gdb/arch-utils.c

   1 /* Dynamic architecture support for GDB, the GNU debugger.
   2
   3    Copyright (C) 1998-2014 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 3 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, see <http://www.gnu.org/licenses/>.  */
  19
  20 #include "defs.h"
  21
  22 #include "arch-utils.h"
  23 #include "buildsym.h"
  24 #include "gdbcmd.h"
  25 #include "inferior.h"           /* enum CALL_DUMMY_LOCATION et al.  */
  26 #include "infrun.h"
  27 #include <string.h>
  28 #include "regcache.h"
  29 #include "gdb_assert.h"
  30 #include "sim-regno.h"
  31 #include "gdbcore.h"
  32 #include "osabi.h"
  33 #include "target-descriptions.h"
  34 #include "objfiles.h"
  35 #include "language.h"
  36
  37 #include "version.h"
  38
  39 #include "floatformat.h"
  40
  41
  42 struct displaced_step_closure *
  43 simple_displaced_step_copy_insn (struct gdbarch *gdbarch,
  44                                  CORE_ADDR from, CORE_ADDR to,
  45                                  struct regcache *regs)
  46 {
  47   size_t len = gdbarch_max_insn_length (gdbarch);
  48   gdb_byte *buf = xmalloc (len);
  49
  50   read_memory (from, buf, len);
  51   write_memory (to, buf, len);
  52
  53   if (debug_displaced)
  54     {
  55       fprintf_unfiltered (gdb_stdlog, "displaced: copy %s->%s: ",
  56                           paddress (gdbarch, from), paddress (gdbarch, to));
  57       displaced_step_dump_bytes (gdb_stdlog, buf, len);
  58     }
  59
  60   return (struct displaced_step_closure *) buf;
  61 }
  62
  63
  64 void
  65 simple_displaced_step_free_closure (struct gdbarch *gdbarch,
  66                                     struct displaced_step_closure *closure)
  67 {
  68   xfree (closure);
  69 }
  70
  71 int
  72 default_displaced_step_hw_singlestep (struct gdbarch *gdbarch,
  73                                       struct displaced_step_closure *closure)
  74 {
  75   return !gdbarch_software_single_step_p (gdbarch);
  76 }
  77
  78 CORE_ADDR
  79 displaced_step_at_entry_point (struct gdbarch *gdbarch)
  80 {
  81   CORE_ADDR addr;
  82   int bp_len;
  83
  84   addr = entry_point_address ();
  85
  86   /* Inferior calls also use the entry point as a breakpoint location.
  87      We don't want displaced stepping to interfere with those
  88      breakpoints, so leave space.  */
  89   gdbarch_breakpoint_from_pc (gdbarch, &addr, &bp_len);
  90   addr += bp_len * 2;
  91
  92   return addr;
  93 }
  94
  95 int
  96 legacy_register_sim_regno (struct gdbarch *gdbarch, int regnum)
  97 {
  98   /* Only makes sense to supply raw registers.  */
  99   gdb_assert (regnum >= 0 && regnum < gdbarch_num_regs (gdbarch));
 100   /* NOTE: cagney/2002-05-13: The old code did it this way and it is
 101      suspected that some GDB/SIM combinations may rely on this
 102      behavour.  The default should be one2one_register_sim_regno
 103      (below).  */
 104   if (gdbarch_register_name (gdbarch, regnum) != NULL
 105       && gdbarch_register_name (gdbarch, regnum)[0] != '\0')
 106     return regnum;
 107   else
 108     return LEGACY_SIM_REGNO_IGNORE;
 109 }
 110
 111 CORE_ADDR
 112 generic_skip_trampoline_code (struct frame_info *frame, CORE_ADDR pc)
 113 {
 114   return 0;
 115 }
 116
 117 CORE_ADDR
 118 generic_skip_solib_resolver (struct gdbarch *gdbarch, CORE_ADDR pc)
 119 {
 120   return 0;
 121 }
 122
 123 int
 124 generic_in_solib_return_trampoline (struct gdbarch *gdbarch,
 125                                     CORE_ADDR pc, const char *name)
 126 {
 127   return 0;
 128 }
 129
 130 int
 131 generic_in_function_epilogue_p (struct gdbarch *gdbarch, CORE_ADDR pc)
 132 {
 133   return 0;
 134 }
 135
 136 /* Helper functions for gdbarch_inner_than */
 137
 138 int
 139 core_addr_lessthan (CORE_ADDR lhs, CORE_ADDR rhs)
