1 // dwarf_reader.cc -- parse dwarf2/3 debug information
3 // Copyright 2007, 2008 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"
37 // Read an unsigned LEB128 number. Each byte contains 7 bits of
38 // information, plus one bit saying whether the number continues or
42 read_unsigned_LEB_128(const unsigned char* buffer
, size_t* len
)
46 unsigned int shift
= 0;
53 result
|= (static_cast<uint64_t>(byte
& 0x7f)) << shift
;
63 // Read a signed LEB128 number. These are like regular LEB128
64 // numbers, except the last byte may have a sign bit set.
67 read_signed_LEB_128(const unsigned char* buffer
, size_t* len
)
78 result
|= (static_cast<uint64_t>(byte
& 0x7f) << shift
);
83 if ((shift
< 8 * static_cast<int>(sizeof(result
))) && (byte
& 0x40))
84 result
|= -((static_cast<int64_t>(1)) << shift
);
89 } // End anonymous namespace.
94 // This is the format of a DWARF2/3 line state machine that we process
95 // opcodes using. There is no need for anything outside the lineinfo
96 // processor to know how this works.
98 struct LineStateMachine
104 unsigned int shndx
; // the section address refers to
105 bool is_stmt
; // stmt means statement.
111 ResetLineStateMachine(struct LineStateMachine
* lsm
, bool default_is_stmt
)
118 lsm
->is_stmt
= default_is_stmt
;
119 lsm
->basic_block
= false;
120 lsm
->end_sequence
= false;
123 template<int size
, bool big_endian
>
124 Sized_dwarf_line_info
<size
, big_endian
>::Sized_dwarf_line_info(Object
* object
,
126 : data_valid_(false), buffer_(NULL
), symtab_buffer_(NULL
),
127 directories_(), files_(), current_header_index_(-1)
129 unsigned int debug_shndx
;
130 for (debug_shndx
= 0; debug_shndx
< object
->shnum(); ++debug_shndx
)
131 // FIXME: do this more efficiently: section_name() isn't super-fast
132 if (object
->section_name(debug_shndx
) == ".debug_line")
134 section_size_type buffer_size
;
135 this->buffer_
= object
->section_contents(debug_shndx
, &buffer_size
,
137 this->buffer_end_
= this->buffer_
+ buffer_size
;
140 if (this->buffer_
== NULL
)
143 // Find the relocation section for ".debug_line".
144 // We expect these for relobjs (.o's) but not dynobjs (.so's).
145 bool got_relocs
= false;
146 for (unsigned int reloc_shndx
= 0;
147 reloc_shndx
< object
->shnum();
150 unsigned int reloc_sh_type
= object
->section_type(reloc_shndx
);
151 if ((reloc_sh_type
== elfcpp::SHT_REL
152 || reloc_sh_type
== elfcpp::SHT_RELA
)
153 && object
->section_info(reloc_shndx
) == debug_shndx
)
155 got_relocs
= this->track_relocs_
.initialize(object
, reloc_shndx
,
161 // Finally, we need the symtab section to interpret the relocs.
164 unsigned int symtab_shndx
;
165 for (symtab_shndx
= 0; symtab_shndx
< object
->shnum(); ++symtab_shndx
)
166 if (object
->section_type(symtab_shndx
) == elfcpp::SHT_SYMTAB
)
168 this->symtab_buffer_
= object
->section_contents(
169 symtab_shndx
, &this->symtab_buffer_size_
, false);
172 if (this->symtab_buffer_
== NULL
)
176 // Now that we have successfully read all the data, parse the debug
178 this->data_valid_
= true;
179 this->read_line_mappings(object
, read_shndx
);
182 // Read the DWARF header.
184 template<int size
, bool big_endian
>
186 Sized_dwarf_line_info
<size
, big_endian
>::read_header_prolog(
187 const unsigned char* lineptr
)
189 uint32_t initial_length
= elfcpp::Swap_unaligned
<32, big_endian
>::readval(lineptr
);
192 // In DWARF2/3, if the initial length is all 1 bits, then the offset
193 // size is 8 and we need to read the next 8 bytes for the real length.
