gdb/arch-utils.c

   1 /* Dynamic architecture support for GDB, the GNU debugger.
   2
   3    Copyright (C) 1998-2020 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 "gdbcmd.h"
  24 #include "inferior.h"           /* enum CALL_DUMMY_LOCATION et al.  */
  25 #include "infrun.h"
  26 #include "regcache.h"
  27 #include "sim-regno.h"
  28 #include "gdbcore.h"
  29 #include "osabi.h"
  30 #include "target-descriptions.h"
  31 #include "objfiles.h"
  32 #include "language.h"
  33 #include "symtab.h"
  34
  35 #include "gdbsupport/version.h"
  36
  37 #include "floatformat.h"
  38
  39 #include "dis-asm.h"
  40
  41 int
  42 default_displaced_step_hw_singlestep (struct gdbarch *gdbarch,
  43                                       struct displaced_step_copy_insn_closure *closure)
  44 {
  45   return !gdbarch_software_single_step_p (gdbarch);
  46 }
  47
  48 CORE_ADDR
  49 displaced_step_at_entry_point (struct gdbarch *gdbarch)
  50 {
  51   CORE_ADDR addr;
  52   int bp_len;
  53
  54   addr = entry_point_address ();
  55
  56   /* Inferior calls also use the entry point as a breakpoint location.
  57      We don't want displaced stepping to interfere with those
  58      breakpoints, so leave space.  */
  59   gdbarch_breakpoint_from_pc (gdbarch, &addr, &bp_len);
  60   addr += bp_len * 2;
  61
  62   return addr;
  63 }
  64
  65 int
  66 legacy_register_sim_regno (struct gdbarch *gdbarch, int regnum)
  67 {
  68   /* Only makes sense to supply raw registers.  */
  69   gdb_assert (regnum >= 0 && regnum < gdbarch_num_regs (gdbarch));
  70   /* NOTE: cagney/2002-05-13: The old code did it this way and it is
  71      suspected that some GDB/SIM combinations may rely on this
  72      behaviour.  The default should be one2one_register_sim_regno
  73      (below).  */
  74   if (gdbarch_register_name (gdbarch, regnum) != NULL
  75       && gdbarch_register_name (gdbarch, regnum)[0] != '\0')
  76     return regnum;
  77   else
  78     return LEGACY_SIM_REGNO_IGNORE;
  79 }
  80
  81 CORE_ADDR
  82 generic_skip_trampoline_code (struct frame_info *frame, CORE_ADDR pc)
  83 {
  84   return 0;
  85 }
  86
  87 CORE_ADDR
  88 generic_skip_solib_resolver (struct gdbarch *gdbarch, CORE_ADDR pc)
  89 {
  90   return 0;
  91 }
  92
  93 int
  94 generic_in_solib_return_trampoline (struct gdbarch *gdbarch,
  95                                     CORE_ADDR pc, const char *name)
  96 {
  97   return 0;
  98 }
  99
 100 int
 101 generic_stack_frame_destroyed_p (struct gdbarch *gdbarch, CORE_ADDR pc)
 102 {
 103   return 0;
 104 }
 105
 106 int
 107 default_code_of_frame_writable (struct gdbarch *gdbarch,
 108                                 struct frame_info *frame)
 109 {
 110   return 1;
 111 }
 112
 113 /* Helper functions for gdbarch_inner_than */
 114
 115 int
 116 core_addr_lessthan (CORE_ADDR lhs, CORE_ADDR rhs)
 117 {
 118   return (lhs < rhs);
 119 }
 120
 121 int
 122 core_addr_greaterthan (CORE_ADDR lhs, CORE_ADDR rhs)
 123 {
 124   return (lhs > rhs);
 125 }
 126
 127 /* Misc helper functions for targets.  */
 128
 129 CORE_ADDR
 130 core_addr_identity (struct gdbarch *gdbarch, CORE_ADDR addr)
 131 {
 132   return addr;
 133 }
 134
 135 CORE_ADDR
 136 convert_from_func_ptr_addr_identity (struct gdbarch *gdbarch, CORE_ADDR addr,
 137                                      struct target_ops *targ)
 138 {
 139   return addr;
 140 }
 141
 142 int
 143 no_op_reg_to_regnum (struct gdbarch *gdbarch, int reg)
