gdb/dwarf2/read.h

   1 /* DWARF 2 debugging format support for GDB.
   2
   3    Copyright (C) 1994-2021 Free Software Foundation, Inc.
   4
   5    This file is part of GDB.
   6
   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.
  11
  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.
  16
  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/>.  */
  19
  20 #ifndef DWARF2READ_H
  21 #define DWARF2READ_H
  22
  23 #include <queue>
  24 #include <unordered_map>
  25 #include "dwarf2/comp-unit.h"
  26 #include "dwarf2/index-cache.h"
  27 #include "dwarf2/section.h"
  28 #include "filename-seen-cache.h"
  29 #include "gdb_obstack.h"
  30 #include "gdbsupport/hash_enum.h"
  31 #include "gdbsupport/function-view.h"
  32 #include "psympriv.h"
  33
  34 /* Hold 'maintenance (set|show) dwarf' commands.  */
  35 extern struct cmd_list_element *set_dwarf_cmdlist;
  36 extern struct cmd_list_element *show_dwarf_cmdlist;
  37
  38 struct tu_stats
  39 {
  40   int nr_uniq_abbrev_tables;
  41   int nr_symtabs;
  42   int nr_symtab_sharers;
  43   int nr_stmt_less_type_units;
  44   int nr_all_type_units_reallocs;
  45 };
  46
  47 struct dwarf2_cu;
  48 struct dwarf2_debug_sections;
  49 struct dwarf2_per_cu_data;
  50 struct mapped_index;
  51 struct mapped_debug_names;
  52 struct signatured_type;
  53 struct type_unit_group;
  54
  55 /* One item on the queue of compilation units to read in full symbols
  56    for.  */
  57 struct dwarf2_queue_item
  58 {
  59   dwarf2_queue_item (dwarf2_per_cu_data *cu, dwarf2_per_objfile *per_objfile,
  60                      enum language lang)
  61     : per_cu (cu),
  62       per_objfile (per_objfile),
  63       pretend_language (lang)
  64   {
  65   }
  66
  67   ~dwarf2_queue_item ();
  68
  69   DISABLE_COPY_AND_ASSIGN (dwarf2_queue_item);
  70
  71   dwarf2_per_cu_data *per_cu;
  72   dwarf2_per_objfile *per_objfile;
  73   enum language pretend_language;
  74 };
  75
  76 /* Some DWARF data can be shared across objfiles who share the same BFD,
  77    this data is stored in this object.
  78
  79    Two dwarf2_per_objfile objects representing objfiles sharing the same BFD
  80    will point to the same instance of dwarf2_per_bfd, unless the BFD requires
  81    relocation.  */
  82
  83 struct dwarf2_per_bfd
  84 {
  85   /* Construct a dwarf2_per_bfd for OBFD.  NAMES points to the
  86      dwarf2 section names, or is NULL if the standard ELF names are
  87      used.  CAN_COPY is true for formats where symbol
  88      interposition is possible and so symbol values must follow copy
  89      relocation rules.  */
  90   dwarf2_per_bfd (bfd *obfd, const dwarf2_debug_sections *names, bool can_copy);
  91
  92   ~dwarf2_per_bfd ();
  93
  94   DISABLE_COPY_AND_ASSIGN (dwarf2_per_bfd);
  95
  96   /* Return the CU/TU given its index.
  97
  98      This is intended for loops like:
  99
 100      for (i = 0; i < (dwarf2_per_bfd->n_comp_units
 101                       + dwarf2_per_bfd->n_type_units); ++i)
 102        {
 103          dwarf2_per_cu_data *per_cu = dwarf2_per_bfd->get_cutu (i);
 104
 105          ...;
 106        }
 107   */
 108   dwarf2_per_cu_data *get_cutu (int index);
 109
 110   /* Return the CU given its index.
 111      This differs from get_cutu in that it's for when you know INDEX refers to a
 112      CU.  */
 113   dwarf2_per_cu_data *get_cu (int index);
 114
 115   /* Return the TU given its index.
