1 /* DWARF 2 debugging format support for GDB.
3 Copyright (C) 1994-2019 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 <unordered_map>
25 /* Local non-gdb includes. */
26 #include "dwarf-index-cache.h"
27 #include "filename-seen-cache.h"
28 #include "gdb_obstack.h"
30 /* Hold 'maintenance (set|show) dwarf' commands. */
31 extern struct cmd_list_element
*set_dwarf_cmdlist
;
32 extern struct cmd_list_element
*show_dwarf_cmdlist
;
34 typedef struct dwarf2_per_cu_data
*dwarf2_per_cu_ptr
;
35 DEF_VEC_P (dwarf2_per_cu_ptr
);
37 /* A descriptor for dwarf sections.
39 S.ASECTION, SIZE are typically initialized when the objfile is first
40 scanned. BUFFER, READIN are filled in later when the section is read.
41 If the section contained compressed data then SIZE is updated to record
42 the uncompressed size of the section.
44 DWP file format V2 introduces a wrinkle that is easiest to handle by
45 creating the concept of virtual sections contained within a real section.
46 In DWP V2 the sections of the input DWO files are concatenated together
47 into one section, but section offsets are kept relative to the original
49 If this is a virtual dwp-v2 section, S.CONTAINING_SECTION is a backlink to
50 the real section this "virtual" section is contained in, and BUFFER,SIZE
51 describe the virtual section. */
53 struct dwarf2_section_info
57 /* If this is a real section, the bfd section. */
59 /* If this is a virtual section, pointer to the containing ("real")
61 struct dwarf2_section_info
*containing_section
;
63 /* Pointer to section data, only valid if readin. */
64 const gdb_byte
*buffer
;
65 /* The size of the section, real or virtual. */
67 /* If this is a virtual section, the offset in the real section.
68 Only valid if is_virtual. */
69 bfd_size_type virtual_offset
;
70 /* True if we have tried to read this section. */
72 /* True if this is a virtual section, False otherwise.
73 This specifies which of s.section and s.containing_section to use. */
77 typedef struct dwarf2_section_info dwarf2_section_info_def
;
78 DEF_VEC_O (dwarf2_section_info_def
);
80 /* Read the contents of the section INFO.
81 OBJFILE is the main object file, but not necessarily the file where
82 the section comes from. E.g., for DWO files the bfd of INFO is the bfd
84 If the section is compressed, uncompress it before returning. */
86 void dwarf2_read_section (struct objfile
*objfile
, dwarf2_section_info
*info
);
90 int nr_uniq_abbrev_tables
;
92 int nr_symtab_sharers
;
93 int nr_stmt_less_type_units
;
94 int nr_all_type_units_reallocs
;
97 struct dwarf2_debug_sections
;
99 struct mapped_debug_names
;
100 struct signatured_type
;
102 typedef struct die_info
*die_info_ptr
;
104 /* Collection of data recorded per objfile.
105 This hangs off of dwarf2_objfile_data_key. */
107 struct dwarf2_per_objfile
: public allocate_on_obstack
109 /* Construct a dwarf2_per_objfile for OBJFILE. NAMES points to the
110 dwarf2 section names, or is NULL if the standard ELF names are
112 dwarf2_per_objfile (struct objfile
*objfile
,
113 const dwarf2_debug_sections
*names
);
115 ~dwarf2_per_objfile ();
117 DISABLE_COPY_AND_ASSIGN (dwarf2_per_objfile
);
119 /* Return the CU/TU given its index.
121 This is intended for loops like:
123 for (i = 0; i < (dwarf2_per_objfile->n_comp_units
124 + dwarf2_per_objfile->n_type_units); ++i)
126 dwarf2_per_cu_data *per_cu = dwarf2_per_objfile->get_cutu (i);
131 dwarf2_per_cu_data
*get_cutu (int index
);
133 /* Return the CU given its index.
134 This differs from get_cutu in that it's for when you know INDEX refers to a
136 dwarf2_per_cu_data
*get_cu (int index
);
138 /* Return the TU given its index.
139 This differs from get_cutu in that it's for when you know INDEX refers to a
141 signatured_type
*get_tu (int index
);
143 /* Free all cached compilation units. */
144 void free_cached_comp_units ();
146 /* This function is mapped across the sections and remembers the
147 offset and size of each of the debugging sections we are
149 void locate_sections (bfd
*abfd
, asection
*sectp
,
150 const dwarf2_debug_sections
&names
);
153 dwarf2_section_info info
{};
154 dwarf2_section_info abbrev
{};
155 dwarf2_section_info line
{};
156 dwarf2_section_info loc
{};
157 dwarf2_section_info loclists
{};
158 dwarf2_section_info macinfo
{};
159 dwarf2_section_info macro
{};
160 dwarf2_section_info str
{};
161 dwarf2_section_info line_str
{};
162 dwarf2_section_info ranges
{};
163 dwarf2_section_info rnglists
{};
164 dwarf2_section_info addr
{};
165 dwarf2_section_info frame
{};
166 dwarf2_section_info eh_frame
{};
167 dwarf2_section_info gdb_index
{};
168 dwarf2_section_info debug_names
{};
169 dwarf2_section_info debug_aranges
{};
171 VEC (dwarf2_section_info_def
) *types
= NULL
;
174 struct objfile
*objfile
= NULL
;
176 /* Table of all the compilation units. This is used to locate
177 the target compilation unit of a particular reference. */
178 std::vector
<dwarf2_per_cu_data
*> all_comp_units
;
180 /* The .debug_types-related CUs (TUs). */
181 std::vector
<signatured_type
*> all_type_units
;
183 /* Table of struct type_unit_group objects.