 144 {
 145   return reg;
 146 }
 147
 148 void
 149 default_coff_make_msymbol_special (int val, struct minimal_symbol *msym)
 150 {
 151   return;
 152 }
 153
 154 /* See arch-utils.h.  */
 155
 156 void
 157 default_make_symbol_special (struct symbol *sym, struct objfile *objfile)
 158 {
 159   return;
 160 }
 161
 162 /* See arch-utils.h.  */
 163
 164 CORE_ADDR
 165 default_adjust_dwarf2_addr (CORE_ADDR pc)
 166 {
 167   return pc;
 168 }
 169
 170 /* See arch-utils.h.  */
 171
 172 CORE_ADDR
 173 default_adjust_dwarf2_line (CORE_ADDR addr, int rel)
 174 {
 175   return addr;
 176 }
 177
 178 /* See arch-utils.h.  */
 179
 180 bool
 181 default_execute_dwarf_cfa_vendor_op (struct gdbarch *gdbarch, gdb_byte op,
 182                                      struct dwarf2_frame_state *fs)
 183 {
 184   return false;
 185 }
 186
 187 int
 188 cannot_register_not (struct gdbarch *gdbarch, int regnum)
 189 {
 190   return 0;
 191 }
 192
 193 /* Legacy version of target_virtual_frame_pointer().  Assumes that
 194    there is an gdbarch_deprecated_fp_regnum and that it is the same,
 195    cooked or raw.  */
 196
 197 void
 198 legacy_virtual_frame_pointer (struct gdbarch *gdbarch,
 199                               CORE_ADDR pc,
 200                               int *frame_regnum,
 201                               LONGEST *frame_offset)
 202 {
 203   /* FIXME: cagney/2002-09-13: This code is used when identifying the
 204      frame pointer of the current PC.  It is assuming that a single
 205      register and an offset can determine this.  I think it should
 206      instead generate a byte code expression as that would work better
 207      with things like Dwarf2's CFI.  */
 208   if (gdbarch_deprecated_fp_regnum (gdbarch) >= 0
 209       && gdbarch_deprecated_fp_regnum (gdbarch)
 210            < gdbarch_num_regs (gdbarch))
 211     *frame_regnum = gdbarch_deprecated_fp_regnum (gdbarch);
 212   else if (gdbarch_sp_regnum (gdbarch) >= 0
 213            && gdbarch_sp_regnum (gdbarch)
 214                 < gdbarch_num_regs (gdbarch))
 215     *frame_regnum = gdbarch_sp_regnum (gdbarch);
 216   else
 217     /* Should this be an internal error?  I guess so, it is reflecting
 218        an architectural limitation in the current design.  */
 219     internal_error (__FILE__, __LINE__,
 220                     _("No virtual frame pointer available"));
 221   *frame_offset = 0;
 222 }
 223
 224 /* Return a floating-point format for a floating-point variable of
 225    length LEN in bits.  If non-NULL, NAME is the name of its type.
 226    If no suitable type is found, return NULL.  */
 227
 228 const struct floatformat **
 229 default_floatformat_for_type (struct gdbarch *gdbarch,
 230                               const char *name, int len)
 231 {
 232   const struct floatformat **format = NULL;
 233
 234   if (len == gdbarch_half_bit (gdbarch))
 235     format = gdbarch_half_format (gdbarch);
 236   else if (len == gdbarch_float_bit (gdbarch))
 237     format = gdbarch_float_format (gdbarch);
 238   else if (len == gdbarch_double_bit (gdbarch))
 239     format = gdbarch_double_format (gdbarch);
 240   else if (len == gdbarch_long_double_bit (gdbarch))
 241     format = gdbarch_long_double_format (gdbarch);
 242   /* On i386 the 'long double' type takes 96 bits,
 243      while the real number of used bits is only 80,
 244      both in processor and in memory.
