gdb/alpha-mdebug-tdep.c

   1 /* Target-dependent mdebug code for the ALPHA architecture.
   2    Copyright 1993, 1994, 1995, 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003
   3    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 2 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, write to the Free Software
  19    Foundation, Inc., 59 Temple Place - Suite 330,
  20    Boston, MA 02111-1307, USA.  */
  21
  22 #include "defs.h"
  23 #include "frame.h"
  24 #include "frame-unwind.h"
  25 #include "frame-base.h"
  26 #include "symtab.h"
  27 #include "gdbcore.h"
  28 #include "block.h"
  29 #include "gdb_assert.h"
  30
  31 #include "alpha-tdep.h"
  32
  33 /* FIXME: Some of this code should perhaps be merged with mips.  */
  34
  35 /* *INDENT-OFF* */
  36 /* Layout of a stack frame on the alpha:
  37
  38                 |                               |
  39  pdr members:   |  7th ... nth arg,             |
  40                 |  `pushed' by caller.          |
  41                 |                               |
  42 ----------------|-------------------------------|<--  old_sp == vfp
  43    ^  ^  ^  ^   |                               |
  44    |  |  |  |   |                               |
  45    |  |localoff |  Copies of 1st .. 6th         |
  46    |  |  |  |   |  argument if necessary.       |
  47    |  |  |  v   |                               |
  48    |  |  |  --- |-------------------------------|<-- LOCALS_ADDRESS
  49    |  |  |      |                               |
  50    |  |  |      |  Locals and temporaries.      |
  51    |  |  |      |                               |
  52    |  |  |      |-------------------------------|
  53    |  |  |      |                               |
  54    |-fregoffset |  Saved float registers.       |
  55    |  |  |      |  F9                           |
  56    |  |  |      |   .                           |
  57    |  |  |      |   .                           |
  58    |  |  |      |  F2                           |
  59    |  |  v      |                               |
  60    |  |  -------|-------------------------------|
  61    |  |         |                               |
  62    |  |         |  Saved registers.             |
  63    |  |         |  S6                           |
  64    |-regoffset  |   .                           |
  65    |  |         |   .                           |
  66    |  |         |  S0                           |
  67    |  |         |  pdr.pcreg                    |
  68    |  v         |                               |
  69    |  ----------|-------------------------------|
  70    |            |                               |
  71  frameoffset    |  Argument build area, gets    |
  72    |            |  7th ... nth arg for any      |
  73    |            |  called procedure.            |
  74    v            |                               |
  75    -------------|-------------------------------|<-- sp
  76                 |                               |
  77 */
  78 /* *INDENT-ON* */
  79
  80 #define PROC_LOW_ADDR(proc) ((proc)->pdr.adr)
  81 #define PROC_FRAME_OFFSET(proc) ((proc)->pdr.frameoffset)
  82 #define PROC_FRAME_REG(proc) ((proc)->pdr.framereg)
  83 #define PROC_REG_MASK(proc) ((proc)->pdr.regmask)
  84 #define PROC_FREG_MASK(proc) ((proc)->pdr.fregmask)
  85 #define PROC_REG_OFFSET(proc) ((proc)->pdr.regoffset)
  86 #define PROC_FREG_OFFSET(proc) ((proc)->pdr.fregoffset)
  87 #define PROC_PC_REG(proc) ((proc)->pdr.pcreg)
