1 // dwarf_reader.cc -- parse dwarf2/3 debug information
3 // Copyright 2007, 2008, 2009, 2010, 2011 Free Software Foundation, Inc.
4 // Written by Ian Lance Taylor <iant@google.com>.
6 // This file is part of gold.
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.
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.
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.
28 #include "elfcpp_swap.h"
31 #include "parameters.h"
33 #include "dwarf_reader.h"
34 #include "int_encoding.h"
35 #include "compressed_output.h"
39 struct LineStateMachine
45 unsigned int shndx; // the section address refers to
46 bool is_stmt; // stmt means statement.
52 ResetLineStateMachine(struct LineStateMachine* lsm, bool default_is_stmt)
59 lsm->is_stmt = default_is_stmt;
60 lsm->basic_block = false;
61 lsm->end_sequence = false;
64 template<int size, bool big_endian>
65 Sized_dwarf_line_info<size, big_endian>::Sized_dwarf_line_info(
67 unsigned int read_shndx)
68 : data_valid_(false), buffer_(NULL), buffer_start_(NULL),
69 symtab_buffer_(NULL), directories_(), files_(), current_header_index_(-1)
71 unsigned int debug_shndx;
73 for (debug_shndx = 1; debug_shndx < object->shnum(); ++debug_shndx)
75 // FIXME: do this more efficiently: section_name() isn't super-fast
76 std::string name = object->section_name(debug_shndx);
77 if (name == ".debug_line" || name == ".zdebug_line")
79 section_size_type buffer_size;
81 this->buffer_ = object->decompressed_section_contents(debug_shndx,
85 this->buffer_start_ = this->buffer_;
86 this->buffer_end_ = this->buffer_ + buffer_size;
90 if (this->buffer_ == NULL)
93 // Find the relocation section for ".debug_line".
94 // We expect these for relobjs (.o's) but not dynobjs (.so's).
95 bool got_relocs = false;
96 for (unsigned int reloc_shndx = 0;
97 reloc_shndx < object->shnum();
100 unsigned int reloc_sh_type = object->section_type(reloc_shndx);
101 if ((reloc_sh_type == elfcpp::SHT_REL
102 || reloc_sh_type == elfcpp::SHT_RELA)
103 && object->section_info(reloc_shndx) == debug_shndx)
105 got_relocs = this->track_relocs_.initialize(object, reloc_shndx,
107 this->track_relocs_type_ = reloc_sh_type;
112 // Finally, we need the symtab section to interpret the relocs.
115 unsigned int symtab_shndx;
116 for (symtab_shndx = 0; symtab_shndx < object->shnum(); ++symtab_shndx)
117 if (object->section_type(symtab_shndx) == elfcpp::SHT_SYMTAB)
119 this->symtab_buffer_ = object->section_contents(
120 symtab_shndx, &this->symtab_buffer_size_, false);
123 if (this->symtab_buffer_ == NULL)
127 // Now that we have successfully read all the data, parse the debug
129 this->data_valid_ = true;
130 this->read_line_mappings(object, read_shndx);
133 // Read the DWARF header.
135 template<int size, bool big_endian>
137 Sized_dwarf_line_info<size, big_endian>::read_header_prolog(
138 const unsigned char* lineptr)
140 uint32_t initial_length = elfcpp::Swap_unaligned<32, big_endian>::readval(lineptr);
143 // In DWARF2/3, if the initial length is all 1 bits, then the offset
144 // size is 8 and we need to read the next 8 bytes for the real length.