 245      The code below accepts the real bit size.  */
 246   else if (gdbarch_long_double_format (gdbarch) != NULL
 247            && len == gdbarch_long_double_format (gdbarch)[0]->totalsize)
 248     format = gdbarch_long_double_format (gdbarch);
 249
 250   return format;
 251 }
 252 \f
 253 int
 254 generic_convert_register_p (struct gdbarch *gdbarch, int regnum,
 255                             struct type *type)
 256 {
 257   return 0;
 258 }
 259
 260 int
 261 default_stabs_argument_has_addr (struct gdbarch *gdbarch, struct type *type)
 262 {
 263   return 0;
 264 }
 265
 266 int
 267 generic_instruction_nullified (struct gdbarch *gdbarch,
 268                                struct regcache *regcache)
 269 {
 270   return 0;
 271 }
 272
 273 int
 274 default_remote_register_number (struct gdbarch *gdbarch,
 275                                 int regno)
 276 {
 277   return regno;
 278 }
 279
 280 /* See arch-utils.h.  */
 281
 282 int
 283 default_vsyscall_range (struct gdbarch *gdbarch, struct mem_range *range)
 284 {
 285   return 0;
 286 }
 287
 288 \f
 289 /* Functions to manipulate the endianness of the target.  */
 290
 291 static enum bfd_endian target_byte_order_user = BFD_ENDIAN_UNKNOWN;
 292
 293 static const char endian_big[] = "big";
 294 static const char endian_little[] = "little";
 295 static const char endian_auto[] = "auto";
 296 static const char *const endian_enum[] =
 297 {
 298   endian_big,
 299   endian_little,
 300   endian_auto,
 301   NULL,
 302 };
 303 static const char *set_endian_string;
 304
 305 enum bfd_endian
 306 selected_byte_order (void)
 307 {
 308   return target_byte_order_user;
 309 }
 310
 311 /* Called by ``show endian''.  */
 312
 313 static void
 314 show_endian (struct ui_file *file, int from_tty, struct cmd_list_element *c,
 315              const char *value)
 316 {
 317   if (target_byte_order_user == BFD_ENDIAN_UNKNOWN)
 318     if (gdbarch_byte_order (get_current_arch ()) == BFD_ENDIAN_BIG)
 319       fprintf_unfiltered (file, _("The target endianness is set automatically "
 320                                   "(currently big endian)\n"));
 321     else
 322       fprintf_unfiltered (file, _("The target endianness is set automatically "
 323                                   "(currently little endian)\n"));
 324   else
 325     if (target_byte_order_user == BFD_ENDIAN_BIG)
 326       fprintf_unfiltered (file,
 327                           _("The target is assumed to be big endian\n"));
 328     else
 329       fprintf_unfiltered (file,
 330                           _("The target is assumed to be little endian\n"));
 331 }
 332
 333 static void
 334 set_endian (const char *ignore_args, int from_tty, struct cmd_list_element *c)
 335 {
 336   struct gdbarch_info info;
 337
 338   gdbarch_info_init (&info);
 339
 340   if (set_endian_string == endian_auto)
 341     {
 342       target_byte_order_user = BFD_ENDIAN_UNKNOWN;
 343       if (! gdbarch_update_p (info))
 344         internal_error (__FILE__, __LINE__,
 345                         _("set_endian: architecture update failed"));
 346     }
 347   else if (set_endian_string == endian_little)
 348     {
 349       info.byte_order = BFD_ENDIAN_LITTLE;
 350       if (! gdbarch_update_p (info))
 351         printf_unfiltered (_("Little endian target not supported by GDB\n"));
 352       else
 353         target_byte_order_user = BFD_ENDIAN_LITTLE;
 354     }
 355   else if (set_endian_string == endian_big)
 356     {
 357       info.byte_order = BFD_ENDIAN_BIG;
 358       if (! gdbarch_update_p (info))
 359         printf_unfiltered (_("Big endian target not supported by GDB\n"));
 360       else
 361         target_byte_order_user = BFD_ENDIAN_BIG;
 362     }
 363   else
 364     internal_error (__FILE__, __LINE__,
 365                     _("set_endian: bad value"));
 366
 367   show_endian (gdb_stdout, from_tty, NULL, NULL);
 368 }
 369
 370 /* Given SELECTED, a currently selected BFD architecture, and
 371    TARGET_DESC, the current target description, return what
 372    architecture to use.
 373
 374    SELECTED may be NULL, in which case we return the architecture
 375    associated with TARGET_DESC.  If SELECTED specifies a variant
 376    of the architecture associated with TARGET_DESC, return the
 377    more specific of the two.
 378
 379    If SELECTED is a different architecture, but it is accepted as
 380    compatible by the target, we can use the target architecture.
