gdb/dwarf2/mapped-index.h

   1 /* Base class for mapped indices
   2
   3    Copyright (C) 2021-2024 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 GDB_DWARF2_MAPPED_INDEX_H
  21 #define GDB_DWARF2_MAPPED_INDEX_H
  22
  23 #include "language.h"
  24
  25 /* An index into a (C++) symbol name component in a symbol name as
  26    recorded in the mapped_index's symbol table.  For each C++ symbol
  27    in the symbol table, we record one entry for the start of each
  28    component in the symbol in a table of name components, and then
  29    sort the table, in order to be able to binary search symbol names,
  30    ignoring leading namespaces, both completion and regular look up.
  31    For example, for symbol "A::B::C", we'll have an entry that points
  32    to "A::B::C", another that points to "B::C", and another for "C".
  33    Note that function symbols in GDB index have no parameter
  34    information, just the function/method names.  You can convert a
  35    name_component to a "const char *" using the
  36    'mapped_index::symbol_name_at(offset_type)' method.  */
  37
  38 struct name_component
  39 {
  40   /* Offset in the symbol name where the component starts.  Stored as
  41      a (32-bit) offset instead of a pointer to save memory and improve
  42      locality on 64-bit architectures.  */
  43   offset_type name_offset;
  44
  45   /* The symbol's index in the symbol and constant pool tables of a
  46      mapped_index.  */
  47   offset_type idx;
  48 };
  49
  50 class cooked_index;
  51
  52 /* Base class of all DWARF scanner types.  */
  53
  54 struct dwarf_scanner_base
  55 {
  56   dwarf_scanner_base () = default;
  57   virtual ~dwarf_scanner_base () = default;
  58   DISABLE_COPY_AND_ASSIGN (dwarf_scanner_base);
  59
  60   /* Return a quick_symbol_functions instance that refers back to this
  61      dwarf_scanner_base.  */
  62   virtual quick_symbol_functions_up make_quick_functions () const = 0;
  63
  64   /* An ad hoc version check.  This is needed for .gdb_index to check
  65      whether a version 8 or above index is in use.  Returns true if
  66      the index is usable, false otherwise.  */
  67   virtual bool version_check () const
  68   {
  69     return true;
  70   }
  71
  72   /* This is called when writing an index.  For a cooked index, it
  73      will return 'this' as a cooked index.  For other forms, it will
  74      throw an exception with an appropriate error message.  */
  75   virtual cooked_index *index_for_writing () = 0;
  76
  77   /* Wait for reading of the debuginfo to be completely finished.
  78      This normally has a trivial implementation, but if a subclass
  79      does any background reading, it's needed to ensure that the
  80      reading is completed before destroying the containing per-BFD
  81      object.  */
  82   virtual void wait_completely ()
  83   {
  84   }
  85 };
  86
  87 /* Base class containing bits shared by both .gdb_index and
  88    .debug_name indexes.  */
  89
  90 struct mapped_index_base : public dwarf_scanner_base
  91 {
  92   mapped_index_base () = default;
  93   DISABLE_COPY_AND_ASSIGN (mapped_index_base);
  94
  95   /* The name_component table (a sorted vector).  See name_component's
  96      description above.  */
  97   std::vector<name_component> name_components;
  98
  99   /* How NAME_COMPONENTS is sorted.  */
 100   enum case_sensitivity name_components_casing;
 101
 102   /* Return the number of names in the symbol table.  */
 103   virtual size_t symbol_name_count () const = 0;
 104
 105   /* Get the name of the symbol at IDX in the symbol table.  */
 106   virtual const char *symbol_name_at
 107     (offset_type idx, dwarf2_per_objfile *per_objfile) const = 0;
 108
 109   /* Return whether the name at IDX in the symbol table should be
 110      ignored.  */
 111   virtual bool symbol_name_slot_invalid (offset_type idx) const
 112   {
 113     return false;
 114   }
 115
 116   /* Build the symbol name component sorted vector, if we haven't
 117      yet.  */
 118   void build_name_components (dwarf2_per_objfile *per_objfile);
 119
 120   /* Returns the lower (inclusive) and upper (exclusive) bounds of the
 121      possible matches for LN_NO_PARAMS in the name component
 122      vector.  */
 123   std::pair<std::vector<name_component>::const_iterator,
 124             std::vector<name_component>::const_iterator>
 125     find_name_components_bounds (const lookup_name_info &ln_no_params,
 126                                  enum language lang,
 127                                  dwarf2_per_objfile *per_objfile) const;
 128
 129   cooked_index *index_for_writing () override
 130   {
 131     error (_("Cannot use an index to create the index"));
 132   }
 133 };
 134
 135 #endif /* GDB_DWARF2_MAPPED_INDEX_H */