  88 #define PROC_LOCALOFF(proc) ((proc)->pdr.localoff)
  89 \f
  90 /* Locate the mdebug PDR for the given PC.  Return null if one can't
  91    be found; you'll have to fall back to other methods in that case.  */
  92
  93 static alpha_extra_func_info_t
  94 find_proc_desc (CORE_ADDR pc)
  95 {
  96   struct block *b = block_for_pc (pc);
  97   alpha_extra_func_info_t proc_desc = NULL;
  98   struct symbol *sym = NULL;
  99
 100   if (b)
 101     {
 102       CORE_ADDR startaddr;
 103       find_pc_partial_function (pc, NULL, &startaddr, NULL);
 104
 105       if (startaddr > BLOCK_START (b))
 106         /* This is the "pathological" case referred to in a comment in
 107            print_frame_info.  It might be better to move this check into
 108            symbol reading.  */
 109         sym = NULL;
 110       else
 111         sym = lookup_symbol (MIPS_EFI_SYMBOL_NAME, b, LABEL_DOMAIN, 0, NULL);
 112     }
 113
 114   if (sym)
 115     {
 116       proc_desc = (alpha_extra_func_info_t) SYMBOL_VALUE (sym);
 117
 118       /* If we never found a PDR for this function in symbol reading,
 119          then examine prologues to find the information.  */
 120       if (proc_desc->pdr.framereg == -1)
 121         proc_desc = NULL;
 122     }
 123
 124   return proc_desc;
 125 }
 126
 127 /* This returns the PC of the first inst after the prologue.  If we can't
 128    find the prologue, then return 0.  */
 129
 130 static CORE_ADDR
 131 alpha_mdebug_after_prologue (CORE_ADDR pc, alpha_extra_func_info_t proc_desc)
 132 {
 133   if (proc_desc)
 134     {
 135       /* If function is frameless, then we need to do it the hard way.  I
 136          strongly suspect that frameless always means prologueless... */
 137       if (PROC_FRAME_REG (proc_desc) == ALPHA_SP_REGNUM
 138           && PROC_FRAME_OFFSET (proc_desc) == 0)
 139         return 0;
 140     }
 141
 142   return alpha_after_prologue (pc);
 143 }
 144
 145 /* Return non-zero if we *might* be in a function prologue.  Return zero
 146    if we are definitively *not* in a function prologue.  */
 147
 148 static int
 149 alpha_mdebug_in_prologue (CORE_ADDR pc, alpha_extra_func_info_t proc_desc)
 150 {
 151   CORE_ADDR after_prologue_pc = alpha_mdebug_after_prologue (pc, proc_desc);
 152   return (after_prologue_pc == 0 || pc < after_prologue_pc);
 153 }
 154
 155 \f
 156 /* Frame unwinder that reads mdebug PDRs.  */
 157
 158 struct alpha_mdebug_unwind_cache
 159 {
 160   alpha_extra_func_info_t proc_desc;
 161   CORE_ADDR vfp;
 162   CORE_ADDR *saved_regs;
 163 };
 164
 165 /* Extract all of the information about the frame from PROC_DESC
 166    and store the resulting register save locations in the structure.  */
 167
 168 static struct alpha_mdebug_unwind_cache *
 169 alpha_mdebug_frame_unwind_cache (struct frame_info *next_frame,
 170                                  void **this_prologue_cache)
 171 {
 172   struct alpha_mdebug_unwind_cache *info;
 173   alpha_extra_func_info_t proc_desc;
 174   ULONGEST vfp;
 175   CORE_ADDR pc, reg_position;
 176   unsigned long mask;
 177   int ireg, returnreg;
 178
 179   if (*this_prologue_cache)
 180     return *this_prologue_cache;
 181
 182   info = FRAME_OBSTACK_ZALLOC (struct alpha_mdebug_unwind_cache);
 183   *this_prologue_cache = info;
 184   pc = frame_pc_unwind (next_frame);
 185
 186   /* ??? We don't seem to be able to cache the lookup of the PDR
 187      from alpha_mdebug_frame_p.  It'd be nice if we could change
