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 #include "language.h"
  41
  42 #ifdef USG
  43 #include <sys/types.h>
  44 #endif
  45
  46 #include <sys/param.h>
  47 #include <sys/dir.h>
  48 #include <signal.h>
  49 #include <sys/ioctl.h>
  50
  51 #include "gdbcore.h"
  52
  53 #ifndef MIPSMAGIC
  54 #ifdef MIPSEL
  55 #define MIPSMAGIC       MIPSELMAGIC
  56 #else
  57 #define MIPSMAGIC       MIPSEBMAGIC
  58 #endif
  59 #endif
  60
  61 #define VM_MIN_ADDRESS (unsigned)0x400000
  62
  63 #include <sys/user.h>           /* After a.out.h  */
  64 #include <sys/file.h>
  65 #include <sys/stat.h>
  66
  67 \f
  68 #define PROC_LOW_ADDR(proc) ((proc)->adr) /* least address */
  69 #define PROC_HIGH_ADDR(proc) ((proc)->pad2) /* upper address bound */
  70 #define PROC_FRAME_OFFSET(proc) ((proc)->framesize)
  71 #define PROC_FRAME_REG(proc) ((proc)->framereg)
  72 #define PROC_REG_MASK(proc) ((proc)->regmask)
  73 #define PROC_FREG_MASK(proc) ((proc)->fregmask)
  74 #define PROC_REG_OFFSET(proc) ((proc)->regoffset)
  75 #define PROC_FREG_OFFSET(proc) ((proc)->fregoffset)
  76 #define PROC_PC_REG(proc) ((proc)->pcreg)
  77 #define PROC_SYMBOL(proc) (*(struct symbol**)&(proc)->isym)
  78 #define _PROC_MAGIC_ 0x0F0F0F0F
  79 #define PROC_DESC_IS_DUMMY(proc) ((proc)->isym == _PROC_MAGIC_)
  80 #define SET_PROC_DESC_IS_DUMMY(proc) ((proc)->isym = _PROC_MAGIC_)
  81
  82 struct linked_proc_info
  83 {
  84   struct mips_extra_func_info info;
  85   struct linked_proc_info *next;
  86 } * linked_proc_desc_table = NULL;
  87
  88 \f
  89 #define READ_FRAME_REG(fi, regno) read_next_frame_reg((fi)->next, regno)
  90
  91 int
  92 read_next_frame_reg(fi, regno)
  93      FRAME fi;
  94      int regno;
  95 {
  96 #define SIGFRAME_BASE   sizeof(struct sigcontext)
  97 #define SIGFRAME_PC_OFF (-SIGFRAME_BASE+ 2*sizeof(int))
  98 #define SIGFRAME_SP_OFF (-SIGFRAME_BASE+32*sizeof(int))
  99 #define SIGFRAME_RA_OFF (-SIGFRAME_BASE+34*sizeof(int))
 100   for (; fi; fi = fi->next)
 101       if (in_sigtramp(fi->pc, 0)) {
 102           /* No idea if this code works. --PB. */
 103           int offset;
 104           if (regno == PC_REGNUM) offset = SIGFRAME_PC_OFF;
 105           else if (regno == RA_REGNUM) offset = SIGFRAME_RA_OFF;
 106           else if (regno == SP_REGNUM) offset = SIGFRAME_SP_OFF;
 107           else return 0;
 108           return read_memory_integer(fi->frame + offset, 4);
 109       }
 110       else if (regno == SP_REGNUM) return fi->frame;
 111       else if (fi->saved_regs->regs[regno])
 112         return read_memory_integer(fi->saved_regs->regs[regno], 4);
 113   return read_register(regno);
 114 }
 115
 116 int
 117 mips_frame_saved_pc(frame)
 118      FRAME frame;
 119 {
 120   mips_extra_func_info_t proc_desc = (mips_extra_func_info_t)frame->proc_desc;
 121   int pcreg = proc_desc ? PROC_PC_REG(proc_desc) : RA_REGNUM;
 122   if (proc_desc && PROC_DESC_IS_DUMMY(proc_desc))
 123       return read_memory_integer(frame->frame - 4, 4);
 124 #if 0
 125   /* If in the procedure prologue, RA_REGNUM might not have been saved yet.