 116      This differs from get_cutu in that it's for when you know INDEX refers to a
 117      TU.  */
 118   signatured_type *get_tu (int index);
 119
 120   /* A convenience function to allocate a dwarf2_per_cu_data.  The
 121      returned object has its "index" field set properly.  The object
 122      is allocated on the dwarf2_per_bfd obstack.  */
 123   dwarf2_per_cu_data *allocate_per_cu ();
 124
 125   /* A convenience function to allocate a signatured_type.  The
 126      returned object has its "index" field set properly.  The object
 127      is allocated on the dwarf2_per_bfd obstack.  */
 128   signatured_type *allocate_signatured_type ();
 129
 130   /* Return the number of partial symtabs allocated with allocate_per_cu
 131      and allocate_signatured_type so far.  */
 132   int num_psymtabs () const
 133   { return m_num_psymtabs; }
 134
 135 private:
 136   /* This function is mapped across the sections and remembers the
 137      offset and size of each of the debugging sections we are
 138      interested in.  */
 139   void locate_sections (bfd *abfd, asection *sectp,
 140                         const dwarf2_debug_sections &names);
 141
 142 public:
 143   /* The corresponding BFD.  */
 144   bfd *obfd;
 145
 146   /* Objects that can be shared across objfiles are stored in this
 147      obstack or on the psymtab obstack, while objects that are
 148      objfile-specific are stored on the objfile obstack.  */
 149   auto_obstack obstack;
 150
 151   dwarf2_section_info info {};
 152   dwarf2_section_info abbrev {};
 153   dwarf2_section_info line {};
 154   dwarf2_section_info loc {};
 155   dwarf2_section_info loclists {};
 156   dwarf2_section_info macinfo {};
 157   dwarf2_section_info macro {};
 158   dwarf2_section_info str {};
 159   dwarf2_section_info str_offsets {};
 160   dwarf2_section_info line_str {};
 161   dwarf2_section_info ranges {};
 162   dwarf2_section_info rnglists {};
 163   dwarf2_section_info addr {};
 164   dwarf2_section_info frame {};
 165   dwarf2_section_info eh_frame {};
 166   dwarf2_section_info gdb_index {};
 167   dwarf2_section_info debug_names {};
 168   dwarf2_section_info debug_aranges {};
 169
 170   std::vector<dwarf2_section_info> types;
 171
 172   /* Table of all the compilation units.  This is used to locate
 173      the target compilation unit of a particular reference.  */
 174   std::vector<dwarf2_per_cu_data *> all_comp_units;
 175
 176   /* The .debug_types-related CUs (TUs).  */
 177   std::vector<signatured_type *> all_type_units;
 178
 179   /* Table of struct type_unit_group objects.
 180      The hash key is the DW_AT_stmt_list value.  */
 181   htab_up type_unit_groups;
 182
 183   /* A table mapping .debug_types signatures to its signatured_type entry.
 184      This is NULL if the .debug_types section hasn't been read in yet.  */
 185   htab_up signatured_types;
 186
 187   /* Type unit statistics, to see how well the scaling improvements
 188      are doing.  */
 189   struct tu_stats tu_stats {};
 190
 191   /* A table mapping DW_AT_dwo_name values to struct dwo_file objects.