 140 {
 141   return (lhs < rhs);
 142 }
 143
 144 int
 145 core_addr_greaterthan (CORE_ADDR lhs, CORE_ADDR rhs)
 146 {
 147   return (lhs > rhs);
 148 }
 149
 150 /* Misc helper functions for targets.  */
 151
 152 CORE_ADDR
 153 core_addr_identity (struct gdbarch *gdbarch, CORE_ADDR addr)
 154 {
 155   return addr;
 156 }
 157
 158 CORE_ADDR
 159 convert_from_func_ptr_addr_identity (struct gdbarch *gdbarch, CORE_ADDR addr,
 160                                      struct target_ops *targ)
 161 {
 162   return addr;
 163 }
 164
 165 int
 166 no_op_reg_to_regnum (struct gdbarch *gdbarch, int reg)
 167 {
 168   return reg;
 169 }
 170
 171 void
 172 default_elf_make_msymbol_special (asymbol *sym, struct minimal_symbol *msym)
 173 {
 174   return;
 175 }
 176
 177 void
 178 default_coff_make_msymbol_special (int val, struct minimal_symbol *msym)
 179 {
 180   return;
 181 }
 182
 183 int
 184 cannot_register_not (struct gdbarch *gdbarch, int regnum)
 185 {
 186   return 0;
 187 }
 188
 189 /* Legacy version of target_virtual_frame_pointer().  Assumes that
 190    there is an gdbarch_deprecated_fp_regnum and that it is the same,
 191    cooked or raw.  */
 192
 193 void
 194 legacy_virtual_frame_pointer (struct gdbarch *gdbarch,
 195                               CORE_ADDR pc,
 196                               int *frame_regnum,
 197                               LONGEST *frame_offset)
 198 {
 199   /* FIXME: cagney/2002-09-13: This code is used when identifying the
 200      frame pointer of the current PC.  It is assuming that a single
 201      register and an offset can determine this.  I think it should
 202      instead generate a byte code expression as that would work better
 203      with things like Dwarf2's CFI.  */
 204   if (gdbarch_deprecated_fp_regnum (gdbarch) >= 0
 205       && gdbarch_deprecated_fp_regnum (gdbarch)
 206            < gdbarch_num_regs (gdbarch))
 207     *frame_regnum = gdbarch_deprecated_fp_regnum (gdbarch);
 208   else if (gdbarch_sp_regnum (gdbarch) >= 0
 209            && gdbarch_sp_regnum (gdbarch)
 210                 < gdbarch_num_regs (gdbarch))
 211     *frame_regnum = gdbarch_sp_regnum (gdbarch);
 212   else
 213     /* Should this be an internal error?  I guess so, it is reflecting
 214        an architectural limitation in the current design.  */
 215     internal_error (__FILE__, __LINE__,
 216                     _("No virtual frame pointer available"));
 217   *frame_offset = 0;
 218 }
 219
 220 \f
 221 int
 222 generic_convert_register_p (struct gdbarch *gdbarch, int regnum,
 223                             struct type *type)
 224 {
 225   return 0;
 226 }
 227
 228 int
 229 default_stabs_argument_has_addr (struct gdbarch *gdbarch, struct type *type)
 230 {
 231   return 0;
 232 }
 233
 234 int
 235 generic_instruction_nullified (struct gdbarch *gdbarch,
 236                                struct regcache *regcache)
 237 {
 238   return 0;
 239 }
 240
 241 int
 242 default_remote_register_number (struct gdbarch *gdbarch,
 243                                 int regno)
 244 {
 245   return regno;
 246 }
 247
 248 \f
 249 /* Functions to manipulate the endianness of the target.  */
 250
 251 static int target_byte_order_user = BFD_ENDIAN_UNKNOWN;
 252
 253 static const char endian_big[] = "big";
 254 static const char endian_little[] = "little";
 255 static const char endian_auto[] = "auto";
 256 static const char *const endian_enum[] =
 257 {
 258   endian_big,
 259   endian_little,
 260   endian_auto,
 261   NULL,
 262 };
 263 static const char *set_endian_string;
 264
 265 enum bfd_endian
 266 selected_byte_order (void)
 267 {
 268   return target_byte_order_user;
 269 }
 270
 271 /* Called by ``show endian''.  */
 272
 273 static void
 274 show_endian (struct ui_file *file, int from_tty, struct cmd_list_element *c,