 381
 382    If SELECTED is obviously incompatible, warn the user.  */
 383
 384 static const struct bfd_arch_info *
 385 choose_architecture_for_target (const struct target_desc *target_desc,
 386                                 const struct bfd_arch_info *selected)
 387 {
 388   const struct bfd_arch_info *from_target = tdesc_architecture (target_desc);
 389   const struct bfd_arch_info *compat1, *compat2;
 390
 391   if (selected == NULL)
 392     return from_target;
 393
 394   if (from_target == NULL)
 395     return selected;
 396
 397   /* struct bfd_arch_info objects are singletons: that is, there's
 398      supposed to be exactly one instance for a given machine.  So you
 399      can tell whether two are equivalent by comparing pointers.  */
 400   if (from_target == selected)
 401     return selected;
 402
 403   /* BFD's 'A->compatible (A, B)' functions return zero if A and B are
 404      incompatible.  But if they are compatible, it returns the 'more
 405      featureful' of the two arches.  That is, if A can run code
 406      written for B, but B can't run code written for A, then it'll
 407      return A.
 408
 409      Some targets (e.g. MIPS as of 2006-12-04) don't fully
 410      implement this, instead always returning NULL or the first
 411      argument.  We detect that case by checking both directions.  */
 412
 413   compat1 = selected->compatible (selected, from_target);
 414   compat2 = from_target->compatible (from_target, selected);
 415
 416   if (compat1 == NULL && compat2 == NULL)
 417     {
 418       /* BFD considers the architectures incompatible.  Check our
 419          target description whether it accepts SELECTED as compatible
 420          anyway.  */
 421       if (tdesc_compatible_p (target_desc, selected))
 422         return from_target;
 423
 424       warning (_("Selected architecture %s is not compatible "
 425                  "with reported target architecture %s"),
 426                selected->printable_name, from_target->printable_name);
 427       return selected;
 428     }
 429
 430   if (compat1 == NULL)
 431     return compat2;
 432   if (compat2 == NULL)
 433     return compat1;
 434   if (compat1 == compat2)
 435     return compat1;
 436
 437   /* If the two didn't match, but one of them was a default
 438      architecture, assume the more specific one is correct.  This
 439      handles the case where an executable or target description just
 440      says "mips", but the other knows which MIPS variant.  */
 441   if (compat1->the_default)
 442     return compat2;
 443   if (compat2->the_default)
 444     return compat1;
 445
 446   /* We have no idea which one is better.  This is a bug, but not
 447      a critical problem; warn the user.  */
 448   warning (_("Selected architecture %s is ambiguous with "
 449              "reported target architecture %s"),
 450            selected->printable_name, from_target->printable_name);
 451   return selected;
 452 }
 453
 454 /* Functions to manipulate the architecture of the target.  */
 455
 456 enum set_arch { set_arch_auto, set_arch_manual };
 457
 458 static const struct bfd_arch_info *target_architecture_user;
 459
 460 static const char *set_architecture_string;
 461
 462 const char *
 463 selected_architecture_name (void)
 464 {
 465   if (target_architecture_user == NULL)
 466     return NULL;
 467   else
 468     return set_architecture_string;
 469 }
 470
 471 /* Called if the user enters ``show architecture'' without an
 472    argument.  */
 473
 474 static void
 475 show_architecture (struct ui_file *file, int from_tty,
 476                    struct cmd_list_element *c, const char *value)
 477 {
 478   if (target_architecture_user == NULL)
 479     fprintf_filtered (file, _("The target architecture is set "
 480                               "automatically (currently %s)\n"),
 481                       gdbarch_bfd_arch_info (get_current_arch ())->printable_name);