 126    * Assume non-leaf functions start with:
 127    *    addiu $sp,$sp,-frame_size
 128    *    sw $ra,ra_offset($sp)
 129    * This if the pc is pointing at either of these instructions,
 130    * then $ra hasn't been trashed.
 131    * If the pc has advanced beyond these two instructions,
 132    * then $ra has been saved.
 133    * critical, and much more complex. Handling $ra is enough to get
 134    * a stack trace, but some register values with be wrong.
 135    */
 136   if (frame->proc_desc && frame->pc < PROC_LOW_ADDR(proc_desc) + 8)
 137       return read_register(pcreg);
 138 #endif
 139   return read_next_frame_reg(frame, pcreg);
 140 }
 141
 142 static struct mips_extra_func_info temp_proc_desc;
 143 static struct frame_saved_regs temp_saved_regs;
 144
 145 CORE_ADDR heuristic_proc_start(pc)
 146     CORE_ADDR pc;
 147 {
 148
 149     CORE_ADDR start_pc = pc;
 150     CORE_ADDR fence = start_pc - 10000;
 151     if (fence < VM_MIN_ADDRESS) fence = VM_MIN_ADDRESS;
 152     /* search back for previous return */
 153     for (start_pc -= 4; ; start_pc -= 4)
 154         if (start_pc < fence) return 0;
 155         else if (ABOUT_TO_RETURN(start_pc))
 156             break;
 157
 158     start_pc += 8; /* skip return, and its delay slot */
 159 #if 0
 160     /* skip nops (usually 1) 0 - is this */
 161     while (start_pc < pc && read_memory_integer (start_pc, 4) == 0)
 162         start_pc += 4;
 163 #endif
 164     return start_pc;
 165 }
 166
 167 mips_extra_func_info_t
 168 heuristic_proc_desc(start_pc, limit_pc, next_frame)
 169     CORE_ADDR start_pc, limit_pc;
 170     FRAME next_frame;
 171 {
 172     CORE_ADDR sp = next_frame ? next_frame->frame : read_register (SP_REGNUM);
 173     CORE_ADDR cur_pc;
 174     int frame_size;
 175     int has_frame_reg = 0;
 176     int reg30; /* Value of $r30. Used by gcc for frame-pointer */
 177     unsigned long reg_mask = 0;
 178
 179     if (start_pc == 0) return NULL;
 180     bzero(&temp_proc_desc, sizeof(temp_proc_desc));
 181     bzero(&temp_saved_regs, sizeof(struct frame_saved_regs));
 182     if (start_pc + 200 < limit_pc) limit_pc = start_pc + 200;
 183   restart:
 184     frame_size = 0;
 185     for (cur_pc = start_pc; cur_pc < limit_pc; cur_pc += 4) {
 186         unsigned long word;
 187         int status;
 188
 189         status = read_memory_nobpt (cur_pc, &word, 4);
 190         if (status) memory_error (status, cur_pc);
 191         if ((word & 0xFFFF0000) == 0x27bd0000) /* addiu $sp,$sp,-i */
 192             frame_size += (-word) & 0xFFFF;
 193         else if ((word & 0xFFFF0000) == 0x23bd0000) /* addu $sp,$sp,-i */
 194             frame_size += (-word) & 0xFFFF;
 195         else if ((word & 0xFFE00000) == 0xafa00000) { /* sw reg,offset($sp) */
 196             int reg = (word & 0x001F0000) >> 16;
 197             reg_mask |= 1 << reg;
 198             temp_saved_regs.regs[reg] = sp + (short)word;
 199         }
 200         else if ((word & 0xFFFF0000) == 0x27be0000) { /* addiu $30,$sp,size */
 201             if ((unsigned short)word != frame_size)
 202                 reg30 = sp + (unsigned short)word;
 203             else if (!has_frame_reg) {
 204                 int alloca_adjust;
 205                 has_frame_reg = 1;
 206                 reg30 = read_next_frame_reg(next_frame, 30);
 207                 alloca_adjust = reg30 - (sp + (unsigned short)word);
 208                 if (alloca_adjust > 0) {
 209                     /* FP > SP + frame_size. This may be because
 210                     /* of an alloca or somethings similar.