 275              const char *value)
 276 {
 277   if (target_byte_order_user == BFD_ENDIAN_UNKNOWN)
 278     if (gdbarch_byte_order (get_current_arch ()) == BFD_ENDIAN_BIG)
 279       fprintf_unfiltered (file, _("The target endianness is set automatically "
 280                                   "(currently big endian)\n"));
 281     else
 282       fprintf_unfiltered (file, _("The target endianness is set automatically "
 283                                   "(currently little endian)\n"));
 284   else
 285     if (target_byte_order_user == BFD_ENDIAN_BIG)
 286       fprintf_unfiltered (file,
 287                           _("The target is assumed to be big endian\n"));
 288     else
 289       fprintf_unfiltered (file,
 290                           _("The target is assumed to be little endian\n"));
 291 }
 292
 293 static void
 294 set_endian (char *ignore_args, int from_tty, struct cmd_list_element *c)
 295 {
 296   struct gdbarch_info info;
 297
 298   gdbarch_info_init (&info);
 299
 300   if (set_endian_string == endian_auto)
 301     {
 302       target_byte_order_user = BFD_ENDIAN_UNKNOWN;
 303       if (! gdbarch_update_p (info))
 304         internal_error (__FILE__, __LINE__,
 305                         _("set_endian: architecture update failed"));
 306     }
 307   else if (set_endian_string == endian_little)
 308     {
 309       info.byte_order = BFD_ENDIAN_LITTLE;
 310       if (! gdbarch_update_p (info))
 311         printf_unfiltered (_("Little endian target not supported by GDB\n"));
 312       else
 313         target_byte_order_user = BFD_ENDIAN_LITTLE;
 314     }
 315   else if (set_endian_string == endian_big)
 316     {
 317       info.byte_order = BFD_ENDIAN_BIG;
 318       if (! gdbarch_update_p (info))
 319         printf_unfiltered (_("Big endian target not supported by GDB\n"));
 320       else
 321         target_byte_order_user = BFD_ENDIAN_BIG;
 322     }
 323   else
 324     internal_error (__FILE__, __LINE__,
 325                     _("set_endian: bad value"));
 326
 327   show_endian (gdb_stdout, from_tty, NULL, NULL);
 328 }
 329
 330 /* Given SELECTED, a currently selected BFD architecture, and
 331    TARGET_DESC, the current target description, return what
 332    architecture to use.
 333
 334    SELECTED may be NULL, in which case we return the architecture
 335    associated with TARGET_DESC.  If SELECTED specifies a variant
 336    of the architecture associtated with TARGET_DESC, return the
 337    more specific of the two.
 338
 339    If SELECTED is a different architecture, but it is accepted as
 340    compatible by the target, we can use the target architecture.
 341
 342    If SELECTED is obviously incompatible, warn the user.  */
 343
 344 static const struct bfd_arch_info *
 345 choose_architecture_for_target (const struct target_desc *target_desc,
 346                                 const struct bfd_arch_info *selected)
 347 {
 348   const struct bfd_arch_info *from_target = tdesc_architecture (target_desc);
 349   const struct bfd_arch_info *compat1, *compat2;
 350
 351   if (selected == NULL)
 352     return from_target;
 353
 354   if (from_target == NULL)
 355     return selected;
 356
 357   /* struct bfd_arch_info objects are singletons: that is, there's
 358      supposed to be exactly one instance for a given machine.  So you
 359      can tell whether two are equivalent by comparing pointers.  */
 360   if (from_target == selected)
 361     return selected;
 362
 363   /* BFD's 'A->compatible (A, B)' functions return zero if A and B are
 364      incompatible.  But if they are compatible, it returns the 'more
 365      featureful' of the two arches.  That is, if A can run code
 366      written for B, but B can't run code written for A, then it'll
 367      return A.
