1 // dwarf_reader.cc -- parse dwarf2/3 debug information
3 // Copyright 2007, 2008, 2009, 2010 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(Object
* object
,
66 unsigned int read_shndx
)
67 : data_valid_(false), buffer_(NULL
), symtab_buffer_(NULL
),
68 directories_(), files_(), current_header_index_(-1)
70 unsigned int debug_shndx
;
71 for (debug_shndx
= 1; debug_shndx
< object
->shnum(); ++debug_shndx
)
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")
77 section_size_type buffer_size
;
78 this->buffer_
= object
->section_contents(debug_shndx
, &buffer_size
,
80 this->buffer_end_
= this->buffer_
+ buffer_size
;
84 if (this->buffer_
== NULL
)
87 section_size_type uncompressed_size
= 0;
88 unsigned char* uncompressed_data
= NULL
;
89 if (object
->section_is_compressed(debug_shndx
, &uncompressed_size
))
91 uncompressed_data
= new unsigned char[uncompressed_size
];
92 if (!decompress_input_section(this->buffer_
,
93 this->buffer_end_
- this->buffer_
,
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
;
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();
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
)
114 got_relocs
= this->track_relocs_
.initialize(object
, reloc_shndx
,
116 this->track_relocs_type_
= reloc_sh_type
;
121 // Finally, we need the symtab section to interpret the relocs.
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
)
128 this->symtab_buffer_
= object
->section_contents(
129 symtab_shndx
, &this->symtab_buffer_size_
, false);
132 if (this->symtab_buffer_
== NULL
)
136 // Now that we have successfully read all the data, parse the debug
138 this->data_valid_
= true;
139 this->read_line_mappings(object
, read_shndx
);
142 // Read the DWARF header.
144 template<int size
, bool big_endian
>
146 Sized_dwarf_line_info
<size
, big_endian
>::read_header_prolog(
147 const unsigned char* lineptr
)
149 uint32_t initial_length
= elfcpp::Swap_unaligned
<32, big_endian
>::readval(lineptr
);
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)
156 header_
.offset_size
= 8;
157 initial_length
= elfcpp::Swap_unaligned
<64, big_endian
>::readval(lineptr
);
161 header_
.offset_size
= 4;
163 header_
.total_length
= initial_length
;
165 gold_assert(lineptr
+ header_
.total_length
<= buffer_end_
);
167 header_
.version
= elfcpp::Swap_unaligned
<16, big_endian
>::readval(lineptr
);
170 if (header_
.offset_size
== 4)
171 header_
.prologue_length
= elfcpp::Swap_unaligned
<32, big_endian
>::readval(lineptr
);
173 header_
.prologue_length
= elfcpp::Swap_unaligned
<64, big_endian
>::readval(lineptr
);
174 lineptr
+= header_
.offset_size
;
176 header_
.min_insn_length
= *lineptr
;
179 header_
.default_is_stmt
= *lineptr
;
182 header_
.line_base
= *reinterpret_cast<const signed char*>(lineptr
);
185 header_
.line_range
= *lineptr
;
188 header_
.opcode_base
= *lineptr
;
191 header_
.std_opcode_lengths
.reserve(header_
.opcode_base
+ 1);
192 header_
.std_opcode_lengths
[0] = 0;
193 for (int i
= 1; i
< header_
.opcode_base
; i
++)
195 header_
.std_opcode_lengths
[i
] = *lineptr
;
202 // The header for a debug_line section is mildly complicated, because
203 // the line info is very tightly encoded.
205 template<int size
, bool big_endian
>
207 Sized_dwarf_line_info
<size
, big_endian
>::read_header_tables(
208 const unsigned char* lineptr
)
210 ++this->current_header_index_
;
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));
222 // It is legal for the directory entry table to be empty.
228 const char* dirname
= reinterpret_cast<const char*>(lineptr
);
230 == static_cast<int>(this->directories_
.back().size()));
231 this->directories_
.back().push_back(dirname
);
232 lineptr
+= this->directories_
.back().back().size() + 1;
238 // It is also legal for the file entry table to be empty.