194 if (initial_length
== 0xffffffff)
196 header_
.offset_size
= 8;
197 initial_length
= elfcpp::Swap_unaligned
<64, big_endian
>::readval(lineptr
);
201 header_
.offset_size
= 4;
203 header_
.total_length
= initial_length
;
205 gold_assert(lineptr
+ header_
.total_length
<= buffer_end_
);
207 header_
.version
= elfcpp::Swap_unaligned
<16, big_endian
>::readval(lineptr
);
210 if (header_
.offset_size
== 4)
211 header_
.prologue_length
= elfcpp::Swap_unaligned
<32, big_endian
>::readval(lineptr
);
213 header_
.prologue_length
= elfcpp::Swap_unaligned
<64, big_endian
>::readval(lineptr
);
214 lineptr
+= header_
.offset_size
;
216 header_
.min_insn_length
= *lineptr
;
219 header_
.default_is_stmt
= *lineptr
;
222 header_
.line_base
= *reinterpret_cast<const signed char*>(lineptr
);
225 header_
.line_range
= *lineptr
;
228 header_
.opcode_base
= *lineptr
;
231 header_
.std_opcode_lengths
.reserve(header_
.opcode_base
+ 1);
232 header_
.std_opcode_lengths
[0] = 0;
233 for (int i
= 1; i
< header_
.opcode_base
; i
++)
235 header_
.std_opcode_lengths
[i
] = *lineptr
;
242 // The header for a debug_line section is mildly complicated, because
243 // the line info is very tightly encoded.
245 template<int size
, bool big_endian
>
247 Sized_dwarf_line_info
<size
, big_endian
>::read_header_tables(
248 const unsigned char* lineptr
)
250 ++this->current_header_index_
;
252 // Create a new directories_ entry and a new files_ entry for our new
253 // header. We initialize each with a single empty element, because
254 // dwarf indexes directory and filenames starting at 1.
255 gold_assert(static_cast<int>(this->directories_
.size())
256 == this->current_header_index_
);
257 gold_assert(static_cast<int>(this->files_
.size())
258 == this->current_header_index_
);
259 this->directories_
.push_back(std::vector
<std::string
>(1));
260 this->files_
.push_back(std::vector
<std::pair
<int, std::string
> >(1));
262 // It is legal for the directory entry table to be empty.
268 const char* dirname
= reinterpret_cast<const char*>(lineptr
);
270 == static_cast<int>(this->directories_
.back().size()));
271 this->directories_
.back().push_back(dirname
);
272 lineptr
+= this->directories_
.back().back().size() + 1;
278 // It is also legal for the file entry table to be empty.
285 const char* filename
= reinterpret_cast<const char*>(lineptr
);
286 lineptr
+= strlen(filename
) + 1;
288 uint64_t dirindex
= read_unsigned_LEB_128(lineptr
, &len
);
291 if (dirindex
>= this->directories_
.back().size())
293 int dirindexi
= static_cast<int>(dirindex
);
295 read_unsigned_LEB_128(lineptr
, &len
); // mod_time
298 read_unsigned_LEB_128(lineptr
, &len
); // filelength
301 gold_assert(fileindex
302 == static_cast<int>(this->files_
.back().size()));
303 this->files_
.back().push_back(std::make_pair(dirindexi
, filename
));
312 // Process a single opcode in the .debug.line structure.
314 // Templating on size and big_endian would yield more efficient (and
315 // simpler) code, but would bloat the binary. Speed isn't important
318 template<int size
, bool big_endian
>
320 Sized_dwarf_line_info
<size
, big_endian
>::process_one_opcode(
321 const unsigned char* start
, struct LineStateMachine
* lsm
, size_t* len
)
325 unsigned char opcode
= *start
;
329 // If the opcode is great than the opcode_base, it is a special
330 // opcode. Most line programs consist mainly of special opcodes.
