1 /* DWARF 2 debugging format support for GDB.
3 Copyright (C) 1994-2020 Free Software Foundation, Inc.
5 This file is part of GDB.
7 This program is free software; you can redistribute it and/or modify
8 it under the terms of the GNU General Public License as published by
9 the Free Software Foundation; either version 3 of the License, or
10 (at your option) any later version.
12 This program is distributed in the hope that it will be useful,
13 but WITHOUT ANY WARRANTY; without even the implied warranty of
14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 GNU General Public License for more details.
17 You should have received a copy of the GNU General Public License
18 along with this program. If not, see <http://www.gnu.org/licenses/>. */
24 #include <unordered_map>
25 #include "dwarf2/index-cache.h"
26 #include "dwarf2/section.h"
27 #include "filename-seen-cache.h"
28 #include "gdb_obstack.h"
29 #include "gdbsupport/hash_enum.h"
32 /* Hold 'maintenance (set|show) dwarf' commands. */
33 extern struct cmd_list_element
*set_dwarf_cmdlist
;
34 extern struct cmd_list_element
*show_dwarf_cmdlist
;
38 int nr_uniq_abbrev_tables
;
40 int nr_symtab_sharers
;
41 int nr_stmt_less_type_units
;
42 int nr_all_type_units_reallocs
;
45 struct dwarf2_debug_sections
;
46 struct dwarf2_per_cu_data
;
48 struct mapped_debug_names
;
49 struct signatured_type
;
51 /* One item on the queue of compilation units to read in full symbols
53 struct dwarf2_queue_item
55 dwarf2_queue_item (dwarf2_per_cu_data
*cu
, enum language lang
)
57 pretend_language (lang
)
61 ~dwarf2_queue_item ();
63 DISABLE_COPY_AND_ASSIGN (dwarf2_queue_item
);
65 struct dwarf2_per_cu_data
*per_cu
;
66 enum language pretend_language
;
69 /* Collection of data recorded per objfile.
70 This hangs off of dwarf2_objfile_data_key. */
72 struct dwarf2_per_objfile
74 /* Construct a dwarf2_per_objfile for OBJFILE. NAMES points to the
75 dwarf2 section names, or is NULL if the standard ELF names are
76 used. CAN_COPY is true for formats where symbol
77 interposition is possible and so symbol values must follow copy
79 dwarf2_per_objfile (struct objfile
*objfile
,
80 const dwarf2_debug_sections
*names
,
83 ~dwarf2_per_objfile ();
85 DISABLE_COPY_AND_ASSIGN (dwarf2_per_objfile
);
87 /* Return the CU/TU given its index.
89 This is intended for loops like:
91 for (i = 0; i < (dwarf2_per_objfile->n_comp_units
92 + dwarf2_per_objfile->n_type_units); ++i)
94 dwarf2_per_cu_data *per_cu = dwarf2_per_objfile->get_cutu (i);
99 dwarf2_per_cu_data
*get_cutu (int index
);
101 /* Return the CU given its index.
102 This differs from get_cutu in that it's for when you know INDEX refers to a
104 dwarf2_per_cu_data
*get_cu (int index
);
106 /* Return the TU given its index.
107 This differs from get_cutu in that it's for when you know INDEX refers to a
109 signatured_type
*get_tu (int index
);
111 /* Free all cached compilation units. */
112 void free_cached_comp_units ();
114 /* This function is mapped across the sections and remembers the
115 offset and size of each of the debugging sections we are
117 void locate_sections (bfd
*abfd
, asection
*sectp
,
118 const dwarf2_debug_sections
&names
);
121 dwarf2_section_info info
{};
122 dwarf2_section_info abbrev
{};
123 dwarf2_section_info line
{};
124 dwarf2_section_info loc
{};
125 dwarf2_section_info loclists
{};
126 dwarf2_section_info macinfo
{};
127 dwarf2_section_info macro
{};
128 dwarf2_section_info str
{};
129 dwarf2_section_info str_offsets
{};
130 dwarf2_section_info line_str
{};
131 dwarf2_section_info ranges
{};
132 dwarf2_section_info rnglists
{};
133 dwarf2_section_info addr
{};
134 dwarf2_section_info frame
{};
135 dwarf2_section_info eh_frame
{};
136 dwarf2_section_info gdb_index
{};
137 dwarf2_section_info debug_names
{};
138 dwarf2_section_info debug_aranges
{};
140 std::vector
<dwarf2_section_info
> types
;
143 struct objfile
*objfile
= NULL
;
145 /* Table of all the compilation units. This is used to locate
146 the target compilation unit of a particular reference. */
147 std::vector
<dwarf2_per_cu_data
*> all_comp_units
;
149 /* The .debug_types-related CUs (TUs). */
150 std::vector
<signatured_type
*> all_type_units
;
152 /* Table of struct type_unit_group objects.