245 const char* filename
= reinterpret_cast<const char*>(lineptr
);
246 lineptr
+= strlen(filename
) + 1;
248 uint64_t dirindex
= read_unsigned_LEB_128(lineptr
, &len
);
251 if (dirindex
>= this->directories_
.back().size())
253 int dirindexi
= static_cast<int>(dirindex
);
255 read_unsigned_LEB_128(lineptr
, &len
); // mod_time
258 read_unsigned_LEB_128(lineptr
, &len
); // filelength
261 gold_assert(fileindex
262 == static_cast<int>(this->files_
.back().size()));
263 this->files_
.back().push_back(std::make_pair(dirindexi
, filename
));
272 // Process a single opcode in the .debug.line structure.
274 // Templating on size and big_endian would yield more efficient (and
275 // simpler) code, but would bloat the binary. Speed isn't important
278 template<int size
, bool big_endian
>
280 Sized_dwarf_line_info
<size
, big_endian
>::process_one_opcode(
281 const unsigned char* start
, struct LineStateMachine
* lsm
, size_t* len
)
285 unsigned char opcode
= *start
;
289 // If the opcode is great than the opcode_base, it is a special
290 // opcode. Most line programs consist mainly of special opcodes.
291 if (opcode
>= header_
.opcode_base
)
293 opcode
-= header_
.opcode_base
;
294 const int advance_address
= ((opcode
/ header_
.line_range
)
295 * header_
.min_insn_length
);
296 lsm
->address
+= advance_address
;
298 const int advance_line
= ((opcode
% header_
.line_range
)
299 + header_
.line_base
);
300 lsm
->line_num
+= advance_line
;
301 lsm
->basic_block
= true;
306 // Otherwise, we have the regular opcodes
309 case elfcpp::DW_LNS_copy
:
310 lsm
->basic_block
= false;
314 case elfcpp::DW_LNS_advance_pc
:
316 const uint64_t advance_address
317 = read_unsigned_LEB_128(start
, &templen
);
319 lsm
->address
+= header_
.min_insn_length
* advance_address
;
323 case elfcpp::DW_LNS_advance_line
:
325 const uint64_t advance_line
= read_signed_LEB_128(start
, &templen
);
327 lsm
->line_num
+= advance_line
;
331 case elfcpp::DW_LNS_set_file
:
333 const uint64_t fileno
= read_unsigned_LEB_128(start
, &templen
);
335 lsm
->file_num
= fileno
;
339 case elfcpp::DW_LNS_set_column
:
341 const uint64_t colno
= read_unsigned_LEB_128(start
, &templen
);
343 lsm
->column_num
= colno
;
347 case elfcpp::DW_LNS_negate_stmt
:
348 lsm
->is_stmt
= !lsm
->is_stmt
;
351 case elfcpp::DW_LNS_set_basic_block
:
352 lsm
->basic_block
= true;
355 case elfcpp::DW_LNS_fixed_advance_pc
:
358 advance_address
= elfcpp::Swap_unaligned
<16, big_endian
>::readval(start
);
360 lsm
->address
+= advance_address
;
364 case elfcpp::DW_LNS_const_add_pc
:
366 const int advance_address
= (header_
.min_insn_length
367 * ((255 - header_
.opcode_base
)
368 / header_
.line_range
));
369 lsm
->address
+= advance_address
;
373 case elfcpp::DW_LNS_extended_op
:
375 const uint64_t extended_op_len
376 = read_unsigned_LEB_128(start
, &templen
);
378 oplen
+= templen
+ extended_op_len
;
380 const unsigned char extended_op
= *start
;
385 case elfcpp::DW_LNE_end_sequence
:
386 // This means that the current byte is the one immediately
387 // after a set of instructions. Record the current line
388 // for up to one less than the current address.
390 lsm
->end_sequence
= true;
394 case elfcpp::DW_LNE_set_address
:
397 elfcpp::Swap_unaligned
<size
, big_endian
>::readval(start
);
398 typename
Reloc_map::const_iterator it
399 = this->reloc_map_
.find(start
- this->buffer_
);
400 if (it
!= reloc_map_
.end())
402 // If this is a SHT_RELA section, then ignore the
403 // section contents. This assumes that this is a
404 // straight reloc which just uses the reloc addend.
405 // The reloc addend has already been included in the
407 if (this->track_relocs_type_
== elfcpp::SHT_RELA
)
409 // Add in the symbol value.
410 lsm
->address
+= it
->second
.second
;
411 lsm
->shndx
= it
->second
.first
;
415 // If we're a normal .o file, with relocs, every
416 // set_address should have an associated relocation.