 368
 369      Some targets (e.g. MIPS as of 2006-12-04) don't fully
 370      implement this, instead always returning NULL or the first
 371      argument.  We detect that case by checking both directions.  */
 372
 373   compat1 = selected->compatible (selected, from_target);
 374   compat2 = from_target->compatible (from_target, selected);
 375
 376   if (compat1 == NULL && compat2 == NULL)
 377     {
 378       /* BFD considers the architectures incompatible.  Check our
 379          target description whether it accepts SELECTED as compatible
 380          anyway.  */
 381       if (tdesc_compatible_p (target_desc, selected))
 382         return from_target;
 383
 384       warning (_("Selected architecture %s is not compatible "
 385                  "with reported target architecture %s"),
 386                selected->printable_name, from_target->printable_name);
 387       return selected;
 388     }
 389
 390   if (compat1 == NULL)
 391     return compat2;
 392   if (compat2 == NULL)
 393     return compat1;
 394   if (compat1 == compat2)
 395     return compat1;
 396
 397   /* If the two didn't match, but one of them was a default
 398      architecture, assume the more specific one is correct.  This
 399      handles the case where an executable or target description just
 400      says "mips", but the other knows which MIPS variant.  */
 401   if (compat1->the_default)
 402     return compat2;
 403   if (compat2->the_default)
 404     return compat1;
 405
 406   /* We have no idea which one is better.  This is a bug, but not
 407      a critical problem; warn the user.  */
 408   warning (_("Selected architecture %s is ambiguous with "
 409              "reported target architecture %s"),
 410            selected->printable_name, from_target->printable_name);
 411   return selected;
 412 }
 413
 414 /* Functions to manipulate the architecture of the target.  */
 415
 416 enum set_arch { set_arch_auto, set_arch_manual };
 417
 418 static const struct bfd_arch_info *target_architecture_user;
 419
 420 static const char *set_architecture_string;
 421
 422 const char *
 423 selected_architecture_name (void)
 424 {
 425   if (target_architecture_user == NULL)
 426     return NULL;
 427   else
 428     return set_architecture_string;
 429 }
 430
 431 /* Called if the user enters ``show architecture'' without an
 432    argument.  */
 433
 434 static void
 435 show_architecture (struct ui_file *file, int from_tty,
 436                    struct cmd_list_element *c, const char *value)
 437 {
 438   if (target_architecture_user == NULL)
 439     fprintf_filtered (file, _("The target architecture is set "
 440                               "automatically (currently %s)\n"),
 441                       gdbarch_bfd_arch_info (get_current_arch ())->printable_name);
 442   else
 443     fprintf_filtered (file, _("The target architecture is assumed to be %s\n"),
 444                       set_architecture_string);
 445 }
 446
 447
 448 /* Called if the user enters ``set architecture'' with or without an
 449    argument.  */
 450
 451 static void
 452 set_architecture (char *ignore_args, int from_tty, struct cmd_list_element *c)
 453 {
 454   struct gdbarch_info info;
 455
 456   gdbarch_info_init (&info);
 457
 458   if (strcmp (set_architecture_string, "auto") == 0)
 459     {
 460       target_architecture_user = NULL;
 461       if (!gdbarch_update_p (info))
 462         internal_error (__FILE__, __LINE__,
 463                         _("could not select an architecture automatically"));
 464     }
 465   else
 466     {
 467       info.bfd_arch_info = bfd_scan_arch (set_architecture_string);
 468       if (info.bfd_arch_info == NULL)
 469         internal_error (__FILE__, __LINE__,
 470                         _("set_architecture: bfd_scan_arch failed"));
 471       if (gdbarch_update_p (info))
 472         target_architecture_user = info.bfd_arch_info;
 473       else
 474         printf_unfiltered (_("Architecture `%s' not recognized.\n"),
 475                            set_architecture_string);
 476     }
 477   show_architecture (gdb_stdout, from_tty, NULL, NULL);
 478 }
 479
 480 /* Try to select a global architecture that matches "info".  Return
 481    non-zero if the attempt succeeds.  */
