gdb/mips-tdep.c

   1 /* Work with core dump and executable files, for GDB on MIPS.
   2    This code would be in core.c if it weren't machine-dependent. */
   3
   4 /* Low level interface to ptrace, for GDB when running under Unix.
   5    Copyright (C) 1988, 1989, 1990  Free Software Foundation, Inc.
   6    Contributed by Alessandro Forin(af@cs.cmu.edu) at CMU
   7    and by Per Bothner(bothner@cs.wisc.edu) at U.Wisconsin.
   8
   9 This file is part of GDB.
  10
  11 This program is free software; you can redistribute it and/or modify
  12 it under the terms of the GNU General Public License as published by
  13 the Free Software Foundation; either version 2 of the License, or
  14 (at your option) any later version.
  15
  16 This program is distributed in the hope that it will be useful,
  17 but WITHOUT ANY WARRANTY; without even the implied warranty of
  18 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  19 GNU General Public License for more details.
  20
  21 You should have received a copy of the GNU General Public License
  22 along with this program; if not, write to the Free Software
  23 Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.  */
  24
  25 /* FIXME: Can a MIPS porter/tester determine which of these include
  26    files we still need?   -- gnu@cygnus.com */
  27 #include <stdio.h>
  28 #ifdef sgi
  29 #include <sys/inst.h>
  30 #else
  31 #include <mips/inst.h>
  32 #endif
  33 #include "defs.h"
  34 #include "param.h"
  35 #include "frame.h"
  36 #include "inferior.h"
  37 #include "symtab.h"
  38 #include "value.h"
  39 #include "gdbcmd.h"
  40
  41 #ifdef USG
  42 #include <sys/types.h>
  43 #endif
  44
  45 #include <sys/param.h>
  46 #include <sys/dir.h>
  47 #include <signal.h>
  48 #include <sys/ioctl.h>
  49
  50 #include "gdbcore.h"
  51
  52 #ifndef MIPSMAGIC
  53 #ifdef MIPSEL
  54 #define MIPSMAGIC       MIPSELMAGIC
  55 #else
  56 #define MIPSMAGIC       MIPSEBMAGIC
  57 #endif
  58 #endif
  59
  60 #define VM_MIN_ADDRESS (unsigned)0x400000
  61
  62 #include <sys/user.h>           /* After a.out.h  */
  63 #include <sys/file.h>
  64 #include <sys/stat.h>
  65
  66 \f
  67 #define PROC_LOW_ADDR(proc) ((proc)->adr) /* least address */
  68 #define PROC_HIGH_ADDR(proc) ((proc)->pad2) /* upper address bound */
  69 #define PROC_FRAME_OFFSET(proc) ((proc)->framesize)
  70 #define PROC_FRAME_REG(proc) ((proc)->framereg)
  71 #define PROC_REG_MASK(proc) ((proc)->regmask)
  72 #define PROC_FREG_MASK(proc) ((proc)->fregmask)
  73 #define PROC_REG_OFFSET(proc) ((proc)->regoffset)
  74 #define PROC_FREG_OFFSET(proc) ((proc)->fregoffset)
  75 #define PROC_PC_REG(proc) ((proc)->pcreg)
  76 #define PROC_SYMBOL(proc) (*(struct symbol**)&(proc)->isym)
  77 #define _PROC_MAGIC_ 0x0F0F0F0F
  78 #define PROC_DESC_IS_DUMMY(proc) ((proc)->isym == _PROC_MAGIC_)
  79 #define SET_PROC_DESC_IS_DUMMY(proc) ((proc)->isym = _PROC_MAGIC_)
  80
  81 struct linked_proc_info
  82 {
  83   struct mips_extra_func_info info;
  84   struct linked_proc_info *next;
  85 } * linked_proc_desc_table = NULL;
  86
  87 \f
  88 #define READ_FRAME_REG(fi, regno) read_next_frame_reg((fi)->next, regno)
  89
  90 int
  91 read_next_frame_reg(fi, regno)
  92      FRAME fi;
  93      int regno;
  94 {