417 if (this->input_is_relobj())
418 this->data_valid_
= false;
422 case elfcpp::DW_LNE_define_file
:
424 const char* filename
= reinterpret_cast<const char*>(start
);
425 templen
= strlen(filename
) + 1;
428 uint64_t dirindex
= read_unsigned_LEB_128(start
, &templen
);
431 if (dirindex
>= this->directories_
.back().size())
433 int dirindexi
= static_cast<int>(dirindex
);
435 read_unsigned_LEB_128(start
, &templen
); // mod_time
438 read_unsigned_LEB_128(start
, &templen
); // filelength
441 this->files_
.back().push_back(std::make_pair(dirindexi
,
451 // Ignore unknown opcode silently
452 for (int i
= 0; i
< header_
.std_opcode_lengths
[opcode
]; i
++)
455 read_unsigned_LEB_128(start
, &templen
);
466 // Read the debug information at LINEPTR and store it in the line
469 template<int size
, bool big_endian
>
471 Sized_dwarf_line_info
<size
, big_endian
>::read_lines(unsigned const char* lineptr
,
474 struct LineStateMachine lsm
;
476 // LENGTHSTART is the place the length field is based on. It is the
477 // point in the header after the initial length field.
478 const unsigned char* lengthstart
= buffer_
;
480 // In 64 bit dwarf, the initial length is 12 bytes, because of the
481 // 0xffffffff at the start.
482 if (header_
.offset_size
== 8)
487 while (lineptr
< lengthstart
+ header_
.total_length
)
489 ResetLineStateMachine(&lsm
, header_
.default_is_stmt
);
490 while (!lsm
.end_sequence
)
493 bool add_line
= this->process_one_opcode(lineptr
, &lsm
, &oplength
);
495 && (shndx
== -1U || lsm
.shndx
== -1U || shndx
== lsm
.shndx
))
497 Offset_to_lineno_entry entry
498 = { lsm
.address
, this->current_header_index_
,
499 lsm
.file_num
, lsm
.line_num
};
500 line_number_map_
[lsm
.shndx
].push_back(entry
);
506 return lengthstart
+ header_
.total_length
;
509 // Looks in the symtab to see what section a symbol is in.
511 template<int size
, bool big_endian
>
513 Sized_dwarf_line_info
<size
, big_endian
>::symbol_section(
516 typename
elfcpp::Elf_types
<size
>::Elf_Addr
* value
,
519 const int symsize
= elfcpp::Elf_sizes
<size
>::sym_size
;
520 gold_assert(sym
* symsize
< this->symtab_buffer_size_
);
521 elfcpp::Sym
<size
, big_endian
> elfsym(this->symtab_buffer_
+ sym
* symsize
);
522 *value
= elfsym
.get_st_value();
523 return object
->adjust_sym_shndx(sym
, elfsym
.get_st_shndx(), is_ordinary
);
526 // Read the relocations into a Reloc_map.
528 template<int size
, bool big_endian
>
530 Sized_dwarf_line_info
<size
, big_endian
>::read_relocs(Object
* object
)
532 if (this->symtab_buffer_
== NULL
)
535 typename
elfcpp::Elf_types
<size
>::Elf_Addr value
;
537 while ((reloc_offset
= this->track_relocs_
.next_offset()) != -1)
539 const unsigned int sym
= this->track_relocs_
.next_symndx();
542 const unsigned int shndx
= this->symbol_section(object
, sym
, &value
,
545 // There is no reason to record non-ordinary section indexes, or
546 // SHN_UNDEF, because they will never match the real section.
547 if (is_ordinary
&& shndx
!= elfcpp::SHN_UNDEF
)
549 value
+= this->track_relocs_
.next_addend();
550 this->reloc_map_
[reloc_offset
] = std::make_pair(shndx
, value
);
553 this->track_relocs_
.advance(reloc_offset
+ 1);
557 // Read the line number info.
559 template<int size
, bool big_endian
>
561 Sized_dwarf_line_info
<size
, big_endian
>::read_line_mappings(Object
* object
,
564 gold_assert(this->data_valid_
== true);
566 this->read_relocs(object
);
567 while (this->buffer_
< this->buffer_end_
)
569 const unsigned char* lineptr
= this->buffer_
;
570 lineptr
= this->read_header_prolog(lineptr
);
571 lineptr
= this->read_header_tables(lineptr
);
572 lineptr
= this->read_lines(lineptr
, shndx
);
573 this->buffer_
= lineptr
;
576 // Sort the lines numbers, so addr2line can use binary search.