145 if (initial_length == 0xffffffff)
147 header_.offset_size = 8;
148 initial_length = elfcpp::Swap_unaligned<64, big_endian>::readval(lineptr);
152 header_.offset_size = 4;
154 header_.total_length = initial_length;
156 gold_assert(lineptr + header_.total_length <= buffer_end_);
158 header_.version = elfcpp::Swap_unaligned<16, big_endian>::readval(lineptr);
161 if (header_.offset_size == 4)
162 header_.prologue_length = elfcpp::Swap_unaligned<32, big_endian>::readval(lineptr);
164 header_.prologue_length = elfcpp::Swap_unaligned<64, big_endian>::readval(lineptr);
165 lineptr += header_.offset_size;
167 header_.min_insn_length = *lineptr;
170 header_.default_is_stmt = *lineptr;
173 header_.line_base = *reinterpret_cast<const signed char*>(lineptr);
176 header_.line_range = *lineptr;
179 header_.opcode_base = *lineptr;
182 header_.std_opcode_lengths.resize(header_.opcode_base + 1);
183 header_.std_opcode_lengths[0] = 0;
184 for (int i = 1; i < header_.opcode_base; i++)
186 header_.std_opcode_lengths[i] = *lineptr;
193 // The header for a debug_line section is mildly complicated, because
194 // the line info is very tightly encoded.
196 template<int size, bool big_endian>
198 Sized_dwarf_line_info<size, big_endian>::read_header_tables(
199 const unsigned char* lineptr)
201 ++this->current_header_index_;
203 // Create a new directories_ entry and a new files_ entry for our new
204 // header. We initialize each with a single empty element, because
205 // dwarf indexes directory and filenames starting at 1.
206 gold_assert(static_cast<int>(this->directories_.size())
207 == this->current_header_index_);
208 gold_assert(static_cast<int>(this->files_.size())
209 == this->current_header_index_);
210 this->directories_.push_back(std::vector<std::string>(1));
211 this->files_.push_back(std::vector<std::pair<int, std::string> >(1));
213 // It is legal for the directory entry table to be empty.
219 const char* dirname = reinterpret_cast<const char*>(lineptr);
221 == static_cast<int>(this->directories_.back().size()));
222 this->directories_.back().push_back(dirname);
223 lineptr += this->directories_.back().back().size() + 1;
229 // It is also legal for the file entry table to be empty.
236 const char* filename = reinterpret_cast<const char*>(lineptr);
237 lineptr += strlen(filename) + 1;
239 uint64_t dirindex = read_unsigned_LEB_128(lineptr, &len);
242 if (dirindex >= this->directories_.back().size())
244 int dirindexi = static_cast<int>(dirindex);
246 read_unsigned_LEB_128(lineptr, &len); // mod_time
249 read_unsigned_LEB_128(lineptr, &len); // filelength
252 gold_assert(fileindex
253 == static_cast<int>(this->files_.back().size()));
254 this->files_.back().push_back(std::make_pair(dirindexi, filename));
263 // Process a single opcode in the .debug.line structure.
265 template<int size, bool big_endian>
267 Sized_dwarf_line_info<size, big_endian>::process_one_opcode(
268 const unsigned char* start, struct LineStateMachine* lsm, size_t* len)
272 unsigned char opcode = *start;
276 // If the opcode is great than the opcode_base, it is a special
277 // opcode. Most line programs consist mainly of special opcodes.
