cast<const signed char*>(lineptr);
183
  lineptr += 1;
184
 
185
  header_.line_range = *lineptr;
186
  lineptr += 1;
187
 
188
  header_.opcode_base = *lineptr;
189
  lineptr += 1;
190
 
191
  header_.std_opcode_lengths.resize(header_.opcode_base + 1);
192
  header_.std_opcode_lengths[0] = 0;
193
  for (int i = 1; i < header_.opcode_base; i++)
194
    {
195
      header_.std_opcode_lengths[i] = *lineptr;
196
      lineptr += 1;
197
    }
198
 
199
  return lineptr;
200
}
201
 
202
// The header for a debug_line section is mildly complicated, because
203
// the line info is very tightly encoded.
204
 
205
template<int size, bool big_endian>
206
const unsigned char*
207
Sized_dwarf_line_info<size, big_endian>::read_header_tables(
208
    const unsigned char* lineptr)
209
{
210
  ++this->current_header_index_;
211
 
212
  // Create a new directories_ entry and a new files_ entry for our new
213
  // header.  We initialize each with a single empty element, because
214
  // dwarf indexes directory and filenames starting at 1.
215
  gold_assert(static_cast<int>(this->directories_.size())
216
              == this->current_header_index_);
217
  gold_assert(static_cast<int>(this->files_.size())
218
              == this->current_header_index_);
219
  this->directories_.push_back(std::vector<std::string>(1));
220
  this->files_.push_back(std::vector<std::pair<int, std::string> >(1));
221
 
222
  // It is legal for the directory entry table to be empty.
223
  if (*lineptr)
224
    {
225
      int dirindex = 1;
226
      while (*lineptr)
227
        {
228
          const char* dirname = reinterpret_cast<const char*>(lineptr);
229
          gold_assert(dirindex
230
                      == static_cast<int>(this->directories_.back().size()));
231
          this->directories_.back().push_back(dirname);
232
          lineptr += this->directories_.back().back().size() + 1;
233
          dirindex++;
234
        }
235
    }
236
  lineptr++;
237
 
238
  // It is also legal for the file entry table to be empty.
239
  if (*lineptr)
240
    {
241
      int fileindex = 1;
242
      size_t len;
243
      while (*lineptr)
244
        {
245
          const char* filename = reinterpret_cast<const char*>(lineptr);
246
          lineptr += strlen(filename) + 1;
247
 
248
          uint64_t dirindex = read_unsigned_LEB_128(lineptr, &len);
249
          lineptr += len;
250
 
251
          if (dirindex >= this->directories_.back().size())
252
            dirindex = 0;
253
          int dirindexi = static_cast<int>(dirindex);
254
 
255
          read_unsigned_LEB_128(lineptr, &len);   // mod_time
256
          lineptr += len;
257
 
258
          read_unsigned_LEB_128(lineptr, &len);   // filelength
259
          lineptr += len;
260
 
261
          gold_assert(fileindex
262
                      == static_cast<int>(this->files_.back().size()));
263
          this->files_.back().push_back(std::make_pair(dirindexi, filename));
264
          fileindex++;
265
        }
266
    }
267
  lineptr++;
268
 
269
  return lineptr;
270
}
271
 
272
// Process a single opcode in the .debug.line structure.
273
 
274
template<int size, bool big_endian>
275
bool
276
Sized_dwarf_line_info<size, big_endian>::process_one_opcode(
277
    const unsigned char* start, struct LineStateMachine* lsm, size_t* len)
278
{
279
  size_t oplen = 0;
280
  size_t templen;
281
  unsigned char opcode = *start;
282
  oplen++;
283
  start++;
284
 
285
  // If the opcode is great than the opcode_base, it is a special
286
  // opcode. Most line programs consist mainly of special opcodes.
287
  if (opcode >= header_.opcode_base)
288
    {
289
      opcode -= header_.opcode_base;
290
      const int advance_address = ((opcode / header_.line_range)
291
                                   * header_.min_insn_length);
292
      lsm->address += advance_address;
293
 
294
      const int advance_line = ((opcode % header_.line_range)
295
                                + header_.line_base);
296
      lsm->line_num += advance_line;
297
      lsm->basic_block = true;
298
      *len = oplen;
299
      return true;
300
    }
301
 