 192      This is NULL if the table hasn't been allocated yet.  */
 193   htab_up dwo_files;
 194
 195   /* True if we've checked for whether there is a DWP file.  */
 196   bool dwp_checked = false;
 197
 198   /* The DWP file if there is one, or NULL.  */
 199   std::unique_ptr<struct dwp_file> dwp_file;
 200
 201   /* The shared '.dwz' file, if one exists.  This is used when the
 202      original data was compressed using 'dwz -m'.  */
 203   std::unique_ptr<struct dwz_file> dwz_file;
 204
 205   /* Whether copy relocations are supported by this object format.  */
 206   bool can_copy;
 207
 208   /* A flag indicating whether this objfile has a section loaded at a
 209      VMA of 0.  */
 210   bool has_section_at_zero = false;
 211
 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;
 215
 216   /* The mapped index, or NULL if .gdb_index is missing or not being used.  */
 217   std::unique_ptr<mapped_index> index_table;
 218
 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;
 221
 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_up quick_file_names_table;
 230
 231   /* Set during partial symbol reading, to prevent queueing of full
 232      symbols.  */
 233   bool reading_partial_symbols = false;
 234
 235   /* The CUs we recently read.  */
 236   std::vector<dwarf2_per_cu_data *> just_read_cus;
 237
 238   /* If we loaded the index from an external file, this contains the
 239      resources associated to the open file, memory mapping, etc.  */
 240   std::unique_ptr<index_cache_resource> index_cache_res;
 241
 242   /* Mapping from abstract origin DIE to concrete DIEs that reference it as
 243      DW_AT_abstract_origin.  */
 244   std::unordered_map<sect_offset, std::vector<sect_offset>,
 245                      gdb::hash_enum<sect_offset>>
 246     abstract_to_concrete;
 247
 248   /* CUs that are queued to be read.  */
 249   gdb::optional<std::queue<dwarf2_queue_item>> queue;
 250
 251   /* We keep a separate reference to the partial symtabs, in case we
 252      are sharing them between objfiles.  This is only set after
 253      partial symbols have been read the first time.  */
 254   std::shared_ptr<psymtab_storage> partial_symtabs;
 255
 256   /* The address map that is used by the DWARF index code.  */
 257   struct addrmap *index_addrmap = nullptr;
 258
 259 private:
 260
 261   /* The total number of per_cu and signatured_type objects that have
 262      been created so far for this reader.  */
 263   size_t m_num_psymtabs = 0;
 264 };
 265
 266 /* This is the per-objfile data associated with a type_unit_group.  */
 267
 268 struct type_unit_group_unshareable
 269 {
 270   /* The compunit symtab.
 271      Type units in a group needn't all be defined in the same source file,
 272      so we create an essentially anonymous symtab as the compunit symtab.  */
 273   struct compunit_symtab *compunit_symtab = nullptr;
 274
 275   /* The number of symtabs from the line header.
 276      The value here must match line_header.num_file_names.  */
 277   unsigned int num_symtabs = 0;
 278
 279   /* The symbol tables for this TU (obtained from the files listed in
 280      DW_AT_stmt_list).
 281      WARNING: The order of entries here must match the order of entries
 282      in the line header.  After the first TU using this type_unit_group, the
 283      line header for the subsequent TUs is recreated from this.  This is done
 284      because we need to use the same symtabs for each TU using the same
 285      DW_AT_stmt_list value.  Also note that symtabs may be repeated here,
 286      there's no guarantee the line header doesn't have duplicate entries.  */
 287   struct symtab **symtabs = nullptr;
 288 };
 289
 290 /* Collection of data recorded per objfile.
 291    This hangs off of dwarf2_objfile_data_key.
 292
 293    Some DWARF data cannot (currently) be shared across objfiles.  Such
 294    data is stored in this object.  */
 295
 296 struct dwarf2_per_objfile
 297 {
 298   dwarf2_per_objfile (struct objfile *objfile, dwarf2_per_bfd *per_bfd)
 299     : objfile (objfile), per_bfd (per_bfd)
 300   {}
 301
 302   ~dwarf2_per_objfile ();
 303
 304   /* Return pointer to string at .debug_line_str offset as read from BUF.
 305      BUF is assumed to be in a compilation unit described by CU_HEADER.
 306      Return *BYTES_READ_PTR count of bytes read from BUF.  */
 307   const char *read_line_string (const gdb_byte *buf,
 308                                 const struct comp_unit_head *cu_header,
 309                                 unsigned int *bytes_read_ptr);
 310
 311   /* Resize the M_SYMTABS vector to the needed size (the number of partial
 312      symtabs allocated by the per-bfd).  */
 313   void resize_symtabs ()
 314   {
 315     /* The symtabs vector should only grow, not shrink.  */
 316     gdb_assert (per_bfd->num_psymtabs () >= m_symtabs.size ());
 317
 318     m_symtabs.resize (per_bfd->num_psymtabs ());
 319   }
 320
 321   /* Return true if the symtab corresponding to PER_CU has been set,
 322      false otherwise.  */
 323   bool symtab_set_p (const dwarf2_per_cu_data *per_cu) const;
 324
 325   /* Return the compunit_symtab associated to PER_CU, if it has been created.  */
 326   compunit_symtab *get_symtab (const dwarf2_per_cu_data *per_cu) const;
 327
 328   /* Set the compunit_symtab associated to PER_CU.  */
 329   void set_symtab (const dwarf2_per_cu_data *per_cu, compunit_symtab *symtab);
 330
 331   /* Get the type_unit_group_unshareable corresponding to TU_GROUP.  If one
 332      does not exist, create it.  */
 333   type_unit_group_unshareable *get_type_unit_group_unshareable
 334     (type_unit_group *tu_group);
 335
 336   struct type *get_type_for_signatured_type (signatured_type *sig_type) const;
 337
 338   void set_type_for_signatured_type (signatured_type *sig_type,
 339                                      struct type *type);
 340
 341   /* Find an integer type SIZE_IN_BYTES bytes in size and return it.