 482   else
 483     fprintf_filtered (file, _("The target architecture is assumed to be %s\n"),
 484                       set_architecture_string);
 485 }
 486
 487
 488 /* Called if the user enters ``set architecture'' with or without an
 489    argument.  */
 490
 491 static void
 492 set_architecture (const char *ignore_args,
 493                   int from_tty, struct cmd_list_element *c)
 494 {
 495   struct gdbarch_info info;
 496
 497   gdbarch_info_init (&info);
 498
 499   if (strcmp (set_architecture_string, "auto") == 0)
 500     {
 501       target_architecture_user = NULL;
 502       if (!gdbarch_update_p (info))
 503         internal_error (__FILE__, __LINE__,
 504                         _("could not select an architecture automatically"));
 505     }
 506   else
 507     {
 508       info.bfd_arch_info = bfd_scan_arch (set_architecture_string);
 509       if (info.bfd_arch_info == NULL)
 510         internal_error (__FILE__, __LINE__,
 511                         _("set_architecture: bfd_scan_arch failed"));
 512       if (gdbarch_update_p (info))
 513         target_architecture_user = info.bfd_arch_info;
 514       else
 515         printf_unfiltered (_("Architecture `%s' not recognized.\n"),
 516                            set_architecture_string);
 517     }
 518   show_architecture (gdb_stdout, from_tty, NULL, NULL);
 519 }
 520
 521 /* Try to select a global architecture that matches "info".  Return
 522    non-zero if the attempt succeeds.  */
 523 int
 524 gdbarch_update_p (struct gdbarch_info info)
 525 {
 526   struct gdbarch *new_gdbarch;
 527
 528   /* Check for the current file.  */
 529   if (info.abfd == NULL)
 530     info.abfd = exec_bfd;
 531   if (info.abfd == NULL)
 532     info.abfd = core_bfd;
 533
 534   /* Check for the current target description.  */
 535   if (info.target_desc == NULL)
 536     info.target_desc = target_current_description ();
 537
 538   new_gdbarch = gdbarch_find_by_info (info);
 539
 540   /* If there no architecture by that name, reject the request.  */
 541   if (new_gdbarch == NULL)
 542     {
 543       if (gdbarch_debug)
 544         fprintf_unfiltered (gdb_stdlog, "gdbarch_update_p: "
 545                             "Architecture not found\n");
 546       return 0;
 547     }
 548
 549   /* If it is the same old architecture, accept the request (but don't
 550      swap anything).  */
 551   if (new_gdbarch == target_gdbarch ())
 552     {
 553       if (gdbarch_debug)
 554         fprintf_unfiltered (gdb_stdlog, "gdbarch_update_p: "
 555                             "Architecture %s (%s) unchanged\n",
 556                             host_address_to_string (new_gdbarch),
 557                             gdbarch_bfd_arch_info (new_gdbarch)->printable_name);
 558       return 1;
 559     }
 560
 561   /* It's a new architecture, swap it in.  */
 562   if (gdbarch_debug)
 563     fprintf_unfiltered (gdb_stdlog, "gdbarch_update_p: "
 564                         "New architecture %s (%s) selected\n",
 565                         host_address_to_string (new_gdbarch),
 566                         gdbarch_bfd_arch_info (new_gdbarch)->printable_name);
 567   set_target_gdbarch (new_gdbarch);
 568
 569   return 1;
 570 }
 571
 572 /* Return the architecture for ABFD.  If no suitable architecture
 573    could be find, return NULL.  */
 574
 575 struct gdbarch *
 576 gdbarch_from_bfd (bfd *abfd)
 577 {
 578   struct gdbarch_info info;
 579   gdbarch_info_init (&info);
 580
 581   info.abfd = abfd;
 582   return gdbarch_find_by_info (info);
 583 }
 584
 585 /* Set the dynamic target-system-dependent parameters (architecture,
 586    byte-order) using information found in the BFD */
 587
 588 void
 589 set_gdbarch_from_file (bfd *abfd)
 590 {
 591   struct gdbarch_info info;
 592   struct gdbarch *gdbarch;
 593
 594   gdbarch_info_init (&info);
 595   info.abfd = abfd;
