gdb/blockframe.c

   1 /* Get info from stack frames; convert between frames, blocks,
   2    functions and pc values.
   3
   4    Copyright (C) 1986, 1987, 1988, 1989, 1990, 1991, 1992, 1993, 1994, 1995,
   5    1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2007, 2008
   6    Free Software Foundation, Inc.
   7
   8    This file is part of GDB.
   9
  10    This program is free software; you can redistribute it and/or modify
  11    it under the terms of the GNU General Public License as published by
  12    the Free Software Foundation; either version 3 of the License, or
  13    (at your option) any later version.
  14
  15    This program is distributed in the hope that it will be useful,
  16    but WITHOUT ANY WARRANTY; without even the implied warranty of
  17    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  18    GNU General Public License for more details.
  19
  20    You should have received a copy of the GNU General Public License
  21    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
  22
  23 #include "defs.h"
  24 #include "symtab.h"
  25 #include "bfd.h"
  26 #include "objfiles.h"
  27 #include "frame.h"
  28 #include "gdbcore.h"
  29 #include "value.h"
  30 #include "target.h"
  31 #include "inferior.h"
  32 #include "annotate.h"
  33 #include "regcache.h"
  34 #include "gdb_assert.h"
  35 #include "dummy-frame.h"
  36 #include "command.h"
  37 #include "gdbcmd.h"
  38 #include "block.h"
  39
  40 /* Prototypes for exported functions. */
  41
  42 void _initialize_blockframe (void);
  43
  44 /* Return the innermost lexical block in execution
  45    in a specified stack frame.  The frame address is assumed valid.
  46
  47    If ADDR_IN_BLOCK is non-zero, set *ADDR_IN_BLOCK to the exact code
  48    address we used to choose the block.  We use this to find a source
  49    line, to decide which macro definitions are in scope.
  50
  51    The value returned in *ADDR_IN_BLOCK isn't necessarily the frame's
  52    PC, and may not really be a valid PC at all.  For example, in the
  53    caller of a function declared to never return, the code at the
  54    return address will never be reached, so the call instruction may
  55    be the very last instruction in the block.  So the address we use
  56    to choose the block is actually one byte before the return address
  57    --- hopefully pointing us at the call instruction, or its delay
  58    slot instruction.  */
  59
  60 struct block *
  61 get_frame_block (struct frame_info *frame, CORE_ADDR *addr_in_block)
  62 {
  63   const CORE_ADDR pc = get_frame_address_in_block (frame);
  64
  65   if (addr_in_block)
  66     *addr_in_block = pc;
  67
  68   return block_for_pc (pc);
  69 }
  70
  71 CORE_ADDR
  72 get_pc_function_start (CORE_ADDR pc)
  73 {
  74   struct block *bl;
  75   struct minimal_symbol *msymbol;
  76
  77   bl = block_for_pc (pc);
  78   if (bl)
  79     {
  80       struct symbol *symbol = block_linkage_function (bl);
  81
  82       if (symbol)
  83         {
  84           bl = SYMBOL_BLOCK_VALUE (symbol);
  85           return BLOCK_START (bl);
  86         }
  87     }
  88
  89   msymbol = lookup_minimal_symbol_by_pc (pc);
  90   if (msymbol)
  91     {
  92       CORE_ADDR fstart = SYMBOL_VALUE_ADDRESS (msymbol);
  93
  94       if (find_pc_section (fstart))
  95         return fstart;
  96     }
  97
  98   return 0;
  99 }
 100
 101 /* Return the symbol for the function executing in frame FRAME.  */
 102
 103 struct symbol *
 104 get_frame_function (struct frame_info *frame)
 105 {
 106   struct block *bl = get_frame_block (frame, 0);
 107   if (bl == 0)
 108     return 0;
 109   return block_linkage_function (bl);
 110 }
 111 \f
 112
 113 /* Return the function containing pc value PC in section SECTION.
 114    Returns 0 if function is not known.  */
 115
 116 struct symbol *
 117 find_pc_sect_function (CORE_ADDR pc, struct bfd_section *section)
 118 {
 119   struct block *b = block_for_pc_sect (pc, section);
 120   if (b == 0)
 121     return 0;
 122   return block_linkage_function (b);
 123 }
 124
 125 /* Return the function containing pc value PC.