 342      UNSIGNED_P controls if the integer is unsigned or not.  */
 343   struct type *int_type (int size_in_bytes, bool unsigned_p) const;
 344
 345   /* Get the dwarf2_cu matching PER_CU for this objfile.  */
 346   dwarf2_cu *get_cu (dwarf2_per_cu_data *per_cu);
 347
 348   /* Set the dwarf2_cu matching PER_CU for this objfile.  */
 349   void set_cu (dwarf2_per_cu_data *per_cu, dwarf2_cu *cu);
 350
 351   /* Remove/free the dwarf2_cu matching PER_CU for this objfile.  */
 352   void remove_cu (dwarf2_per_cu_data *per_cu);
 353
 354   /* Free all cached compilation units.  */
 355   void remove_all_cus ();
 356
 357   /* Increase the age counter on each CU compilation unit and free
 358      any that are too old.  */
 359   void age_comp_units ();
 360
 361   /* Back link.  */
 362   struct objfile *objfile;
 363
 364   /* Pointer to the data that is (possibly) shared between this objfile and
 365      other objfiles backed by the same BFD.  */
 366   struct dwarf2_per_bfd *per_bfd;
 367
 368   /* Table mapping type DIEs to their struct type *.
 369      This is nullptr if not allocated yet.
 370      The mapping is done via (CU/TU + DIE offset) -> type.  */
 371   htab_up die_type_hash;
 372
 373   /* Table containing line_header indexed by offset and offset_in_dwz.  */
 374   htab_up line_header_hash;
 375
 376 private:
 377   /* Hold the corresponding compunit_symtab for each CU or TU.  This
 378      is indexed by dwarf2_per_cu_data::index.  A NULL value means
 379      that the CU/TU has not been expanded yet.  */
 380   std::vector<compunit_symtab *> m_symtabs;
 381
 382   /* Map from a type unit group to the corresponding unshared
 383      structure.  */
 384   typedef std::unique_ptr<type_unit_group_unshareable>
 385     type_unit_group_unshareable_up;
 386
 387   std::unordered_map<type_unit_group *, type_unit_group_unshareable_up>
 388     m_type_units;
 389
 390   /* Map from signatured types to the corresponding struct type.  */
 391   std::unordered_map<signatured_type *, struct type *> m_type_map;
 392
 393   /* Map from the objfile-independent dwarf2_per_cu_data instances to the
 394      corresponding objfile-dependent dwarf2_cu instances.  */
 395   std::unordered_map<dwarf2_per_cu_data *, dwarf2_cu *> m_dwarf2_cus;
 396 };
 397
 398 /* Get the dwarf2_per_objfile associated to OBJFILE.  */
 399
 400 dwarf2_per_objfile *get_dwarf2_per_objfile (struct objfile *objfile);
 401
 402 /* A partial symtab specialized for DWARF.  */
 403 struct dwarf2_psymtab : public partial_symtab
 404 {
 405   dwarf2_psymtab (const char *filename,
 406                   psymtab_storage *partial_symtabs,
 407                   objfile_per_bfd_storage *objfile_per_bfd,
 408                   dwarf2_per_cu_data *per_cu)
 409     : partial_symtab (filename, partial_symtabs, objfile_per_bfd, 0),
 410       per_cu_data (per_cu)
 411   {
 412   }
 413
 414   void read_symtab (struct objfile *) override;
 415   void expand_psymtab (struct objfile *) override;
 416   bool readin_p (struct objfile *) const override;
 417   compunit_symtab *get_compunit_symtab (struct objfile *) const override;
 418
 419   struct dwarf2_per_cu_data *per_cu_data;
 420 };
 421
 422 /* Persistent data held for a compilation unit, even when not
 423    processing it.  We put a pointer to this structure in the
 424    psymtab.  */
 425
 426 struct dwarf2_per_cu_data
 427 {
 428   /* The start offset and length of this compilation unit.