 211                      * Fix sp to "pre-alloca" value, and try again.
 212                      */
 213                     sp += alloca_adjust;
 214                     goto restart;
 215                 }
 216             }
 217         }
 218         else if ((word & 0xFFE00000) == 0xafc00000) { /* sw reg,offset($30) */
 219             int reg = (word & 0x001F0000) >> 16;
 220             reg_mask |= 1 << reg;
 221             temp_saved_regs.regs[reg] = reg30 + (short)word;
 222         }
 223     }
 224     if (has_frame_reg) {
 225         PROC_FRAME_REG(&temp_proc_desc) = 30;
 226         PROC_FRAME_OFFSET(&temp_proc_desc) = 0;
 227     }
 228     else {
 229         PROC_FRAME_REG(&temp_proc_desc) = SP_REGNUM;
 230         PROC_FRAME_OFFSET(&temp_proc_desc) = frame_size;
 231     }
 232     PROC_REG_MASK(&temp_proc_desc) = reg_mask;
 233     PROC_PC_REG(&temp_proc_desc) = RA_REGNUM;
 234     return &temp_proc_desc;
 235 }
 236
 237 mips_extra_func_info_t
 238 find_proc_desc(pc, next_frame)
 239     CORE_ADDR pc;
 240     FRAME next_frame;
 241 {
 242   mips_extra_func_info_t proc_desc;
 243   extern struct block *block_for_pc();
 244   struct block   *b = block_for_pc(pc);
 245
 246   struct symbol *sym =
 247       b ? lookup_symbol(".gdbinfo.", b, LABEL_NAMESPACE, 0, NULL) : NULL;
 248   if (sym != NULL)
 249     {
 250         /* IF this is the topmost frame AND
 251          * (this proc does not have debugging information OR
 252          * the PC is in the procedure prologue)
 253          * THEN create a "hueristic" proc_desc (by analyzing
 254          * the actual code) to replace the "official" proc_desc.
 255          */
 256         proc_desc = (struct mips_extra_func_info *)sym->value.value;
 257         if (next_frame == NULL) {
 258             struct symtab_and_line val;
 259             struct symbol *proc_symbol =
 260                 PROC_DESC_IS_DUMMY(proc_desc) ? 0 : PROC_SYMBOL(proc_desc);
 261             if (proc_symbol) {
 262                 val = find_pc_line (BLOCK_START
 263                                     (SYMBOL_BLOCK_VALUE(proc_symbol)),
 264                                     0);
 265                 val.pc = val.end ? val.end : pc;
 266             }
 267             if (!proc_symbol || pc < val.pc) {
 268                 mips_extra_func_info_t found_heuristic =
 269                     heuristic_proc_desc(PROC_LOW_ADDR(proc_desc),
 270                                         pc, next_frame);
 271                 if (found_heuristic) proc_desc = found_heuristic;
 272             }
 273         }
 274     }
 275   else
 276     {
 277       register struct linked_proc_info *link;
 278       for (link = linked_proc_desc_table; link; link = link->next)
 279           if (PROC_LOW_ADDR(&link->info) <= pc
 280               && PROC_HIGH_ADDR(&link->info) > pc)
 281               return &link->info;
 282       proc_desc =
 283           heuristic_proc_desc(heuristic_proc_start(pc), pc, next_frame);
 284     }
 285   return proc_desc;
 286 }
 287