 482 int
 483 gdbarch_update_p (struct gdbarch_info info)
 484 {
 485   struct gdbarch *new_gdbarch;
 486
 487   /* Check for the current file.  */
 488   if (info.abfd == NULL)
 489     info.abfd = exec_bfd;
 490   if (info.abfd == NULL)
 491     info.abfd = core_bfd;
 492
 493   /* Check for the current target description.  */
 494   if (info.target_desc == NULL)
 495     info.target_desc = target_current_description ();
 496
 497   new_gdbarch = gdbarch_find_by_info (info);
 498
 499   /* If there no architecture by that name, reject the request.  */
 500   if (new_gdbarch == NULL)
 501     {
 502       if (gdbarch_debug)
 503         fprintf_unfiltered (gdb_stdlog, "gdbarch_update_p: "
 504                             "Architecture not found\n");
 505       return 0;
 506     }
 507
 508   /* If it is the same old architecture, accept the request (but don't
 509      swap anything).  */
 510   if (new_gdbarch == target_gdbarch ())
 511     {
 512       if (gdbarch_debug)
 513         fprintf_unfiltered (gdb_stdlog, "gdbarch_update_p: "
 514                             "Architecture %s (%s) unchanged\n",
 515                             host_address_to_string (new_gdbarch),
 516                             gdbarch_bfd_arch_info (new_gdbarch)->printable_name);
 517       return 1;
 518     }
 519
 520   /* It's a new architecture, swap it in.  */
 521   if (gdbarch_debug)
 522     fprintf_unfiltered (gdb_stdlog, "gdbarch_update_p: "
 523                         "New architecture %s (%s) selected\n",
 524                         host_address_to_string (new_gdbarch),
 525                         gdbarch_bfd_arch_info (new_gdbarch)->printable_name);
 526   set_target_gdbarch (new_gdbarch);
 527
 528   return 1;
 529 }
 530
 531 /* Return the architecture for ABFD.  If no suitable architecture
 532    could be find, return NULL.  */
 533
 534 struct gdbarch *
 535 gdbarch_from_bfd (bfd *abfd)
 536 {
 537   struct gdbarch_info info;
 538   gdbarch_info_init (&info);
 539
 540   info.abfd = abfd;
 541   return gdbarch_find_by_info (info);
 542 }
 543
 544 /* Set the dynamic target-system-dependent parameters (architecture,
 545    byte-order) using information found in the BFD */
 546
 547 void
 548 set_gdbarch_from_file (bfd *abfd)
 549 {
 550   struct gdbarch_info info;
 551   struct gdbarch *gdbarch;
 552
 553   gdbarch_info_init (&info);
 554   info.abfd = abfd;
 555   info.target_desc = target_current_description ();
 556   gdbarch = gdbarch_find_by_info (info);
 557
 558   if (gdbarch == NULL)
 559     error (_("Architecture of file not recognized."));
 560   set_target_gdbarch (gdbarch);
 561 }
 562
 563 /* Initialize the current architecture.  Update the ``set
 564    architecture'' command so that it specifies a list of valid
 565    architectures.  */
 566
 567 #ifdef DEFAULT_BFD_ARCH
 568 extern const bfd_arch_info_type DEFAULT_BFD_ARCH;
 569 static const bfd_arch_info_type *default_bfd_arch = &DEFAULT_BFD_ARCH;
 570 #else
 571 static const bfd_arch_info_type *default_bfd_arch;
 572 #endif
 573
 574 #ifdef DEFAULT_BFD_VEC
 575 extern const bfd_target DEFAULT_BFD_VEC;
 576 static const bfd_target *default_bfd_vec = &DEFAULT_BFD_VEC;
 577 #else
 578 static const bfd_target *default_bfd_vec;
 579 #endif
 580
 581 static int default_byte_order = BFD_ENDIAN_UNKNOWN;
 582
 583 void
 584 initialize_current_architecture (void)
 585 {
 586   const char **arches = gdbarch_printable_names ();
 587   struct gdbarch_info info;
 588
 589   /* determine a default architecture and byte order.  */
 590   gdbarch_info_init (&info);
 591
 592   /* Find a default architecture.  */
 593   if (default_bfd_arch == NULL)
 594     {
 595       /* Choose the architecture by taking the first one
 596          alphabetically.  */
 597       const char *chosen = arches[0];
 598       const char **arch;
 599       for (arch = arches; *arch != NULL; arch++)
 600         {
 601           if (strcmp (*arch, chosen) < 0)
 602             chosen = *arch;
 603         }
 604       if (chosen == NULL)
 605         internal_error (__FILE__, __LINE__,
 606                         _("initialize_current_architecture: No arch"));
 607       default_bfd_arch = bfd_scan_arch (chosen);
 608       if (default_bfd_arch == NULL)