 429      NOTE: Unlike comp_unit_head.length, this length includes
 430      initial_length_size.
 431      If the DIE refers to a DWO file, this is always of the original die,
 432      not the DWO file.  */
 433   sect_offset sect_off;
 434   unsigned int length;
 435
 436   /* DWARF standard version this data has been read from (such as 4 or 5).  */
 437   unsigned char dwarf_version;
 438
 439   /* Flag indicating this compilation unit will be read in before
 440      any of the current compilation units are processed.  */
 441   unsigned int queued : 1;
 442
 443   /* This flag will be set when reading partial DIEs if we need to load
 444      absolutely all DIEs for this compilation unit, instead of just the ones
 445      we think are interesting.  It gets set if we look for a DIE in the
 446      hash table and don't find it.  */
 447   unsigned int load_all_dies : 1;
 448
 449   /* Non-zero if this CU is from .debug_types.
 450      Struct dwarf2_per_cu_data is contained in struct signatured_type iff
 451      this is non-zero.  */
 452   unsigned int is_debug_types : 1;
 453
 454   /* Non-zero if this CU is from the .dwz file.  */
 455   unsigned int is_dwz : 1;
 456
 457   /* Non-zero if reading a TU directly from a DWO file, bypassing the stub.
 458      This flag is only valid if is_debug_types is true.
 459      We can't read a CU directly from a DWO file: There are required
 460      attributes in the stub.  */
 461   unsigned int reading_dwo_directly : 1;
 462
 463   /* Non-zero if the TU has been read.
 464      This is used to assist the "Stay in DWO Optimization" for Fission:
 465      When reading a DWO, it's faster to read TUs from the DWO instead of
 466      fetching them from random other DWOs (due to comdat folding).
 467      If the TU has already been read, the optimization is unnecessary
 468      (and unwise - we don't want to change where gdb thinks the TU lives
 469      "midflight").
 470      This flag is only valid if is_debug_types is true.  */
 471   unsigned int tu_read : 1;
 472
 473   /* True if HEADER has been read in.
 474
 475      Don't access this field directly.  It should be private, but we can't make
 476      it private at the moment.  */
 477   mutable bool m_header_read_in : 1;
 478
 479   /* The unit type of this CU.  */
 480   ENUM_BITFIELD (dwarf_unit_type) unit_type : 8;
 481
 482   /* The language of this CU.  */
 483   ENUM_BITFIELD (language) lang : LANGUAGE_BITS;
 484
 485   /* Our index in the unshared "symtabs" vector.  */
 486   unsigned index;
 487
 488   /* The section this CU/TU lives in.
 489      If the DIE refers to a DWO file, this is always the original die,
 490      not the DWO file.  */
 491   struct dwarf2_section_info *section;
 492
 493   /* Backlink to the owner of this.  */
 494   dwarf2_per_bfd *per_bfd;
 495
 496   /* DWARF header of this CU.  Note that dwarf2_cu reads its own version of the
 497      header, which may differ from this one, since it may pass rcuh_kind::TYPE
 498      to read_comp_unit_head, whereas for dwarf2_per_cu_data we always pass
 499      rcuh_kind::COMPILE.
 500
 501      Don't access this field directly, use the get_header method instead.  It
 502      should be private, but we can't make it private at the moment.  */
 503   mutable comp_unit_head m_header;
 504
 505   /* When dwarf2_per_bfd::using_index is true, the 'quick' field
 506      is active.  Otherwise, the 'psymtab' field is active.  */
 507   union
 508   {
 509     /* The partial symbol table associated with this compilation unit,
 510        or NULL for unread partial units.  */
 511     dwarf2_psymtab *psymtab;
 512
 513     /* Data needed by the "quick" functions.  */
 514     struct dwarf2_per_cu_quick_data *quick;
 515   } v;
 516
 517   /* The CUs we import using DW_TAG_imported_unit.  This is filled in
 518      while reading psymtabs, used to compute the psymtab dependencies,
 519      and then cleared.  Then it is filled in again while reading full
 520      symbols, and only deleted when the objfile is destroyed.