 288 mips_extra_func_info_t cached_proc_desc;
 289
 290 FRAME_ADDR mips_frame_chain(frame)
 291     FRAME frame;
 292 {
 293     extern CORE_ADDR startup_file_start;        /* From blockframe.c */
 294     mips_extra_func_info_t proc_desc;
 295     CORE_ADDR saved_pc = FRAME_SAVED_PC(frame);
 296     if (startup_file_start)
 297       { /* has at least the __start symbol */
 298         if (saved_pc == 0 || !outside_startup_file (saved_pc)) return 0;
 299       }
 300     else
 301       { /* This hack depends on the internals of __start. */
 302         /* We also assume the breakpoints are *not* inserted */
 303         if (saved_pc == 0
 304             || read_memory_integer (saved_pc + 8, 4) & 0xFC00003F == 0xD)
 305             return 0;  /* break */
 306       }
 307     proc_desc = find_proc_desc(saved_pc, frame);
 308     if (!proc_desc) return 0;
 309     cached_proc_desc = proc_desc;
 310     return read_next_frame_reg(frame, PROC_FRAME_REG(proc_desc))
 311         + PROC_FRAME_OFFSET(proc_desc);
 312 }
 313
 314 void
 315 init_extra_frame_info(fci)
 316      struct frame_info *fci;
 317 {
 318   extern struct obstack frame_cache_obstack;
 319   /* Use proc_desc calculated in frame_chain */
 320   mips_extra_func_info_t proc_desc = fci->next ? cached_proc_desc :
 321       find_proc_desc(fci->pc, fci->next);
 322   fci->saved_regs = (struct frame_saved_regs*)
 323     obstack_alloc (&frame_cache_obstack, sizeof(struct frame_saved_regs));
 324   bzero(fci->saved_regs, sizeof(struct frame_saved_regs));
 325   fci->proc_desc =
 326       proc_desc == &temp_proc_desc ? (char*)NULL : (char*)proc_desc;
 327   if (proc_desc)
 328     {
 329       int ireg;
 330       CORE_ADDR reg_position;
 331       unsigned long mask;
 332       /* r0 bit means kernel trap */
 333       int kernel_trap = PROC_REG_MASK(proc_desc) & 1;
 334
 335       /* Fixup frame-pointer - only needed for top frame */
 336       /* This may not be quite right, if procedure has a real frame register */
 337       if (fci->pc == PROC_LOW_ADDR(proc_desc))
 338           fci->frame = read_register (SP_REGNUM);
 339       else
 340           fci->frame = READ_FRAME_REG(fci, PROC_FRAME_REG(proc_desc))
 341               + PROC_FRAME_OFFSET(proc_desc);
 342
 343       if (proc_desc == &temp_proc_desc)
 344           *fci->saved_regs = temp_saved_regs;
 345       else
 346       {
 347           /* find which general-purpose registers were saved */
 348           reg_position = fci->frame + PROC_REG_OFFSET(proc_desc);
 349           mask = kernel_trap ? 0xFFFFFFFF : PROC_REG_MASK(proc_desc);
 350           for (ireg= 31; mask; --ireg, mask <<= 1)
 351               if (mask & 0x80000000)
 352               {
 353                   fci->saved_regs->regs[ireg] = reg_position;
 354                   reg_position -= 4;
 355               }
 356           /* find which floating-point registers were saved */
 357           reg_position = fci->frame + PROC_FREG_OFFSET(proc_desc);
 358           /* The freg_offset points to where the first *double* register is saved.