278 if (opcode >= header_.opcode_base)
280 opcode -= header_.opcode_base;
281 const int advance_address = ((opcode / header_.line_range)
282 * header_.min_insn_length);
283 lsm->address += advance_address;
285 const int advance_line = ((opcode % header_.line_range)
286 + header_.line_base);
287 lsm->line_num += advance_line;
288 lsm->basic_block = true;
293 // Otherwise, we have the regular opcodes
296 case elfcpp::DW_LNS_copy:
297 lsm->basic_block = false;
301 case elfcpp::DW_LNS_advance_pc:
303 const uint64_t advance_address
304 = read_unsigned_LEB_128(start, &templen);
306 lsm->address += header_.min_insn_length * advance_address;
310 case elfcpp::DW_LNS_advance_line:
312 const uint64_t advance_line = read_signed_LEB_128(start, &templen);
314 lsm->line_num += advance_line;
318 case elfcpp::DW_LNS_set_file:
320 const uint64_t fileno = read_unsigned_LEB_128(start, &templen);
322 lsm->file_num = fileno;
326 case elfcpp::DW_LNS_set_column:
328 const uint64_t colno = read_unsigned_LEB_128(start, &templen);
330 lsm->column_num = colno;
334 case elfcpp::DW_LNS_negate_stmt:
335 lsm->is_stmt = !lsm->is_stmt;
338 case elfcpp::DW_LNS_set_basic_block:
339 lsm->basic_block = true;
342 case elfcpp::DW_LNS_fixed_advance_pc:
345 advance_address = elfcpp::Swap_unaligned<16, big_endian>::readval(start);
347 lsm->address += advance_address;
351 case elfcpp::DW_LNS_const_add_pc:
353 const int advance_address = (header_.min_insn_length
354 * ((255 - header_.opcode_base)
355 / header_.line_range));
356 lsm->address += advance_address;
360 case elfcpp::DW_LNS_extended_op:
362 const uint64_t extended_op_len
363 = read_unsigned_LEB_128(start, &templen);
365 oplen += templen + extended_op_len;
367 const unsigned char extended_op = *start;
372 case elfcpp::DW_LNE_end_sequence:
373 // This means that the current byte is the one immediately
374 // after a set of instructions. Record the current line
375 // for up to one less than the current address.
377 lsm->end_sequence = true;
381 case elfcpp::DW_LNE_set_address:
384 elfcpp::Swap_unaligned<size, big_endian>::readval(start);
385 typename Reloc_map::const_iterator it
386 = this->reloc_map_.find(start - this->buffer_);
387 if (it != reloc_map_.end())
389 // If this is a SHT_RELA section, then ignore the
390 // section contents. This assumes that this is a
391 // straight reloc which just uses the reloc addend.
392 // The reloc addend has already been included in the
394 if (this->track_relocs_type_ == elfcpp::SHT_RELA)
396 // Add in the symbol value.
397 lsm->address += it->second.second;
398 lsm->shndx = it->second.first;
402 // If we're a normal .o file, with relocs, every
403 // set_address should have an associated relocation.
404 if (this->input_is_relobj())
405 this->data_valid_ = false;
409 case elfcpp::DW_LNE_define_file:
411 const char* filename = reinterpret_cast<const char*>(start);
412 templen = strlen(filename) + 1;
415 uint64_t dirindex = read_unsigned_LEB_128(start, &templen);
418 if (dirindex >= this->directories_.back().size())
420 int dirindexi = static_cast<int>(dirindex);
422 read_unsigned_LEB_128(start, &templen); // mod_time
425 read_unsigned_LEB_128(start, &templen); // filelength
428 this->files_.back().push_back(std::make_pair(dirindexi,
438 // Ignore unknown opcode silently
439 for (int i = 0; i < header_.std_opcode_lengths[opcode]; i++)
442 read_unsigned_LEB_128(start, &templen);
453 // Read the debug information at LINEPTR and store it in the line
456 template<int size, bool big_endian>
458 Sized_dwarf_line_info<size, big_endian>::read_lines(unsigned const char* lineptr,
461 struct LineStateMachine lsm;
463 // LENGTHSTART is the place the length field is based on. It is the
464 // point in the header after the initial length field.
465 const unsigned char* lengthstart = buffer_;
467 // In 64 bit dwarf, the initial length is 12 bytes, because of the
468 // 0xffffffff at the start.
469 if (header_.offset_size == 8)
474 while (lineptr < lengthstart + header_.total_length)
476 ResetLineStateMachine(&lsm, header_.default_is_stmt);
477 while (!lsm.end_sequence)
480 bool add_line = this->process_one_opcode(lineptr, &lsm, &oplength);
482 && (shndx == -1U || lsm.shndx == -1U || shndx == lsm.shndx))
484 Offset_to_lineno_entry entry
485 = { static_cast<off_t>(lsm.address),
486 this->current_header_index_,
487 static_cast<unsigned int>(lsm.file_num),
488 true, lsm.line_num };
489 std::vector<Offset_to_lineno_entry>&
490 map(this->line_number_map_[lsm.shndx]);
491 // If we see two consecutive entries with the same
492 // offset and a real line number, then mark the first
493 // one as non-canonical.