577 for (typename
Lineno_map::iterator it
= line_number_map_
.begin();
578 it
!= line_number_map_
.end();
580 // Each vector needs to be sorted by offset.
581 std::sort(it
->second
.begin(), it
->second
.end());
584 // Some processing depends on whether the input is a .o file or not.
585 // For instance, .o files have relocs, and have .debug_lines
586 // information on a per section basis. .so files, on the other hand,
587 // lack relocs, and offsets are unique, so we can ignore the section
590 template<int size
, bool big_endian
>
592 Sized_dwarf_line_info
<size
, big_endian
>::input_is_relobj()
594 // Only .o files have relocs and the symtab buffer that goes with them.
595 return this->symtab_buffer_
!= NULL
;
598 // Given an Offset_to_lineno_entry vector, and an offset, figure out
599 // if the offset points into a function according to the vector (see
600 // comments below for the algorithm). If it does, return an iterator
601 // into the vector that points to the line-number that contains that
602 // offset. If not, it returns vector::end().
604 static std::vector
<Offset_to_lineno_entry
>::const_iterator
605 offset_to_iterator(const std::vector
<Offset_to_lineno_entry
>* offsets
,
608 const Offset_to_lineno_entry lookup_key
= { offset
, 0, 0, 0 };
610 // lower_bound() returns the smallest offset which is >= lookup_key.
611 // If no offset in offsets is >= lookup_key, returns end().
612 std::vector
<Offset_to_lineno_entry
>::const_iterator it
613 = std::lower_bound(offsets
->begin(), offsets
->end(), lookup_key
);
615 // This code is easiest to understand with a concrete example.
616 // Here's a possible offsets array:
617 // {{offset = 3211, header_num = 0, file_num = 1, line_num = 16}, // 0
618 // {offset = 3224, header_num = 0, file_num = 1, line_num = 20}, // 1
619 // {offset = 3226, header_num = 0, file_num = 1, line_num = 22}, // 2
620 // {offset = 3231, header_num = 0, file_num = 1, line_num = 25}, // 3
621 // {offset = 3232, header_num = 0, file_num = 1, line_num = -1}, // 4
622 // {offset = 3232, header_num = 0, file_num = 1, line_num = 65}, // 5
623 // {offset = 3235, header_num = 0, file_num = 1, line_num = 66}, // 6
624 // {offset = 3236, header_num = 0, file_num = 1, line_num = -1}, // 7
625 // {offset = 5764, header_num = 0, file_num = 1, line_num = 47}, // 8
626 // {offset = 5765, header_num = 0, file_num = 1, line_num = 48}, // 9
627 // {offset = 5767, header_num = 0, file_num = 1, line_num = 49}, // 10
628 // {offset = 5768, header_num = 0, file_num = 1, line_num = 50}, // 11
629 // {offset = 5773, header_num = 0, file_num = 1, line_num = -1}, // 12
630 // {offset = 5787, header_num = 1, file_num = 1, line_num = 19}, // 13
631 // {offset = 5790, header_num = 1, file_num = 1, line_num = 20}, // 14
632 // {offset = 5793, header_num = 1, file_num = 1, line_num = 67}, // 15
633 // {offset = 5793, header_num = 1, file_num = 1, line_num = -1}, // 16
634 // {offset = 5795, header_num = 1, file_num = 1, line_num = 68}, // 17
635 // {offset = 5798, header_num = 1, file_num = 1, line_num = -1}, // 18
636 // The entries with line_num == -1 mark the end of a function: the
637 // associated offset is one past the last instruction in the
638 // function. This can correspond to the beginning of the next
639 // function (as is true for offset 3232); alternately, there can be
640 // a gap between the end of one function and the start of the next
641 // (as is true for some others, most obviously from 3236->5764).
643 // Case 1: lookup_key has offset == 10. lower_bound returns
644 // offsets[0]. Since it's not an exact match and we're
645 // at the beginning of offsets, we return end() (invalid).
646 // Case 2: lookup_key has offset 10000. lower_bound returns
647 // offset[19] (end()). We return end() (invalid).
648 // Case 3: lookup_key has offset == 3211. lower_bound matches
649 // offsets[0] exactly, and that's the entry we return.
