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,
   5    1995, 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004
   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 2 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, write to the Free Software
  22    Foundation, Inc., 51 Franklin Street, Fifth Floor,
  23    Boston, MA 02110-1301, USA.  */
  24
  25 #include "defs.h"
  26 #include "symtab.h"
  27 #include "bfd.h"
  28 #include "objfiles.h"
  29 #include "frame.h"
  30 #include "gdbcore.h"
  31 #include "value.h"              /* for read_register */
  32 #include "target.h"             /* for target_has_stack */
  33 #include "inferior.h"           /* for read_pc */
  34 #include "annotate.h"
  35 #include "regcache.h"
  36 #include "gdb_assert.h"
  37 #include "dummy-frame.h"
  38 #include "command.h"
  39 #include "gdbcmd.h"
  40 #include "block.h"
  41
  42 /* Prototypes for exported functions. */
  43
  44 void _initialize_blockframe (void);
  45
  46 /* Return the innermost lexical block in execution
  47    in a specified stack frame.  The frame address is assumed valid.
  48
  49    If ADDR_IN_BLOCK is non-zero, set *ADDR_IN_BLOCK to the exact code
  50    address we used to choose the block.  We use this to find a source
  51    line, to decide which macro definitions are in scope.
  52
  53    The value returned in *ADDR_IN_BLOCK isn't necessarily the frame's
  54    PC, and may not really be a valid PC at all.  For example, in the
  55    caller of a function declared to never return, the code at the
  56    return address will never be reached, so the call instruction may
  57    be the very last instruction in the block.  So the address we use
  58    to choose the block is actually one byte before the return address
  59    --- hopefully pointing us at the call instruction, or its delay
  60    slot instruction.  */
  61
  62 struct block *
  63 get_frame_block (struct frame_info *frame, CORE_ADDR *addr_in_block)
  64 {
  65   const CORE_ADDR pc = get_frame_address_in_block (frame);
  66
  67   if (addr_in_block)
  68     *addr_in_block = pc;
  69
  70   return block_for_pc (pc);
  71 }
  72
  73 CORE_ADDR
  74 get_pc_function_start (CORE_ADDR pc)
  75 {
  76   struct block *bl;
  77   struct minimal_symbol *msymbol;
  78
  79   bl = block_for_pc (pc);
  80   if (bl)
  81     {
  82       struct symbol *symbol = block_function (bl);
  83
  84       if (symbol)
  85         {
  86           bl = SYMBOL_BLOCK_VALUE (symbol);
  87           return BLOCK_START (bl);
  88         }
  89     }
  90
  91   msymbol = lookup_minimal_symbol_by_pc (pc);
  92   if (msymbol)
  93     {
  94       CORE_ADDR fstart = SYMBOL_VALUE_ADDRESS (msymbol);
  95
  96       if (find_pc_section (fstart))
  97         return fstart;
  98     }
  99
 100   return 0;
 101 }
 102
 103 /* Return the symbol for the function executing in frame FRAME.  */
 104
 105 struct symbol *
 106 get_frame_function (struct frame_info *frame)
 107 {
 108   struct block *bl = get_frame_block (frame, 0);
 109   if (bl == 0)
 110     return 0;
 111   return block_function (bl);
 112 }
 113 \f
 114
 115 /* Return the function containing pc value PC in section SECTION.
 116    Returns 0 if function is not known.  */
 117
 118 struct symbol *
 119 find_pc_sect_function (CORE_ADDR pc, struct bfd_section *section)
 120 {
 121   struct block *b = block_for_pc_sect (pc, section);
 122   if (b == 0)
 123     return 0;
 124   return block_function (b);
 125 }
 126
 127 /* Return the function containing pc value PC.
 128    Returns 0 if function is not known.  Backward compatibility, no section */
 129
 130 struct symbol *
 131 find_pc_function (CORE_ADDR pc)
 132 {
 133   return find_pc_sect_function (pc, find_pc_mapped_section (pc));
 134 }
 135
 136 /* These variables are used to cache the most recent result
 137  * of find_pc_partial_function. */
 138
 139 static CORE_ADDR cache_pc_function_low = 0;
 140 static CORE_ADDR cache_pc_function_high = 0;
 141 static char *cache_pc_function_name = 0;
 142 static struct bfd_section *cache_pc_function_section = NULL;
 143
 144 /* Clear cache, e.g. when symbol table is discarded. */
 145
 146 void
 147 clear_pc_function_cache (void)
 148 {
 149   cache_pc_function_low = 0;
 150   cache_pc_function_high = 0;
 151   cache_pc_function_name = (char *) 0;
 152   cache_pc_function_section = NULL;
 153 }
 154
 155 /* Finds the "function" (text symbol) that is smaller than PC but
 156    greatest of all of the potential text symbols in SECTION.  Sets
 157    *NAME and/or *ADDRESS conditionally if that pointer is non-null.