495 && (map.back().offset == static_cast<off_t>(lsm.address))
496 && lsm.line_num != -1
497 && map.back().line_num != -1)
498 map.back().last_line_for_offset = false;
499 map.push_back(entry);
505 return lengthstart + header_.total_length;
508 // Looks in the symtab to see what section a symbol is in.
510 template<int size, bool big_endian>
512 Sized_dwarf_line_info<size, big_endian>::symbol_section(
515 typename elfcpp::Elf_types<size>::Elf_Addr* value,
518 const int symsize = elfcpp::Elf_sizes<size>::sym_size;
519 gold_assert(sym * symsize < this->symtab_buffer_size_);
520 elfcpp::Sym<size, big_endian> elfsym(this->symtab_buffer_ + sym * symsize);
521 *value = elfsym.get_st_value();
522 return object->adjust_sym_shndx(sym, elfsym.get_st_shndx(), is_ordinary);
525 // Read the relocations into a Reloc_map.
527 template<int size, bool big_endian>
529 Sized_dwarf_line_info<size, big_endian>::read_relocs(Object* object)
531 if (this->symtab_buffer_ == NULL)
534 typename elfcpp::Elf_types<size>::Elf_Addr value;
536 while ((reloc_offset = this->track_relocs_.next_offset()) != -1)
538 const unsigned int sym = this->track_relocs_.next_symndx();
541 const unsigned int shndx = this->symbol_section(object, sym, &value,
544 // There is no reason to record non-ordinary section indexes, or
545 // SHN_UNDEF, because they will never match the real section.
546 if (is_ordinary && shndx != elfcpp::SHN_UNDEF)
548 value += this->track_relocs_.next_addend();
549 this->reloc_map_[reloc_offset] = std::make_pair(shndx, value);
552 this->track_relocs_.advance(reloc_offset + 1);
556 // Read the line number info.
558 template<int size, bool big_endian>
560 Sized_dwarf_line_info<size, big_endian>::read_line_mappings(Object* object,
563 gold_assert(this->data_valid_ == true);
565 this->read_relocs(object);
566 while (this->buffer_ < this->buffer_end_)
568 const unsigned char* lineptr = this->buffer_;
569 lineptr = this->read_header_prolog(lineptr);
570 lineptr = this->read_header_tables(lineptr);
571 lineptr = this->read_lines(lineptr, shndx);
572 this->buffer_ = lineptr;
575 // Sort the lines numbers, so addr2line can use binary search.
576 for (typename Lineno_map::iterator it = line_number_map_.begin();
577 it != line_number_map_.end();
579 // Each vector needs to be sorted by offset.
580 std::sort(it->second.begin(), it->second.end());
583 // Some processing depends on whether the input is a .o file or not.
584 // For instance, .o files have relocs, and have .debug_lines
585 // information on a per section basis. .so files, on the other hand,
586 // lack relocs, and offsets are unique, so we can ignore the section
589 template<int size, bool big_endian>
591 Sized_dwarf_line_info<size, big_endian>::input_is_relobj()
593 // Only .o files have relocs and the symtab buffer that goes with them.
594 return this->symtab_buffer_ != NULL;
597 // Given an Offset_to_lineno_entry vector, and an offset, figure out
598 // if the offset points into a function according to the vector (see
599 // comments below for the algorithm). If it does, return an iterator
600 // into the vector that points to the line-number that contains that
601 // offset. If not, it returns vector::end().
603 static std::vector<Offset_to_lineno_entry>::const_iterator
604 offset_to_iterator(const std::vector<Offset_to_lineno_entry>* offsets,
607 const Offset_to_lineno_entry lookup_key = { offset, 0, 0, true, 0 };
609 // lower_bound() returns the smallest offset which is >= lookup_key.
610 // If no offset in offsets is >= lookup_key, returns end().
611 std::vector<Offset_to_lineno_entry>::const_iterator it
612 = std::lower_bound(offsets->begin(), offsets->end(), lookup_key);
614 // This code is easiest to understand with a concrete example.