 596   info.target_desc = target_current_description ();
 597   gdbarch = gdbarch_find_by_info (info);
 598
 599   if (gdbarch == NULL)
 600     error (_("Architecture of file not recognized."));
 601   set_target_gdbarch (gdbarch);
 602 }
 603
 604 /* Initialize the current architecture.  Update the ``set
 605    architecture'' command so that it specifies a list of valid
 606    architectures.  */
 607
 608 #ifdef DEFAULT_BFD_ARCH
 609 extern const bfd_arch_info_type DEFAULT_BFD_ARCH;
 610 static const bfd_arch_info_type *default_bfd_arch = &DEFAULT_BFD_ARCH;
 611 #else
 612 static const bfd_arch_info_type *default_bfd_arch;
 613 #endif
 614
 615 #ifdef DEFAULT_BFD_VEC
 616 extern const bfd_target DEFAULT_BFD_VEC;
 617 static const bfd_target *default_bfd_vec = &DEFAULT_BFD_VEC;
 618 #else
 619 static const bfd_target *default_bfd_vec;
 620 #endif
 621
 622 static enum bfd_endian default_byte_order = BFD_ENDIAN_UNKNOWN;
 623
 624 void
 625 initialize_current_architecture (void)
 626 {
 627   const char **arches = gdbarch_printable_names ();
 628   struct gdbarch_info info;
 629
 630   /* determine a default architecture and byte order.  */
 631   gdbarch_info_init (&info);
 632
 633   /* Find a default architecture.  */
 634   if (default_bfd_arch == NULL)
 635     {
 636       /* Choose the architecture by taking the first one
 637          alphabetically.  */
 638       const char *chosen = arches[0];
 639       const char **arch;
 640       for (arch = arches; *arch != NULL; arch++)
 641         {
 642           if (strcmp (*arch, chosen) < 0)
 643             chosen = *arch;
 644         }
 645       if (chosen == NULL)
 646         internal_error (__FILE__, __LINE__,
 647                         _("initialize_current_architecture: No arch"));
 648       default_bfd_arch = bfd_scan_arch (chosen);
 649       if (default_bfd_arch == NULL)
 650         internal_error (__FILE__, __LINE__,
 651                         _("initialize_current_architecture: Arch not found"));
 652     }
 653
 654   info.bfd_arch_info = default_bfd_arch;
 655
 656   /* Take several guesses at a byte order.  */
 657   if (default_byte_order == BFD_ENDIAN_UNKNOWN
 658       && default_bfd_vec != NULL)
 659     {
 660       /* Extract BFD's default vector's byte order.  */
 661       switch (default_bfd_vec->byteorder)
 662         {
 663         case BFD_ENDIAN_BIG:
 664           default_byte_order = BFD_ENDIAN_BIG;
 665           break;
 666         case BFD_ENDIAN_LITTLE:
 667           default_byte_order = BFD_ENDIAN_LITTLE;
 668           break;
 669         default:
 670           break;
 671         }
 672     }
 673   if (default_byte_order == BFD_ENDIAN_UNKNOWN)
 674     {
 675       /* look for ``*el-*'' in the target name.  */
 676       const char *chp;
 677       chp = strchr (target_name, '-');
 678       if (chp != NULL
 679           && chp - 2 >= target_name
 680           && startswith (chp - 2, "el"))
 681         default_byte_order = BFD_ENDIAN_LITTLE;
 682     }
 683   if (default_byte_order == BFD_ENDIAN_UNKNOWN)
 684     {
 685       /* Wire it to big-endian!!! */
 686       default_byte_order = BFD_ENDIAN_BIG;
 687     }
 688
 689   info.byte_order = default_byte_order;
 690   info.byte_order_for_code = info.byte_order;
 691
 692   if (! gdbarch_update_p (info))
 693     internal_error (__FILE__, __LINE__,
 694                     _("initialize_current_architecture: Selection of "
 695                       "initial architecture failed"));
 696
 697   /* Create the ``set architecture'' command appending ``auto'' to the
 698      list of architectures.  */
 699   {
 700     /* Append ``auto''.  */
 701     int nr;
 702     for (nr = 0; arches[nr] != NULL; nr++);
 703     arches = XRESIZEVEC (const char *, arches, nr + 2);
 704     arches[nr + 0] = "auto";
 705     arches[nr + 1] = NULL;
 706     add_setshow_enum_cmd ("architecture", class_support,