 188      the arguments to that function.  Oh well.  */
 189   proc_desc = find_proc_desc (pc);
 190   info->proc_desc = proc_desc;
 191   gdb_assert (proc_desc != NULL);
 192
 193   info->saved_regs = frame_obstack_zalloc (SIZEOF_FRAME_SAVED_REGS);
 194
 195   /* The VFP of the frame is at FRAME_REG+FRAME_OFFSET.  */
 196   frame_unwind_unsigned_register (next_frame, PROC_FRAME_REG (proc_desc), &vfp);
 197   vfp += PROC_FRAME_OFFSET (info->proc_desc);
 198   info->vfp = vfp;
 199
 200   /* Fill in the offsets for the registers which gen_mask says were saved.  */
 201
 202   reg_position = vfp + PROC_REG_OFFSET (proc_desc);
 203   mask = PROC_REG_MASK (proc_desc);
 204   returnreg = PROC_PC_REG (proc_desc);
 205
 206   /* Note that RA is always saved first, regardless of its actual
 207      register number.  */
 208   if (mask & (1 << returnreg))
 209     {
 210       /* Clear bit for RA so we don't save it again later. */
 211       mask &= ~(1 << returnreg);
 212
 213       info->saved_regs[returnreg] = reg_position;
 214       reg_position += 8;
 215     }
 216
 217   for (ireg = 0; ireg <= 31; ++ireg)
 218     if (mask & (1 << ireg))
 219       {
 220         info->saved_regs[ireg] = reg_position;
 221         reg_position += 8;
 222       }
 223
 224   reg_position = vfp + PROC_FREG_OFFSET (proc_desc);
 225   mask = PROC_FREG_MASK (proc_desc);
 226
 227   for (ireg = 0; ireg <= 31; ++ireg)
 228     if (mask & (1 << ireg))
 229       {
 230         info->saved_regs[ALPHA_FP0_REGNUM + ireg] = reg_position;
 231         reg_position += 8;
 232       }
 233
 234   return info;
 235 }
 236
 237 /* Given a GDB frame, determine the address of the calling function's
 238    frame.  This will be used to create a new GDB frame struct.  */
 239
 240 static void
 241 alpha_mdebug_frame_this_id (struct frame_info *next_frame,
 242                             void **this_prologue_cache,
 243                             struct frame_id *this_id)
 244 {
 245   struct alpha_mdebug_unwind_cache *info
 246     = alpha_mdebug_frame_unwind_cache (next_frame, this_prologue_cache);
 247
 248   *this_id = frame_id_build (info->vfp, frame_func_unwind (next_frame));
 249 }
 250
 251 /* Retrieve the value of REGNUM in FRAME.  Don't give up!  */
 252
 253 static void
 254 alpha_mdebug_frame_prev_register (struct frame_info *next_frame,
 255                                   void **this_prologue_cache,
 256                                   int regnum, int *optimizedp,
 257                                   enum lval_type *lvalp, CORE_ADDR *addrp,
 258                                   int *realnump, void *bufferp)
 259 {
 260   struct alpha_mdebug_unwind_cache *info
 261     = alpha_mdebug_frame_unwind_cache (next_frame, this_prologue_cache);
 262
 263   /* The PC of the previous frame is stored in the link register of
 264      the current frame.  Frob regnum so that we pull the value from
 265      the correct place.  */
 266   if (regnum == ALPHA_PC_REGNUM)
 267     regnum = PROC_PC_REG (info->proc_desc);
 268
 269   /* For all registers known to be saved in the current frame,
 270      do the obvious and pull the value out.  */
 271   if (info->saved_regs[regnum])
 272     {
 273       *optimizedp = 0;
 274       *lvalp = lval_memory;
 275       *addrp = info->saved_regs[regnum];
 276       *realnump = -1;
 277       if (bufferp != NULL)
 278         get_frame_memory (next_frame, *addrp, bufferp, ALPHA_REGISTER_SIZE);
 279       return;
 280     }
 281