615 // Here's a possible offsets array:
616 // {{offset = 3211, header_num = 0, file_num = 1, last, line_num = 16}, // 0
617 // {offset = 3224, header_num = 0, file_num = 1, last, line_num = 20}, // 1
618 // {offset = 3226, header_num = 0, file_num = 1, last, line_num = 22}, // 2
619 // {offset = 3231, header_num = 0, file_num = 1, last, line_num = 25}, // 3
620 // {offset = 3232, header_num = 0, file_num = 1, last, line_num = -1}, // 4
621 // {offset = 3232, header_num = 0, file_num = 1, last, line_num = 65}, // 5
622 // {offset = 3235, header_num = 0, file_num = 1, last, line_num = 66}, // 6
623 // {offset = 3236, header_num = 0, file_num = 1, last, line_num = -1}, // 7
624 // {offset = 5764, header_num = 0, file_num = 1, last, line_num = 48}, // 8
625 // {offset = 5764, header_num = 0, file_num = 1,!last, line_num = 47}, // 9
626 // {offset = 5765, header_num = 0, file_num = 1, last, line_num = 49}, // 10
627 // {offset = 5767, header_num = 0, file_num = 1, last, line_num = 50}, // 11
628 // {offset = 5768, header_num = 0, file_num = 1, last, line_num = 51}, // 12
629 // {offset = 5773, header_num = 0, file_num = 1, last, line_num = -1}, // 13
630 // {offset = 5787, header_num = 1, file_num = 1, last, line_num = 19}, // 14
631 // {offset = 5790, header_num = 1, file_num = 1, last, line_num = 20}, // 15
632 // {offset = 5793, header_num = 1, file_num = 1, last, line_num = 67}, // 16
633 // {offset = 5793, header_num = 1, file_num = 1, last, line_num = -1}, // 17
634 // {offset = 5793, header_num = 1, file_num = 1,!last, line_num = 66}, // 18
635 // {offset = 5795, header_num = 1, file_num = 1, last, line_num = 68}, // 19
636 // {offset = 5798, header_num = 1, file_num = 1, last, line_num = -1}, // 20
637 // The entries with line_num == -1 mark the end of a function: the
638 // associated offset is one past the last instruction in the
639 // function. This can correspond to the beginning of the next
640 // function (as is true for offset 3232); alternately, there can be
641 // a gap between the end of one function and the start of the next
642 // (as is true for some others, most obviously from 3236->5764).
644 // Case 1: lookup_key has offset == 10. lower_bound returns
645 // offsets[0]. Since it's not an exact match and we're
646 // at the beginning of offsets, we return end() (invalid).
647 // Case 2: lookup_key has offset 10000. lower_bound returns
648 // offset[21] (end()). We return end() (invalid).
649 // Case 3: lookup_key has offset == 3211. lower_bound matches
650 // offsets[0] exactly, and that's the entry we return.
651 // Case 4: lookup_key has offset == 3232. lower_bound returns
652 // offsets[4]. That's an exact match, but indicates
653 // end-of-function. We check if offsets[5] is also an
654 // exact match but not end-of-function. It is, so we
655 // return offsets[5].
656 // Case 5: lookup_key has offset == 3214. lower_bound returns
657 // offsets[1]. Since it's not an exact match, we back
658 // up to the offset that's < lookup_key, offsets[0].
659 // We note offsets[0] is a valid entry (not end-of-function),
660 // so that's the entry we return.
661 // Case 6: lookup_key has offset == 4000. lower_bound returns
662 // offsets[8]. Since it's not an exact match, we back
663 // up to offsets[7]. Since offsets[7] indicates
664 // end-of-function, we know lookup_key is between
665 // functions, so we return end() (not a valid offset).
666 // Case 7: lookup_key has offset == 5794. lower_bound returns
667 // offsets[19]. Since it's not an exact match, we back
668 // up to offsets[16]. Note we back up to the *first*
669 // entry with offset 5793, not just offsets[19-1].