 126    Returns 0 if function is not known.  Backward compatibility, no section */
 127
 128 struct symbol *
 129 find_pc_function (CORE_ADDR pc)
 130 {
 131   return find_pc_sect_function (pc, find_pc_mapped_section (pc));
 132 }
 133
 134 /* These variables are used to cache the most recent result
 135  * of find_pc_partial_function. */
 136
 137 static CORE_ADDR cache_pc_function_low = 0;
 138 static CORE_ADDR cache_pc_function_high = 0;
 139 static char *cache_pc_function_name = 0;
 140 static struct bfd_section *cache_pc_function_section = NULL;
 141
 142 /* Clear cache, e.g. when symbol table is discarded. */
 143
 144 void
 145 clear_pc_function_cache (void)
 146 {
 147   cache_pc_function_low = 0;
 148   cache_pc_function_high = 0;
 149   cache_pc_function_name = (char *) 0;
 150   cache_pc_function_section = NULL;
 151 }
 152
 153 /* Finds the "function" (text symbol) that is smaller than PC but
 154    greatest of all of the potential text symbols in SECTION.  Sets
 155    *NAME and/or *ADDRESS conditionally if that pointer is non-null.
 156    If ENDADDR is non-null, then set *ENDADDR to be the end of the
 157    function (exclusive), but passing ENDADDR as non-null means that
 158    the function might cause symbols to be read.  This function either
 159    succeeds or fails (not halfway succeeds).  If it succeeds, it sets
 160    *NAME, *ADDRESS, and *ENDADDR to real information and returns 1.
 161    If it fails, it sets *NAME, *ADDRESS, and *ENDADDR to zero and
 162    returns 0.  */
 163
 164 /* Backward compatibility, no section argument.  */
 165
 166 int
 167 find_pc_partial_function (CORE_ADDR pc, char **name, CORE_ADDR *address,
 168                           CORE_ADDR *endaddr)
 169 {
 170   struct bfd_section *section;
 171   struct partial_symtab *pst;
 172   struct symbol *f;
 173   struct minimal_symbol *msymbol;
 174   struct partial_symbol *psb;
 175   struct obj_section *osect;
 176   int i;
 177   CORE_ADDR mapped_pc;
 178
 179   /* To ensure that the symbol returned belongs to the correct setion
 180      (and that the last [random] symbol from the previous section
 181      isn't returned) try to find the section containing PC.  First try
 182      the overlay code (which by default returns NULL); and second try
 183      the normal section code (which almost always succeeds).  */
 184   section = find_pc_overlay (pc);
 185   if (section == NULL)
 186     {
 187       struct obj_section *obj_section = find_pc_section (pc);
 188       if (obj_section == NULL)
 189         section = NULL;
 190       else
 191         section = obj_section->the_bfd_section;
 192     }
 193
 194   mapped_pc = overlay_mapped_address (pc, section);
 195
 196   if (mapped_pc >= cache_pc_function_low
 197       && mapped_pc < cache_pc_function_high
 198       && section == cache_pc_function_section)
 199     goto return_cached_value;
 200
 201   msymbol = lookup_minimal_symbol_by_pc_section (mapped_pc, section);
 202   pst = find_pc_sect_psymtab (mapped_pc, section);
 203   if (pst)
 204     {
 205       /* Need to read the symbols to get a good value for the end address.  */
 206       if (endaddr != NULL && !pst->readin)
 207         {
 208           /* Need to get the terminal in case symbol-reading produces
 209              output.  */
 210           target_terminal_ours_for_output ();
 211           PSYMTAB_TO_SYMTAB (pst);
 212         }
 213
 214       if (pst->readin)
 215         {
 216           /* Checking whether the msymbol has a larger value is for the
 217              "pathological" case mentioned in print_frame_info.  */
 218           f = find_pc_sect_function (mapped_pc, section);
 219           if (f != NULL
 220               && (msymbol == NULL
 221                   || (BLOCK_START (SYMBOL_BLOCK_VALUE (f))
 222                       >= SYMBOL_VALUE_ADDRESS (msymbol))))
 223             {
 224               cache_pc_function_low = BLOCK_START (SYMBOL_BLOCK_VALUE (f));
 225               cache_pc_function_high = BLOCK_END (SYMBOL_BLOCK_VALUE (f));
 226               cache_pc_function_name = DEPRECATED_SYMBOL_NAME (f);
 227               cache_pc_function_section = section;
 228               goto return_cached_value;
 229             }
 230         }
 231       else
 232         {
 233           /* Now that static symbols go in the minimal symbol table, perhaps
 234              we could just ignore the partial symbols.  But at least for now
 235              we use the partial or minimal symbol, whichever is larger.  */
 236           psb = find_pc_sect_psymbol (pst, mapped_pc, section);
 237
 238           if (psb
 239               && (msymbol == NULL ||
 240                   (SYMBOL_VALUE_ADDRESS (psb)
 241                    >= SYMBOL_VALUE_ADDRESS (msymbol))))
 242             {
 243               /* This case isn't being cached currently. */
 244               if (address)
 245                 *address = SYMBOL_VALUE_ADDRESS (psb);
 246               if (name)
 247                 *name = DEPRECATED_SYMBOL_NAME (psb);
 248               /* endaddr non-NULL can't happen here.  */
 249               return 1;
 250             }
 251         }
 252     }
 253
 254   /* Not in the normal symbol tables, see if the pc is in a known section.