  95 #define SIGFRAME_BASE   sizeof(struct sigcontext)
  96 #define SIGFRAME_PC_OFF (-SIGFRAME_BASE+ 2*sizeof(int))
  97 #define SIGFRAME_SP_OFF (-SIGFRAME_BASE+32*sizeof(int))
  98 #define SIGFRAME_RA_OFF (-SIGFRAME_BASE+34*sizeof(int))
  99   for (; fi; fi = fi->next)
 100       if (in_sigtramp(fi->pc, 0)) {
 101           /* No idea if this code works. --PB. */
 102           int offset;
 103           if (regno == PC_REGNUM) offset = SIGFRAME_PC_OFF;
 104           else if (regno == RA_REGNUM) offset = SIGFRAME_RA_OFF;
 105           else if (regno == SP_REGNUM) offset = SIGFRAME_SP_OFF;
 106           else return 0;
 107           return read_memory_integer(fi->frame + offset, 4);
 108       }
 109       else if (regno == SP_REGNUM) return fi->frame;
 110       else if (fi->saved_regs->regs[regno])
 111         return read_memory_integer(fi->saved_regs->regs[regno], 4);
 112   return read_register(regno);
 113 }
 114
 115 int
 116 mips_frame_saved_pc(frame)
 117      FRAME frame;
 118 {
 119   mips_extra_func_info_t proc_desc = (mips_extra_func_info_t)frame->proc_desc;
 120   int pcreg = proc_desc ? PROC_PC_REG(proc_desc) : RA_REGNUM;
 121   if (proc_desc && PROC_DESC_IS_DUMMY(proc_desc))
 122       return read_memory_integer(frame->frame - 4, 4);
 123 #if 0
 124   /* If in the procedure prologue, RA_REGNUM might not have been saved yet.
 125    * Assume non-leaf functions start with:
 126    *    addiu $sp,$sp,-frame_size
 127    *    sw $ra,ra_offset($sp)
 128    * This if the pc is pointing at either of these instructions,
 129    * then $ra hasn't been trashed.
 130    * If the pc has advanced beyond these two instructions,
 131    * then $ra has been saved.
 132    * critical, and much more complex. Handling $ra is enough to get
 133    * a stack trace, but some register values with be wrong.
 134    */
 135   if (frame->proc_desc && frame->pc < PROC_LOW_ADDR(proc_desc) + 8)
 136       return read_register(pcreg);
 137 #endif
 138   return read_next_frame_reg(frame, pcreg);
 139 }
 140
 141 static struct mips_extra_func_info temp_proc_desc;
 142 static struct frame_saved_regs temp_saved_regs;
 143
 144 CORE_ADDR heuristic_proc_start(pc)
 145     CORE_ADDR pc;
 146 {
 147
 148     CORE_ADDR start_pc = pc;
 149     CORE_ADDR fence = start_pc - 10000;
 150     if (fence < VM_MIN_ADDRESS) fence = VM_MIN_ADDRESS;
 151     /* search back for previous return */
 152     for (start_pc -= 4; ; start_pc -= 4)
 153         if (start_pc < fence) return 0;
 154         else if (ABOUT_TO_RETURN(start_pc))
 155             break;
 156
 157     start_pc += 8; /* skip return, and its delay slot */
 158 #if 0
 159     /* skip nops (usually 1) 0 - is this */
 160     while (start_pc < pc && read_memory_integer (start_pc, 4) == 0)
 161         start_pc += 4;
 162 #endif
 163     return start_pc;
 164 }
 165
 166 mips_extra_func_info_t
 167 heuristic_proc_desc(start_pc, limit_pc, next_frame)
 168     CORE_ADDR start_pc, limit_pc;
 169     FRAME next_frame;
 170 {
 171     CORE_ADDR sp = next_frame ? next_frame->frame : read_register (SP_REGNUM);
 172     CORE_ADDR cur_pc;
 173     int frame_size;
 174     int has_frame_reg = 0;
 175     int reg30; /* Value of $r30. Used by gcc for frame-pointer */
 176     unsigned long reg_mask = 0;
 177
 178     if (start_pc == 0) return NULL;