 158    If ENDADDR is non-null, then set *ENDADDR to be the end of the
 159    function (exclusive), but passing ENDADDR as non-null means that
 160    the function might cause symbols to be read.  This function either
 161    succeeds or fails (not halfway succeeds).  If it succeeds, it sets
 162    *NAME, *ADDRESS, and *ENDADDR to real information and returns 1.
 163    If it fails, it sets *NAME, *ADDRESS, and *ENDADDR to zero and
 164    returns 0.  */
 165
 166 /* Backward compatibility, no section argument.  */
 167
 168 int
 169 find_pc_partial_function (CORE_ADDR pc, char **name, CORE_ADDR *address,
 170                           CORE_ADDR *endaddr)
 171 {
 172   struct bfd_section *section;
 173   struct partial_symtab *pst;
 174   struct symbol *f;
 175   struct minimal_symbol *msymbol;
 176   struct partial_symbol *psb;
 177   struct obj_section *osect;
 178   int i;
 179   CORE_ADDR mapped_pc;
 180
 181   /* To ensure that the symbol returned belongs to the correct setion
 182      (and that the last [random] symbol from the previous section
 183      isn't returned) try to find the section containing PC.  First try
 184      the overlay code (which by default returns NULL); and second try
 185      the normal section code (which almost always succeeds).  */
 186   section = find_pc_overlay (pc);
 187   if (section == NULL)
 188     {
 189       struct obj_section *obj_section = find_pc_section (pc);
 190       if (obj_section == NULL)
 191         section = NULL;
 192       else
 193         section = obj_section->the_bfd_section;
 194     }
 195
 196   mapped_pc = overlay_mapped_address (pc, section);
 197
 198   if (mapped_pc >= cache_pc_function_low
 199       && mapped_pc < cache_pc_function_high
 200       && section == cache_pc_function_section)
 201     goto return_cached_value;
 202
 203   msymbol = lookup_minimal_symbol_by_pc_section (mapped_pc, section);
 204   pst = find_pc_sect_psymtab (mapped_pc, section);
 205   if (pst)
 206     {
 207       /* Need to read the symbols to get a good value for the end address.  */
 208       if (endaddr != NULL && !pst->readin)
 209         {
 210           /* Need to get the terminal in case symbol-reading produces
 211              output.  */
 212           target_terminal_ours_for_output ();
 213           PSYMTAB_TO_SYMTAB (pst);
 214         }
 215
 216       if (pst->readin)
 217         {
 218           /* Checking whether the msymbol has a larger value is for the
 219              "pathological" case mentioned in print_frame_info.  */
 220           f = find_pc_sect_function (mapped_pc, section);
 221           if (f != NULL
 222               && (msymbol == NULL
 223                   || (BLOCK_START (SYMBOL_BLOCK_VALUE (f))
 224                       >= SYMBOL_VALUE_ADDRESS (msymbol))))
 225             {
 226               cache_pc_function_low = BLOCK_START (SYMBOL_BLOCK_VALUE (f));
 227               cache_pc_function_high = BLOCK_END (SYMBOL_BLOCK_VALUE (f));
 228               cache_pc_function_name = DEPRECATED_SYMBOL_NAME (f);
 229               cache_pc_function_section = section;
 230               goto return_cached_value;
 231             }
 232         }
 233       else
 234         {
 235           /* Now that static symbols go in the minimal symbol table, perhaps
 236              we could just ignore the partial symbols.  But at least for now
 237              we use the partial or minimal symbol, whichever is larger.  */
 238           psb = find_pc_sect_psymbol (pst, mapped_pc, section);
 239
 240           if (psb
 241               && (msymbol == NULL ||
 242                   (SYMBOL_VALUE_ADDRESS (psb)
 243                    >= SYMBOL_VALUE_ADDRESS (msymbol))))
 244             {
 245               /* This case isn't being cached currently. */
 246               if (address)
 247                 *address = SYMBOL_VALUE_ADDRESS (psb);
 248               if (name)
 249                 *name = DEPRECATED_SYMBOL_NAME (psb);
 250               /* endaddr non-NULL can't happen here.  */
 251               return 1;
 252             }
 253         }
 254     }
 255
 256   /* Not in the normal symbol tables, see if the pc is in a known section.