 707                           arches, &set_architecture_string,
 708                           _("Set architecture of target."),
 709                           _("Show architecture of target."), NULL,
 710                           set_architecture, show_architecture,
 711                           &setlist, &showlist);
 712     add_alias_cmd ("processor", "architecture", class_support, 1, &setlist);
 713   }
 714 }
 715
 716
 717 /* Initialize a gdbarch info to values that will be automatically
 718    overridden.  Note: Originally, this ``struct info'' was initialized
 719    using memset(0).  Unfortunately, that ran into problems, namely
 720    BFD_ENDIAN_BIG is zero.  An explicit initialization function that
 721    can explicitly set each field to a well defined value is used.  */
 722
 723 void
 724 gdbarch_info_init (struct gdbarch_info *info)
 725 {
 726   memset (info, 0, sizeof (struct gdbarch_info));
 727   info->byte_order = BFD_ENDIAN_UNKNOWN;
 728   info->byte_order_for_code = info->byte_order;
 729 }
 730
 731 /* Similar to init, but this time fill in the blanks.  Information is
 732    obtained from the global "set ..." options and explicitly
 733    initialized INFO fields.  */
 734
 735 void
 736 gdbarch_info_fill (struct gdbarch_info *info)
 737 {
 738   /* "(gdb) set architecture ...".  */
 739   if (info->bfd_arch_info == NULL
 740       && target_architecture_user)
 741     info->bfd_arch_info = target_architecture_user;
 742   /* From the file.  */
 743   if (info->bfd_arch_info == NULL
 744       && info->abfd != NULL
 745       && bfd_get_arch (info->abfd) != bfd_arch_unknown
 746       && bfd_get_arch (info->abfd) != bfd_arch_obscure)
 747     info->bfd_arch_info = bfd_get_arch_info (info->abfd);
 748   /* From the target.  */
 749   if (info->target_desc != NULL)
 750     info->bfd_arch_info = choose_architecture_for_target
 751                            (info->target_desc, info->bfd_arch_info);
 752   /* From the default.  */
 753   if (info->bfd_arch_info == NULL)
 754     info->bfd_arch_info = default_bfd_arch;
 755
 756   /* "(gdb) set byte-order ...".  */
 757   if (info->byte_order == BFD_ENDIAN_UNKNOWN
 758       && target_byte_order_user != BFD_ENDIAN_UNKNOWN)
 759     info->byte_order = target_byte_order_user;
 760   /* From the INFO struct.  */
 761   if (info->byte_order == BFD_ENDIAN_UNKNOWN
 762       && info->abfd != NULL)
 763     info->byte_order = (bfd_big_endian (info->abfd) ? BFD_ENDIAN_BIG
 764                         : bfd_little_endian (info->abfd) ? BFD_ENDIAN_LITTLE
 765                         : BFD_ENDIAN_UNKNOWN);
 766   /* From the default.  */
 767   if (info->byte_order == BFD_ENDIAN_UNKNOWN)
 768     info->byte_order = default_byte_order;
 769   info->byte_order_for_code = info->byte_order;
 770   /* Wire the default to the last selected byte order.  */
 771   default_byte_order = info->byte_order;
 772
 773   /* "(gdb) set osabi ...".  Handled by gdbarch_lookup_osabi.  */
 774   /* From the manual override, or from file.  */
 775   if (info->osabi == GDB_OSABI_UNKNOWN)
 776     info->osabi = gdbarch_lookup_osabi (info->abfd);
 777   /* From the target.  */
 778
 779   if (info->osabi == GDB_OSABI_UNKNOWN && info->target_desc != NULL)
 780     info->osabi = tdesc_osabi (info->target_desc);
 781   /* From the configured default.  */
 782 #ifdef GDB_OSABI_DEFAULT
 783   if (info->osabi == GDB_OSABI_UNKNOWN)
 784     info->osabi = GDB_OSABI_DEFAULT;
 785 #endif
 786   /* If we still don't know which osabi to pick, pick none.  */
 787   if (info->osabi == GDB_OSABI_UNKNOWN)
 788     info->osabi = GDB_OSABI_NONE;
 789
 790   /* Must have at least filled in the architecture.  */
 791   gdb_assert (info->bfd_arch_info != NULL);
 792 }
 793
 794 /* Return "current" architecture.  If the target is running, this is
 795    the architecture of the selected frame.  Otherwise, the "current"
 796    architecture defaults to the target architecture.
