gdb/block.c

   1 /* Block-related functions for the GNU debugger, GDB.
   2
   3    Copyright (C) 2003, 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 #include "defs.h"
  21 #include "block.h"
  22 #include "symtab.h"
  23 #include "symfile.h"
  24 #include "gdb_obstack.h"
  25 #include "cp-support.h"
  26 #include "addrmap.h"
  27
  28 /* This is used by struct block to store namespace-related info for
  29    C++ files, namely using declarations and the current namespace in
  30    scope.  */
  31
  32 struct block_namespace_info
  33 {
  34   const char *scope;
  35   struct using_direct *using;
  36 };
  37
  38 static void block_initialize_namespace (struct block *block,
  39                                         struct obstack *obstack);
  40
  41 /* Return Nonzero if block a is lexically nested within block b,
  42    or if a and b have the same pc range.
  43    Return zero otherwise. */
  44
  45 int
  46 contained_in (const struct block *a, const struct block *b)
  47 {
  48   if (!a || !b)
  49     return 0;
  50   return BLOCK_START (a) >= BLOCK_START (b)
  51     && BLOCK_END (a) <= BLOCK_END (b);
  52 }
  53
  54
  55 /* Return the symbol for the function which contains a specified
  56    lexical block, described by a struct block BL.  */
  57
  58 struct symbol *
  59 block_function (const struct block *bl)
  60 {
  61   while (BLOCK_FUNCTION (bl) == 0 && BLOCK_SUPERBLOCK (bl) != 0)
  62     bl = BLOCK_SUPERBLOCK (bl);
  63
  64   return BLOCK_FUNCTION (bl);
  65 }
  66
  67 /* Return the blockvector immediately containing the innermost lexical
  68    block containing the specified pc value and section, or 0 if there
  69    is none.  PBLOCK is a pointer to the block.  If PBLOCK is NULL, we
  70    don't pass this information back to the caller.  */
  71
  72 struct blockvector *
  73 blockvector_for_pc_sect (CORE_ADDR pc, struct bfd_section *section,
  74                          struct block **pblock, struct symtab *symtab)
  75 {
  76   struct block *b;
  77   int bot, top, half;
  78   struct blockvector *bl;
  79
  80   if (symtab == 0)              /* if no symtab specified by caller */
  81     {
  82       /* First search all symtabs for one whose file contains our pc */
  83       symtab = find_pc_sect_symtab (pc, section);
  84       if (symtab == 0)
  85         return 0;
  86     }
  87
  88   bl = BLOCKVECTOR (symtab);
  89
  90   /* Then search that symtab for the smallest block that wins.  */
  91
  92   /* If we have an addrmap mapping code addresses to blocks, then use
  93      that.  */
  94   if (BLOCKVECTOR_MAP (bl))
  95     {
  96       b = addrmap_find (BLOCKVECTOR_MAP (bl), pc);
  97       if (b)
  98         {
  99           if (pblock)
 100             *pblock = b;
 101           return bl;
 102         }
 103       else
 104         return 0;
 105     }
 106
 107
 108   /* Otherwise, use binary search to find the last block that starts
 109      before PC.  */
 110   bot = 0;
 111   top = BLOCKVECTOR_NBLOCKS (bl);
 112
 113   while (top - bot > 1)
 114     {
 115       half = (top - bot + 1) >> 1;
 116       b = BLOCKVECTOR_BLOCK (bl, bot + half);
 117       if (BLOCK_START (b) <= pc)
 118         bot += half;
 119       else
 120         top = bot + half;
 121     }
 122
 123   /* Now search backward for a block that ends after PC.  */
 124
 125   while (bot >= 0)
 126     {
 127       b = BLOCKVECTOR_BLOCK (bl, bot);
 128       if (BLOCK_END (b) > pc)
 129         {
 130           if (pblock)
 131             *pblock = b;
 132           return bl;
 133         }
 134       bot--;
 135     }
 136   return 0;
 137 }
 138
 139 /* Return the blockvector immediately containing the innermost lexical block
 140    containing the specified pc value, or 0 if there is none.
 141    Backward compatibility, no section.  */
 142
 143 struct blockvector *
 144 blockvector_for_pc (CORE_ADDR pc, struct block **pblock)
 145 {
 146   return blockvector_for_pc_sect (pc, find_pc_mapped_section (pc),
 147                                   pblock, NULL);
 148 }
 149
 150 /* Return the innermost lexical block containing the specified pc value
 151    in the specified section, or 0 if there is none.  */
 152
 153 struct block *
 154 block_for_pc_sect (CORE_ADDR pc, struct bfd_section *section)
 155 {
 156   struct blockvector *bl;
 157   struct block *b;
 158
 159   bl = blockvector_for_pc_sect (pc, section, &b, NULL);
 160   if (bl)
 161     return b;
 162   return 0;
 163 }
 164
 165 /* Return the innermost lexical block containing the specified pc value,
 166    or 0 if there is none.  Backward compatibility, no section.  */
 167
 168 struct block *
 169 block_for_pc (CORE_ADDR pc)
 170 {
 171   return block_for_pc_sect (pc, find_pc_mapped_section (pc));
 172 }
 173
 174 /* Now come some functions designed to deal with C++ namespace issues.