 359            * So skip to the high-order word. */
 360           reg_position += 4;
 361           mask = kernel_trap ? 0xFFFFFFFF : PROC_FREG_MASK(proc_desc);
 362           for (ireg = 31; mask; --ireg, mask <<= 1)
 363               if (mask & 0x80000000)
 364               {
 365                   fci->saved_regs->regs[32+ireg] = reg_position;
 366                   reg_position -= 4;
 367               }
 368       }
 369
 370       /* hack: if argument regs are saved, guess these contain args */
 371       if ((PROC_REG_MASK(proc_desc) & 0xF0) == 0) fci->num_args = -1;
 372       else if ((PROC_REG_MASK(proc_desc) & 0x80) == 0) fci->num_args = 4;
 373       else if ((PROC_REG_MASK(proc_desc) & 0x40) == 0) fci->num_args = 3;
 374       else if ((PROC_REG_MASK(proc_desc) & 0x20) == 0) fci->num_args = 2;
 375       else if ((PROC_REG_MASK(proc_desc) & 0x10) == 0) fci->num_args = 1;
 376
 377       fci->saved_regs->regs[PC_REGNUM] = fci->saved_regs->regs[RA_REGNUM];
 378     }
 379   if (fci->next == 0)
 380       supply_register(FP_REGNUM, &fci->frame);
 381 }
 382
 383
 384 CORE_ADDR mips_push_arguments(nargs, args, sp, struct_return, struct_addr)
 385   int nargs;
 386   value *args;
 387   CORE_ADDR sp;
 388   int struct_return;
 389   CORE_ADDR struct_addr;
 390 {
 391   CORE_ADDR buf;
 392   register i;
 393   int accumulate_size = struct_return ? 4 : 0;
 394   struct mips_arg { char *contents; int len; int offset; };
 395   struct mips_arg *mips_args =
 396       (struct mips_arg*)alloca(nargs * sizeof(struct mips_arg));
 397   register struct mips_arg *m_arg;
 398   for (i = 0, m_arg = mips_args; i < nargs; i++, m_arg++) {
 399     extern value value_arg_coerce();
 400     value arg = value_arg_coerce (args[i]);
 401     m_arg->len = TYPE_LENGTH (VALUE_TYPE (arg));
 402     /* This entire mips-specific routine is because doubles must be aligned
 403      * on 8-byte boundaries. It still isn't quite right, because MIPS decided
 404      * to align 'struct {int a, b}' on 4-byte boundaries (even though this
 405      * breaks their varargs implementation...). A correct solution
 406      * requires an simulation of gcc's 'alignof' (and use of 'alignof'
 407      * in stdarg.h/varargs.h).
 408      */
 409     if (m_arg->len > 4) accumulate_size = (accumulate_size + 7) & -8;
 410     m_arg->offset = accumulate_size;
 411     accumulate_size = (accumulate_size + m_arg->len + 3) & -4;
 412     m_arg->contents = VALUE_CONTENTS(arg);
 413   }
 414   accumulate_size = (accumulate_size + 7) & (-8);
 415   if (accumulate_size < 16) accumulate_size = 16;
 416   sp -= accumulate_size;
 417   for (i = nargs; m_arg--, --i >= 0; )
 418     write_memory(sp + m_arg->offset, m_arg->contents, m_arg->len);
 419   if (struct_return) {
 420     buf = struct_addr;
 421     write_memory(sp, &buf, sizeof(CORE_ADDR));
 422 }
 423   return sp;
 424 }
 425
 426 /* MASK(i,j) == (1<<i) + (1<<(i+1)) + ... + (1<<j)). Assume i<=j<31. */
 427 #define MASK(i,j) ((1 << (j)+1)-1 ^ (1 << (i))-1)
 428
 429 void
 430 mips_push_dummy_frame()
 431 {
 432   int ireg;
 433   struct linked_proc_info *link = (struct linked_proc_info*)
 434       xmalloc(sizeof(struct linked_proc_info));
 435   mips_extra_func_info_t proc_desc = &link->info;
 436   CORE_ADDR sp = read_register (SP_REGNUM);
 437   CORE_ADDR save_address;
 438   REGISTER_TYPE buffer;
 439   link->next = linked_proc_desc_table;
 440   linked_proc_desc_table = link;
 441 #define PUSH_FP_REGNUM 16 /* must be a register preserved across calls */
 442 #define GEN_REG_SAVE_MASK MASK(1,16)|MASK(24,28)|(1<<31)
 443 #define GEN_REG_SAVE_COUNT 22
 444 #define FLOAT_REG_SAVE_MASK MASK(0,19)
 445 #define FLOAT_REG_SAVE_COUNT 20
 446 #define SPECIAL_REG_SAVE_COUNT 4
 447   /*
 448    * The registers we must save are all those not preserved across
 449    * procedure calls. Dest_Reg (see tm-mips.h) must also be saved.
