gdb/psymtab.h

   1 /* Public partial symbol table definitions.
   2
   3    Copyright (C) 2009-2021 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 PSYMTAB_H
  21 #define PSYMTAB_H
  22
  23 #include "gdb_obstack.h"
  24 #include "symfile.h"
  25 #include "gdbsupport/next-iterator.h"
  26 #include "bcache.h"
  27
  28 struct partial_symbol;
  29
  30 /* Specialization of bcache to store partial symbols.  */
  31
  32 struct psymbol_bcache : public gdb::bcache
  33 {
  34   /* Calculate a hash code for the given partial symbol.  The hash is
  35      calculated using the symbol's value, language, domain, class
  36      and name.  These are the values which are set by
  37      add_psymbol_to_bcache.  */
  38   unsigned long hash (const void *addr, int length) override;
  39
  40   /* Returns true if the symbol LEFT equals the symbol RIGHT.
  41      For the comparison this function uses a symbols value,
  42      language, domain, class and name.  */
  43   int compare (const void *left, const void *right, int length) override;
  44 };
  45
  46 /* An instance of this class manages the partial symbol tables and
  47    partial symbols for a given objfile.
  48
  49    The core psymtab functions -- those in psymtab.c -- arrange for
  50    nearly all psymtab- and psymbol-related allocations to happen
  51    either in the psymtab_storage object (either on its obstack or in
  52    other memory managed by this class), or on the per-BFD object.  The
  53    only link from the psymtab storage object back to the objfile (or
  54    objfile_obstack) that is made by the core psymtab code is the
  55    compunit_symtab member in the standard_psymtab -- and a given
  56    symbol reader can avoid this by implementing its own subclasses of
  57    partial_symtab.
  58
  59    However, it is up to each symbol reader to maintain this invariant
  60    in other ways, if it wants to reuse psymtabs across multiple
  61    objfiles.  The main issue here is ensuring that read_symtab_private
  62    does not point into objfile_obstack.  */
  63
  64 class psymtab_storage
  65 {
  66 public:
  67   psymtab_storage () = default;
  68   ~psymtab_storage ();
  69
  70   DISABLE_COPY_AND_ASSIGN (psymtab_storage);
  71
  72   /* Discard all partial symbol tables starting with "psymtabs" and
  73      proceeding until "to" has been discarded.  */
  74
  75   void discard_psymtabs_to (struct partial_symtab *to)
  76   {
  77     while (psymtabs != to)
  78       discard_psymtab (psymtabs);
  79   }
  80
  81   /* Discard the partial symbol table.  */
  82
  83   void discard_psymtab (struct partial_symtab *pst);
  84
  85   /* Return the obstack that is used for storage by this object.  */
  86
  87   struct obstack *obstack ()
  88   {
  89     if (!m_obstack.has_value ())
  90       m_obstack.emplace ();
  91     return &*m_obstack;
  92   }
  93
  94   /* Allocate storage for the "dependencies" field of a psymtab.
  95      NUMBER says how many dependencies there are.  */
  96
  97   struct partial_symtab **allocate_dependencies (int number)
  98   {
  99     return OBSTACK_CALLOC (obstack (), number, struct partial_symtab *);
 100   }
 101
 102   /* Install a psymtab on the psymtab list.  This transfers ownership
 103      of PST to this object.  */
 104
 105   void install_psymtab (partial_symtab *pst);
 106
 107   typedef next_adapter<struct partial_symtab> partial_symtab_range;
 108
 109   /* A range adapter that makes it possible to iterate over all
 110      psymtabs in one objfile.  */
 111
 112   partial_symtab_range range ()
 113   {
 114     return partial_symtab_range (psymtabs);
 115   }
 116
 117
 118   /* Each objfile points to a linked list of partial symtabs derived from
 119      this file, one partial symtab structure for each compilation unit
 120      (source file).  */
 121
 122   struct partial_symtab *psymtabs = nullptr;
 123
 124   /* Map addresses to the entries of PSYMTABS.  It would be more efficient to
 125      have a map per the whole process but ADDRMAP cannot selectively remove
 126      its items during FREE_OBJFILE.  This mapping is already present even for
 127      PARTIAL_SYMTABs which still have no corresponding full SYMTABs read.
 128
 129      The DWARF parser reuses this addrmap to store things other than
 130      psymtabs in the cases where debug information is being read from, for
 131      example, the .debug-names section.  */
 132
 133   struct addrmap *psymtabs_addrmap = nullptr;
 134
 135   /* A byte cache where we can stash arbitrary "chunks" of bytes that
 136      will not change.  */
 137
 138   psymbol_bcache psymbol_cache;
 139
 140 private:
 141
 142   /* The obstack where allocations are made.  This is lazily allocated
 143      so that we don't waste memory when there are no psymtabs.  */
 144
 145   gdb::optional<auto_obstack> m_obstack;
 146 };
 147
 148 #endif /* PSYMTAB_H */