302
  // Otherwise, we have the regular opcodes
303
  switch (opcode)
304
    {
305
    case elfcpp::DW_LNS_copy:
306
      lsm->basic_block = false;
307
      *len = oplen;
308
      return true;
309
 
310
    case elfcpp::DW_LNS_advance_pc:
311
      {
312
        const uint64_t advance_address
313
            = read_unsigned_LEB_128(start, &templen);
314
        oplen += templen;
315
        lsm->address += header_.min_insn_length * advance_address;
316
      }
317
      break;
318
 
319
    case elfcpp::DW_LNS_advance_line:
320
      {
321
        const uint64_t advance_line = read_signed_LEB_128(start, &templen);
322
        oplen += templen;
323
        lsm->line_num += advance_line;
324
      }
325
      break;
326
 
327
    case elfcpp::DW_LNS_set_file:
328
      {
329
        const uint64_t fileno = read_unsigned_LEB_128(start, &templen);
330
        oplen += templen;
331
        lsm->file_num = fileno;
332
      }
333
      break;
334
 
335
    case elfcpp::DW_LNS_set_column:
336
      {
337
        const uint64_t colno = read_unsigned_LEB_128(start, &templen);
338
        oplen += templen;
339
        lsm->column_num = colno;
340
      }
341
      break;
342
 
343
    case elfcpp::DW_LNS_negate_stmt:
344
      lsm->is_stmt = !lsm->is_stmt;
345
      break;
346
 
347
    case elfcpp::DW_LNS_set_basic_block:
348
      lsm->basic_block = true;
349
      break;
350
 
351
    case elfcpp::DW_LNS_fixed_advance_pc:
352
      {
353
        int advance_address;
354
        advance_address = elfcpp::Swap_unaligned<16, big_endian>::readval(start);
355
        oplen += 2;
356
        lsm->address += advance_address;
357
      }
358
      break;
359
 
360
    case elfcpp::DW_LNS_const_add_pc:
361
      {
362
        const int advance_address = (header_.min_insn_length
363
                                     * ((255 - header_.opcode_base)
364
                                        / header_.line_range));
365
        lsm->address += advance_address;
366
      }
367
      break;
368
 
369
    case elfcpp::DW_LNS_extended_op:
370
      {
371
        const uint64_t extended_op_len
372
            = read_unsigned_LEB_128(start, &templen);
373
        start += templen;
374
        oplen += templen + extended_op_len;
375
 
376
        const unsigned char extended_op = *start;
377
        start++;
378
 
379
        switch (extended_op)
380
          {
381
          case elfcpp::DW_LNE_end_sequence:
382
            // This means that the current byte is the one immediately
383
            // after a set of instructions.  Record the current line
384
            // for up to one less than the current address.
385
            lsm->line_num = -1;
386
            lsm->end_sequence = true;
387
            *len = oplen;
388
            return true;
389
 
390
          case elfcpp::DW_LNE_set_address:
391
            {
392
              lsm->address =
393
                elfcpp::Swap_unaligned<size, big_endian>::readval(start);
394
              typename Reloc_map::const_iterator it
395
                  = this->reloc_map_.find(start - this->buffer_);
396
              if (it != reloc_map_.end())
397
                {
398
                  // If this is a SHT_RELA section, then ignore the
399
                  // section contents.  This assumes that this is a
400
                  // straight reloc which just uses the reloc addend.
401
                  // The reloc addend has already been included in the
402
                  // symbol value.
403
                  if (this->track_relocs_type_ == elfcpp::SHT_RELA)
404
                    lsm->address = 0;
405
                  // Add in the symbol value.
406
                  lsm->address += it->second.second;
407
                  lsm->shndx = it->second.first;
408
                }
409
              else
410
                {
411
                  // If we're a normal .o file, with relocs, every
412
                  // set_address should have an associated relocation.
413
                  if (this->input_is_relobj())
414
                    this->data_valid_ = false;
415
                }
416
              break;
417
            }
418
          case elfcpp::DW_LNE_define_file:
419
            {
420
              const char* filename  = reinterpret_cast<const char*>(start);
421
              templen = strlen(filename) + 1;
422
              start += templen;
423
 
424
              uint64_t dirindex = read_unsigned_LEB_128(start, &templen);
425
              oplen += templen;
426
 
427
              if (dirindex >= this->directories_.back().size())
428
                dirindex = 0;
429
              int dirindexi = static_cast<int>(dirindex);
430
 