 450    * In addition, we must save the PC, and PUSH_FP_REGNUM.
 451    * (Ideally, we should also save MDLO/-HI and FP Control/Status reg.)
 452    *
 453    * Dummy frame layout:
 454    *  (high memory)
 455    *    Saved PC
 456    *    Saved MMHI, MMLO, FPC_CSR
 457    *    Saved R31
 458    *    Saved R28
 459    *    ...
 460    *    Saved R1
 461    *    Saved D18 (i.e. F19, F18)
 462    *    ...
 463    *    Saved D0 (i.e. F1, F0)
 464    *    CALL_DUMMY (subroutine stub; see m-mips.h)
 465    *    Parameter build area (not yet implemented)
 466    *  (low memory)
 467    */
 468   PROC_REG_MASK(proc_desc) = GEN_REG_SAVE_MASK;
 469   PROC_FREG_MASK(proc_desc) = FLOAT_REG_SAVE_MASK;
 470   PROC_REG_OFFSET(proc_desc) = /* offset of (Saved R31) from FP */
 471       -sizeof(long) - 4 * SPECIAL_REG_SAVE_COUNT;
 472   PROC_FREG_OFFSET(proc_desc) = /* offset of (Saved D18) from FP */
 473       -sizeof(double) - 4 * (SPECIAL_REG_SAVE_COUNT + GEN_REG_SAVE_COUNT);
 474   /* save general registers */
 475   save_address = sp + PROC_REG_OFFSET(proc_desc);
 476   for (ireg = 32; --ireg >= 0; )
 477     if (PROC_REG_MASK(proc_desc) & (1 << ireg))
 478       {
 479         buffer = read_register (ireg);
 480         write_memory (save_address, &buffer, sizeof(REGISTER_TYPE));
 481         save_address -= 4;
 482       }
 483   /* save floating-points registers */
 484   save_address = sp + PROC_FREG_OFFSET(proc_desc);
 485   for (ireg = 32; --ireg >= 0; )
 486     if (PROC_FREG_MASK(proc_desc) & (1 << ireg))
 487       {
 488         buffer = read_register (ireg);
 489         write_memory (save_address, &buffer, 4);
 490         save_address -= 4;
 491       }
 492   write_register (PUSH_FP_REGNUM, sp);
 493   PROC_FRAME_REG(proc_desc) = PUSH_FP_REGNUM;
 494   PROC_FRAME_OFFSET(proc_desc) = 0;
 495   buffer = read_register (PC_REGNUM);
 496   write_memory (sp - 4, &buffer, sizeof(REGISTER_TYPE));
 497   buffer = read_register (HI_REGNUM);
 498   write_memory (sp - 8, &buffer, sizeof(REGISTER_TYPE));
 499   buffer = read_register (LO_REGNUM);
 500   write_memory (sp - 12, &buffer, sizeof(REGISTER_TYPE));
 501   buffer = read_register (FCRCS_REGNUM);
 502   write_memory (sp - 16, &buffer, sizeof(REGISTER_TYPE));
 503   sp -= 4 * (GEN_REG_SAVE_COUNT+FLOAT_REG_SAVE_COUNT+SPECIAL_REG_SAVE_COUNT);
 504   write_register (SP_REGNUM, sp);
 505   PROC_LOW_ADDR(proc_desc) = sp - CALL_DUMMY_SIZE + CALL_DUMMY_START_OFFSET;
 506   PROC_HIGH_ADDR(proc_desc) = sp;
 507   SET_PROC_DESC_IS_DUMMY(proc_desc);
 508   PROC_PC_REG(proc_desc) = RA_REGNUM;
 509 }
 510
 511 void
 512 mips_pop_frame()
 513 { register int regnum;
 514   FRAME frame = get_current_frame ();
 515   CORE_ADDR new_sp = frame->frame;
 516   mips_extra_func_info_t proc_desc = (mips_extra_func_info_t)frame->proc_desc;
 517   if (PROC_DESC_IS_DUMMY(proc_desc))
 518     {
 519       struct linked_proc_info **ptr = &linked_proc_desc_table;;
 520       for (; &ptr[0]->info != proc_desc; ptr = &ptr[0]->next )
 521           if (ptr[0] == NULL) abort();
 522       *ptr = ptr[0]->next;
 523       free (ptr[0]);
 524       write_register (HI_REGNUM, read_memory_integer(new_sp - 8, 4));
 525       write_register (LO_REGNUM, read_memory_integer(new_sp - 12, 4));