670 // We note offsets[16] is a valid entry, so we return it.
671 // If offsets[16] had had line_num == -1, we would have
672 // checked offsets[17]. The reason for this is that
673 // 16 and 17 can be in an arbitrary order, since we sort
674 // only by offset and last_line_for_offset. (Note it
675 // doesn't help to use line_number as a tertiary sort key,
676 // since sometimes we want the -1 to be first and sometimes
677 // we want it to be last.)
679 // This deals with cases (1) and (2).
680 if ((it == offsets->begin() && offset < it->offset)
681 || it == offsets->end())
682 return offsets->end();
684 // This deals with cases (3) and (4).
685 if (offset == it->offset)
687 while (it != offsets->end()
688 && it->offset == offset
689 && it->line_num == -1)
691 if (it == offsets->end() || it->offset != offset)
692 return offsets->end();
697 // This handles the first part of case (7) -- we back up to the
698 // *first* entry that has the offset that's behind us.
699 gold_assert(it != offsets->begin());
700 std::vector<Offset_to_lineno_entry>::const_iterator range_end = it;
702 const off_t range_value = it->offset;
703 while (it != offsets->begin() && (it-1)->offset == range_value)
706 // This handles cases (5), (6), and (7): if any entry in the
707 // equal_range [it, range_end) has a line_num != -1, it's a valid
708 // match. If not, we're not in a function. The line number we saw
709 // last for an offset will be sorted first, so it'll get returned if
711 for (; it != range_end; ++it)
712 if (it->line_num != -1)
714 return offsets->end();
717 // Returns the canonical filename:lineno for the address passed in.
718 // If other_lines is not NULL, appends the non-canonical lines
719 // assigned to the same address.
721 template<int size, bool big_endian>
723 Sized_dwarf_line_info<size, big_endian>::do_addr2line(
726 std::vector<std::string>* other_lines)
728 if (this->data_valid_ == false)
731 const std::vector<Offset_to_lineno_entry>* offsets;
732 // If we do not have reloc information, then our input is a .so or
733 // some similar data structure where all the information is held in
734 // the offset. In that case, we ignore the input shndx.
735 if (this->input_is_relobj())
736 offsets = &this->line_number_map_[shndx];
738 offsets = &this->line_number_map_[-1U];
739 if (offsets->empty())
742 typename std::vector<Offset_to_lineno_entry>::const_iterator it
743 = offset_to_iterator(offsets, offset);
744 if (it == offsets->end())
747 std::string result = this->format_file_lineno(*it);
748 if (other_lines != NULL)
749 for (++it; it != offsets->end() && it->offset == offset; ++it)
751 if (it->line_num == -1)
752 continue; // The end of a previous function.
753 other_lines->push_back(this->format_file_lineno(*it));
758 // Convert the file_num + line_num into a string.
760 template<int size, bool big_endian>
762 Sized_dwarf_line_info<size, big_endian>::format_file_lineno(
763 const Offset_to_lineno_entry& loc) const
767 gold_assert(loc.header_num < static_cast<int>(this->files_.size()));
768 gold_assert(loc.file_num
769 < static_cast<int>(this->files_[loc.header_num].size()));
770 const std::pair<int, std::string>& filename_pair
771 = this->files_[loc.header_num][loc.file_num];
772 const std::string& filename = filename_pair.second;
774 gold_assert(loc.header_num < static_cast<int>(this->directories_.size()));
775 gold_assert(filename_pair.first
776 < static_cast<int>(this->directories_[loc.header_num].size()));
777 const std::string& dirname
778 = this->directories_[loc.header_num][filename_pair.first];
780 if (!dirname.empty())
789 char buffer[64]; // enough to hold a line number
790 snprintf(buffer, sizeof(buffer), "%d", loc.line_num);
797 // Dwarf_line_info routines.
