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 #include "mdebugread.h"
  33
  34 /* FIXME: Some of this code should perhaps be merged with mips.  */
  35
  36 /* *INDENT-OFF* */
  37 /* Layout of a stack frame on the alpha:
  38
  39                 |                               |
  40  pdr members:   |  7th ... nth arg,             |
  41                 |  `pushed' by caller.          |
  42                 |                               |
  43 ----------------|-------------------------------|<--  old_sp == vfp
  44    ^  ^  ^  ^   |                               |
  45    |  |  |  |   |                               |
  46    |  |localoff |  Copies of 1st .. 6th         |
  47    |  |  |  |   |  argument if necessary.       |
  48    |  |  |  v   |                               |
  49    |  |  |  --- |-------------------------------|<-- LOCALS_ADDRESS
  50    |  |  |      |                               |
  51    |  |  |      |  Locals and temporaries.      |
  52    |  |  |      |                               |
  53    |  |  |      |-------------------------------|
  54    |  |  |      |                               |
  55    |-fregoffset |  Saved float registers.       |
  56    |  |  |      |  F9                           |
  57    |  |  |      |   .                           |
  58    |  |  |      |   .                           |
  59    |  |  |      |  F2                           |
  60    |  |  v      |                               |
  61    |  |  -------|-------------------------------|
  62    |  |         |                               |
  63    |  |         |  Saved registers.             |
  64    |  |         |  S6                           |
  65    |-regoffset  |   .                           |
  66    |  |         |   .                           |
  67    |  |         |  S0                           |
  68    |  |         |  pdr.pcreg                    |
  69    |  v         |                               |
  70    |  ----------|-------------------------------|
  71    |            |                               |
  72  frameoffset    |  Argument build area, gets    |
  73    |            |  7th ... nth arg for any      |
  74    |            |  called procedure.            |
  75    v            |                               |
  76    -------------|-------------------------------|<-- sp
  77                 |                               |
  78 */
  79 /* *INDENT-ON* */
  80
  81 #define PROC_LOW_ADDR(proc) ((proc)->pdr.adr)
  82 #define PROC_FRAME_OFFSET(proc) ((proc)->pdr.frameoffset)
  83 #define PROC_FRAME_REG(proc) ((proc)->pdr.framereg)
  84 #define PROC_REG_MASK(proc) ((proc)->pdr.regmask)
  85 #define PROC_FREG_MASK(proc) ((proc)->pdr.fregmask)
  86 #define PROC_REG_OFFSET(proc) ((proc)->pdr.regoffset)
  87 #define PROC_FREG_OFFSET(proc) ((proc)->pdr.fregoffset)
  88 #define PROC_PC_REG(proc) ((proc)->pdr.pcreg)
  89 #define PROC_LOCALOFF(proc) ((proc)->pdr.localoff)
  90 \f
  91 /* Locate the mdebug PDR for the given PC.  Return null if one can't
  92    be found; you'll have to fall back to other methods in that case.  */
  93
  94 static struct mdebug_extra_func_info *
  95 find_proc_desc (CORE_ADDR pc)
  96 {
  97   struct block *b = block_for_pc (pc);
  98   struct mdebug_extra_func_info *proc_desc = NULL;
  99   struct symbol *sym = NULL;
 100
 101   if (b)
 102     {
 103       CORE_ADDR startaddr;
 104       find_pc_partial_function (pc, NULL, &startaddr, NULL);
 105
 106       if (startaddr > BLOCK_START (b))
 107         /* This is the "pathological" case referred to in a comment in
 108            print_frame_info.  It might be better to move this check into
 109            symbol reading.  */
 110         sym = NULL;
 111       else
 112         sym = lookup_symbol (MDEBUG_EFI_SYMBOL_NAME, b, LABEL_DOMAIN, 0, NULL);
 113     }
 114
 115   if (sym)
 116     {
 117       proc_desc = (struct mdebug_extra_func_info *) SYMBOL_VALUE (sym);
 118
 119       /* If we never found a PDR for this function in symbol reading,
 120          then examine prologues to find the information.  */
 121       if (proc_desc->pdr.framereg == -1)
 122         proc_desc = NULL;
 123     }
 124
 125   return proc_desc;
 126 }
 127
 128 /* This returns the PC of the first inst after the prologue.  If we can't
 129    find the prologue, then return 0.  */
 130
 131 static CORE_ADDR
 132 alpha_mdebug_after_prologue (CORE_ADDR pc, struct mdebug_extra_func_info *proc_desc)
 133 {
 134   if (proc_desc)