 179     bzero(&temp_proc_desc, sizeof(temp_proc_desc));
 180     bzero(&temp_saved_regs, sizeof(struct frame_saved_regs));
 181     if (start_pc + 200 < limit_pc) limit_pc = start_pc + 200;
 182   restart:
 183     frame_size = 0;
 184     for (cur_pc = start_pc; cur_pc < limit_pc; cur_pc += 4) {
 185         unsigned long word;
 186         int status;
 187
 188         status = read_memory_nobpt (cur_pc, &word, 4);
 189         if (status) memory_error (status, cur_pc);
 190         if ((word & 0xFFFF0000) == 0x27bd0000) /* addiu $sp,$sp,-i */
 191             frame_size += (-word) & 0xFFFF;
 192         else if ((word & 0xFFFF0000) == 0x23bd0000) /* addu $sp,$sp,-i */
 193             frame_size += (-word) & 0xFFFF;
 194         else if ((word & 0xFFE00000) == 0xafa00000) { /* sw reg,offset($sp) */
 195             int reg = (word & 0x001F0000) >> 16;
 196             reg_mask |= 1 << reg;
 197             temp_saved_regs.regs[reg] = sp + (short)word;
 198         }
 199         else if ((word & 0xFFFF0000) == 0x27be0000) { /* addiu $30,$sp,size */
 200             if ((unsigned short)word != frame_size)
 201                 reg30 = sp + (unsigned short)word;
 202             else if (!has_frame_reg) {
 203                 int alloca_adjust;
 204                 has_frame_reg = 1;
 205                 reg30 = read_next_frame_reg(next_frame, 30);
 206                 alloca_adjust = reg30 - (sp + (unsigned short)word);
 207                 if (alloca_adjust > 0) {
 208                     /* FP > SP + frame_size. This may be because
 209                     /* of an alloca or somethings similar.
 210                      * Fix sp to "pre-alloca" value, and try again.
 211                      */
 212                     sp += alloca_adjust;
 213                     goto restart;
 214                 }
 215             }
 216         }
 217         else if ((word & 0xFFE00000) == 0xafc00000) { /* sw reg,offset($30) */
 218             int reg = (word & 0x001F0000) >> 16;
 219             reg_mask |= 1 << reg;
 220             temp_saved_regs.regs[reg] = reg30 + (short)word;
 221         }
 222     }
 223     if (has_frame_reg) {
 224         PROC_FRAME_REG(&temp_proc_desc) = 30;
 225         PROC_FRAME_OFFSET(&temp_proc_desc) = 0;
 226     }
 227     else {
 228         PROC_FRAME_REG(&temp_proc_desc) = SP_REGNUM;
 229         PROC_FRAME_OFFSET(&temp_proc_desc) = frame_size;
 230     }
 231     PROC_REG_MASK(&temp_proc_desc) = reg_mask;
 232     PROC_PC_REG(&temp_proc_desc) = RA_REGNUM;
 233     return &temp_proc_desc;
 234 }
 235
 236 mips_extra_func_info_t
 237 find_proc_desc(pc, next_frame)
 238     CORE_ADDR pc;
 239     FRAME next_frame;
 240 {
 241   mips_extra_func_info_t proc_desc;
 242   extern struct block *block_for_pc();
 243   struct block   *b = block_for_pc(pc);
 244
 245   struct symbol *sym =
 246       b ? lookup_symbol(".gdbinfo.", b, LABEL_NAMESPACE, 0, NULL) : NULL;
 247   if (sym != NULL)
 248     {
 249         /* IF this is the topmost frame AND
 250          * (this proc does not have debugging information OR
 251          * the PC is in the procedure prologue)
 252          * THEN create a "hueristic" proc_desc (by analyzing
 253          * the actual code) to replace the "official" proc_desc.