331 if (opcode
>= header_
.opcode_base
)
333 opcode
-= header_
.opcode_base
;
334 const int advance_address
= ((opcode
/ header_
.line_range
)
335 * header_
.min_insn_length
);
336 lsm
->address
+= advance_address
;
338 const int advance_line
= ((opcode
% header_
.line_range
)
339 + header_
.line_base
);
340 lsm
->line_num
+= advance_line
;
341 lsm
->basic_block
= true;
346 // Otherwise, we have the regular opcodes
349 case elfcpp::DW_LNS_copy
:
350 lsm
->basic_block
= false;
354 case elfcpp::DW_LNS_advance_pc
:
356 const uint64_t advance_address
357 = read_unsigned_LEB_128(start
, &templen
);
359 lsm
->address
+= header_
.min_insn_length
* advance_address
;
363 case elfcpp::DW_LNS_advance_line
:
365 const uint64_t advance_line
= read_signed_LEB_128(start
, &templen
);
367 lsm
->line_num
+= advance_line
;
371 case elfcpp::DW_LNS_set_file
:
373 const uint64_t fileno
= read_unsigned_LEB_128(start
, &templen
);
375 lsm
->file_num
= fileno
;
379 case elfcpp::DW_LNS_set_column
:
381 const uint64_t colno
= read_unsigned_LEB_128(start
, &templen
);
383 lsm
->column_num
= colno
;
387 case elfcpp::DW_LNS_negate_stmt
:
388 lsm
->is_stmt
= !lsm
->is_stmt
;
391 case elfcpp::DW_LNS_set_basic_block
:
392 lsm
->basic_block
= true;
395 case elfcpp::DW_LNS_fixed_advance_pc
:
398 advance_address
= elfcpp::Swap_unaligned
<16, big_endian
>::readval(start
);
400 lsm
->address
+= advance_address
;
404 case elfcpp::DW_LNS_const_add_pc
:
406 const int advance_address
= (header_
.min_insn_length
407 * ((255 - header_
.opcode_base
)
408 / header_
.line_range
));
409 lsm
->address
+= advance_address
;
413 case elfcpp::DW_LNS_extended_op
:
415 const uint64_t extended_op_len
416 = read_unsigned_LEB_128(start
, &templen
);
418 oplen
+= templen
+ extended_op_len
;
420 const unsigned char extended_op
= *start
;
425 case elfcpp::DW_LNE_end_sequence
:
426 // This means that the current byte is the one immediately
427 // after a set of instructions. Record the current line
428 // for up to one less than the current address.
430 lsm
->end_sequence
= true;
434 case elfcpp::DW_LNE_set_address
:
436 lsm
->address
= elfcpp::Swap_unaligned
<size
, big_endian
>::readval(start
);
437 typename
Reloc_map::const_iterator it
438 = reloc_map_
.find(start
- this->buffer_
);
439 if (it
!= reloc_map_
.end())
442 lsm
->address
+= it
->second
.second
;
443 lsm
->shndx
= it
->second
.first
;
447 // If we're a normal .o file, with relocs, every
448 // set_address should have an associated relocation.
449 if (this->input_is_relobj())
450 this->data_valid_
= false;
454 case elfcpp::DW_LNE_define_file
:
456 const char* filename
= reinterpret_cast<const char*>(start
);
457 templen
= strlen(filename
) + 1;
460 uint64_t dirindex
= read_unsigned_LEB_128(start
, &templen
);
463 if (dirindex
>= this->directories_
.back().size())
465 int dirindexi
= static_cast<int>(dirindex
);
467 read_unsigned_LEB_128(start
, &templen
); // mod_time
470 read_unsigned_LEB_128(start
, &templen
); // filelength
473 this->files_
.back().push_back(std::make_pair(dirindexi
,
483 // Ignore unknown opcode silently
484 for (int i
= 0; i
< header_
.std_opcode_lengths
[opcode
]; i
++)
487 read_unsigned_LEB_128(start
, &templen
);
498 // Read the debug information at LINEPTR and store it in the line
501 template<int size
, bool big_endian
>
503 Sized_dwarf_line_info
<size
, big_endian
>::read_lines(unsigned const char* lineptr
,
506 struct LineStateMachine lsm
;
508 // LENGTHSTART is the place the length field is based on. It is the
509 // point in the header after the initial length field.