 526       write_register (FCRCS_REGNUM, read_memory_integer(new_sp - 16, 4));
 527     }
 528   write_register (PC_REGNUM, FRAME_SAVED_PC(frame));
 529   if (frame->proc_desc) {
 530     for (regnum = 32; --regnum >= 0; )
 531       if (PROC_REG_MASK(proc_desc) & (1 << regnum))
 532         write_register (regnum,
 533                   read_memory_integer (frame->saved_regs->regs[regnum], 4));
 534     for (regnum = 64; --regnum >= 32; )
 535       if (PROC_FREG_MASK(proc_desc) & (1 << regnum))
 536         write_register (regnum,
 537                   read_memory_integer (frame->saved_regs->regs[regnum], 4));
 538   }
 539   write_register (SP_REGNUM, new_sp);
 540   flush_cached_frames ();
 541   set_current_frame (create_new_frame (new_sp, read_pc ()));
 542 }
 543
 544 static
 545 mips_print_register(regnum, all)
 546      int regnum, all;
 547 {
 548       unsigned char raw_buffer[8];
 549       REGISTER_TYPE val;
 550
 551       read_relative_register_raw_bytes (regnum, raw_buffer);
 552
 553       if (!(regnum & 1) && regnum >= FP0_REGNUM && regnum < FP0_REGNUM+32) {
 554           read_relative_register_raw_bytes (regnum+1, raw_buffer+4);
 555           printf_filtered ("(d%d: ", regnum&31);
 556           val_print (builtin_type_double, raw_buffer, 0,
 557                      stdout, 0, 1, 0, Val_pretty_default);
 558           printf_filtered ("); ", regnum&31);
 559       }
 560       fputs_filtered (reg_names[regnum], stdout);
 561 #ifndef NUMERIC_REG_NAMES
 562       if (regnum < 32)
 563           printf_filtered ("(r%d): ", regnum);
 564       else
 565 #endif
 566           printf_filtered (": ");
 567
 568       /* If virtual format is floating, print it that way.  */
 569       if (TYPE_CODE (REGISTER_VIRTUAL_TYPE (regnum)) == TYPE_CODE_FLT
 570           && ! INVALID_FLOAT (raw_buffer, REGISTER_VIRTUAL_SIZE(regnum))) {
 571           val_print (REGISTER_VIRTUAL_TYPE (regnum), raw_buffer, 0,
 572                      stdout, 0, 1, 0, Val_pretty_default);
 573       }
 574       /* Else print as integer in hex.  */
 575       else
 576         {
 577           long val;
 578
 579           bcopy (raw_buffer, &val, sizeof (long));
 580           if (val == 0)
 581             printf_filtered ("0");
 582           else if (all)
 583             printf_filtered (local_hex_format(), val);
 584           else
 585             printf_filtered ("%s=%d", local_hex_string(val), val);
 586         }
 587 }
 588
 589 /* Replacement for generic do_registers_info.  */
 590 mips_do_registers_info (regnum, fpregs)
 591      int regnum;
 592      int fpregs;
 593 {
 594   if (regnum != -1) {
 595       mips_print_register (regnum, 0);
 596       printf_filtered ("\n");
 597   }
 598   else {
 599       for (regnum = 0; regnum < NUM_REGS; ) {
 600           if ((!fpregs) && regnum >= FP0_REGNUM && regnum <= FCRIR_REGNUM) {
 601             regnum++;
 602             continue;
 603           }
 604           mips_print_register (regnum, 1);
 605           regnum++;
 606           if ((regnum & 3) == 0 || regnum == NUM_REGS)
 607               printf_filtered (";\n");
 608           else
 609               printf_filtered ("; ");
 610       }
 611   }
 612 }
 613 /* Return number of args passed to a frame. described by FIP.