 521
 522      This is also used to work around a difference between the way gold
 523      generates .gdb_index version <=7 and the way gdb does.  Arguably this
 524      is a gold bug.  For symbols coming from TUs, gold records in the index
 525      the CU that includes the TU instead of the TU itself.  This breaks
 526      dw2_lookup_symbol: It assumes that if the index says symbol X lives
 527      in CU/TU Y, then one need only expand Y and a subsequent lookup in Y
 528      will find X.  Alas TUs live in their own symtab, so after expanding CU Y
 529      we need to look in TU Z to find X.  Fortunately, this is akin to
 530      DW_TAG_imported_unit, so we just use the same mechanism: For
 531      .gdb_index version <=7 this also records the TUs that the CU referred
 532      to.  Concurrently with this change gdb was modified to emit version 8
 533      indices so we only pay a price for gold generated indices.
 534      http://sourceware.org/bugzilla/show_bug.cgi?id=15021.
 535
 536      This currently needs to be a public member due to how
 537      dwarf2_per_cu_data is allocated and used.  Ideally in future things
 538      could be refactored to make this private.  Until then please try to
 539      avoid direct access to this member, and instead use the helper
 540      functions above.  */
 541   std::vector <dwarf2_per_cu_data *> *imported_symtabs;
 542
 543   /* Return true of IMPORTED_SYMTABS is empty or not yet allocated.  */
 544   bool imported_symtabs_empty () const
 545   {
 546     return (imported_symtabs == nullptr || imported_symtabs->empty ());
 547   }
 548
 549   /* Push P to the back of IMPORTED_SYMTABS, allocated IMPORTED_SYMTABS
 550      first if required.  */
 551   void imported_symtabs_push (dwarf2_per_cu_data *p)
 552   {
 553     if (imported_symtabs == nullptr)
 554       imported_symtabs = new std::vector <dwarf2_per_cu_data *>;
 555     imported_symtabs->push_back (p);
 556   }
 557
 558   /* Return the size of IMPORTED_SYMTABS if it is allocated, otherwise
 559      return 0.  */
 560   size_t imported_symtabs_size () const
 561   {
 562     if (imported_symtabs == nullptr)
 563       return 0;
 564     return imported_symtabs->size ();
 565   }
 566
 567   /* Delete IMPORTED_SYMTABS and set the pointer back to nullptr.  */
 568   void imported_symtabs_free ()
 569   {
 570     delete imported_symtabs;
 571     imported_symtabs = nullptr;
 572   }
 573
 574   /* Get the header of this per_cu, reading it if necessary.  */
 575   const comp_unit_head *get_header () const;
 576
 577   /* Return the address size given in the compilation unit header for
 578      this CU.  */
 579   int addr_size () const;
 580
 581   /* Return the offset size given in the compilation unit header for
 582      this CU.  */
 583   int offset_size () const;
 584
 585   /* Return the DW_FORM_ref_addr size given in the compilation unit
 586      header for this CU.  */
 587   int ref_addr_size () const;
 588
 589   /* Return DWARF version number of this CU.  */
 590   short version () const
 591   {
 592     return dwarf_version;
 593   }
 594
 595   /* A type unit group has a per_cu object that is recognized by
 596      having no section.  */
 597   bool type_unit_group_p () const
 598   {
 599     return section == nullptr;
 600   }
 601 };
 602
 603 /* Entry in the signatured_types hash table.  */
 604
 605 struct signatured_type
 606 {
 607   /* The "per_cu" object of this type.
 608      This struct is used iff per_cu.is_debug_types.
 609      N.B.: This is the first member so that it's easy to convert pointers
 610      between them.  */
 611   struct dwarf2_per_cu_data per_cu;
 612
 613   /* The type's signature.  */
 614   ULONGEST signature;
 615
 616   /* Offset in the TU of the type's DIE, as read from the TU header.