 609         internal_error (__FILE__, __LINE__,
 610                         _("initialize_current_architecture: Arch not found"));
 611     }
 612
 613   info.bfd_arch_info = default_bfd_arch;
 614
 615   /* Take several guesses at a byte order.  */
 616   if (default_byte_order == BFD_ENDIAN_UNKNOWN
 617       && default_bfd_vec != NULL)
 618     {
 619       /* Extract BFD's default vector's byte order.  */
 620       switch (default_bfd_vec->byteorder)
 621         {
 622         case BFD_ENDIAN_BIG:
 623           default_byte_order = BFD_ENDIAN_BIG;
 624           break;
 625         case BFD_ENDIAN_LITTLE:
 626           default_byte_order = BFD_ENDIAN_LITTLE;
 627           break;
 628         default:
 629           break;
 630         }
 631     }
 632   if (default_byte_order == BFD_ENDIAN_UNKNOWN)
 633     {
 634       /* look for ``*el-*'' in the target name.  */
 635       const char *chp;
 636       chp = strchr (target_name, '-');
 637       if (chp != NULL
 638           && chp - 2 >= target_name
 639           && strncmp (chp - 2, "el", 2) == 0)
 640         default_byte_order = BFD_ENDIAN_LITTLE;
 641     }
 642   if (default_byte_order == BFD_ENDIAN_UNKNOWN)
 643     {
 644       /* Wire it to big-endian!!! */
 645       default_byte_order = BFD_ENDIAN_BIG;
 646     }
 647
 648   info.byte_order = default_byte_order;
 649   info.byte_order_for_code = info.byte_order;
 650
 651   if (! gdbarch_update_p (info))
 652     internal_error (__FILE__, __LINE__,
 653                     _("initialize_current_architecture: Selection of "
 654                       "initial architecture failed"));
 655
 656   /* Create the ``set architecture'' command appending ``auto'' to the
 657      list of architectures.  */
 658   {
 659     /* Append ``auto''.  */
 660     int nr;
 661     for (nr = 0; arches[nr] != NULL; nr++);
 662     arches = xrealloc (arches, sizeof (char*) * (nr + 2));
 663     arches[nr + 0] = "auto";
 664     arches[nr + 1] = NULL;
 665     add_setshow_enum_cmd ("architecture", class_support,
 666                           arches, &set_architecture_string,
 667                           _("Set architecture of target."),
 668                           _("Show architecture of target."), NULL,
 669                           set_architecture, show_architecture,
 670                           &setlist, &showlist);
 671     add_alias_cmd ("processor", "architecture", class_support, 1, &setlist);
 672   }
 673 }
 674
 675
 676 /* Initialize a gdbarch info to values that will be automatically
 677    overridden.  Note: Originally, this ``struct info'' was initialized
 678    using memset(0).  Unfortunately, that ran into problems, namely
 679    BFD_ENDIAN_BIG is zero.  An explicit initialization function that
 680    can explicitly set each field to a well defined value is used.  */
 681
 682 void
 683 gdbarch_info_init (struct gdbarch_info *info)
 684 {
 685   memset (info, 0, sizeof (struct gdbarch_info));
 686   info->byte_order = BFD_ENDIAN_UNKNOWN;
 687   info->byte_order_for_code = info->byte_order;
 688   info->osabi = GDB_OSABI_UNINITIALIZED;
 689 }
 690
 691 /* Similar to init, but this time fill in the blanks.  Information is
 692    obtained from the global "set ..." options and explicitly
 693    initialized INFO fields.  */
 694
 695 void
 696 gdbarch_info_fill (struct gdbarch_info *info)
 697 {
 698   /* "(gdb) set architecture ...".  */
 699   if (info->bfd_arch_info == NULL
 700       && target_architecture_user)
 701     info->bfd_arch_info = target_architecture_user;
 702   /* From the file.  */
 703   if (info->bfd_arch_info == NULL
 704       && info->abfd != NULL
 705       && bfd_get_arch (info->abfd) != bfd_arch_unknown
 706       && bfd_get_arch (info->abfd) != bfd_arch_obscure)
 707     info->bfd_arch_info = bfd_get_arch_info (info->abfd);
 708   /* From the target.  */
 709   if (info->target_desc != NULL)
 710     info->bfd_arch_info = choose_architecture_for_target
 711                            (info->target_desc, info->bfd_arch_info);
 712   /* From the default.  */
 713   if (info->bfd_arch_info == NULL)
 714     info->bfd_arch_info = default_bfd_arch;
 715
 716   /* "(gdb) set byte-order ...".  */
 717   if (info->byte_order == BFD_ENDIAN_UNKNOWN
