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