431
              read_unsigned_LEB_128(start, &templen);   // mod_time
432
              oplen += templen;
433
 
434
              read_unsigned_LEB_128(start, &templen);   // filelength
435
              oplen += templen;
436
 
437
              this->files_.back().push_back(std::make_pair(dirindexi,
438
                                                           filename));
439
            }
440
            break;
441
          }
442
      }
443
      break;
444
 
445
    default:
446
      {
447
        // Ignore unknown opcode  silently
448
        for (int i = 0; i < header_.std_opcode_lengths[opcode]; i++)
449
          {
450
            size_t templen;
451
            read_unsigned_LEB_128(start, &templen);
452
            start += templen;
453
            oplen += templen;
454
          }
455
      }
456
      break;
457
  }
458
  *len = oplen;
459
  return false;
460
}
461
 
462
// Read the debug information at LINEPTR and store it in the line
463
// number map.
464
 
465
template<int size, bool big_endian>
466
unsigned const char*
467
Sized_dwarf_line_info<size, big_endian>::read_lines(unsigned const char* lineptr,
468
                                                    unsigned int shndx)
469
{
470
  struct LineStateMachine lsm;
471
 
472
  // LENGTHSTART is the place the length field is based on.  It is the
473
  // point in the header after the initial length field.
474
  const unsigned char* lengthstart = buffer_;
475
 
476
  // In 64 bit dwarf, the initial length is 12 bytes, because of the
477
  // 0xffffffff at the start.
478
  if (header_.offset_size == 8)
479
    lengthstart += 12;
480
  else
481
    lengthstart += 4;
482
 
483
  while (lineptr < lengthstart + header_.total_length)
484
    {
485
      ResetLineStateMachine(&lsm, header_.default_is_stmt);
486
      while (!lsm.end_sequence)
487
        {
488
          size_t oplength;
489
          bool add_line = this->process_one_opcode(lineptr, &lsm, &oplength);
490
          if (add_line
491
              && (shndx == -1U || lsm.shndx == -1U || shndx == lsm.shndx))
492
            {
493
              Offset_to_lineno_entry entry
494
                  = { lsm.address, this->current_header_index_,
495
                      lsm.file_num, true, lsm.line_num };
496
              std::vector<Offset_to_lineno_entry>&
497
                map(this->line_number_map_[lsm.shndx]);
498
              // If we see two consecutive entries with the same
499
              // offset and a real line number, then mark the first
500
              // one as non-canonical.
501
              if (!map.empty()
502
                  && (map.back().offset == static_cast<off_t>(lsm.address))
503
                  && lsm.line_num != -1
504
                  && map.back().line_num != -1)
505
                map.back().last_line_for_offset = false;
506
              map.push_back(entry);
507
            }
508
          lineptr += oplength;
509
        }
510
    }
511
 
512
  return lengthstart + header_.total_length;
513
}
514
 
515
// Looks in the symtab to see what section a symbol is in.
516
 
517
template<int size, bool big_endian>
518
unsigned int
519
Sized_dwarf_line_info<size, big_endian>::symbol_section(
520
    Object* object,
521
    unsigned int sym,
522
    typename elfcpp::Elf_types<size>::Elf_Addr* value,
523
    bool* is_ordinary)
524
{
525
  const int symsize = elfcpp::Elf_sizes<size>::sym_size;
526
  gold_assert(sym * symsize < this->symtab_buffer_size_);
527
  elfcpp::Sym<size, big_endian> elfsym(this->symtab_buffer_ + sym * symsize);
528
  *value = elfsym.get_st_value();
529
  return object->adjust_sym_shndx(sym, elfsym.get_st_shndx(), is_ordinary);
530
}
531
 
532
// Read the relocations into a Reloc_map.
533
 
534
template<int size, bool big_endian>
535
void
536
Sized_dwarf_line_info<size, big_endian>::read_relocs(Object* object)
537
{
538
  if (this->symtab_buffer_ == NULL)
539
    return;
540
 
541
  typename elfcpp::Elf_types<size>::Elf_Addr value;
542
  off_t reloc_offset;
543
  while ((reloc_offset = this->track_relocs_.next_offset()) != -1)
544
    {
545
      const unsigned int sym = this->track_relocs_.next_symndx();
546
 
547
      bool is_ordinary;
548
      const unsigned int shndx = this->symbol_section(object, sym, &value,
549
                                                      &is_ordinary);
550
 