153 The hash key is the DW_AT_stmt_list value. */
154 htab_up type_unit_groups
;
156 /* A table mapping .debug_types signatures to its signatured_type entry.
157 This is NULL if the .debug_types section hasn't been read in yet. */
158 htab_up signatured_types
;
160 /* Type unit statistics, to see how well the scaling improvements
162 struct tu_stats tu_stats
{};
164 /* A chain of compilation units that are currently read in, so that
165 they can be freed later. */
166 dwarf2_per_cu_data
*read_in_chain
= NULL
;
168 /* A table mapping DW_AT_dwo_name values to struct dwo_file objects.
169 This is NULL if the table hasn't been allocated yet. */
172 /* True if we've checked for whether there is a DWP file. */
173 bool dwp_checked
= false;
175 /* The DWP file if there is one, or NULL. */
176 std::unique_ptr
<struct dwp_file
> dwp_file
;
178 /* The shared '.dwz' file, if one exists. This is used when the
179 original data was compressed using 'dwz -m'. */
180 std::unique_ptr
<struct dwz_file
> dwz_file
;
182 /* Whether copy relocations are supported by this object format. */
185 /* A flag indicating whether this objfile has a section loaded at a
187 bool has_section_at_zero
= false;
189 /* True if we are using the mapped index,
190 or we are faking it for OBJF_READNOW's sake. */
191 bool using_index
= false;
193 /* The mapped index, or NULL if .gdb_index is missing or not being used. */
194 std::unique_ptr
<mapped_index
> index_table
;
196 /* The mapped index, or NULL if .debug_names is missing or not being used. */
197 std::unique_ptr
<mapped_debug_names
> debug_names_table
;
199 /* When using index_table, this keeps track of all quick_file_names entries.
200 TUs typically share line table entries with a CU, so we maintain a
201 separate table of all line table entries to support the sharing.
202 Note that while there can be way more TUs than CUs, we've already
203 sorted all the TUs into "type unit groups", grouped by their
204 DW_AT_stmt_list value. Therefore the only sharing done here is with a
205 CU and its associated TU group if there is one. */
206 htab_up quick_file_names_table
;
208 /* Set during partial symbol reading, to prevent queueing of full
210 bool reading_partial_symbols
= false;
212 /* Table mapping type DIEs to their struct type *.
