gdb/addrmap.h

   1 /* addrmap.h --- interface to address map data structure.
   2
   3    Copyright (C) 2007-2023 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 #include "splay-tree.h"
  24 #include "gdbsupport/function-view.h"
  25
  26 /* An address map is essentially a table mapping CORE_ADDRs onto GDB
  27    data structures, like blocks, symtabs, partial symtabs, and so on.
  28    An address map uses memory proportional to the number of
  29    transitions in the map, where a CORE_ADDR N is mapped to one
  30    object, and N+1 is mapped to a different object.
  31
  32    Address maps come in two flavors: fixed, and mutable.  Mutable
  33    address maps consume more memory, but can be changed and extended.
  34    A fixed address map, once constructed (from a mutable address map),
  35    can't be edited.  */
  36
  37 /* The type of a function used to iterate over the map.
  38    OBJ is NULL for unmapped regions.  */
  39 using addrmap_foreach_fn
  40   = gdb::function_view<int (CORE_ADDR start_addr, void *obj)>;
  41 using addrmap_foreach_const_fn
  42   = gdb::function_view<int (CORE_ADDR start_addr, const void *obj)>;
  43
  44 /* The base class for addrmaps.  */
  45 struct addrmap
  46 {
  47   virtual ~addrmap () = default;
  48
  49   /* In the mutable address map MAP, associate the addresses from START
  50      to END_INCLUSIVE that are currently associated with NULL with OBJ
  51      instead.  Addresses mapped to an object other than NULL are left
  52      unchanged.
  53
  54      As the name suggests, END_INCLUSIVE is also mapped to OBJ.  This
  55      convention is unusual, but it allows callers to accurately specify
  56      ranges that abut the top of the address space, and ranges that
  57      cover the entire address space.
  58
  59      This operation seems a bit complicated for a primitive: if it's
  60      needed, why not just have a simpler primitive operation that sets a
  61      range to a value, wiping out whatever was there before, and then
  62      let the caller construct more complicated operations from that,
  63      along with some others for traversal?
  64
  65      It turns out this is the mutation operation we want to use all the
  66      time, at least for now.  Our immediate use for address maps is to
  67      represent lexical blocks whose address ranges are not contiguous.
  68      We walk the tree of lexical blocks present in the debug info, and
  69      only create 'struct block' objects after we've traversed all a
  70      block's children.  If a lexical block declares no local variables
  71      (and isn't the lexical block for a function's body), we omit it
  72      from GDB's data structures entirely.
  73
  74      However, this means that we don't decide to create a block (and
  75      thus record it in the address map) until after we've traversed its
  76      children.  If we do decide to create the block, we do so at a time
  77      when all its children have already been recorded in the map.  So
  78      this operation --- change only those addresses left unset --- is
  79      actually the operation we want to use every time.
  80
  81      It seems simpler to let the code which operates on the
  82      representation directly deal with the hair of implementing these
  83      semantics than to provide an interface which allows it to be
  84      implemented efficiently, but doesn't reveal too much of the
  85      representation.  */
  86   virtual void set_empty (CORE_ADDR start, CORE_ADDR end_inclusive,
  87                           void *obj) = 0;
  88
  89   /* Return the object associated with ADDR in MAP.  */
  90   const void *find (CORE_ADDR addr) const
  91   { return this->do_find (addr); }
  92
  93   void *find (CORE_ADDR addr)
  94   { return this->do_find (addr); }
  95
  96   /* Relocate all the addresses in MAP by OFFSET.  (This can be applied
  97      to either mutable or immutable maps.)  */
  98   virtual void relocate (CORE_ADDR offset) = 0;
  99
 100   /* Call FN for every address in MAP, following an in-order traversal.