650 // Case 4: lookup_key has offset == 3232. lower_bound returns
651 // offsets[4]. That's an exact match, but indicates
652 // end-of-function. We check if offsets[5] is also an
653 // exact match but not end-of-function. It is, so we
654 // return offsets[5].
655 // Case 5: lookup_key has offset == 3214. lower_bound returns
656 // offsets[1]. Since it's not an exact match, we back
657 // up to the offset that's < lookup_key, offsets[0].
658 // We note offsets[0] is a valid entry (not end-of-function),
659 // so that's the entry we return.
660 // Case 6: lookup_key has offset == 4000. lower_bound returns
661 // offsets[8]. Since it's not an exact match, we back
662 // up to offsets[7]. Since offsets[7] indicates
663 // end-of-function, we know lookup_key is between
664 // functions, so we return end() (not a valid offset).
665 // Case 7: lookup_key has offset == 5794. lower_bound returns
666 // offsets[17]. Since it's not an exact match, we back
667 // up to offsets[15]. Note we back up to the *first*
668 // entry with offset 5793, not just offsets[17-1].
669 // We note offsets[15] is a valid entry, so we return it.
670 // If offsets[15] had had line_num == -1, we would have
671 // checked offsets[16]. The reason for this is that
672 // 15 and 16 can be in an arbitrary order, since we sort
673 // only by offset. (Note it doesn't help to use line_number
674 // as a secondary sort key, since sometimes we want the -1
675 // to be first and sometimes we want it to be last.)
677 // This deals with cases (1) and (2).
678 if ((it
== offsets
->begin() && offset
< it
->offset
)
679 || it
== offsets
->end())
680 return offsets
->end();
682 // This deals with cases (3) and (4).
683 if (offset
== it
->offset
)
685 while (it
!= offsets
->end()
686 && it
->offset
== offset
687 && it
->line_num
== -1)
689 if (it
== offsets
->end() || it
->offset
!= offset
)
690 return offsets
->end();
695 // This handles the first part of case (7) -- we back up to the
696 // *first* entry that has the offset that's behind us.
697 gold_assert(it
!= offsets
->begin());
698 std::vector
<Offset_to_lineno_entry
>::const_iterator range_end
= it
;
700 const off_t range_value
= it
->offset
;
701 while (it
!= offsets
->begin() && (it
-1)->offset
== range_value
)
704 // This handles cases (5), (6), and (7): if any entry in the
705 // equal_range [it, range_end) has a line_num != -1, it's a valid
706 // match. If not, we're not in a function.
707 for (; it
!= range_end
; ++it
)
708 if (it
->line_num
!= -1)
710 return offsets
->end();
713 // Return a string for a file name and line number.
715 template<int size
, bool big_endian
>
717 Sized_dwarf_line_info
<size
, big_endian
>::do_addr2line(unsigned int shndx
,
720 if (this->data_valid_
== false)
723 const std::vector
<Offset_to_lineno_entry
>* offsets
;
724 // If we do not have reloc information, then our input is a .so or
725 // some similar data structure where all the information is held in
726 // the offset. In that case, we ignore the input shndx.
727 if (this->input_is_relobj())
728 offsets
= &this->line_number_map_
[shndx
];
730 offsets
= &this->line_number_map_
[-1U];
731 if (offsets
->empty())
734 typename
std::vector
<Offset_to_lineno_entry
>::const_iterator it
735 = offset_to_iterator(offsets
, offset
);
736 if (it
== offsets
->end())
739 // Convert the file_num + line_num into a string.
742 gold_assert(it
->header_num
< static_cast<int>(this->files_
.size()));
743 gold_assert(it
->file_num
744 < static_cast<int>(this->files_
[it
->header_num
].size()));
745 const std::pair
<int, std::string
>& filename_pair
746 = this->files_
[it
->header_num
][it
->file_num
];
747 const std::string
& filename
= filename_pair
.second
;
749 gold_assert(it
->header_num
< static_cast<int>(this->directories_
.size()));
750 gold_assert(filename_pair
.first
751 < static_cast<int>(this->directories_
[it
->header_num
].size()));
752 const std::string
& dirname
753 = this->directories_
[it
->header_num
][filename_pair
.first
];
755 if (!dirname
.empty())
764 char buffer
[64]; // enough to hold a line number
765 snprintf(buffer
, sizeof(buffer
), "%d", it
->line_num
);
772 // Dwarf_line_info routines.
