gdb/addrmap.h

   1 /* addrmap.h --- interface to address map data structure.
   2
   3    Copyright (C) 2007, 2008 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 ADDRMAP_H
  21 #define ADDRMAP_H
  22
  23 /* An address map is essentially a table mapping CORE_ADDRs onto GDB
  24    data structures, like blocks, symtabs, partial symtabs, and so on.
  25    An address map uses memory proportional to the number of
  26    transitions in the map, where a CORE_ADDR N is mapped to one
  27    object, and N+1 is mapped to a different object.
  28
  29    Address maps come in two flavors: fixed, and mutable.  Mutable
  30    address maps consume more memory, but can be changed and extended.
  31    A fixed address map, once constructed (from a mutable address map),
  32    can't be edited.  Both kinds of map are allocated in obstacks.  */
  33
  34 /* The opaque type representing address maps.  */
  35 struct addrmap;
  36
  37 /* Create a mutable address map which maps every address to NULL.
  38    Allocate entries in OBSTACK.  */
  39 struct addrmap *addrmap_create_mutable (struct obstack *obstack);
  40
  41 /* In the mutable address map MAP, associate the addresses from START
  42    to END_INCLUSIVE that are currently associated with NULL with OBJ
  43    instead.  Addresses mapped to an object other than NULL are left
  44    unchanged.
  45
  46    As the name suggests, END_INCLUSIVE is also mapped to OBJ.  This
  47    convention is unusual, but it allows callers to accurately specify
  48    ranges that abut the top of the address space, and ranges that
  49    cover the entire address space.
  50
  51    This operation seems a bit complicated for a primitive: if it's
  52    needed, why not just have a simpler primitive operation that sets a
  53    range to a value, wiping out whatever was there before, and then
  54    let the caller construct more complicated operations from that,
  55    along with some others for traversal?
  56
  57    It turns out this is the mutation operation we want to use all the
  58    time, at least for now.  Our immediate use for address maps is to
  59    represent lexical blocks whose address ranges are not contiguous.
  60    We walk the tree of lexical blocks present in the debug info, and
  61    only create 'struct block' objects after we've traversed all a
  62    block's children.  If a lexical block declares no local variables
  63    (and isn't the lexical block for a function's body), we omit it
  64    from GDB's data structures entirely.
  65
  66    However, this menas that we don't decide to create a block (and
  67    thus record it in the address map) until after we've traversed its
  68    children.  If we do decide to create the block, we do so at a time
  69    when all its children have already been recorded in the map.  So
  70    this operation --- change only those addresses left unset --- is
  71    actually the operation we want to use every time.
  72
  73    It seems simpler to let the code which operates on the
  74    representation directly deal with the hair of implementing these
  75    semantics than to provide an interface which allows it to be
  76    implemented efficiently, but doesn't reveal too much of the
  77    representation.  */
  78 void addrmap_set_empty (struct addrmap *map,
  79                         CORE_ADDR start, CORE_ADDR end_inclusive,
  80                         void *obj);
  81
  82 /* Return the object associated with ADDR in MAP.  */
  83 void *addrmap_find (struct addrmap *map, CORE_ADDR addr);
  84
  85 /* Create a fixed address map which is a copy of the mutable address
  86    map ORIGINAL.  Allocate entries in OBSTACK.  */
  87 struct addrmap *addrmap_create_fixed (struct addrmap *original,
  88                                       struct obstack *obstack);
  89
  90 /* Relocate all the addresses in MAP by OFFSET.  (This can be applied
  91    to either mutable or immutable maps.)  */
  92 void addrmap_relocate (struct addrmap *map, CORE_ADDR offset);
  93
  94 #endif /* ADDRMAP_H */