184 The hash key is the DW_AT_stmt_list value. */
185 htab_t type_unit_groups
{};
187 /* A table mapping .debug_types signatures to its signatured_type entry.
188 This is NULL if the .debug_types section hasn't been read in yet. */
189 htab_t signatured_types
{};
191 /* Type unit statistics, to see how well the scaling improvements
193 struct tu_stats tu_stats
{};
195 /* A chain of compilation units that are currently read in, so that
196 they can be freed later. */
197 dwarf2_per_cu_data
*read_in_chain
= NULL
;
199 /* A table mapping DW_AT_dwo_name values to struct dwo_file objects.
200 This is NULL if the table hasn't been allocated yet. */
203 /* True if we've checked for whether there is a DWP file. */
204 bool dwp_checked
= false;
206 /* The DWP file if there is one, or NULL. */
207 std::unique_ptr
<struct dwp_file
> dwp_file
;
209 /* The shared '.dwz' file, if one exists. This is used when the
210 original data was compressed using 'dwz -m'. */
211 std::unique_ptr
<struct dwz_file
> dwz_file
;
213 /* A flag indicating whether this objfile has a section loaded at a
215 bool has_section_at_zero
= false;
217 /* True if we are using the mapped index,
218 or we are faking it for OBJF_READNOW's sake. */
219 bool using_index
= false;
221 /* The mapped index, or NULL if .gdb_index is missing or not being used. */
222 std::unique_ptr
<mapped_index
> index_table
;
224 /* The mapped index, or NULL if .debug_names is missing or not being used. */
225 std::unique_ptr
<mapped_debug_names
> debug_names_table
;
227 /* When using index_table, this keeps track of all quick_file_names entries.
228 TUs typically share line table entries with a CU, so we maintain a
229 separate table of all line table entries to support the sharing.
230 Note that while there can be way more TUs than CUs, we've already
231 sorted all the TUs into "type unit groups", grouped by their
232 DW_AT_stmt_list value. Therefore the only sharing done here is with a
233 CU and its associated TU group if there is one. */
234 htab_t quick_file_names_table
{};
236 /* Set during partial symbol reading, to prevent queueing of full
238 bool reading_partial_symbols
= false;
240 /* Table mapping type DIEs to their struct type *.
241 This is NULL if not allocated yet.
242 The mapping is done via (CU/TU + DIE offset) -> type. */
243 htab_t die_type_hash
{};
245 /* The CUs we recently read. */
246 std::vector
<dwarf2_per_cu_data
*> just_read_cus
;
248 /* Table containing line_header indexed by offset and offset_in_dwz. */
249 htab_t line_header_hash
{};
251 /* Table containing all filenames. This is an optional because the
252 table is lazily constructed on first access. */
253 gdb::optional
<filename_seen_cache
> filenames_cache
;
255 /* If we loaded the index from an external file, this contains the
256 resources associated to the open file, memory mapping, etc. */
257 std::unique_ptr
<index_cache_resource
> index_cache_res
;
259 /* Mapping from abstract origin DIE to concrete DIEs that reference it as
260 DW_AT_abstract_origin. */
261 std::unordered_map
<die_info_ptr
, std::vector
<die_info_ptr
>>
262 abstract_to_concrete
;
265 /* Get the dwarf2_per_objfile associated to OBJFILE. */
267 dwarf2_per_objfile
*get_dwarf2_per_objfile (struct objfile
*objfile
);
269 /* Persistent data held for a compilation unit, even when not
270 processing it. We put a pointer to this structure in the
271 read_symtab_private field of the psymtab. */
273 struct dwarf2_per_cu_data
275 /* The start offset and length of this compilation unit.
276 NOTE: Unlike comp_unit_head.length, this length includes
278 If the DIE refers to a DWO file, this is always of the original die,
280 sect_offset sect_off
;
283 /* DWARF standard version this data has been read from (such as 4 or 5). */
286 /* Flag indicating this compilation unit will be read in before
287 any of the current compilation units are processed. */
288 unsigned int queued
: 1;
290 /* This flag will be set when reading partial DIEs if we need to load
291 absolutely all DIEs for this compilation unit, instead of just the ones
292 we think are interesting. It gets set if we look for a DIE in the
293 hash table and don't find it. */
294 unsigned int load_all_dies
: 1;
296 /* Non-zero if this CU is from .debug_types.