213 This is NULL if not allocated yet.
214 The mapping is done via (CU/TU + DIE offset) -> type. */
215 htab_up die_type_hash
;
217 /* The CUs we recently read. */
218 std::vector
<dwarf2_per_cu_data
*> just_read_cus
;
220 /* Table containing line_header indexed by offset and offset_in_dwz. */
221 htab_up line_header_hash
;
223 /* Table containing all filenames. This is an optional because the
224 table is lazily constructed on first access. */
225 gdb::optional
<filename_seen_cache
> filenames_cache
;
227 /* If we loaded the index from an external file, this contains the
228 resources associated to the open file, memory mapping, etc. */
229 std::unique_ptr
<index_cache_resource
> index_cache_res
;
231 /* Mapping from abstract origin DIE to concrete DIEs that reference it as
232 DW_AT_abstract_origin. */
233 std::unordered_map
<sect_offset
, std::vector
<sect_offset
>,
234 gdb::hash_enum
<sect_offset
>>
235 abstract_to_concrete
;
237 /* CUs that are queued to be read. */
238 std::queue
<dwarf2_queue_item
> queue
;
241 /* Get the dwarf2_per_objfile associated to OBJFILE. */
243 dwarf2_per_objfile
*get_dwarf2_per_objfile (struct objfile
*objfile
);
245 /* A partial symtab specialized for DWARF. */
246 struct dwarf2_psymtab
: public standard_psymtab
248 dwarf2_psymtab (const char *filename
, struct objfile
*objfile
)
249 : standard_psymtab (filename
, objfile
)
253 dwarf2_psymtab (const char *filename
, struct objfile
*objfile
,
255 : standard_psymtab (filename
, objfile
, addr
)
259 void read_symtab (struct objfile
*) override
;
260 void expand_psymtab (struct objfile
*) override
;
262 struct dwarf2_per_cu_data
*per_cu_data
;
265 /* Persistent data held for a compilation unit, even when not
266 processing it. We put a pointer to this structure in the
269 struct dwarf2_per_cu_data
271 /* The start offset and length of this compilation unit.
272 NOTE: Unlike comp_unit_head.length, this length includes
274 If the DIE refers to a DWO file, this is always of the original die,
276 sect_offset sect_off
;
279 /* DWARF standard version this data has been read from (such as 4 or 5). */
282 /* Flag indicating this compilation unit will be read in before
283 any of the current compilation units are processed. */
284 unsigned int queued
: 1;
286 /* This flag will be set when reading partial DIEs if we need to load
287 absolutely all DIEs for this compilation unit, instead of just the ones
288 we think are interesting. It gets set if we look for a DIE in the
289 hash table and don't find it. */
290 unsigned int load_all_dies
: 1;
292 /* Non-zero if this CU is from .debug_types.
293 Struct dwarf2_per_cu_data is contained in struct signatured_type iff
295 unsigned int is_debug_types
: 1;
297 /* Non-zero if this CU is from the .dwz file. */
298 unsigned int is_dwz
: 1;
300 /* Non-zero if reading a TU directly from a DWO file, bypassing the stub.
301 This flag is only valid if is_debug_types is true.
302 We can't read a CU directly from a DWO file: There are required
303 attributes in the stub. */
304 unsigned int reading_dwo_directly
: 1;
306 /* Non-zero if the TU has been read.
307 This is used to assist the "Stay in DWO Optimization" for Fission:
308 When reading a DWO, it's faster to read TUs from the DWO instead of
309 fetching them from random other DWOs (due to comdat folding).
310 If the TU has already been read, the optimization is unnecessary
311 (and unwise - we don't want to change where gdb thinks the TU lives
313 This flag is only valid if is_debug_types is true. */
314 unsigned int tu_read
: 1;
316 /* The section this CU/TU lives in.
317 If the DIE refers to a DWO file, this is always the original die,
319 struct dwarf2_section_info
*section
;
321 /* Set to non-NULL iff this CU is currently loaded. When it gets freed out
322 of the CU cache it gets reset to NULL again. This is left as NULL for
323 dummy CUs (a CU header, but nothing else). */
324 struct dwarf2_cu
*cu
;
326 /* The unit type of this CU. */
327 enum dwarf_unit_type unit_type
;
329 /* The language of this CU. */
332 /* The corresponding dwarf2_per_objfile. */
333 struct dwarf2_per_objfile
*dwarf2_per_objfile
;
335 /* When dwarf2_per_objfile->using_index is true, the 'quick' field
336 is active. Otherwise, the 'psymtab' field is active. */
339 /* The partial symbol table associated with this compilation unit,
340 or NULL for unread partial units. */
341 dwarf2_psymtab
*psymtab
;
343 /* Data needed by the "quick" functions. */
344 struct dwarf2_per_cu_quick_data
*quick
;
347 /* The CUs we import using DW_TAG_imported_unit. This is filled in
348 while reading psymtabs, used to compute the psymtab dependencies,
349 and then cleared. Then it is filled in again while reading full
350 symbols, and only deleted when the objfile is destroyed.