774 static unsigned int next_generation_count
= 0;
776 struct Addr2line_cache_entry
780 Dwarf_line_info
* dwarf_line_info
;
781 unsigned int generation_count
;
782 unsigned int access_count
;
784 Addr2line_cache_entry(Object
* o
, unsigned int s
, Dwarf_line_info
* d
)
785 : object(o
), shndx(s
), dwarf_line_info(d
),
786 generation_count(next_generation_count
), access_count(0)
788 if (next_generation_count
< (1U << 31))
789 ++next_generation_count
;
792 // We expect this cache to be small, so don't bother with a hashtable
793 // or priority queue or anything: just use a simple vector.
794 static std::vector
<Addr2line_cache_entry
> addr2line_cache
;
797 Dwarf_line_info::one_addr2line(Object
* object
,
798 unsigned int shndx
, off_t offset
,
801 Dwarf_line_info
* lineinfo
= NULL
;
802 std::vector
<Addr2line_cache_entry
>::iterator it
;
804 // First, check the cache. If we hit, update the counts.
805 for (it
= addr2line_cache
.begin(); it
!= addr2line_cache
.end(); ++it
)
807 if (it
->object
== object
&& it
->shndx
== shndx
)
809 lineinfo
= it
->dwarf_line_info
;
810 it
->generation_count
= next_generation_count
;
811 // We cap generation_count at 2^31 -1 to avoid overflow.
812 if (next_generation_count
< (1U << 31))
813 ++next_generation_count
;
814 // We cap access_count at 31 so 2^access_count doesn't overflow
815 if (it
->access_count
< 31)
821 // If we don't hit the cache, create a new object and insert into the
823 if (lineinfo
== NULL
)
825 switch (parameters
->size_and_endianness())
827 #ifdef HAVE_TARGET_32_LITTLE
828 case Parameters::TARGET_32_LITTLE
:
829 lineinfo
= new Sized_dwarf_line_info
<32, false>(object
, shndx
); break;
831 #ifdef HAVE_TARGET_32_BIG
832 case Parameters::TARGET_32_BIG
:
833 lineinfo
= new Sized_dwarf_line_info
<32, true>(object
, shndx
); break;
835 #ifdef HAVE_TARGET_64_LITTLE
836 case Parameters::TARGET_64_LITTLE
:
837 lineinfo
= new Sized_dwarf_line_info
<64, false>(object
, shndx
); break;
839 #ifdef HAVE_TARGET_64_BIG
840 case Parameters::TARGET_64_BIG
:
841 lineinfo
= new Sized_dwarf_line_info
<64, true>(object
, shndx
); break;
846 addr2line_cache
.push_back(Addr2line_cache_entry(object
, shndx
, lineinfo
));
849 // Now that we have our object, figure out the answer
850 std::string retval
= lineinfo
->addr2line(shndx
, offset
);
852 // Finally, if our cache has grown too big, delete old objects. We
853 // assume the common (probably only) case is deleting only one object.
854 // We use a pretty simple scheme to evict: function of LRU and MFU.
855 while (addr2line_cache
.size() > cache_size
)
857 unsigned int lowest_score
= ~0U;
858 std::vector
<Addr2line_cache_entry
>::iterator lowest
859 = addr2line_cache
.end();
860 for (it
= addr2line_cache
.begin(); it
!= addr2line_cache
.end(); ++it
)
862 const unsigned int score
= (it
->generation_count
863 + (1U << it
->access_count
));
864 if (score
< lowest_score
)
866 lowest_score
= score
;
870 if (lowest
!= addr2line_cache
.end())
872 delete lowest
->dwarf_line_info
;
873 addr2line_cache
.erase(lowest
);
881 Dwarf_line_info::clear_addr2line_cache()
883 for (std::vector
<Addr2line_cache_entry
>::iterator it
= addr2line_cache
.begin();
884 it
!= addr2line_cache
.end();
886 delete it
->dwarf_line_info
;
887 addr2line_cache
.clear();
890 #ifdef HAVE_TARGET_32_LITTLE
892 class Sized_dwarf_line_info
<32, false>;
895 #ifdef HAVE_TARGET_32_BIG
897 class Sized_dwarf_line_info
<32, true>;
900 #ifdef HAVE_TARGET_64_LITTLE
902 class Sized_dwarf_line_info
<64, false>;
905 #ifdef HAVE_TARGET_64_BIG
907 class Sized_dwarf_line_info
<64, true>;
910 } // End namespace gold.