 617      If this TU is a DWO stub and the definition lives in a DWO file
 618      (specified by DW_AT_GNU_dwo_name), this value is unusable.  */
 619   cu_offset type_offset_in_tu;
 620
 621   /* Offset in the section of the type's DIE.
 622      If the definition lives in a DWO file, this is the offset in the
 623      .debug_types.dwo section.
 624      The value is zero until the actual value is known.
 625      Zero is otherwise not a valid section offset.  */
 626   sect_offset type_offset_in_section;
 627
 628   /* Type units are grouped by their DW_AT_stmt_list entry so that they
 629      can share them.  This points to the containing symtab.  */
 630   struct type_unit_group *type_unit_group;
 631
 632   /* Containing DWO unit.
 633      This field is valid iff per_cu.reading_dwo_directly.  */
 634   struct dwo_unit *dwo_unit;
 635 };
 636
 637 /* Return the type of the DIE at DIE_OFFSET in the CU named by
 638    PER_CU.  */
 639
 640 struct type *dwarf2_get_die_type (cu_offset die_offset,
 641                                   dwarf2_per_cu_data *per_cu,
 642                                   dwarf2_per_objfile *per_objfile);
 643
 644 /* Given an index in .debug_addr, fetch the value.
 645    NOTE: This can be called during dwarf expression evaluation,
 646    long after the debug information has been read, and thus per_cu->cu
 647    may no longer exist.  */
 648
 649 CORE_ADDR dwarf2_read_addr_index (dwarf2_per_cu_data *per_cu,
 650                                   dwarf2_per_objfile *per_objfile,
 651                                   unsigned int addr_index);
 652
 653 /* Return DWARF block referenced by DW_AT_location of DIE at SECT_OFF at PER_CU.
 654    Returned value is intended for DW_OP_call*.  Returned
 655    dwarf2_locexpr_baton->data has lifetime of
 656    PER_CU->DWARF2_PER_OBJFILE->OBJFILE.  */
 657
 658 struct dwarf2_locexpr_baton dwarf2_fetch_die_loc_sect_off
 659   (sect_offset sect_off, dwarf2_per_cu_data *per_cu,
 660    dwarf2_per_objfile *per_objfile,
 661    gdb::function_view<CORE_ADDR ()> get_frame_pc,
 662    bool resolve_abstract_p = false);
 663
 664 /* Like dwarf2_fetch_die_loc_sect_off, but take a CU
 665    offset.  */
 666
 667 struct dwarf2_locexpr_baton dwarf2_fetch_die_loc_cu_off
 668   (cu_offset offset_in_cu, dwarf2_per_cu_data *per_cu,
 669    dwarf2_per_objfile *per_objfile,
 670    gdb::function_view<CORE_ADDR ()> get_frame_pc);
 671
 672 /* If the DIE at SECT_OFF in PER_CU has a DW_AT_const_value, return a
 673    pointer to the constant bytes and set LEN to the length of the
 674    data.  If memory is needed, allocate it on OBSTACK.  If the DIE
 675    does not have a DW_AT_const_value, return NULL.  */
 676
 677 extern const gdb_byte *dwarf2_fetch_constant_bytes
 678   (sect_offset sect_off, dwarf2_per_cu_data *per_cu,
 679    dwarf2_per_objfile *per_objfile, obstack *obstack,
 680    LONGEST *len);
 681
 682 /* Return the type of the die at SECT_OFF in PER_CU.  Return NULL if no
 683    valid type for this die is found.  */
 684
 685 struct type *dwarf2_fetch_die_type_sect_off
 686   (sect_offset sect_off, dwarf2_per_cu_data *per_cu,
 687    dwarf2_per_objfile *per_objfile);
 688
 689 /* When non-zero, dump line number entries as they are read in.  */
 690 extern unsigned int dwarf_line_debug;
 691
 692 /* Dwarf2 sections that can be accessed by dwarf2_get_section_info.  */
 693 enum dwarf2_section_enum {
 694   DWARF2_DEBUG_FRAME,
 695   DWARF2_EH_FRAME
 696 };
 697
 698 extern void dwarf2_get_section_info (struct objfile *,
 699                                      enum dwarf2_section_enum,
 700                                      asection **, const gdb_byte **,
 701                                      bfd_size_type *);
 702
 703 #endif /* DWARF2READ_H */