352 This is also used to work around a difference between the way gold
353 generates .gdb_index version <=7 and the way gdb does. Arguably this
354 is a gold bug. For symbols coming from TUs, gold records in the index
355 the CU that includes the TU instead of the TU itself. This breaks
356 dw2_lookup_symbol: It assumes that if the index says symbol X lives
357 in CU/TU Y, then one need only expand Y and a subsequent lookup in Y
358 will find X. Alas TUs live in their own symtab, so after expanding CU Y
359 we need to look in TU Z to find X. Fortunately, this is akin to
360 DW_TAG_imported_unit, so we just use the same mechanism: For
361 .gdb_index version <=7 this also records the TUs that the CU referred
362 to. Concurrently with this change gdb was modified to emit version 8
363 indices so we only pay a price for gold generated indices.
364 http://sourceware.org/bugzilla/show_bug.cgi?id=15021.
366 This currently needs to be a public member due to how
367 dwarf2_per_cu_data is allocated and used. Ideally in future things
368 could be refactored to make this private. Until then please try to
369 avoid direct access to this member, and instead use the helper
371 std::vector
<dwarf2_per_cu_data
*> *imported_symtabs
;
373 /* Return true of IMPORTED_SYMTABS is empty or not yet allocated. */
374 bool imported_symtabs_empty () const
376 return (imported_symtabs
== nullptr || imported_symtabs
->empty ());
379 /* Push P to the back of IMPORTED_SYMTABS, allocated IMPORTED_SYMTABS
380 first if required. */
381 void imported_symtabs_push (dwarf2_per_cu_data
*p
)
383 if (imported_symtabs
== nullptr)
384 imported_symtabs
= new std::vector
<dwarf2_per_cu_data
*>;
385 imported_symtabs
->push_back (p
);
388 /* Return the size of IMPORTED_SYMTABS if it is allocated, otherwise
390 size_t imported_symtabs_size () const
392 if (imported_symtabs
== nullptr)
394 return imported_symtabs
->size ();
397 /* Delete IMPORTED_SYMTABS and set the pointer back to nullptr. */
398 void imported_symtabs_free ()
400 delete imported_symtabs
;
401 imported_symtabs
= nullptr;
404 /* Return the OBJFILE associated with this compilation unit. If
405 this compilation unit came from a separate debuginfo file, then
406 the master objfile is returned. */
407 struct objfile
*objfile () const;
409 /* Return the address size given in the compilation unit header for
411 int addr_size () const;
413 /* Return the offset size given in the compilation unit header for
415 int offset_size () const;
417 /* Return the DW_FORM_ref_addr size given in the compilation unit
418 header for this CU. */
419 int ref_addr_size () const;
421 /* Return the text offset of the CU. The returned offset comes from
422 this CU's objfile. If this objfile came from a separate
423 debuginfo file, then the offset may be different from the
424 corresponding offset in the parent objfile. */
425 CORE_ADDR
text_offset () const;
427 /* Return a type that is a generic pointer type, the size of which
428 matches the address size given in the compilation unit header for
430 struct type
*addr_type () const;
432 /* Find an integer type SIZE_IN_BYTES bytes in size and return it.
433 UNSIGNED_P controls if the integer is unsigned or not. */
434 struct type
*int_type (int size_in_bytes
, bool unsigned_p
) const;
436 /* Find an integer type the same size as the address size given in
437 the compilation unit header for this CU. UNSIGNED_P controls if
438 the integer is unsigned or not. */
439 struct type
*addr_sized_int_type (bool unsigned_p
) const;
441 /* Return DWARF version number of this CU. */
442 short version () const
444 return dwarf_version
;
447 /* A type unit group has a per_cu object that is recognized by
448 having no section. */
449 bool type_unit_group_p () const
451 return section
== nullptr;
455 /* Entry in the signatured_types hash table. */
457 struct signatured_type
459 /* The "per_cu" object of this type.