551
      // There is no reason to record non-ordinary section indexes, or
552
      // SHN_UNDEF, because they will never match the real section.
553
      if (is_ordinary && shndx != elfcpp::SHN_UNDEF)
554
        {
555
          value += this->track_relocs_.next_addend();
556
          this->reloc_map_[reloc_offset] = std::make_pair(shndx, value);
557
        }
558
 
559
      this->track_relocs_.advance(reloc_offset + 1);
560
    }
561
}
562
 
563
// Read the line number info.
564
 
565
template<int size, bool big_endian>
566
void
567
Sized_dwarf_line_info<size, big_endian>::read_line_mappings(Object* object,
568
                                                            unsigned int shndx)
569
{
570
  gold_assert(this->data_valid_ == true);
571
 
572
  this->read_relocs(object);
573
  while (this->buffer_ < this->buffer_end_)
574
    {
575
      const unsigned char* lineptr = this->buffer_;
576
      lineptr = this->read_header_prolog(lineptr);
577
      lineptr = this->read_header_tables(lineptr);
578
      lineptr = this->read_lines(lineptr, shndx);
579
      this->buffer_ = lineptr;
580
    }
581
 
582
  // Sort the lines numbers, so addr2line can use binary search.
583
  for (typename Lineno_map::iterator it = line_number_map_.begin();
584
       it != line_number_map_.end();
585
       ++it)
586
    // Each vector needs to be sorted by offset.
587
    std::sort(it->second.begin(), it->second.end());
588
}
589
 
590
// Some processing depends on whether the input is a .o file or not.
591
// For instance, .o files have relocs, and have .debug_lines
592
// information on a per section basis.  .so files, on the other hand,
593
// lack relocs, and offsets are unique, so we can ignore the section
594
// information.
595
 
596
template<int size, bool big_endian>
597
bool
598
Sized_dwarf_line_info<size, big_endian>::input_is_relobj()
599
{
600
  // Only .o files have relocs and the symtab buffer that goes with them.
601
  return this->symtab_buffer_ != NULL;
602
}
603
 
604
// Given an Offset_to_lineno_entry vector, and an offset, figure out
605
// if the offset points into a function according to the vector (see
606
// comments below for the algorithm).  If it does, return an iterator
607
// into the vector that points to the line-number that contains that
608
// offset.  If not, it returns vector::end().
609
 
610
static std::vector<Offset_to_lineno_entry>::const_iterator
611
offset_to_iterator(const std::vector<Offset_to_lineno_entry>* offsets,
612
                   off_t offset)
613
{
614
  const Offset_to_lineno_entry lookup_key = { offset, 0, 0, true, 0 };
615
 
616
  // lower_bound() returns the smallest offset which is >= lookup_key.
617
  // If no offset in offsets is >= lookup_key, returns end().
618
  std::vector<Offset_to_lineno_entry>::const_iterator it
619
      = std::lower_bound(offsets->begin(), offsets->end(), lookup_key);
620
 