510 const unsigned char* lengthstart
= buffer_
;
512 // In 64 bit dwarf, the initial length is 12 bytes, because of the
513 // 0xffffffff at the start.
514 if (header_
.offset_size
== 8)
519 while (lineptr
< lengthstart
+ header_
.total_length
)
521 ResetLineStateMachine(&lsm
, header_
.default_is_stmt
);
522 while (!lsm
.end_sequence
)
525 bool add_line
= this->process_one_opcode(lineptr
, &lsm
, &oplength
);
527 && (shndx
== -1U || lsm
.shndx
== -1U || shndx
== lsm
.shndx
))
529 Offset_to_lineno_entry entry
530 = { lsm
.address
, this->current_header_index_
,
531 lsm
.file_num
, lsm
.line_num
};
532 line_number_map_
[lsm
.shndx
].push_back(entry
);
538 return lengthstart
+ header_
.total_length
;
541 // Looks in the symtab to see what section a symbol is in.
543 template<int size
, bool big_endian
>
545 Sized_dwarf_line_info
<size
, big_endian
>::symbol_section(
548 typename
elfcpp::Elf_types
<size
>::Elf_Addr
* value
,
551 const int symsize
= elfcpp::Elf_sizes
<size
>::sym_size
;
552 gold_assert(sym
* symsize
< this->symtab_buffer_size_
);
553 elfcpp::Sym
<size
, big_endian
> elfsym(this->symtab_buffer_
+ sym
* symsize
);
554 *value
= elfsym
.get_st_value();
555 return object
->adjust_sym_shndx(sym
, elfsym
.get_st_shndx(), is_ordinary
);
558 // Read the relocations into a Reloc_map.
560 template<int size
, bool big_endian
>
562 Sized_dwarf_line_info
<size
, big_endian
>::read_relocs(Object
* object
)
564 if (this->symtab_buffer_
== NULL
)
567 typename
elfcpp::Elf_types
<size
>::Elf_Addr value
;
569 while ((reloc_offset
= this->track_relocs_
.next_offset()) != -1)
571 const unsigned int sym
= this->track_relocs_
.next_symndx();
574 const unsigned int shndx
= this->symbol_section(object
, sym
, &value
,
577 // There is no reason to record non-ordinary section indexes, or
578 // SHN_UNDEF, because they will never match the real section.
579 if (is_ordinary
&& shndx
!= elfcpp::SHN_UNDEF
)
580 this->reloc_map_
[reloc_offset
] = std::make_pair(shndx
, value
);
582 this->track_relocs_
.advance(reloc_offset
+ 1);
586 // Read the line number info.
588 template<int size
, bool big_endian
>
590 Sized_dwarf_line_info
<size
, big_endian
>::read_line_mappings(Object
* object
,
593 gold_assert(this->data_valid_
== true);
595 this->read_relocs(object
);
596 while (this->buffer_
< this->buffer_end_
)
598 const unsigned char* lineptr
= this->buffer_
;
599 lineptr
= this->read_header_prolog(lineptr
);
600 lineptr
= this->read_header_tables(lineptr
);
601 lineptr
= this->read_lines(lineptr
, shndx
);
602 this->buffer_
= lineptr
;
605 // Sort the lines numbers, so addr2line can use binary search.
606 for (typename
Lineno_map::iterator it
= line_number_map_
.begin();
607 it
!= line_number_map_
.end();
609 // Each vector needs to be sorted by offset.
610 std::sort(it
->second
.begin(), it
->second
.end());
613 // Some processing depends on whether the input is a .o file or not.
614 // For instance, .o files have relocs, and have .debug_lines
615 // information on a per section basis. .so files, on the other hand,
616 // lack relocs, and offsets are unique, so we can ignore the section
619 template<int size
, bool big_endian
>
621 Sized_dwarf_line_info
<size
, big_endian
>::input_is_relobj()
623 // Only .o files have relocs and the symtab buffer that goes with them.