 255      If it's not, then give up.  This ensures that anything beyond the end
 256      of the text seg doesn't appear to be part of the last function in the
 257      text segment.  */
 258
 259   osect = find_pc_sect_section (mapped_pc, section);
 260
 261   if (!osect)
 262     msymbol = NULL;
 263
 264   /* Must be in the minimal symbol table.  */
 265   if (msymbol == NULL)
 266     {
 267       /* No available symbol.  */
 268       if (name != NULL)
 269         *name = 0;
 270       if (address != NULL)
 271         *address = 0;
 272       if (endaddr != NULL)
 273         *endaddr = 0;
 274       return 0;
 275     }
 276
 277   cache_pc_function_low = SYMBOL_VALUE_ADDRESS (msymbol);
 278   cache_pc_function_name = DEPRECATED_SYMBOL_NAME (msymbol);
 279   cache_pc_function_section = section;
 280
 281   /* If the minimal symbol has a size, use it for the cache.
 282      Otherwise use the lesser of the next minimal symbol in the same
 283      section, or the end of the section, as the end of the
 284      function.  */
 285
 286   if (MSYMBOL_SIZE (msymbol) != 0)
 287     cache_pc_function_high = cache_pc_function_low + MSYMBOL_SIZE (msymbol);
 288   else
 289     {
 290       /* Step over other symbols at this same address, and symbols in
 291          other sections, to find the next symbol in this section with
 292          a different address.  */
 293
 294       for (i = 1; DEPRECATED_SYMBOL_NAME (msymbol + i) != NULL; i++)
 295         {
 296           if (SYMBOL_VALUE_ADDRESS (msymbol + i) != SYMBOL_VALUE_ADDRESS (msymbol)
 297               && SYMBOL_BFD_SECTION (msymbol + i) == SYMBOL_BFD_SECTION (msymbol))
 298             break;
 299         }
 300
 301       if (DEPRECATED_SYMBOL_NAME (msymbol + i) != NULL
 302           && SYMBOL_VALUE_ADDRESS (msymbol + i) < osect->endaddr)
 303         cache_pc_function_high = SYMBOL_VALUE_ADDRESS (msymbol + i);
 304       else
 305         /* We got the start address from the last msymbol in the objfile.
 306            So the end address is the end of the section.  */
 307         cache_pc_function_high = osect->endaddr;
 308     }
 309
 310  return_cached_value:
 311
 312   if (address)
 313     {
 314       if (pc_in_unmapped_range (pc, section))
 315         *address = overlay_unmapped_address (cache_pc_function_low, section);
 316       else
 317         *address = cache_pc_function_low;
 318     }
 319
 320   if (name)
 321     *name = cache_pc_function_name;
 322
 323   if (endaddr)
 324     {
 325       if (pc_in_unmapped_range (pc, section))
 326         {
 327           /* Because the high address is actually beyond the end of
 328              the function (and therefore possibly beyond the end of
 329              the overlay), we must actually convert (high - 1) and
 330              then add one to that. */
 331
 332           *endaddr = 1 + overlay_unmapped_address (cache_pc_function_high - 1,
 333                                                    section);
 334         }
 335       else
 336         *endaddr = cache_pc_function_high;
 337     }
 338
 339   return 1;
 340 }
 341
 342 /* Return the innermost stack frame executing inside of BLOCK,
 343    or NULL if there is no such frame.  If BLOCK is NULL, just return NULL.  */
 344
 345 struct frame_info *
 346 block_innermost_frame (struct block *block)
 347 {
 348   struct frame_info *frame;
 349   CORE_ADDR start;
 350   CORE_ADDR end;
 351   CORE_ADDR calling_pc;
 352
 353   if (block == NULL)
 354     return NULL;
 355
 356   start = BLOCK_START (block);
 357   end = BLOCK_END (block);
 358
 359   frame = get_current_frame ();
 360   while (frame != NULL)
 361     {
 362       calling_pc = get_frame_address_in_block (frame);
 363       if (calling_pc >= start && calling_pc < end)
 364         return frame;
 365
 366       frame = get_prev_frame (frame);
 367     }
 368
 369   return NULL;
 370 }