1 /* DWARF 2 debugging format support for GDB.
3 Copyright (C) 1994-2018 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/>. */
23 #include "dwarf-index-cache.h"
24 #include "filename-seen-cache.h"
25 #include "gdb_obstack.h"
27 /* Hold 'maintenance (set|show) dwarf' commands. */
28 extern struct cmd_list_element
*set_dwarf_cmdlist
;
29 extern struct cmd_list_element
*show_dwarf_cmdlist
;
31 typedef struct dwarf2_per_cu_data
*dwarf2_per_cu_ptr
;
32 DEF_VEC_P (dwarf2_per_cu_ptr
);
34 /* A descriptor for dwarf sections.
36 S.ASECTION, SIZE are typically initialized when the objfile is first
37 scanned. BUFFER, READIN are filled in later when the section is read.
38 If the section contained compressed data then SIZE is updated to record
39 the uncompressed size of the section.
41 DWP file format V2 introduces a wrinkle that is easiest to handle by
42 creating the concept of virtual sections contained within a real section.
43 In DWP V2 the sections of the input DWO files are concatenated together
44 into one section, but section offsets are kept relative to the original
46 If this is a virtual dwp-v2 section, S.CONTAINING_SECTION is a backlink to
47 the real section this "virtual" section is contained in, and BUFFER,SIZE
48 describe the virtual section. */
50 struct dwarf2_section_info
54 /* If this is a real section, the bfd section. */
56 /* If this is a virtual section, pointer to the containing ("real")
58 struct dwarf2_section_info
*containing_section
;
60 /* Pointer to section data, only valid if readin. */
61 const gdb_byte
*buffer
;
62 /* The size of the section, real or virtual. */
64 /* If this is a virtual section, the offset in the real section.
65 Only valid if is_virtual. */
66 bfd_size_type virtual_offset
;
67 /* True if we have tried to read this section. */
69 /* True if this is a virtual section, False otherwise.
70 This specifies which of s.section and s.containing_section to use. */
74 typedef struct dwarf2_section_info dwarf2_section_info_def
;
75 DEF_VEC_O (dwarf2_section_info_def
);
77 /* Read the contents of the section INFO.
78 OBJFILE is the main object file, but not necessarily the file where
79 the section comes from. E.g., for DWO files the bfd of INFO is the bfd
81 If the section is compressed, uncompress it before returning. */
83 void dwarf2_read_section (struct objfile
*objfile
, dwarf2_section_info
*info
);
87 int nr_uniq_abbrev_tables
;
89 int nr_symtab_sharers
;
90 int nr_stmt_less_type_units
;
91 int nr_all_type_units_reallocs
;
94 struct dwarf2_debug_sections
;
96 struct mapped_debug_names
;
97 struct signatured_type
;
99 /* Collection of data recorded per objfile.
100 This hangs off of dwarf2_objfile_data_key. */
102 struct dwarf2_per_objfile
: public allocate_on_obstack
104 /* Construct a dwarf2_per_objfile for OBJFILE. NAMES points to the
105 dwarf2 section names, or is NULL if the standard ELF names are
107 dwarf2_per_objfile (struct objfile
*objfile
,
108 const dwarf2_debug_sections
*names
);
110 ~dwarf2_per_objfile ();
112 DISABLE_COPY_AND_ASSIGN (dwarf2_per_objfile
);
114 /* Return the CU/TU given its index.
116 This is intended for loops like:
118 for (i = 0; i < (dwarf2_per_objfile->n_comp_units
119 + dwarf2_per_objfile->n_type_units); ++i)
121 dwarf2_per_cu_data *per_cu = dwarf2_per_objfile->get_cutu (i);
126 dwarf2_per_cu_data
*get_cutu (int index
);
128 /* Return the CU given its index.
129 This differs from get_cutu in that it's for when you know INDEX refers to a
131 dwarf2_per_cu_data
*get_cu (int index
);
133 /* Return the TU given its index.
134 This differs from get_cutu in that it's for when you know INDEX refers to a
136 signatured_type
*get_tu (int index
);
138 /* Free all cached compilation units. */
139 void free_cached_comp_units ();
141 /* This function is mapped across the sections and remembers the
142 offset and size of each of the debugging sections we are
144 void locate_sections (bfd
*abfd
, asection
*sectp
,
145 const dwarf2_debug_sections
&names
);
148 dwarf2_section_info info
{};
149 dwarf2_section_info abbrev
{};
150 dwarf2_section_info line
{};
151 dwarf2_section_info loc
{};
152 dwarf2_section_info loclists
{};
153 dwarf2_section_info macinfo
{};
154 dwarf2_section_info macro
{};
155 dwarf2_section_info str
{};
156 dwarf2_section_info line_str
{};
157 dwarf2_section_info ranges
{};
158 dwarf2_section_info rnglists
{};
159 dwarf2_section_info addr
{};
160 dwarf2_section_info frame
{};
161 dwarf2_section_info eh_frame
{};
162 dwarf2_section_info gdb_index
{};
163 dwarf2_section_info debug_names
{};
164 dwarf2_section_info debug_aranges
{};
166 VEC (dwarf2_section_info_def
) *types
= NULL
;
169 struct objfile
*objfile
= NULL
;
171 /* Table of all the compilation units. This is used to locate
172 the target compilation unit of a particular reference. */
173 std::vector
<dwarf2_per_cu_data
*> all_comp_units
;
175 /* The .debug_types-related CUs (TUs). */
176 std::vector
<signatured_type
*> all_type_units
;
178 /* Table of struct type_unit_group objects.