624 return this->symtab_buffer_
!= NULL
;
627 // Given an Offset_to_lineno_entry vector, and an offset, figure out
628 // if the offset points into a function according to the vector (see
629 // comments below for the algorithm). If it does, return an iterator
630 // into the vector that points to the line-number that contains that
631 // offset. If not, it returns vector::end().
633 static std::vector
<Offset_to_lineno_entry
>::const_iterator
634 offset_to_iterator(const std::vector
<Offset_to_lineno_entry
>* offsets
,
637 const Offset_to_lineno_entry lookup_key
= { offset
, 0, 0, 0 };
639 // lower_bound() returns the smallest offset which is >= lookup_key.
640 // If no offset in offsets is >= lookup_key, returns end().
641 std::vector
<Offset_to_lineno_entry
>::const_iterator it
642 = std::lower_bound(offsets
->begin(), offsets
->end(), lookup_key
);
644 // This code is easiest to understand with a concrete example.
645 // Here's a possible offsets array:
646 // {{offset = 3211, header_num = 0, file_num = 1, line_num = 16}, // 0
647 // {offset = 3224, header_num = 0, file_num = 1, line_num = 20}, // 1
648 // {offset = 3226, header_num = 0, file_num = 1, line_num = 22}, // 2
649 // {offset = 3231, header_num = 0, file_num = 1, line_num = 25}, // 3
650 // {offset = 3232, header_num = 0, file_num = 1, line_num = -1}, // 4
651 // {offset = 3232, header_num = 0, file_num = 1, line_num = 65}, // 5
652 // {offset = 3235, header_num = 0, file_num = 1, line_num = 66}, // 6
653 // {offset = 3236, header_num = 0, file_num = 1, line_num = -1}, // 7
654 // {offset = 5764, header_num = 0, file_num = 1, line_num = 47}, // 8
655 // {offset = 5765, header_num = 0, file_num = 1, line_num = 48}, // 9
656 // {offset = 5767, header_num = 0, file_num = 1, line_num = 49}, // 10
657 // {offset = 5768, header_num = 0, file_num = 1, line_num = 50}, // 11
658 // {offset = 5773, header_num = 0, file_num = 1, line_num = -1}, // 12
659 // {offset = 5787, header_num = 1, file_num = 1, line_num = 19}, // 13
660 // {offset = 5790, header_num = 1, file_num = 1, line_num = 20}, // 14
661 // {offset = 5793, header_num = 1, file_num = 1, line_num = 67}, // 15
662 // {offset = 5793, header_num = 1, file_num = 1, line_num = -1}, // 16
663 // {offset = 5795, header_num = 1, file_num = 1, line_num = 68}, // 17
664 // {offset = 5798, header_num = 1, file_num = 1, line_num = -1}, // 18
665 // The entries with line_num == -1 mark the end of a function: the
666 // associated offset is one past the last instruction in the
667 // function. This can correspond to the beginning of the next
668 // function (as is true for offset 3232); alternately, there can be
669 // a gap between the end of one function and the start of the next
670 // (as is true for some others, most obviously from 3236->5764).
672 // Case 1: lookup_key has offset == 10. lower_bound returns
673 // offsets[0]. Since it's not an exact match and we're
674 // at the beginning of offsets, we return end() (invalid).
675 // Case 2: lookup_key has offset 10000. lower_bound returns
676 // offset[19] (end()). We return end() (invalid).
677 // Case 3: lookup_key has offset == 3211. lower_bound matches
678 // offsets[0] exactly, and that's the entry we return.
679 // Case 4: lookup_key has offset == 3232. lower_bound returns
680 // offsets[4]. That's an exact match, but indicates
681 // end-of-function. We check if offsets[5] is also an
682 // exact match but not end-of-function. It is, so we
683 // return offsets[5].
684 // Case 5: lookup_key has offset == 3214. lower_bound returns
685 // offsets[1]. Since it's not an exact match, we back
686 // up to the offset that's < lookup_key, offsets[0].
687 // We note offsets[0] is a valid entry (not end-of-function),
688 // so that's the entry we return.
689 // Case 6: lookup_key has offset == 4000. lower_bound returns
690 // offsets[8]. Since it's not an exact match, we back
691 // up to offsets[7]. Since offsets[7] indicates
692 // end-of-function, we know lookup_key is between
693 // functions, so we return end() (not a valid offset).