297 Struct dwarf2_per_cu_data is contained in struct signatured_type iff
299 unsigned int is_debug_types
: 1;
301 /* Non-zero if this CU is from the .dwz file. */
302 unsigned int is_dwz
: 1;
304 /* Non-zero if reading a TU directly from a DWO file, bypassing the stub.
305 This flag is only valid if is_debug_types is true.
306 We can't read a CU directly from a DWO file: There are required
307 attributes in the stub. */
308 unsigned int reading_dwo_directly
: 1;
310 /* Non-zero if the TU has been read.
311 This is used to assist the "Stay in DWO Optimization" for Fission:
312 When reading a DWO, it's faster to read TUs from the DWO instead of
313 fetching them from random other DWOs (due to comdat folding).
314 If the TU has already been read, the optimization is unnecessary
315 (and unwise - we don't want to change where gdb thinks the TU lives
317 This flag is only valid if is_debug_types is true. */
318 unsigned int tu_read
: 1;
320 /* The section this CU/TU lives in.
321 If the DIE refers to a DWO file, this is always the original die,
323 struct dwarf2_section_info
*section
;
325 /* Set to non-NULL iff this CU is currently loaded. When it gets freed out
326 of the CU cache it gets reset to NULL again. This is left as NULL for
327 dummy CUs (a CU header, but nothing else). */
328 struct dwarf2_cu
*cu
;
330 /* The corresponding dwarf2_per_objfile. */
331 struct dwarf2_per_objfile
*dwarf2_per_objfile
;
333 /* When dwarf2_per_objfile->using_index is true, the 'quick' field
334 is active. Otherwise, the 'psymtab' field is active. */
337 /* The partial symbol table associated with this compilation unit,
338 or NULL for unread partial units. */
339 struct partial_symtab
*psymtab
;
341 /* Data needed by the "quick" functions. */
342 struct dwarf2_per_cu_quick_data
*quick
;
345 /* The CUs we import using DW_TAG_imported_unit. This is filled in
346 while reading psymtabs, used to compute the psymtab dependencies,
347 and then cleared. Then it is filled in again while reading full
348 symbols, and only deleted when the objfile is destroyed.
350 This is also used to work around a difference between the way gold
351 generates .gdb_index version <=7 and the way gdb does. Arguably this
352 is a gold bug. For symbols coming from TUs, gold records in the index
353 the CU that includes the TU instead of the TU itself. This breaks
354 dw2_lookup_symbol: It assumes that if the index says symbol X lives
355 in CU/TU Y, then one need only expand Y and a subsequent lookup in Y
356 will find X. Alas TUs live in their own symtab, so after expanding CU Y
357 we need to look in TU Z to find X. Fortunately, this is akin to
358 DW_TAG_imported_unit, so we just use the same mechanism: For
359 .gdb_index version <=7 this also records the TUs that the CU referred
360 to. Concurrently with this change gdb was modified to emit version 8
361 indices so we only pay a price for gold generated indices.
362 http://sourceware.org/bugzilla/show_bug.cgi?id=15021. */
363 VEC (dwarf2_per_cu_ptr
) *imported_symtabs
;
366 /* Entry in the signatured_types hash table. */
368 struct signatured_type
370 /* The "per_cu" object of this type.
371 This struct is used iff per_cu.is_debug_types.
372 N.B.: This is the first member so that it's easy to convert pointers
374 struct dwarf2_per_cu_data per_cu
;
376 /* The type's signature. */
379 /* Offset in the TU of the type's DIE, as read from the TU header.
380 If this TU is a DWO stub and the definition lives in a DWO file
381 (specified by DW_AT_GNU_dwo_name), this value is unusable. */
382 cu_offset type_offset_in_tu
;
384 /* Offset in the section of the type's DIE.
385 If the definition lives in a DWO file, this is the offset in the
386 .debug_types.dwo section.
387 The value is zero until the actual value is known.
388 Zero is otherwise not a valid section offset. */
389 sect_offset type_offset_in_section
;
391 /* Type units are grouped by their DW_AT_stmt_list entry so that they
392 can share them. This points to the containing symtab. */
393 struct type_unit_group
*type_unit_group
;
396 The first time we encounter this type we fully read it in and install it
397 in the symbol tables. Subsequent times we only need the type. */
400 /* Containing DWO unit.
401 This field is valid iff per_cu.reading_dwo_directly. */
402 struct dwo_unit
*dwo_unit
;
405 typedef struct signatured_type
*sig_type_ptr
;
406 DEF_VEC_P (sig_type_ptr
);
408 #endif /* DWARF2READ_H */