 135     {
 136       /* If function is frameless, then we need to do it the hard way.  I
 137          strongly suspect that frameless always means prologueless... */
 138       if (PROC_FRAME_REG (proc_desc) == ALPHA_SP_REGNUM
 139           && PROC_FRAME_OFFSET (proc_desc) == 0)
 140         return 0;
 141     }
 142
 143   return alpha_after_prologue (pc);
 144 }
 145
 146 /* Return non-zero if we *might* be in a function prologue.  Return zero
 147    if we are definitively *not* in a function prologue.  */
 148
 149 static int
 150 alpha_mdebug_in_prologue (CORE_ADDR pc, struct mdebug_extra_func_info *proc_desc)
 151 {
 152   CORE_ADDR after_prologue_pc = alpha_mdebug_after_prologue (pc, proc_desc);
 153   return (after_prologue_pc == 0 || pc < after_prologue_pc);
 154 }
 155
 156 \f
 157 /* Frame unwinder that reads mdebug PDRs.  */
 158
 159 struct alpha_mdebug_unwind_cache
 160 {
 161   struct mdebug_extra_func_info *proc_desc;
 162   CORE_ADDR vfp;
 163   CORE_ADDR *saved_regs;
 164 };
 165
 166 /* Extract all of the information about the frame from PROC_DESC
 167    and store the resulting register save locations in the structure.  */
 168
 169 static struct alpha_mdebug_unwind_cache *
 170 alpha_mdebug_frame_unwind_cache (struct frame_info *next_frame,
 171                                  void **this_prologue_cache)
 172 {
 173   struct alpha_mdebug_unwind_cache *info;
 174   struct mdebug_extra_func_info *proc_desc;
 175   ULONGEST vfp;
 176   CORE_ADDR pc, reg_position;
 177   unsigned long mask;
 178   int ireg, returnreg;
 179
 180   if (*this_prologue_cache)
 181     return *this_prologue_cache;
 182
 183   info = FRAME_OBSTACK_ZALLOC (struct alpha_mdebug_unwind_cache);
 184   *this_prologue_cache = info;
 185   pc = frame_pc_unwind (next_frame);
 186
 187   /* ??? We don't seem to be able to cache the lookup of the PDR
 188      from alpha_mdebug_frame_p.  It'd be nice if we could change
 189      the arguments to that function.  Oh well.  */
 190   proc_desc = find_proc_desc (pc);
 191   info->proc_desc = proc_desc;
 192   gdb_assert (proc_desc != NULL);
 193
 194   info->saved_regs = frame_obstack_zalloc (SIZEOF_FRAME_SAVED_REGS);
 195
 196   /* The VFP of the frame is at FRAME_REG+FRAME_OFFSET.  */
 197   frame_unwind_unsigned_register (next_frame, PROC_FRAME_REG (proc_desc), &vfp);
 198   vfp += PROC_FRAME_OFFSET (info->proc_desc);
 199   info->vfp = vfp;
 200
 201   /* Fill in the offsets for the registers which gen_mask says were saved.  */
 202
 203   reg_position = vfp + PROC_REG_OFFSET (proc_desc);
 204   mask = PROC_REG_MASK (proc_desc);
 205   returnreg = PROC_PC_REG (proc_desc);
 206
 207   /* Note that RA is always saved first, regardless of its actual
 208      register number.  */
 209   if (mask & (1 << returnreg))
 210     {
 211       /* Clear bit for RA so we don't save it again later. */
 212       mask &= ~(1 << returnreg);
 213
 214       info->saved_regs[returnreg] = reg_position;
 215       reg_position += 8;
 216     }
 217
 218   for (ireg = 0; ireg <= 31; ++ireg)
 219     if (mask & (1 << ireg))
 220       {
 221         info->saved_regs[ireg] = reg_position;
 222         reg_position += 8;
 223       }
 224
 225   reg_position = vfp + PROC_FREG_OFFSET (proc_desc);
 226   mask = PROC_FREG_MASK (proc_desc);
 227
 228   for (ireg = 0; ireg <= 31; ++ireg)
 229     if (mask & (1 << ireg))
 230       {
 231         info->saved_regs[ALPHA_FP0_REGNUM + ireg] = reg_position;
 232         reg_position += 8;
 233       }
 234
 235   return info;
 236 }
 237
 238 /* Given a GDB frame, determine the address of the calling function's
 239    frame.  This will be used to create a new GDB frame struct.  */
 240
 241 static void
 242 alpha_mdebug_frame_this_id (struct frame_info *next_frame,
 243                             void **this_prologue_cache,
 244                             struct frame_id *this_id)
 245 {
 246   struct alpha_mdebug_unwind_cache *info
 247     = alpha_mdebug_frame_unwind_cache (next_frame, this_prologue_cache);
 248
 249   *this_id = frame_id_build (info->vfp, frame_func_unwind (next_frame));
 250 }
 251
 252 /* Retrieve the value of REGNUM in FRAME.  Don't give up!  */
 253
 254 static void
 255 alpha_mdebug_frame_prev_register (struct frame_info *next_frame,
 256                                   void **this_prologue_cache,
 257                                   int regnum, int *optimizedp,
 258                                   enum lval_type *lvalp, CORE_ADDR *addrp,