694 // Case 7: lookup_key has offset == 5794. lower_bound returns
695 // offsets[17]. Since it's not an exact match, we back
696 // up to offsets[15]. Note we back up to the *first*
697 // entry with offset 5793, not just offsets[17-1].
698 // We note offsets[15] is a valid entry, so we return it.
699 // If offsets[15] had had line_num == -1, we would have
700 // checked offsets[16]. The reason for this is that
701 // 15 and 16 can be in an arbitrary order, since we sort
702 // only by offset. (Note it doesn't help to use line_number
703 // as a secondary sort key, since sometimes we want the -1
704 // to be first and sometimes we want it to be last.)
706 // This deals with cases (1) and (2).
707 if ((it
== offsets
->begin() && offset
< it
->offset
)
708 || it
== offsets
->end())
709 return offsets
->end();
711 // This deals with cases (3) and (4).
712 if (offset
== it
->offset
)
714 while (it
!= offsets
->end()
715 && it
->offset
== offset
716 && it
->line_num
== -1)
718 if (it
== offsets
->end() || it
->offset
!= offset
)
719 return offsets
->end();
724 // This handles the first part of case (7) -- we back up to the
725 // *first* entry that has the offset that's behind us.
726 gold_assert(it
!= offsets
->begin());
727 std::vector
<Offset_to_lineno_entry
>::const_iterator range_end
= it
;
729 const off_t range_value
= it
->offset
;
730 while (it
!= offsets
->begin() && (it
-1)->offset
== range_value
)
733 // This handles cases (5), (6), and (7): if any entry in the
734 // equal_range [it, range_end) has a line_num != -1, it's a valid
735 // match. If not, we're not in a function.
736 for (; it
!= range_end
; ++it
)
737 if (it
->line_num
!= -1)
739 return offsets
->end();
742 // Return a string for a file name and line number.
744 template<int size
, bool big_endian
>
746 Sized_dwarf_line_info
<size
, big_endian
>::do_addr2line(unsigned int shndx
,
749 if (this->data_valid_
== false)
752 const std::vector
<Offset_to_lineno_entry
>* offsets
;
753 // If we do not have reloc information, then our input is a .so or
754 // some similar data structure where all the information is held in
755 // the offset. In that case, we ignore the input shndx.
756 if (this->input_is_relobj())
757 offsets
= &this->line_number_map_
[shndx
];
759 offsets
= &this->line_number_map_
[-1U];
760 if (offsets
->empty())
763 typename
std::vector
<Offset_to_lineno_entry
>::const_iterator it
764 = offset_to_iterator(offsets
, offset
);
765 if (it
== offsets
->end())
768 // Convert the file_num + line_num into a string.
771 gold_assert(it
->header_num
< static_cast<int>(this->files_
.size()));
772 gold_assert(it
->file_num
773 < static_cast<int>(this->files_
[it
->header_num
].size()));
774 const std::pair
<int, std::string
>& filename_pair
775 = this->files_
[it
->header_num
][it
->file_num
];
776 const std::string
& filename
= filename_pair
.second
;
778 gold_assert(it
->header_num
< static_cast<int>(this->directories_
.size()));
779 gold_assert(filename_pair
.first
780 < static_cast<int>(this->directories_
[it
->header_num
].size()));
781 const std::string
& dirname
782 = this->directories_
[it
->header_num
][filename_pair
.first
];
784 if (!dirname
.empty())
793 char buffer
[64]; // enough to hold a line number
794 snprintf(buffer
, sizeof(buffer
), "%d", it
->line_num
);
801 // Dwarf_line_info routines.
803 static unsigned int next_generation_count
= 0;
805 struct Addr2line_cache_entry
809 Dwarf_line_info
* dwarf_line_info
;
810 unsigned int generation_count
;
811 unsigned int access_count
;
813 Addr2line_cache_entry(Object
* o
, unsigned int s
, Dwarf_line_info
* d
)
814 : object(o
), shndx(s
), dwarf_line_info(d
),
815 generation_count(next_generation_count
), access_count(0)
817 if (next_generation_count
< (1U << 31))
818 ++next_generation_count
;
821 // We expect this cache to be small, so don't bother with a hashtable
822 // or priority queue or anything: just use a simple vector.