 101      If FN ever returns a non-zero value, the iteration ceases
 102      immediately, and the value is returned.  Otherwise, this function
 103      returns 0.  */
 104   int foreach (addrmap_foreach_const_fn fn) const
 105   { return this->do_foreach (fn); }
 106
 107   int foreach (addrmap_foreach_fn fn)
 108   { return this->do_foreach (fn); }
 109
 110
 111 private:
 112   /* Worker for find, implemented by sub-classes.  */
 113   virtual void *do_find (CORE_ADDR addr) const = 0;
 114
 115   /* Worker for foreach, implemented by sub-classes.  */
 116   virtual int do_foreach (addrmap_foreach_fn fn) const = 0;
 117 };
 118
 119 struct addrmap_mutable;
 120
 121 /* Fixed address maps.  */
 122 struct addrmap_fixed : public addrmap,
 123                        public allocate_on_obstack
 124 {
 125 public:
 126
 127   addrmap_fixed (struct obstack *obstack, addrmap_mutable *mut);
 128   DISABLE_COPY_AND_ASSIGN (addrmap_fixed);
 129
 130   void set_empty (CORE_ADDR start, CORE_ADDR end_inclusive,
 131                   void *obj) override;
 132   void relocate (CORE_ADDR offset) override;
 133
 134 private:
 135   void *do_find (CORE_ADDR addr) const override;
 136   int do_foreach (addrmap_foreach_fn fn) const override;
 137
 138   /* A transition: a point in an address map where the value changes.
 139      The map maps ADDR to VALUE, but if ADDR > 0, it maps ADDR-1 to
 140      something else.  */
 141   struct addrmap_transition
 142   {
 143     CORE_ADDR addr;
 144     void *value;
 145   };
 146
 147   /* The number of transitions in TRANSITIONS.  */
 148   size_t num_transitions;
 149
 150   /* An array of transitions, sorted by address.  For every point in
 151      the map where either ADDR == 0 or ADDR is mapped to one value and
 152      ADDR - 1 is mapped to something different, we have an entry here
 153      containing ADDR and VALUE.  (Note that this means we always have
 154      an entry for address 0).  */
 155   struct addrmap_transition *transitions;
 156 };
 157
 158 /* Mutable address maps.  */
 159
 160 struct addrmap_mutable : public addrmap
 161 {
 162 public:
 163
 164   addrmap_mutable ();
 165   ~addrmap_mutable ();
 166   DISABLE_COPY_AND_ASSIGN (addrmap_mutable);
 167
 168   void set_empty (CORE_ADDR start, CORE_ADDR end_inclusive,
 169                   void *obj) override;
 170   void relocate (CORE_ADDR offset) override;
 171
 172 private:
 173   void *do_find (CORE_ADDR addr) const override;
 174   int do_foreach (addrmap_foreach_fn fn) const override;
 175
 176   /* A splay tree, with a node for each transition; there is a
 177      transition at address T if T-1 and T map to different objects.
 178
 179      Any addresses below the first node map to NULL.  (Unlike
 180      fixed maps, we have no entry at (CORE_ADDR) 0; it doesn't
 181      simplify enough.)
 182
 183      The last region is assumed to end at CORE_ADDR_MAX.
 184
 185      Since we can't know whether CORE_ADDR is larger or smaller than
 186      splay_tree_key (unsigned long) --- I think both are possible,
 187      given all combinations of 32- and 64-bit hosts and targets ---
 188      our keys are pointers to CORE_ADDR values.  Since the splay tree
 189      library doesn't pass any closure pointer to the key free
 190      function, we can't keep a freelist for keys.  Since mutable
 191      addrmaps are only used temporarily right now, we just leak keys
 192      from deleted nodes; they'll be freed when the obstack is freed.  */
 193   splay_tree tree;
 194
 195   /* Various helper methods.  */
 196   splay_tree_key allocate_key (CORE_ADDR addr);
 197   void force_transition (CORE_ADDR addr);
 198   splay_tree_node splay_tree_lookup (CORE_ADDR addr) const;
 199   splay_tree_node splay_tree_predecessor (CORE_ADDR addr) const;
 200   splay_tree_node splay_tree_successor (CORE_ADDR addr);
 201   void splay_tree_remove (CORE_ADDR addr);
 202   void splay_tree_insert (CORE_ADDR key, void *value);
 203 };
 204
 205
 206 /* Dump the addrmap to OUTFILE.  If PAYLOAD is non-NULL, only dump any
 207    components that map to PAYLOAD.  (If PAYLOAD is NULL, the entire
 208    map is dumped.)  */
 209 void addrmap_dump (struct addrmap *map, struct ui_file *outfile,
 210                    void *payload);
 211
 212 #endif /* ADDRMAP_H */