 718       && target_byte_order_user != BFD_ENDIAN_UNKNOWN)
 719     info->byte_order = target_byte_order_user;
 720   /* From the INFO struct.  */
 721   if (info->byte_order == BFD_ENDIAN_UNKNOWN
 722       && info->abfd != NULL)
 723     info->byte_order = (bfd_big_endian (info->abfd) ? BFD_ENDIAN_BIG
 724                         : bfd_little_endian (info->abfd) ? BFD_ENDIAN_LITTLE
 725                         : BFD_ENDIAN_UNKNOWN);
 726   /* From the default.  */
 727   if (info->byte_order == BFD_ENDIAN_UNKNOWN)
 728     info->byte_order = default_byte_order;
 729   info->byte_order_for_code = info->byte_order;
 730
 731   /* "(gdb) set osabi ...".  Handled by gdbarch_lookup_osabi.  */
 732   /* From the manual override, or from file.  */
 733   if (info->osabi == GDB_OSABI_UNINITIALIZED)
 734     info->osabi = gdbarch_lookup_osabi (info->abfd);
 735   /* From the target.  */
 736   if (info->osabi == GDB_OSABI_UNKNOWN && info->target_desc != NULL)
 737     info->osabi = tdesc_osabi (info->target_desc);
 738   /* From the configured default.  */
 739 #ifdef GDB_OSABI_DEFAULT
 740   if (info->osabi == GDB_OSABI_UNKNOWN)
 741     info->osabi = GDB_OSABI_DEFAULT;
 742 #endif
 743
 744   /* Must have at least filled in the architecture.  */
 745   gdb_assert (info->bfd_arch_info != NULL);
 746 }
 747
 748 /* Return "current" architecture.  If the target is running, this is
 749    the architecture of the selected frame.  Otherwise, the "current"
 750    architecture defaults to the target architecture.
 751
 752    This function should normally be called solely by the command
 753    interpreter routines to determine the architecture to execute a
 754    command in.  */
 755 struct gdbarch *
 756 get_current_arch (void)
 757 {
 758   if (has_stack_frames ())
 759     return get_frame_arch (get_selected_frame (NULL));
 760   else
 761     return target_gdbarch ();
 762 }
 763
 764 int
 765 default_has_shared_address_space (struct gdbarch *gdbarch)
 766 {
 767   /* Simply say no.  In most unix-like targets each inferior/process
 768      has its own address space.  */
 769   return 0;
 770 }
 771
 772 int
 773 default_fast_tracepoint_valid_at (struct gdbarch *gdbarch,
 774                                   CORE_ADDR addr, int *isize, char **msg)
 775 {
 776   /* We don't know if maybe the target has some way to do fast
 777      tracepoints that doesn't need gdbarch, so always say yes.  */
 778   if (msg)
 779     *msg = NULL;
 780   return 1;
 781 }
 782
 783 void
 784 default_remote_breakpoint_from_pc (struct gdbarch *gdbarch, CORE_ADDR *pcptr,
 785                                    int *kindptr)
 786 {
 787   gdbarch_breakpoint_from_pc (gdbarch, pcptr, kindptr);
 788 }
 789
 790 void
 791 default_gen_return_address (struct gdbarch *gdbarch,
 792                             struct agent_expr *ax, struct axs_value *value,
 793                             CORE_ADDR scope)
 794 {
 795   error (_("This architecture has no method to collect a return address."));
 796 }
 797
 798 int
 799 default_return_in_first_hidden_param_p (struct gdbarch *gdbarch,
 800                                         struct type *type)
 801 {
 802   /* Usually, the return value's address is stored the in the "first hidden"
 803      parameter if the return value should be passed by reference, as
 804      specified in ABI.  */
 805   return language_pass_by_reference (type);
 806 }
 807
 808 int default_insn_is_call (struct gdbarch *gdbarch, CORE_ADDR addr)
 809 {
 810   return 0;
 811 }
 812
 813 int default_insn_is_ret (struct gdbarch *gdbarch, CORE_ADDR addr)
 814 {
 815   return 0;
 816 }
 817
 818 int default_insn_is_jump (struct gdbarch *gdbarch, CORE_ADDR addr)
 819 {
 820   return 0;
 821 }
 822
 823 /* */
 824
 825 /* -Wmissing-prototypes */
 826 extern initialize_file_ftype _initialize_gdbarch_utils;
 827
 828 void
 829 _initialize_gdbarch_utils (void)
 830 {
 831   add_setshow_enum_cmd ("endian", class_support,
 832                         endian_enum, &set_endian_string,
 833                         _("Set endianness of target."),
 834                         _("Show endianness of target."),
 835                         NULL, set_endian, show_endian,
 836                         &setlist, &showlist);
 837 }