823 static std::vector
<Addr2line_cache_entry
> addr2line_cache
;
826 Dwarf_line_info::one_addr2line(Object
* object
,
827 unsigned int shndx
, off_t offset
,
830 Dwarf_line_info
* lineinfo
= NULL
;
831 std::vector
<Addr2line_cache_entry
>::iterator it
;
833 // First, check the cache. If we hit, update the counts.
834 for (it
= addr2line_cache
.begin(); it
!= addr2line_cache
.end(); ++it
)
836 if (it
->object
== object
&& it
->shndx
== shndx
)
838 lineinfo
= it
->dwarf_line_info
;
839 it
->generation_count
= next_generation_count
;
840 // We cap generation_count at 2^31 -1 to avoid overflow.
841 if (next_generation_count
< (1U << 31))
842 ++next_generation_count
;
843 // We cap access_count at 31 so 2^access_count doesn't overflow
844 if (it
->access_count
< 31)
850 // If we don't hit the cache, create a new object and insert into the
852 if (lineinfo
== NULL
)
854 switch (parameters
->size_and_endianness())
856 #ifdef HAVE_TARGET_32_LITTLE
857 case Parameters::TARGET_32_LITTLE
:
858 lineinfo
= new Sized_dwarf_line_info
<32, false>(object
, shndx
); break;
860 #ifdef HAVE_TARGET_32_BIG
861 case Parameters::TARGET_32_BIG
:
862 lineinfo
= new Sized_dwarf_line_info
<32, true>(object
, shndx
); break;
864 #ifdef HAVE_TARGET_64_LITTLE
865 case Parameters::TARGET_64_LITTLE
:
866 lineinfo
= new Sized_dwarf_line_info
<64, false>(object
, shndx
); break;
868 #ifdef HAVE_TARGET_64_BIG
869 case Parameters::TARGET_64_BIG
:
870 lineinfo
= new Sized_dwarf_line_info
<64, true>(object
, shndx
); break;
875 addr2line_cache
.push_back(Addr2line_cache_entry(object
, shndx
, lineinfo
));
878 // Now that we have our object, figure out the answer
879 std::string retval
= lineinfo
->addr2line(shndx
, offset
);
881 // Finally, if our cache has grown too big, delete old objects. We
882 // assume the common (probably only) case is deleting only one object.
883 // We use a pretty simple scheme to evict: function of LRU and MFU.
884 while (addr2line_cache
.size() > cache_size
)
886 unsigned int lowest_score
= ~0U;
887 std::vector
<Addr2line_cache_entry
>::iterator lowest
888 = addr2line_cache
.end();
889 for (it
= addr2line_cache
.begin(); it
!= addr2line_cache
.end(); ++it
)
891 const unsigned int score
= (it
->generation_count
892 + (1U << it
->access_count
));
893 if (score
< lowest_score
)
895 lowest_score
= score
;
899 if (lowest
!= addr2line_cache
.end())
901 delete lowest
->dwarf_line_info
;
902 addr2line_cache
.erase(lowest
);
910 Dwarf_line_info::clear_addr2line_cache()
912 for (std::vector
<Addr2line_cache_entry
>::iterator it
= addr2line_cache
.begin();
913 it
!= addr2line_cache
.end();
915 delete it
->dwarf_line_info
;
916 addr2line_cache
.clear();
919 #ifdef HAVE_TARGET_32_LITTLE
921 class Sized_dwarf_line_info
<32, false>;
924 #ifdef HAVE_TARGET_32_BIG
926 class Sized_dwarf_line_info
<32, true>;
929 #ifdef HAVE_TARGET_64_LITTLE
931 class Sized_dwarf_line_info
<64, false>;
934 #ifdef HAVE_TARGET_64_BIG
936 class Sized_dwarf_line_info
<64, true>;
939 } // End namespace gold.