 254          */
 255         proc_desc = (struct mips_extra_func_info *)sym->value.value;
 256         if (next_frame == NULL) {
 257             struct symtab_and_line val;
 258             struct symbol *proc_symbol =
 259                 PROC_DESC_IS_DUMMY(proc_desc) ? 0 : PROC_SYMBOL(proc_desc);
 260             if (proc_symbol) {
 261                 val = find_pc_line (BLOCK_START
 262                                     (SYMBOL_BLOCK_VALUE(proc_symbol)),
 263                                     0);
 264                 val.pc = val.end ? val.end : pc;
 265             }
 266             if (!proc_symbol || pc < val.pc) {
 267                 mips_extra_func_info_t found_heuristic =
 268                     heuristic_proc_desc(PROC_LOW_ADDR(proc_desc),
 269                                         pc, next_frame);
 270                 if (found_heuristic) proc_desc = found_heuristic;
 271             }
 272         }
 273     }
 274   else
 275     {
 276       register struct linked_proc_info *link;
 277       for (link = linked_proc_desc_table; link; link = link->next)
 278           if (PROC_LOW_ADDR(&link->info) <= pc
 279               && PROC_HIGH_ADDR(&link->info) > pc)
 280               return &link->info;
 281       proc_desc =
 282           heuristic_proc_desc(heuristic_proc_start(pc), pc, next_frame);
 283     }
 284   return proc_desc;
 285 }
 286
 287 mips_extra_func_info_t cached_proc_desc;
 288
 289 FRAME_ADDR mips_frame_chain(frame)
 290     FRAME frame;
 291 {
 292     extern CORE_ADDR startup_file_start;        /* From blockframe.c */
 293     mips_extra_func_info_t proc_desc;
 294     CORE_ADDR saved_pc = FRAME_SAVED_PC(frame);
 295     if (startup_file_start)
 296       { /* has at least the __start symbol */
 297         if (saved_pc == 0 || !outside_startup_file (saved_pc)) return 0;
 298       }
 299     else
 300       { /* This hack depends on the internals of __start. */
 301         /* We also assume the breakpoints are *not* inserted */
 302         if (saved_pc == 0
 303             || read_memory_integer (saved_pc + 8, 4) & 0xFC00003F == 0xD)
 304             return 0;  /* break */
 305       }
 306     proc_desc = find_proc_desc(saved_pc, frame);
 307     if (!proc_desc) return 0;
 308     cached_proc_desc = proc_desc;
 309     return read_next_frame_reg(frame, PROC_FRAME_REG(proc_desc))
 310         + PROC_FRAME_OFFSET(proc_desc);
 311 }
 312
 313 void
 314 init_extra_frame_info(fci)
 315      struct frame_info *fci;
 316 {
 317   extern struct obstack frame_cache_obstack;
 318   /* Use proc_desc calculated in frame_chain */
 319   mips_extra_func_info_t proc_desc = fci->next ? cached_proc_desc :
 320       find_proc_desc(fci->pc, fci->next);
 321   fci->saved_regs = (struct frame_saved_regs*)
 322     obstack_alloc (&frame_cache_obstack, sizeof(struct frame_saved_regs));
 323   bzero(fci->saved_regs, sizeof(struct frame_saved_regs));
 324   fci->proc_desc =
 325       proc_desc == &temp_proc_desc ? (char*)NULL : (char*)proc_desc;
 326   if (proc_desc)
 327     {
 328       int ireg;
 329       CORE_ADDR reg_position;
 330       unsigned long mask;
 331       /* r0 bit means kernel trap */
 332       int kernel_trap = PROC_REG_MASK(proc_desc) & 1;
 333
 334       /* Fixup frame-pointer - only needed for top frame */
 335       /* This may not be quite right, if procedure has a real frame register */
 336       if (fci->pc == PROC_LOW_ADDR(proc_desc))
 337           fci->frame = read_register (SP_REGNUM);
 338       else
 339           fci->frame = READ_FRAME_REG(fci, PROC_FRAME_REG(proc_desc))
 340               + PROC_FRAME_OFFSET(proc_desc);
 341
 342       if (proc_desc == &temp_proc_desc)
 343           *fci->saved_regs = temp_saved_regs;
 344       else
 345       {
 346           /* find which general-purpose registers were saved */
 347           reg_position = fci->frame + PROC_REG_OFFSET(proc_desc);
 348           mask = kernel_trap ? 0xFFFFFFFF : PROC_REG_MASK(proc_desc);
 349           for (ireg= 31; mask; --ireg, mask <<= 1)
 350               if (mask & 0x80000000)
 351               {
 352                   fci->saved_regs->regs[ireg] = reg_position;
 353                   reg_position -= 4;
 354               }
 355           /* find which floating-point registers were saved */
 356           reg_position = fci->frame + PROC_FREG_OFFSET(proc_desc);
 357           /* The freg_offset points to where the first *double* register is saved.