 257      If it's not, then give up.  This ensures that anything beyond the end
 258      of the text seg doesn't appear to be part of the last function in the
 259      text segment.  */
 260
 261   osect = find_pc_sect_section (mapped_pc, section);
 262
 263   if (!osect)
 264     msymbol = NULL;
 265
 266   /* Must be in the minimal symbol table.  */
 267   if (msymbol == NULL)
 268     {
 269       /* No available symbol.  */
 270       if (name != NULL)
 271         *name = 0;
 272       if (address != NULL)
 273         *address = 0;
 274       if (endaddr != NULL)
 275         *endaddr = 0;
 276       return 0;
 277     }
 278
 279   cache_pc_function_low = SYMBOL_VALUE_ADDRESS (msymbol);
 280   cache_pc_function_name = DEPRECATED_SYMBOL_NAME (msymbol);
 281   cache_pc_function_section = section;
 282
 283   /* If the minimal symbol has a size, use it for the cache.
 284      Otherwise use the lesser of the next minimal symbol in the same
 285      section, or the end of the section, as the end of the
 286      function.  */
 287
 288   if (MSYMBOL_SIZE (msymbol) != 0)
 289     cache_pc_function_high = cache_pc_function_low + MSYMBOL_SIZE (msymbol);
 290   else
 291     {
 292       /* Step over other symbols at this same address, and symbols in
 293          other sections, to find the next symbol in this section with
 294          a different address.  */
 295
 296       for (i = 1; DEPRECATED_SYMBOL_NAME (msymbol + i) != NULL; i++)
 297         {
 298           if (SYMBOL_VALUE_ADDRESS (msymbol + i) != SYMBOL_VALUE_ADDRESS (msymbol)
 299               && SYMBOL_BFD_SECTION (msymbol + i) == SYMBOL_BFD_SECTION (msymbol))
 300             break;
 301         }
 302
 303       if (DEPRECATED_SYMBOL_NAME (msymbol + i) != NULL
 304           && SYMBOL_VALUE_ADDRESS (msymbol + i) < osect->endaddr)
 305         cache_pc_function_high = SYMBOL_VALUE_ADDRESS (msymbol + i);
 306       else
 307         /* We got the start address from the last msymbol in the objfile.
 308            So the end address is the end of the section.  */
 309         cache_pc_function_high = osect->endaddr;
 310     }
 311
 312  return_cached_value:
 313
 314   if (address)
 315     {
 316       if (pc_in_unmapped_range (pc, section))
 317         *address = overlay_unmapped_address (cache_pc_function_low, section);
 318       else
 319         *address = cache_pc_function_low;
 320     }
 321
 322   if (name)
 323     *name = cache_pc_function_name;
 324
 325   if (endaddr)
 326     {
 327       if (pc_in_unmapped_range (pc, section))
 328         {
 329           /* Because the high address is actually beyond the end of
 330              the function (and therefore possibly beyond the end of
 331              the overlay), we must actually convert (high - 1) and
 332              then add one to that. */
 333
 334           *endaddr = 1 + overlay_unmapped_address (cache_pc_function_high - 1,
 335                                                    section);
 336         }
 337       else
 338         *endaddr = cache_pc_function_high;
 339     }
 340
 341   return 1;
 342 }
 343
 344 /* Return the innermost stack frame executing inside of BLOCK,
 345    or NULL if there is no such frame.  If BLOCK is NULL, just return NULL.  */
 346
 347 struct frame_info *
 348 block_innermost_frame (struct block *block)
 349 {
 350   struct frame_info *frame;
 351   CORE_ADDR start;
 352   CORE_ADDR end;
 353   CORE_ADDR calling_pc;
 354
 355   if (block == NULL)
 356     return NULL;
 357
 358   start = BLOCK_START (block);
 359   end = BLOCK_END (block);
 360
 361   frame = NULL;
 362   while (1)
 363     {
 364       frame = get_prev_frame (frame);
 365       if (frame == NULL)
 366         return NULL;
 367       calling_pc = get_frame_address_in_block (frame);
 368       if (calling_pc >= start && calling_pc < end)
 369         return frame;
 370     }
 371 }