621
  // This code is easiest to understand with a concrete example.
622
  // Here's a possible offsets array:
623
  // {{offset = 3211, header_num = 0, file_num = 1, last, line_num = 16},  // 0
624
  //  {offset = 3224, header_num = 0, file_num = 1, last, line_num = 20},  // 1
625
  //  {offset = 3226, header_num = 0, file_num = 1, last, line_num = 22},  // 2
626
  //  {offset = 3231, header_num = 0, file_num = 1, last, line_num = 25},  // 3
627
  //  {offset = 3232, header_num = 0, file_num = 1, last, line_num = -1},  // 4
628
  //  {offset = 3232, header_num = 0, file_num = 1, last, line_num = 65},  // 5
629
  //  {offset = 3235, header_num = 0, file_num = 1, last, line_num = 66},  // 6
630
  //  {offset = 3236, header_num = 0, file_num = 1, last, line_num = -1},  // 7
631
  //  {offset = 5764, header_num = 0, file_num = 1, last, line_num = 48},  // 8
632
  //  {offset = 5764, header_num = 0, file_num = 1,!last, line_num = 47},  // 9
633
  //  {offset = 5765, header_num = 0, file_num = 1, last, line_num = 49},  // 10
634
  //  {offset = 5767, header_num = 0, file_num = 1, last, line_num = 50},  // 11
635
  //  {offset = 5768, header_num = 0, file_num = 1, last, line_num = 51},  // 12
636
  //  {offset = 5773, header_num = 0, file_num = 1, last, line_num = -1},  // 13
637
  //  {offset = 5787, header_num = 1, file_num = 1, last, line_num = 19},  // 14
638
  //  {offset = 5790, header_num = 1, file_num = 1, last, line_num = 20},  // 15
639
  //  {offset = 5793, header_num = 1, file_num = 1, last, line_num = 67},  // 16
640
  //  {offset = 5793, header_num = 1, file_num = 1, last, line_num = -1},  // 17
641
  //  {offset = 5793, header_num = 1, file_num = 1,!last, line_num = 66},  // 18
642
  //  {offset = 5795, header_num = 1, file_num = 1, last, line_num = 68},  // 19
643
  //  {offset = 5798, header_num = 1, file_num = 1, last, line_num = -1},  // 20
644
  // The entries with line_num == -1 mark the end of a function: the
645
  // associated offset is one past the last instruction in the
646
  // function.  This can correspond to the beginning of the next
647
  // function (as is true for offset 3232); alternately, there can be
648
  // a gap between the end of one function and the start of the next
649
  // (as is true for some others, most obviously from 3236->5764).
650
  //
651
  // Case 1: lookup_key has offset == 10.  lower_bound returns
652
  //         offsets[0].  Since it's not an exact match and we're
653
  //         at the beginning of offsets, we return end() (invalid).
654
  // Case 2: lookup_key has offset 10000.  lower_bound returns
655
  //         offset[21] (end()).  We return end() (invalid).
656
  // Case 3: lookup_key has offset == 3211.  lower_bound matches
657
  //         offsets[0] exactly, and that's the entry we return.
658
  // Case 4: lookup_key has offset == 3232.  lower_bound returns
659
  //         offsets[4].  That's an exact match, but indicates
660
  //         end-of-function.  We check if offsets[5] is also an
661
  //         exact match but not end-of-function.  It is, so we
662
  //         return offsets[5].
663
  // Case 5: lookup_key has offset == 3214.  lower_bound returns
664
  //         offsets[1].  Since it's not an exact match, we back
665
  //         up to the offset that's < lookup_key, offsets[0].
666
  //         We note offsets[0] is a valid entry (not end-of-function),
667
  //         so that's the entry we return.
668
  // Case 6: lookup_key has offset == 4000.  lower_bound returns
669
  //         offsets[8].  Since it's not an exact match, we back
670
  //         up to offsets[7].  Since offsets[7] indicates
671
  //         end-of-function, we know lookup_key is between
672
  //         functions, so we return end() (not a valid offset).
673
  // Case 7: lookup_key has offset == 5794.  lower_bound returns
674
  //         offsets[19].  Since it's not an exact match, we back
675
  //         up to offsets[16].  Note we back up to the *first*
676
  //         entry with offset 5793, not just offsets[19-1].
677
  //         We note offsets[16] is a valid entry, so we return it.
678
  //         If offsets[16] had had line_num == -1, we would have
679
  //         checked offsets[17].  The reason for this is that
680
  //         16 and 17 can be in an arbitrary order, since we sort
681
  //         only by offset and last_line_for_offset.  (Note it
682
  //         doesn't help to use line_number as a tertiary sort key,
683
  //         since sometimes we want the -1 to be first and sometimes
684
  //         we want it to be last.)
685
 
686
  // This deals with cases (1) and (2).
687
  if ((it == offsets->begin() && offset < it->offset)
688
      || it == offsets->end())
689
    return offsets->end();
690
 
691
  // This deals with cases (3) and (4).
692
  if (offset == it->offset)
693
    {
694
      while (it != offsets->end()
695
             && it->offset == offset
696
             && it->line_num == -1)
697
        ++it;
698
      if (it == offsets->end() || it->offset != offset)
699
        return offsets->end();
700
      else
701
        return it;
702
    }
703
 
704
  // This handles the first part of case (7) -- we back up to the
705
  // *first* entry that has the offset that's behind us.
706
  gold_assert(it != offsets->begin());
707
  std::vector<Offset_to_lineno_entry>::const_iterator range_end = it;
708
  --it;
709
  const off_t range_value = it->offset;
710
  while (it != offsets->begin() && (it-1)->offset == range_value)
711
    --it;
712
 