179 The hash key is the DW_AT_stmt_list value. */
180 htab_t type_unit_groups
{};
182 /* A table mapping .debug_types signatures to its signatured_type entry.
183 This is NULL if the .debug_types section hasn't been read in yet. */
184 htab_t signatured_types
{};
186 /* Type unit statistics, to see how well the scaling improvements
188 struct tu_stats tu_stats
{};
190 /* A chain of compilation units that are currently read in, so that
191 they can be freed later. */
192 dwarf2_per_cu_data
*read_in_chain
= NULL
;
194 /* A table mapping DW_AT_dwo_name values to struct dwo_file objects.
195 This is NULL if the table hasn't been allocated yet. */
198 /* True if we've checked for whether there is a DWP file. */
199 bool dwp_checked
= false;
201 /* The DWP file if there is one, or NULL. */
202 std::unique_ptr
<struct dwp_file
> dwp_file
;
204 /* The shared '.dwz' file, if one exists. This is used when the
205 original data was compressed using 'dwz -m'. */
206 std::unique_ptr
<struct dwz_file
> dwz_file
;
208 /* A flag indicating whether this objfile has a section loaded at a
210 bool has_section_at_zero
= false;
212 /* True if we are using the mapped index,
213 or we are faking it for OBJF_READNOW's sake. */
214 bool using_index
= false;
216 /* The mapped index, or NULL if .gdb_index is missing or not being used. */
217 std::unique_ptr
<mapped_index
> index_table
;
219 /* The mapped index, or NULL if .debug_names is missing or not being used. */
220 std::unique_ptr
<mapped_debug_names
> debug_names_table
;
222 /* When using index_table, this keeps track of all quick_file_names entries.
223 TUs typically share line table entries with a CU, so we maintain a
224 separate table of all line table entries to support the sharing.
225 Note that while there can be way more TUs than CUs, we've already
226 sorted all the TUs into "type unit groups", grouped by their
227 DW_AT_stmt_list value. Therefore the only sharing done here is with a
228 CU and its associated TU group if there is one. */
229 htab_t quick_file_names_table
{};
231 /* Set during partial symbol reading, to prevent queueing of full
233 bool reading_partial_symbols
= false;
235 /* Table mapping type DIEs to their struct type *.
236 This is NULL if not allocated yet.
237 The mapping is done via (CU/TU + DIE offset) -> type. */
238 htab_t die_type_hash
{};
240 /* The CUs we recently read. */
241 std::vector
<dwarf2_per_cu_data
*> just_read_cus
;
243 /* Table containing line_header indexed by offset and offset_in_dwz. */
244 htab_t line_header_hash
{};
246 /* Table containing all filenames. This is an optional because the
247 table is lazily constructed on first access. */
248 gdb::optional
<filename_seen_cache
> filenames_cache
;
250 /* If we loaded the index from an external file, this contains the
251 resources associated to the open file, memory mapping, etc. */
252 std::unique_ptr
<index_cache_resource
> index_cache_res
;
255 /* Get the dwarf2_per_objfile associated to OBJFILE. */
257 dwarf2_per_objfile
*get_dwarf2_per_objfile (struct objfile
*objfile
);
259 /* Persistent data held for a compilation unit, even when not
260 processing it. We put a pointer to this structure in the
261 read_symtab_private field of the psymtab. */
263 struct dwarf2_per_cu_data
265 /* The start offset and length of this compilation unit.
266 NOTE: Unlike comp_unit_head.length, this length includes
268 If the DIE refers to a DWO file, this is always of the original die,
270 sect_offset sect_off
;
273 /* DWARF standard version this data has been read from (such as 4 or 5). */
276 /* Flag indicating this compilation unit will be read in before
277 any of the current compilation units are processed. */
278 unsigned int queued
: 1;
280 /* This flag will be set when reading partial DIEs if we need to load
281 absolutely all DIEs for this compilation unit, instead of just the ones
282 we think are interesting. It gets set if we look for a DIE in the
283 hash table and don't find it. */
284 unsigned int load_all_dies
: 1;
286 /* Non-zero if this CU is from .debug_types.