 358            * So skip to the high-order word. */
 359           reg_position += 4;
 360           mask = kernel_trap ? 0xFFFFFFFF : PROC_FREG_MASK(proc_desc);
 361           for (ireg = 31; mask; --ireg, mask <<= 1)
 362               if (mask & 0x80000000)
 363               {
 364                   fci->saved_regs->regs[32+ireg] = reg_position;
 365                   reg_position -= 4;
 366               }
 367       }
 368
 369       /* hack: if argument regs are saved, guess these contain args */
 370       if ((PROC_REG_MASK(proc_desc) & 0xF0) == 0) fci->num_args = -1;
 371       else if ((PROC_REG_MASK(proc_desc) & 0x80) == 0) fci->num_args = 4;
 372       else if ((PROC_REG_MASK(proc_desc) & 0x40) == 0) fci->num_args = 3;
 373       else if ((PROC_REG_MASK(proc_desc) & 0x20) == 0) fci->num_args = 2;
 374       else if ((PROC_REG_MASK(proc_desc) & 0x10) == 0) fci->num_args = 1;
 375
 376       fci->saved_regs->regs[PC_REGNUM] = fci->saved_regs->regs[RA_REGNUM];
 377     }
 378   if (fci->next == 0)
 379       supply_register(FP_REGNUM, &fci->frame);
 380 }
 381
 382
 383 CORE_ADDR mips_push_arguments(nargs, args, sp, struct_return, struct_addr)
 384   int nargs;
 385   value *args;
 386   CORE_ADDR sp;
 387   int struct_return;
 388   CORE_ADDR struct_addr;
 389 {
 390   CORE_ADDR buf;
 391   register i;
 392   int accumulate_size = struct_return ? 4 : 0;
 393   struct mips_arg { char *contents; int len; int offset; };
 394   struct mips_arg *mips_args =
 395       (struct mips_arg*)alloca(nargs * sizeof(struct mips_arg));
 396   register struct mips_arg *m_arg;
 397   for (i = 0, m_arg = mips_args; i < nargs; i++, m_arg++) {
 398     extern value value_arg_coerce();
 399     value arg = value_arg_coerce (args[i]);
 400     m_arg->len = TYPE_LENGTH (VALUE_TYPE (arg));
 401     /* This entire mips-specific routine is because doubles must be aligned
 402      * on 8-byte boundaries. It still isn't quite right, because MIPS decided
 403      * to align 'struct {int a, b}' on 4-byte boundaries (even though this
 404      * breaks their varargs implementation...). A correct solution
 405      * requires an simulation of gcc's 'alignof' (and use of 'alignof'
 406      * in stdarg.h/varargs.h).