 282   /* The stack pointer of the previous frame is computed by popping
 283      the current stack frame.  */
 284   if (regnum == ALPHA_SP_REGNUM)
 285     {
 286       *optimizedp = 0;
 287       *lvalp = not_lval;
 288       *addrp = 0;
 289       *realnump = -1;
 290       if (bufferp != NULL)
 291         store_unsigned_integer (bufferp, ALPHA_REGISTER_SIZE, info->vfp);
 292       return;
 293     }
 294
 295   /* Otherwise assume the next frame has the same register value.  */
 296   frame_register (next_frame, regnum, optimizedp, lvalp, addrp,
 297                   realnump, bufferp);
 298 }
 299
 300 static const struct frame_unwind alpha_mdebug_frame_unwind = {
 301   NORMAL_FRAME,
 302   alpha_mdebug_frame_this_id,
 303   alpha_mdebug_frame_prev_register
 304 };
 305
 306 const struct frame_unwind *
 307 alpha_mdebug_frame_sniffer (struct frame_info *next_frame)
 308 {
 309   CORE_ADDR pc = frame_pc_unwind (next_frame);
 310   alpha_extra_func_info_t proc_desc;
 311
 312   /* If this PC does not map to a PDR, then clearly this isn't an
 313      mdebug frame.  */
 314   proc_desc = find_proc_desc (pc);
 315   if (proc_desc == NULL)
 316     return NULL;
 317
 318   /* If we're in the prologue, the PDR for this frame is not yet valid.
 319      Say no here and we'll fall back on the heuristic unwinder.  */
 320   if (alpha_mdebug_in_prologue (pc, proc_desc))
 321     return NULL;
 322
 323   return &alpha_mdebug_frame_unwind;
 324 }
 325
 326 static CORE_ADDR
 327 alpha_mdebug_frame_base_address (struct frame_info *next_frame,
 328                                  void **this_prologue_cache)
 329 {
 330   struct alpha_mdebug_unwind_cache *info
 331     = alpha_mdebug_frame_unwind_cache (next_frame, this_prologue_cache);
 332
 333   return info->vfp;
 334 }
 335
 336 static CORE_ADDR
 337 alpha_mdebug_frame_locals_address (struct frame_info *next_frame,
 338                                    void **this_prologue_cache)
 339 {
 340   struct alpha_mdebug_unwind_cache *info
 341     = alpha_mdebug_frame_unwind_cache (next_frame, this_prologue_cache);
 342
 343   return info->vfp - PROC_LOCALOFF (info->proc_desc);
 344 }
 345
 346 static CORE_ADDR
 347 alpha_mdebug_frame_args_address (struct frame_info *next_frame,
 348                                  void **this_prologue_cache)
 349 {
 350   struct alpha_mdebug_unwind_cache *info
 351     = alpha_mdebug_frame_unwind_cache (next_frame, this_prologue_cache);
 352
 353   return info->vfp - ALPHA_NUM_ARG_REGS * 8;
 354 }
 355
 356 static const struct frame_base alpha_mdebug_frame_base = {
 357   &alpha_mdebug_frame_unwind,
 358   alpha_mdebug_frame_base_address,
 359   alpha_mdebug_frame_locals_address,
 360   alpha_mdebug_frame_args_address
 361 };
 362
 363 static const struct frame_base *
 364 alpha_mdebug_frame_base_sniffer (struct frame_info *next_frame)
 365 {
 366   CORE_ADDR pc = frame_pc_unwind (next_frame);
 367   alpha_extra_func_info_t proc_desc;
 368
 369   /* If this PC does not map to a PDR, then clearly this isn't an
 370      mdebug frame.  */
 371   proc_desc = find_proc_desc (pc);
 372   if (proc_desc == NULL)
 373     return NULL;
 374
 375   return &alpha_mdebug_frame_base;
 376 }
 377
 378 \f
 379 void
 380 alpha_mdebug_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
 381 {
 382   struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
 383
 384   frame_unwind_append_sniffer (gdbarch, alpha_mdebug_frame_sniffer);
 385   frame_base_append_sniffer (gdbarch, alpha_mdebug_frame_base_sniffer);
 386 }