460 This struct is used iff per_cu.is_debug_types.
461 N.B.: This is the first member so that it's easy to convert pointers
463 struct dwarf2_per_cu_data per_cu
;
465 /* The type's signature. */
468 /* Offset in the TU of the type's DIE, as read from the TU header.
469 If this TU is a DWO stub and the definition lives in a DWO file
470 (specified by DW_AT_GNU_dwo_name), this value is unusable. */
471 cu_offset type_offset_in_tu
;
473 /* Offset in the section of the type's DIE.
474 If the definition lives in a DWO file, this is the offset in the
475 .debug_types.dwo section.
476 The value is zero until the actual value is known.
477 Zero is otherwise not a valid section offset. */
478 sect_offset type_offset_in_section
;
480 /* Type units are grouped by their DW_AT_stmt_list entry so that they
481 can share them. This points to the containing symtab. */
482 struct type_unit_group
*type_unit_group
;
485 The first time we encounter this type we fully read it in and install it
486 in the symbol tables. Subsequent times we only need the type. */
489 /* Containing DWO unit.
490 This field is valid iff per_cu.reading_dwo_directly. */
491 struct dwo_unit
*dwo_unit
;
494 /* Open the separate '.dwz' debug file, if needed. Return NULL if
495 there is no .gnu_debugaltlink section in the file. Error if there
496 is such a section but the file cannot be found. */
498 extern struct dwz_file
*dwarf2_get_dwz_file
499 (struct dwarf2_per_objfile
*dwarf2_per_objfile
);
501 /* Return the type of the DIE at DIE_OFFSET in the CU named by
504 struct type
*dwarf2_get_die_type (cu_offset die_offset
,
505 struct dwarf2_per_cu_data
*per_cu
);
507 /* Given an index in .debug_addr, fetch the value.
508 NOTE: This can be called during dwarf expression evaluation,
509 long after the debug information has been read, and thus per_cu->cu
510 may no longer exist. */
512 CORE_ADDR
dwarf2_read_addr_index (dwarf2_per_cu_data
*per_cu
,
513 unsigned int addr_index
);
515 /* Return DWARF block referenced by DW_AT_location of DIE at SECT_OFF at PER_CU.
516 Returned value is intended for DW_OP_call*. Returned
517 dwarf2_locexpr_baton->data has lifetime of
518 PER_CU->DWARF2_PER_OBJFILE->OBJFILE. */
520 struct dwarf2_locexpr_baton dwarf2_fetch_die_loc_sect_off
521 (sect_offset sect_off
, dwarf2_per_cu_data
*per_cu
,
522 CORE_ADDR (*get_frame_pc
) (void *baton
),
523 void *baton
, bool resolve_abstract_p
= false);
525 /* Like dwarf2_fetch_die_loc_sect_off, but take a CU
528 struct dwarf2_locexpr_baton dwarf2_fetch_die_loc_cu_off
529 (cu_offset offset_in_cu
, dwarf2_per_cu_data
*per_cu
,
530 CORE_ADDR (*get_frame_pc
) (void *baton
),
533 /* If the DIE at SECT_OFF in PER_CU has a DW_AT_const_value, return a
534 pointer to the constant bytes and set LEN to the length of the
535 data. If memory is needed, allocate it on OBSTACK. If the DIE
536 does not have a DW_AT_const_value, return NULL. */
538 extern const gdb_byte
*dwarf2_fetch_constant_bytes
539 (sect_offset sect_off
, dwarf2_per_cu_data
*per_cu
, obstack
*obstack
,
542 /* Return the type of the die at SECT_OFF in PER_CU. Return NULL if no
543 valid type for this die is found. */
545 struct type
*dwarf2_fetch_die_type_sect_off
546 (sect_offset sect_off
, dwarf2_per_cu_data
*per_cu
);
548 /* When non-zero, dump line number entries as they are read in. */
549 extern unsigned int dwarf_line_debug
;
551 #endif /* DWARF2READ_H */