 407      */
 408     if (m_arg->len > 4) accumulate_size = (accumulate_size + 7) & -8;
 409     m_arg->offset = accumulate_size;
 410     accumulate_size = (accumulate_size + m_arg->len + 3) & -4;
 411     m_arg->contents = VALUE_CONTENTS(arg);
 412   }
 413   accumulate_size = (accumulate_size + 7) & (-8);
 414   if (accumulate_size < 16) accumulate_size = 16;
 415   sp -= accumulate_size;
 416   for (i = nargs; m_arg--, --i >= 0; )
 417     write_memory(sp + m_arg->offset, m_arg->contents, m_arg->len);
 418   if (struct_return) {
 419     buf = struct_addr;
 420     write_memory(sp, &buf, sizeof(CORE_ADDR));
 421 }
 422   return sp;
 423 }
 424
 425 /* MASK(i,j) == (1<<i) + (1<<(i+1)) + ... + (1<<j)). Assume i<=j<31. */
 426 #define MASK(i,j) ((1 << (j)+1)-1 ^ (1 << (i))-1)
 427
 428 void
 429 mips_push_dummy_frame()
 430 {
 431   int ireg;
 432   struct linked_proc_info *link = (struct linked_proc_info*)
 433       xmalloc(sizeof(struct linked_proc_info));
 434   mips_extra_func_info_t proc_desc = &link->info;
 435   CORE_ADDR sp = read_register (SP_REGNUM);
 436   CORE_ADDR save_address;
 437   REGISTER_TYPE buffer;
 438   link->next = linked_proc_desc_table;
 439   linked_proc_desc_table = link;
 440 #define PUSH_FP_REGNUM 16 /* must be a register preserved across calls */
 441 #define GEN_REG_SAVE_MASK MASK(1,16)|MASK(24,28)|(1<<31)
 442 #define GEN_REG_SAVE_COUNT 22
 443 #define FLOAT_REG_SAVE_MASK MASK(0,19)
 444 #define FLOAT_REG_SAVE_COUNT 20
 445 #define SPECIAL_REG_SAVE_COUNT 4
 446   /*
 447    * The registers we must save are all those not preserved across
 448    * procedure calls. Dest_Reg (see tm-mips.h) must also be saved.
 449    * In addition, we must save the PC, and PUSH_FP_REGNUM.
 450    * (Ideally, we should also save MDLO/-HI and FP Control/Status reg.)
 451    *
 452    * Dummy frame layout:
 453    *  (high memory)
 454    *    Saved PC
 455    *    Saved MMHI, MMLO, FPC_CSR
 456    *    Saved R31
 457    *    Saved R28
 458    *    ...
 459    *    Saved R1
 460    *    Saved D18 (i.e. F19, F18)
 461    *    ...
 462    *    Saved D0 (i.e. F1, F0)
 463    *    CALL_DUMMY (subroutine stub; see m-mips.h)
 464    *    Parameter build area (not yet implemented)
 465    *  (low memory)
 466    */
 467   PROC_REG_MASK(proc_desc) = GEN_REG_SAVE_MASK;
 468   PROC_FREG_MASK(proc_desc) = FLOAT_REG_SAVE_MASK;
 469   PROC_REG_OFFSET(proc_desc) = /* offset of (Saved R31) from FP */
 470       -sizeof(long) - 4 * SPECIAL_REG_SAVE_COUNT;
 471   PROC_FREG_OFFSET(proc_desc) = /* offset of (Saved D18) from FP */
 472       -sizeof(double) - 4 * (SPECIAL_REG_SAVE_COUNT + GEN_REG_SAVE_COUNT);
 473   /* save general registers */
 474   save_address = sp + PROC_REG_OFFSET(proc_desc);
 475   for (ireg = 32; --ireg >= 0; )
 476     if (PROC_REG_MASK(proc_desc) & (1 << ireg))
 477       {
 478         buffer = read_register (ireg);
 479         write_memory (save_address, &buffer, sizeof(REGISTER_TYPE));
 480         save_address -= 4;
 481       }
 482   /* save floating-points registers */
 483   save_address = sp + PROC_FREG_OFFSET(proc_desc);
 484   for (ireg = 32; --ireg >= 0; )
 485     if (PROC_FREG_MASK(proc_desc) & (1 << ireg))
 486       {
 487         buffer = read_register (ireg);
 488         write_memory (save_address, &buffer, 4);
 489         save_address -= 4;
 490       }
 491   write_register (PUSH_FP_REGNUM, sp);
 492   PROC_FRAME_REG(proc_desc) = PUSH_FP_REGNUM;
 493   PROC_FRAME_OFFSET(proc_desc) = 0;
 494   buffer = read_register (PC_REGNUM);
 495   write_memory (sp - 4, &buffer, sizeof(REGISTER_TYPE));
 496   buffer = read_register (HI_REGNUM);
 497   write_memory (sp - 8, &buffer, sizeof(REGISTER_TYPE));
 498   buffer = read_register (LO_REGNUM);
 499   write_memory (sp - 12, &buffer, sizeof(REGISTER_TYPE));
 500   buffer = read_register (FCRCS_REGNUM);
 501   write_memory (sp - 16, &buffer, sizeof(REGISTER_TYPE));
 502   sp -= 4 * (GEN_REG_SAVE_COUNT+FLOAT_REG_SAVE_COUNT+SPECIAL_REG_SAVE_COUNT);
 503   write_register (SP_REGNUM, sp);
 504   PROC_LOW_ADDR(proc_desc) = sp - CALL_DUMMY_SIZE + CALL_DUMMY_START_OFFSET;