 614    Can return -1, meaning no way to tell.  */
 615
 616 mips_frame_num_args(fip)
 617         FRAME fip;
 618 {
 619 #if 0
 620         struct chain_info_t *p;
 621
 622         p = mips_find_cached_frame(FRAME_FP(fip));
 623         if (p->valid)
 624                 return p->the_info.numargs;
 625 #endif
 626         return -1;
 627 }
 628
 629 \f
 630 /* Bad floats: Returns 0 if P points to a valid IEEE floating point number,
 631    1 if P points to a denormalized number or a NaN. LEN says whether this is
 632    a single-precision or double-precision float */
 633 #define SINGLE_EXP_BITS  8
 634 #define DOUBLE_EXP_BITS 11
 635 int
 636 isa_NAN(p, len)
 637      int *p, len;
 638 {
 639   int exponent;
 640   if (len == 4)
 641     {
 642       exponent = *p;
 643       exponent = exponent << 1 >> (32 - SINGLE_EXP_BITS - 1);
 644       return ((exponent == -1) || (! exponent && *p));
 645     }
 646   else if (len == 8)
 647     {
 648       exponent = *(p+1);
 649       exponent = exponent << 1 >> (32 - DOUBLE_EXP_BITS - 1);
 650       return ((exponent == -1) || (! exponent && *p * *(p+1)));
 651     }
 652   else return 1;
 653 }
 654
 655 /* To skip prologues, I use this predicate. Returns either PC
 656    itself if the code at PC does not look like a function prologue,
 657    PC+4 if it does (our caller does not need anything more fancy). */
 658
 659 CORE_ADDR mips_skip_prologue(pc)
 660      CORE_ADDR pc;
 661 {
 662     struct symbol *f;
 663     struct block *b;
 664     unsigned long inst;
 665
 666     /* For -g modules and most functions anyways the
 667        first instruction adjusts the stack. */
 668     inst = read_memory_integer(pc, 4);
 669     if ((inst & 0xffff0000) == 0x27bd0000)
 670         return pc + 4;
 671
 672     /* Well, it looks like a frameless. Let's make sure.
 673        Note that we are not called on the current PC,
 674        but on the function`s start PC, and I have definitely
 675        seen optimized code that adjusts the SP quite later */
 676     b = block_for_pc(pc);
 677     if (!b) return pc;
 678
 679     f = lookup_symbol(".gdbinfo.", b, LABEL_NAMESPACE, 0, NULL);
 680     if (!f) return pc;
 681     /* Ideally, I would like to use the adjusted info
 682        from mips_frame_info(), but for all practical
 683        purposes it will not matter (and it would require
 684        a different definition of SKIP_PROLOGUE())
 685
 686        Actually, it would not hurt to skip the storing
 687        of arguments on the stack as well. */
 688     if (((struct mips_extra_func_info *)f->value.value)->framesize)
 689         return pc + 4;
 690
 691     return pc;
 692 }