713
  // This handles cases (5), (6), and (7): if any entry in the
714
  // equal_range [it, range_end) has a line_num != -1, it's a valid
715
  // match.  If not, we're not in a function.  The line number we saw
716
  // last for an offset will be sorted first, so it'll get returned if
717
  // it's present.
718
  for (; it != range_end; ++it)
719
    if (it->line_num != -1)
720
      return it;
721
  return offsets->end();
722
}
723
 
724
// Returns the canonical filename:lineno for the address passed in.
725
// If other_lines is not NULL, appends the non-canonical lines
726
// assigned to the same address.
727
 
728
template<int size, bool big_endian>
729
std::string
730
Sized_dwarf_line_info<size, big_endian>::do_addr2line(
731
    unsigned int shndx,
732
    off_t offset,
733
    std::vector<std::string>* other_lines)
734
{
735
  if (this->data_valid_ == false)
736
    return "";
737
 
738
  const std::vector<Offset_to_lineno_entry>* offsets;
739
  // If we do not have reloc information, then our input is a .so or
740
  // some similar data structure where all the information is held in
741
  // the offset.  In that case, we ignore the input shndx.
742
  if (this->input_is_relobj())
743
    offsets = &this->line_number_map_[shndx];
744
  else
745
    offsets = &this->line_number_map_[-1U];
746
  if (offsets->empty())
747
    return "";
748
 
749
  typename std::vector<Offset_to_lineno_entry>::const_iterator it
750
      = offset_to_iterator(offsets, offset);
751
  if (it == offsets->end())
752
    return "";
753
 
754
  std::string result = this->format_file_lineno(*it);
755
  if (other_lines != NULL)
756
    for (++it; it != offsets->end() && it->offset == offset; ++it)
757
      {
758
        if (it->line_num == -1)
759
          continue;  // The end of a previous function.
760
        other_lines->push_back(this->format_file_lineno(*it));
761
      }
762
  return result;
763
}
764
 
765
// Convert the file_num + line_num into a string.
766
 
767
template<int size, bool big_endian>
768
std::string
769
Sized_dwarf_line_info<size, big_endian>::format_file_lineno(
770
    const Offset_to_lineno_entry& loc) const
771
{
772
  std::string ret;
773
 
774
  gold_assert(loc.header_num < static_cast<int>(this->files_.size()));
775
  gold_assert(loc.file_num
776
              < static_cast<int>(this->files_[loc.header_num].size()));
777
  const std::pair<int, std::string>& filename_pair
778
      = this->files_[loc.header_num][loc.file_num];
779
  const std::string& filename = filename_pair.second;
780
 
781
  gold_assert(loc.header_num < static_cast<int>(this->directories_.size()));
782
  gold_assert(filename_pair.first
783
              < static_cast<int>(this->directories_[loc.header_num].size()));
784
  const std::string& dirname
785
      = this->directories_[loc.header_num][filename_pair.first];
786
 
787
  if (!dirname.empty())
788
    {
789
      ret += dirname;
790
      ret += "/";
791
    }
792
  ret += filename;
793
  if (ret.empty())
794
    ret = "(unknown)";
795
 
796
  char buffer[64];   // enough to hold a line number
797
  snprintf(buffer, sizeof(buffer), "%d", loc.line_num);
798
  ret += ":";
799
  ret += buffer;
800
 
801
  return ret;
802
}
803
 
804
// Dwarf_line_info routines.
805
 
806
static unsigned int next_generation_count = 0;
807
 
808
struct Addr2line_cache_entry
809
{
810
  Object* object;
811
  unsigned int shndx;
812
  Dwarf_line_info* dwarf_line_info;
813
  unsigned int generation_count;
814
  unsigned int access_count;
815
 
816
  Addr2line_cache_entry(Object* o, unsigned int s, Dwarf_line_info* d)
817
      : object(o), shndx(s), dwarf_line_info(d),
818
        generation_count(next_generation_count), access_count(0)
819
  {
820
    if (next_generation_count < (1U << 31))
821
      ++next_generation_count;
822
  }
823
};
824
// We expect this cache to be small, so don't bother with a hashtable
825
// or priority queue or anything: just use a simple vector.
826
static std::vector<Addr2line_cache_entry> addr2line_cache;
827
 