 505   PROC_HIGH_ADDR(proc_desc) = sp;
 506   SET_PROC_DESC_IS_DUMMY(proc_desc);
 507   PROC_PC_REG(proc_desc) = RA_REGNUM;
 508 }
 509
 510 void
 511 mips_pop_frame()
 512 { register int regnum;
 513   FRAME frame = get_current_frame ();
 514   CORE_ADDR new_sp = frame->frame;
 515   mips_extra_func_info_t proc_desc = (mips_extra_func_info_t)frame->proc_desc;
 516   if (PROC_DESC_IS_DUMMY(proc_desc))
 517     {
 518       struct linked_proc_info **ptr = &linked_proc_desc_table;;
 519       for (; &ptr[0]->info != proc_desc; ptr = &ptr[0]->next )
 520           if (ptr[0] == NULL) abort();
 521       *ptr = ptr[0]->next;
 522       free (ptr[0]);
 523       write_register (HI_REGNUM, read_memory_integer(new_sp - 8, 4));
 524       write_register (LO_REGNUM, read_memory_integer(new_sp - 12, 4));
 525       write_register (FCRCS_REGNUM, read_memory_integer(new_sp - 16, 4));
 526     }
 527   write_register (PC_REGNUM, FRAME_SAVED_PC(frame));
 528   if (frame->proc_desc) {
 529     for (regnum = 32; --regnum >= 0; )
 530       if (PROC_REG_MASK(proc_desc) & (1 << regnum))
 531         write_register (regnum,
 532                   read_memory_integer (frame->saved_regs->regs[regnum], 4));
 533     for (regnum = 64; --regnum >= 32; )
 534       if (PROC_FREG_MASK(proc_desc) & (1 << regnum))
 535         write_register (regnum,
 536                   read_memory_integer (frame->saved_regs->regs[regnum], 4));
 537   }
 538   write_register (SP_REGNUM, new_sp);
 539   flush_cached_frames ();
 540   set_current_frame (create_new_frame (new_sp, read_pc ()));
 541 }
 542
 543 static
 544 mips_print_register(regnum, all)
 545      int regnum, all;
 546 {
 547       unsigned char raw_buffer[8];
 548       REGISTER_TYPE val;
 549
 550       read_relative_register_raw_bytes (regnum, raw_buffer);
 551
 552       if (!(regnum & 1) && regnum >= FP0_REGNUM && regnum < FP0_REGNUM+32) {
 553           read_relative_register_raw_bytes (regnum+1, raw_buffer+4);
 554           printf_filtered ("(d%d: ", regnum&31);
 555           val_print (builtin_type_double, raw_buffer, 0,
 556                      stdout, 0, 1, 0, Val_pretty_default);
 557           printf_filtered ("); ", regnum&31);
 558       }
 559       fputs_filtered (reg_names[regnum], stdout);
 560 #ifndef NUMERIC_REG_NAMES
 561       if (regnum < 32)
 562           printf_filtered ("(r%d): ", regnum);
 563       else
 564 #endif
 565           printf_filtered (": ");
 566
 567       /* If virtual format is floating, print it that way.  */
 568       if (TYPE_CODE (REGISTER_VIRTUAL_TYPE (regnum)) == TYPE_CODE_FLT
 569           && ! INVALID_FLOAT (raw_buffer, REGISTER_VIRTUAL_SIZE(regnum))) {
 570           val_print (REGISTER_VIRTUAL_TYPE (regnum), raw_buffer, 0,
 571                      stdout, 0, 1, 0, Val_pretty_default);
 572       }
 573       /* Else print as integer in hex.  */
 574       else
 575         {
 576           long val;
 577
 578           bcopy (raw_buffer, &val, sizeof (long));
 579           if (val == 0)
 580             printf_filtered ("0");
 581           else if (all)
 582             printf_filtered (local_hex_format(), val);
 583           else
 584             printf_filtered ("%s=%d", local_hex_string(val), val);
 585         }
 586 }
 587
 588 /* Replacement for generic do_registers_info.  */
 589 mips_do_registers_info (regnum, fpregs)
 590      int regnum;
 591      int fpregs;
 592 {
 593   if (regnum != -1) {
 594       mips_print_register (regnum, 0);
 595       printf_filtered ("\n");
 596   }
 597   else {
 598       for (regnum = 0; regnum < NUM_REGS; ) {
 599           if ((!fpregs) && regnum >= FP0_REGNUM && regnum <= FCRIR_REGNUM) {
 600             regnum++;
 601             continue;
 602           }
 603           mips_print_register (regnum, 1);
 604           regnum++;
 605           if ((regnum & 3) == 0 || regnum == NUM_REGS)
 606               printf_filtered (";\n");
 607           else
 608               printf_filtered ("; ");
 609       }
 610   }
 611 }
 612 /* Return number of args passed to a frame. described by FIP.