799 static unsigned int next_generation_count = 0;
801 struct Addr2line_cache_entry
805 Dwarf_line_info* dwarf_line_info;
806 unsigned int generation_count;
807 unsigned int access_count;
809 Addr2line_cache_entry(Object* o, unsigned int s, Dwarf_line_info* d)
810 : object(o), shndx(s), dwarf_line_info(d),
811 generation_count(next_generation_count), access_count(0)
813 if (next_generation_count < (1U << 31))
814 ++next_generation_count;
817 // We expect this cache to be small, so don't bother with a hashtable
818 // or priority queue or anything: just use a simple vector.
819 static std::vector<Addr2line_cache_entry> addr2line_cache;
822 Dwarf_line_info::one_addr2line(Object* object,
823 unsigned int shndx, off_t offset,
825 std::vector<std::string>* other_lines)
827 Dwarf_line_info* lineinfo = NULL;
828 std::vector<Addr2line_cache_entry>::iterator it;
830 // First, check the cache. If we hit, update the counts.
831 for (it = addr2line_cache.begin(); it != addr2line_cache.end(); ++it)
833 if (it->object == object && it->shndx == shndx)
835 lineinfo = it->dwarf_line_info;
836 it->generation_count = next_generation_count;
837 // We cap generation_count at 2^31 -1 to avoid overflow.
838 if (next_generation_count < (1U << 31))
839 ++next_generation_count;
840 // We cap access_count at 31 so 2^access_count doesn't overflow
841 if (it->access_count < 31)
847 // If we don't hit the cache, create a new object and insert into the
849 if (lineinfo == NULL)
851 switch (parameters->size_and_endianness())
853 #ifdef HAVE_TARGET_32_LITTLE
854 case Parameters::TARGET_32_LITTLE:
855 lineinfo = new Sized_dwarf_line_info<32, false>(object, shndx); break;
857 #ifdef HAVE_TARGET_32_BIG
858 case Parameters::TARGET_32_BIG:
859 lineinfo = new Sized_dwarf_line_info<32, true>(object, shndx); break;
861 #ifdef HAVE_TARGET_64_LITTLE
862 case Parameters::TARGET_64_LITTLE:
863 lineinfo = new Sized_dwarf_line_info<64, false>(object, shndx); break;
865 #ifdef HAVE_TARGET_64_BIG
866 case Parameters::TARGET_64_BIG:
867 lineinfo = new Sized_dwarf_line_info<64, true>(object, shndx); break;
872 addr2line_cache.push_back(Addr2line_cache_entry(object, shndx, lineinfo));
875 // Now that we have our object, figure out the answer
876 std::string retval = lineinfo->addr2line(shndx, offset, other_lines);
878 // Finally, if our cache has grown too big, delete old objects. We
879 // assume the common (probably only) case is deleting only one object.
880 // We use a pretty simple scheme to evict: function of LRU and MFU.
881 while (addr2line_cache.size() > cache_size)
883 unsigned int lowest_score = ~0U;
884 std::vector<Addr2line_cache_entry>::iterator lowest
885 = addr2line_cache.end();
886 for (it = addr2line_cache.begin(); it != addr2line_cache.end(); ++it)
888 const unsigned int score = (it->generation_count
889 + (1U << it->access_count));
890 if (score < lowest_score)
892 lowest_score = score;
896 if (lowest != addr2line_cache.end())
898 delete lowest->dwarf_line_info;
899 addr2line_cache.erase(lowest);
907 Dwarf_line_info::clear_addr2line_cache()
909 for (std::vector<Addr2line_cache_entry>::iterator it = addr2line_cache.begin();
910 it != addr2line_cache.end();
912 delete it->dwarf_line_info;
913 addr2line_cache.clear();
916 #ifdef HAVE_TARGET_32_LITTLE
918 class Sized_dwarf_line_info<32, false>;
921 #ifdef HAVE_TARGET_32_BIG
923 class Sized_dwarf_line_info<32, true>;
926 #ifdef HAVE_TARGET_64_LITTLE
928 class Sized_dwarf_line_info<64, false>;
931 #ifdef HAVE_TARGET_64_BIG
933 class Sized_dwarf_line_info<64, true>;
936 } // End namespace gold.