 175    The accessors are safe to use even in the non-C++ case.  */
 176
 177 /* This returns the namespace that BLOCK is enclosed in, or "" if it
 178    isn't enclosed in a namespace at all.  This travels the chain of
 179    superblocks looking for a scope, if necessary.  */
 180
 181 const char *
 182 block_scope (const struct block *block)
 183 {
 184   for (; block != NULL; block = BLOCK_SUPERBLOCK (block))
 185     {
 186       if (BLOCK_NAMESPACE (block) != NULL
 187           && BLOCK_NAMESPACE (block)->scope != NULL)
 188         return BLOCK_NAMESPACE (block)->scope;
 189     }
 190
 191   return "";
 192 }
 193
 194 /* Set BLOCK's scope member to SCOPE; if needed, allocate memory via
 195    OBSTACK.  (It won't make a copy of SCOPE, however, so that already
 196    has to be allocated correctly.)  */
 197
 198 void
 199 block_set_scope (struct block *block, const char *scope,
 200                  struct obstack *obstack)
 201 {
 202   block_initialize_namespace (block, obstack);
 203
 204   BLOCK_NAMESPACE (block)->scope = scope;
 205 }
 206
 207 /* This returns the first using directives associated to BLOCK, if
 208    any.  */
 209
 210 /* FIXME: carlton/2003-04-23: This uses the fact that we currently
 211    only have using directives in static blocks, because we only
 212    generate using directives from anonymous namespaces.  Eventually,
 213    when we support using directives everywhere, we'll want to replace
 214    this by some iterator functions.  */
 215
 216 struct using_direct *
 217 block_using (const struct block *block)
 218 {
 219   const struct block *static_block = block_static_block (block);
 220
 221   if (static_block == NULL
 222       || BLOCK_NAMESPACE (static_block) == NULL)
 223     return NULL;
 224   else
 225     return BLOCK_NAMESPACE (static_block)->using;
 226 }
 227
 228 /* Set BLOCK's using member to USING; if needed, allocate memory via
 229    OBSTACK.  (It won't make a copy of USING, however, so that already
 230    has to be allocated correctly.)  */
 231
 232 void
 233 block_set_using (struct block *block,
 234                  struct using_direct *using,
 235                  struct obstack *obstack)
 236 {
 237   block_initialize_namespace (block, obstack);
 238
 239   BLOCK_NAMESPACE (block)->using = using;
 240 }
 241
 242 /* If BLOCK_NAMESPACE (block) is NULL, allocate it via OBSTACK and
 243    ititialize its members to zero.  */
 244
 245 static void
 246 block_initialize_namespace (struct block *block, struct obstack *obstack)
 247 {
 248   if (BLOCK_NAMESPACE (block) == NULL)
 249     {
 250       BLOCK_NAMESPACE (block)
 251         = obstack_alloc (obstack, sizeof (struct block_namespace_info));
 252       BLOCK_NAMESPACE (block)->scope = NULL;
 253       BLOCK_NAMESPACE (block)->using = NULL;
 254     }
 255 }
 256
 257 /* Return the static block associated to BLOCK.  Return NULL if block
 258    is NULL or if block is a global block.  */
 259
 260 const struct block *
 261 block_static_block (const struct block *block)
 262 {
 263   if (block == NULL || BLOCK_SUPERBLOCK (block) == NULL)
 264     return NULL;
 265
 266   while (BLOCK_SUPERBLOCK (BLOCK_SUPERBLOCK (block)) != NULL)
 267     block = BLOCK_SUPERBLOCK (block);
 268
 269   return block;
 270 }
 271
 272 /* Return the static block associated to BLOCK.  Return NULL if block
 273    is NULL.  */
 274
 275 const struct block *
 276 block_global_block (const struct block *block)
 277 {
 278   if (block == NULL)
 279     return NULL;
 280
 281   while (BLOCK_SUPERBLOCK (block) != NULL)
 282     block = BLOCK_SUPERBLOCK (block);
 283
 284   return block;
 285 }
 286
 287 /* Allocate a block on OBSTACK, and initialize its elements to
 288    zero/NULL.  This is useful for creating "dummy" blocks that don't
 289    correspond to actual source files.
 290
 291    Warning: it sets the block's BLOCK_DICT to NULL, which isn't a
 292    valid value.  If you really don't want the block to have a
 293    dictionary, then you should subsequently set its BLOCK_DICT to
 294    dict_create_linear (obstack, NULL).  */
 295
 296 struct block *
 297 allocate_block (struct obstack *obstack)
 298 {
 299   struct block *bl = obstack_alloc (obstack, sizeof (struct block));
 300
 301   BLOCK_START (bl) = 0;
 302   BLOCK_END (bl) = 0;
 303   BLOCK_FUNCTION (bl) = NULL;
 304   BLOCK_SUPERBLOCK (bl) = NULL;
 305   BLOCK_DICT (bl) = NULL;
 306   BLOCK_NAMESPACE (bl) = NULL;
 307
 308   return bl;
 309 }