 613    Can return -1, meaning no way to tell.  */
 614
 615 mips_frame_num_args(fip)
 616         FRAME fip;
 617 {
 618 #if 0
 619         struct chain_info_t *p;
 620
 621         p = mips_find_cached_frame(FRAME_FP(fip));
 622         if (p->valid)
 623                 return p->the_info.numargs;
 624 #endif
 625         return -1;
 626 }
 627
 628 \f
 629 /* Bad floats: Returns 0 if P points to a valid IEEE floating point number,
 630    1 if P points to a denormalized number or a NaN. LEN says whether this is
 631    a single-precision or double-precision float */
 632 #define SINGLE_EXP_BITS  8
 633 #define DOUBLE_EXP_BITS 11
 634 int
 635 isa_NAN(p, len)
 636      int *p, len;
 637 {
 638   int exponent;
 639   if (len == 4)
 640     {
 641       exponent = *p;
 642       exponent = exponent << 1 >> (32 - SINGLE_EXP_BITS - 1);
 643       return ((exponent == -1) || (! exponent && *p));
 644     }
 645   else if (len == 8)
 646     {
 647       exponent = *(p+1);
 648       exponent = exponent << 1 >> (32 - DOUBLE_EXP_BITS - 1);
 649       return ((exponent == -1) || (! exponent && *p * *(p+1)));
 650     }
 651   else return 1;
 652 }
 653
 654 /* To skip prologues, I use this predicate. Returns either PC
 655    itself if the code at PC does not look like a function prologue,
 656    PC+4 if it does (our caller does not need anything more fancy). */
 657
 658 CORE_ADDR mips_skip_prologue(pc)
 659      CORE_ADDR pc;
 660 {
 661     struct symbol *f;
 662     struct block *b;
 663     unsigned long inst;
 664
 665     /* For -g modules and most functions anyways the
 666        first instruction adjusts the stack. */
 667     inst = read_memory_integer(pc, 4);
 668     if ((inst & 0xffff0000) == 0x27bd0000)
 669         return pc + 4;
 670
 671     /* Well, it looks like a frameless. Let's make sure.
 672        Note that we are not called on the current PC,
 673        but on the function`s start PC, and I have definitely
 674        seen optimized code that adjusts the SP quite later */
 675     b = block_for_pc(pc);
 676     if (!b) return pc;
 677
 678     f = lookup_symbol(".gdbinfo.", b, LABEL_NAMESPACE, 0, NULL);
 679     if (!f) return pc;
 680     /* Ideally, I would like to use the adjusted info
 681        from mips_frame_info(), but for all practical
 682        purposes it will not matter (and it would require
 683        a different definition of SKIP_PROLOGUE())
 684
 685        Actually, it would not hurt to skip the storing
 686        of arguments on the stack as well. */
 687     if (((struct mips_extra_func_info *)f->value.value)->framesize)
 688         return pc + 4;
 689
 690     return pc;
 691 }