287 Struct dwarf2_per_cu_data is contained in struct signatured_type iff
289 unsigned int is_debug_types
: 1;
291 /* Non-zero if this CU is from the .dwz file. */
292 unsigned int is_dwz
: 1;
294 /* Non-zero if reading a TU directly from a DWO file, bypassing the stub.
295 This flag is only valid if is_debug_types is true.
296 We can't read a CU directly from a DWO file: There are required
297 attributes in the stub. */
298 unsigned int reading_dwo_directly
: 1;
300 /* Non-zero if the TU has been read.
301 This is used to assist the "Stay in DWO Optimization" for Fission:
302 When reading a DWO, it's faster to read TUs from the DWO instead of
303 fetching them from random other DWOs (due to comdat folding).
304 If the TU has already been read, the optimization is unnecessary
305 (and unwise - we don't want to change where gdb thinks the TU lives
307 This flag is only valid if is_debug_types is true. */
308 unsigned int tu_read
: 1;
310 /* The section this CU/TU lives in.
311 If the DIE refers to a DWO file, this is always the original die,
313 struct dwarf2_section_info
*section
;
315 /* Set to non-NULL iff this CU is currently loaded. When it gets freed out
316 of the CU cache it gets reset to NULL again. This is left as NULL for
317 dummy CUs (a CU header, but nothing else). */
318 struct dwarf2_cu
*cu
;
320 /* The corresponding dwarf2_per_objfile. */
321 struct dwarf2_per_objfile
*dwarf2_per_objfile
;
323 /* When dwarf2_per_objfile->using_index is true, the 'quick' field
324 is active. Otherwise, the 'psymtab' field is active. */
327 /* The partial symbol table associated with this compilation unit,
328 or NULL for unread partial units. */
329 struct partial_symtab
*psymtab
;
331 /* Data needed by the "quick" functions. */
332 struct dwarf2_per_cu_quick_data
*quick
;
335 /* The CUs we import using DW_TAG_imported_unit. This is filled in
336 while reading psymtabs, used to compute the psymtab dependencies,
337 and then cleared. Then it is filled in again while reading full
338 symbols, and only deleted when the objfile is destroyed.
340 This is also used to work around a difference between the way gold
341 generates .gdb_index version <=7 and the way gdb does. Arguably this
342 is a gold bug. For symbols coming from TUs, gold records in the index
343 the CU that includes the TU instead of the TU itself. This breaks
344 dw2_lookup_symbol: It assumes that if the index says symbol X lives
345 in CU/TU Y, then one need only expand Y and a subsequent lookup in Y
346 will find X. Alas TUs live in their own symtab, so after expanding CU Y
347 we need to look in TU Z to find X. Fortunately, this is akin to
348 DW_TAG_imported_unit, so we just use the same mechanism: For
349 .gdb_index version <=7 this also records the TUs that the CU referred
350 to. Concurrently with this change gdb was modified to emit version 8
351 indices so we only pay a price for gold generated indices.
352 http://sourceware.org/bugzilla/show_bug.cgi?id=15021. */
353 VEC (dwarf2_per_cu_ptr
) *imported_symtabs
;
356 /* Entry in the signatured_types hash table. */
358 struct signatured_type
360 /* The "per_cu" object of this type.
361 This struct is used iff per_cu.is_debug_types.
362 N.B.: This is the first member so that it's easy to convert pointers
364 struct dwarf2_per_cu_data per_cu
;
366 /* The type's signature. */
369 /* Offset in the TU of the type's DIE, as read from the TU header.
370 If this TU is a DWO stub and the definition lives in a DWO file
371 (specified by DW_AT_GNU_dwo_name), this value is unusable. */
372 cu_offset type_offset_in_tu
;
374 /* Offset in the section of the type's DIE.
375 If the definition lives in a DWO file, this is the offset in the
376 .debug_types.dwo section.
377 The value is zero until the actual value is known.
378 Zero is otherwise not a valid section offset. */
379 sect_offset type_offset_in_section
;
381 /* Type units are grouped by their DW_AT_stmt_list entry so that they
382 can share them. This points to the containing symtab. */
383 struct type_unit_group
*type_unit_group
;
386 The first time we encounter this type we fully read it in and install it
387 in the symbol tables. Subsequent times we only need the type. */
390 /* Containing DWO unit.
391 This field is valid iff per_cu.reading_dwo_directly. */
392 struct dwo_unit
*dwo_unit
;
395 typedef struct signatured_type
*sig_type_ptr
;
396 DEF_VEC_P (sig_type_ptr
);
398 #endif /* DWARF2READ_H */