 259                                   int *realnump, void *bufferp)
 260 {
 261   struct alpha_mdebug_unwind_cache *info
 262     = alpha_mdebug_frame_unwind_cache (next_frame, this_prologue_cache);
 263
 264   /* The PC of the previous frame is stored in the link register of
 265      the current frame.  Frob regnum so that we pull the value from
 266      the correct place.  */
 267   if (regnum == ALPHA_PC_REGNUM)
 268     regnum = PROC_PC_REG (info->proc_desc);
 269
 270   /* For all registers known to be saved in the current frame,
 271      do the obvious and pull the value out.  */
 272   if (info->saved_regs[regnum])
 273     {
 274       *optimizedp = 0;
 275       *lvalp = lval_memory;
 276       *addrp = info->saved_regs[regnum];
 277       *realnump = -1;
 278       if (bufferp != NULL)
 279         get_frame_memory (next_frame, *addrp, bufferp, ALPHA_REGISTER_SIZE);
 280       return;
 281     }
 282
 283   /* The stack pointer of the previous frame is computed by popping
 284      the current stack frame.  */
 285   if (regnum == ALPHA_SP_REGNUM)
 286     {
 287       *optimizedp = 0;
 288       *lvalp = not_lval;
 289       *addrp = 0;
 290       *realnump = -1;
 291       if (bufferp != NULL)
 292         store_unsigned_integer (bufferp, ALPHA_REGISTER_SIZE, info->vfp);
 293       return;
 294     }
 295
 296   /* Otherwise assume the next frame has the same register value.  */
 297   frame_register (next_frame, regnum, optimizedp, lvalp, addrp,
 298                   realnump, bufferp);
 299 }
 300
 301 static const struct frame_unwind alpha_mdebug_frame_unwind = {
 302   NORMAL_FRAME,
 303   alpha_mdebug_frame_this_id,
 304   alpha_mdebug_frame_prev_register
 305 };
 306
 307 const struct frame_unwind *
 308 alpha_mdebug_frame_sniffer (struct frame_info *next_frame)
 309 {
 310   CORE_ADDR pc = frame_pc_unwind (next_frame);
 311   struct mdebug_extra_func_info *proc_desc;
 312
 313   /* If this PC does not map to a PDR, then clearly this isn't an
 314      mdebug frame.  */
 315   proc_desc = find_proc_desc (pc);
 316   if (proc_desc == NULL)
 317     return NULL;
 318
 319   /* If we're in the prologue, the PDR for this frame is not yet valid.
 320      Say no here and we'll fall back on the heuristic unwinder.  */
 321   if (alpha_mdebug_in_prologue (pc, proc_desc))
 322     return NULL;
 323
 324   return &alpha_mdebug_frame_unwind;
 325 }
 326
 327 static CORE_ADDR
 328 alpha_mdebug_frame_base_address (struct frame_info *next_frame,
 329                                  void **this_prologue_cache)
 330 {
 331   struct alpha_mdebug_unwind_cache *info
 332     = alpha_mdebug_frame_unwind_cache (next_frame, this_prologue_cache);
 333
 334   return info->vfp;
 335 }
 336
 337 static CORE_ADDR
 338 alpha_mdebug_frame_locals_address (struct frame_info *next_frame,
 339                                    void **this_prologue_cache)
 340 {
 341   struct alpha_mdebug_unwind_cache *info
 342     = alpha_mdebug_frame_unwind_cache (next_frame, this_prologue_cache);
 343
 344   return info->vfp - PROC_LOCALOFF (info->proc_desc);
 345 }
 346
 347 static CORE_ADDR
 348 alpha_mdebug_frame_args_address (struct frame_info *next_frame,
 349                                  void **this_prologue_cache)
 350 {
 351   struct alpha_mdebug_unwind_cache *info
 352     = alpha_mdebug_frame_unwind_cache (next_frame, this_prologue_cache);
 353
 354   return info->vfp - ALPHA_NUM_ARG_REGS * 8;
 355 }
 356
 357 static const struct frame_base alpha_mdebug_frame_base = {
 358   &alpha_mdebug_frame_unwind,
 359   alpha_mdebug_frame_base_address,
 360   alpha_mdebug_frame_locals_address,
 361   alpha_mdebug_frame_args_address
 362 };
 363
 364 static const struct frame_base *
 365 alpha_mdebug_frame_base_sniffer (struct frame_info *next_frame)
 366 {
 367   CORE_ADDR pc = frame_pc_unwind (next_frame);
 368   struct mdebug_extra_func_info *proc_desc;
 369
 370   /* If this PC does not map to a PDR, then clearly this isn't an
 371      mdebug frame.  */
 372   proc_desc = find_proc_desc (pc);
 373   if (proc_desc == NULL)
 374     return NULL;
 375
 376   return &alpha_mdebug_frame_base;
 377 }
 378
 379 \f
 380 void
 381 alpha_mdebug_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
 382 {
 383   struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
 384
 385   frame_unwind_append_sniffer (gdbarch, alpha_mdebug_frame_sniffer);
 386   frame_base_append_sniffer (gdbarch, alpha_mdebug_frame_base_sniffer);
 387 }