828
std::string
829
Dwarf_line_info::one_addr2line(Object* object,
830
                               unsigned int shndx, off_t offset,
831
                               size_t cache_size,
832
                               std::vector<std::string>* other_lines)
833
{
834
  Dwarf_line_info* lineinfo = NULL;
835
  std::vector<Addr2line_cache_entry>::iterator it;
836
 
837
  // First, check the cache.  If we hit, update the counts.
838
  for (it = addr2line_cache.begin(); it != addr2line_cache.end(); ++it)
839
    {
840
      if (it->object == object && it->shndx == shndx)
841
        {
842
          lineinfo = it->dwarf_line_info;
843
          it->generation_count = next_generation_count;
844
          // We cap generation_count at 2^31 -1 to avoid overflow.
845
          if (next_generation_count < (1U << 31))
846
            ++next_generation_count;
847
          // We cap access_count at 31 so 2^access_count doesn't overflow
848
          if (it->access_count < 31)
849
            ++it->access_count;
850
          break;
851
        }
852
    }
853
 
854
  // If we don't hit the cache, create a new object and insert into the
855
  // cache.
856
  if (lineinfo == NULL)
857
  {
858
    switch (parameters->size_and_endianness())
859
      {
860
#ifdef HAVE_TARGET_32_LITTLE
861
        case Parameters::TARGET_32_LITTLE:
862
          lineinfo = new Sized_dwarf_line_info<32, false>(object, shndx); break;
863
#endif
864
#ifdef HAVE_TARGET_32_BIG
865
        case Parameters::TARGET_32_BIG:
866
          lineinfo = new Sized_dwarf_line_info<32, true>(object, shndx); break;
867
#endif
868
#ifdef HAVE_TARGET_64_LITTLE
869
        case Parameters::TARGET_64_LITTLE:
870
          lineinfo = new Sized_dwarf_line_info<64, false>(object, shndx); break;
871
#endif
872
#ifdef HAVE_TARGET_64_BIG
873
        case Parameters::TARGET_64_BIG:
874
          lineinfo = new Sized_dwarf_line_info<64, true>(object, shndx); break;
875
#endif
876
        default:
877
          gold_unreachable();
878
      }
879
    addr2line_cache.push_back(Addr2line_cache_entry(object, shndx, lineinfo));
880
  }
881
 
882
  // Now that we have our object, figure out the answer
883
  std::string retval = lineinfo->addr2line(shndx, offset, other_lines);
884
 
885
  // Finally, if our cache has grown too big, delete old objects.  We
886
  // assume the common (probably only) case is deleting only one object.
887
  // We use a pretty simple scheme to evict: function of LRU and MFU.
888
  while (addr2line_cache.size() > cache_size)
889
    {
890
      unsigned int lowest_score = ~0U;
891
      std::vector<Addr2line_cache_entry>::iterator lowest
892
          = addr2line_cache.end();
893
      for (it = addr2line_cache.begin(); it != addr2line_cache.end(); ++it)
894
        {
895
          const unsigned int score = (it->generation_count
896
                                      + (1U << it->access_count));
897
          if (score < lowest_score)
898
            {
899
              lowest_score = score;
900
              lowest = it;
901
            }
902
        }
903
      if (lowest != addr2line_cache.end())
904
        {
905
          delete lowest->dwarf_line_info;
906
          addr2line_cache.erase(lowest);
907
        }
908
    }
909
 
910
  return retval;
911
}
912
 
913
void
914
Dwarf_line_info::clear_addr2line_cache()
915
{
916
  for (std::vector<Addr2line_cache_entry>::iterator it = addr2line_cache.begin();
917
       it != addr2line_cache.end();
918
       ++it)
919
    delete it->dwarf_line_info;
920
  addr2line_cache.clear();
921
}
922
 
923
#ifdef HAVE_TARGET_32_LITTLE
924
template
925
class Sized_dwarf_line_info<32, false>;
926
#endif
927
 
928
#ifdef HAVE_TARGET_32_BIG
929
template
930
class Sized_dwarf_line_info<32, true>;
931
#endif
932
 
933
#ifdef HAVE_TARGET_64_LITTLE
934
template
935
class Sized_dwarf_line_info<64, false>;
936
#endif
937
 
938
#ifdef HAVE_TARGET_64_BIG
939
template
940
class Sized_dwarf_line_info<64, true>;
941
#endif
942
 
943
} // End namespace gold.

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