 797
 798    This function should normally be called solely by the command
 799    interpreter routines to determine the architecture to execute a
 800    command in.  */
 801 struct gdbarch *
 802 get_current_arch (void)
 803 {
 804   if (has_stack_frames ())
 805     return get_frame_arch (get_selected_frame (NULL));
 806   else
 807     return target_gdbarch ();
 808 }
 809
 810 int
 811 default_has_shared_address_space (struct gdbarch *gdbarch)
 812 {
 813   /* Simply say no.  In most unix-like targets each inferior/process
 814      has its own address space.  */
 815   return 0;
 816 }
 817
 818 int
 819 default_fast_tracepoint_valid_at (struct gdbarch *gdbarch, CORE_ADDR addr,
 820                                   std::string *msg)
 821 {
 822   /* We don't know if maybe the target has some way to do fast
 823      tracepoints that doesn't need gdbarch, so always say yes.  */
 824   if (msg)
 825     msg->clear ();
 826   return 1;
 827 }
 828
 829 const gdb_byte *
 830 default_breakpoint_from_pc (struct gdbarch *gdbarch, CORE_ADDR *pcptr,
 831                             int *lenptr)
 832 {
 833   int kind = gdbarch_breakpoint_kind_from_pc (gdbarch, pcptr);
 834
 835   return gdbarch_sw_breakpoint_from_kind (gdbarch, kind, lenptr);
 836 }
 837 int
 838 default_breakpoint_kind_from_current_state (struct gdbarch *gdbarch,
 839                                             struct regcache *regcache,
 840                                             CORE_ADDR *pcptr)
 841 {
 842   return gdbarch_breakpoint_kind_from_pc (gdbarch, pcptr);
 843 }
 844
 845
 846 void
 847 default_gen_return_address (struct gdbarch *gdbarch,
 848                             struct agent_expr *ax, struct axs_value *value,
 849                             CORE_ADDR scope)
 850 {
 851   error (_("This architecture has no method to collect a return address."));
 852 }
 853
 854 int
 855 default_return_in_first_hidden_param_p (struct gdbarch *gdbarch,
 856                                         struct type *type)
 857 {
 858   /* Usually, the return value's address is stored the in the "first hidden"
 859      parameter if the return value should be passed by reference, as
 860      specified in ABI.  */
 861   return !(language_pass_by_reference (type).trivially_copyable);
 862 }
 863
 864 int default_insn_is_call (struct gdbarch *gdbarch, CORE_ADDR addr)
 865 {
 866   return 0;
 867 }
 868
 869 int default_insn_is_ret (struct gdbarch *gdbarch, CORE_ADDR addr)
 870 {
 871   return 0;
 872 }
 873
 874 int default_insn_is_jump (struct gdbarch *gdbarch, CORE_ADDR addr)
 875 {
 876   return 0;
 877 }
 878
 879 /*  See arch-utils.h.  */
 880
 881 bool
 882 default_program_breakpoint_here_p (struct gdbarch *gdbarch,
 883                                    CORE_ADDR address)
 884 {
 885   int len;
 886   const gdb_byte *bpoint = gdbarch_breakpoint_from_pc (gdbarch, &address, &len);
 887
 888   /* Software breakpoints unsupported?  */
 889   if (bpoint == nullptr)
 890     return false;
 891
 892   gdb_byte *target_mem = (gdb_byte *) alloca (len);
 893
 894   /* Enable the automatic memory restoration from breakpoints while
 895      we read the memory.  Otherwise we may find temporary breakpoints, ones
 896      inserted by GDB, and flag them as permanent breakpoints.  */
 897   scoped_restore restore_memory
 898     = make_scoped_restore_show_memory_breakpoints (0);
 899
 900   if (target_read_memory (address, target_mem, len) == 0)
 901     {
 902       /* Check if this is a breakpoint instruction for this architecture,
 903          including ones used by GDB.  */
 904       if (memcmp (target_mem, bpoint, len) == 0)
 905         return true;
 906     }
 907
 908   return false;
 909 }
 910
 911 void
 912 default_skip_permanent_breakpoint (struct regcache *regcache)
 913 {
 914   struct gdbarch *gdbarch = regcache->arch ();
 915   CORE_ADDR current_pc = regcache_read_pc (regcache);
 916   int bp_len;
 917
 918   gdbarch_breakpoint_from_pc (gdbarch, &current_pc, &bp_len);
 919   current_pc += bp_len;
 920   regcache_write_pc (regcache, current_pc);
 921 }
 922
 923 CORE_ADDR
 924 default_infcall_mmap (CORE_ADDR size, unsigned prot)
 925 {
 926   error (_("This target does not support inferior memory allocation by mmap."));
 927 }
 928
 929 void
 930 default_infcall_munmap (CORE_ADDR addr, CORE_ADDR size)
 931 {
 932   /* Memory reserved by inferior mmap is kept leaked.  */
 933 }
 934
 935 /* -mcmodel=large is used so that no GOT (Global Offset Table) is needed to be
 936    created in inferior memory by GDB (normally it is set by ld.so).  */
 937
 938 std::string
 939 default_gcc_target_options (struct gdbarch *gdbarch)
 940 {
 941   return string_printf ("-m%d%s", gdbarch_ptr_bit (gdbarch),
 942                         (gdbarch_ptr_bit (gdbarch) == 64
 943                          ? " -mcmodel=large" : ""));
 944 }
 945
 946 /* gdbarch gnu_triplet_regexp method.  */
 947
 948 const char *
 949 default_gnu_triplet_regexp (struct gdbarch *gdbarch)
 950 {
 951   return gdbarch_bfd_arch_info (gdbarch)->arch_name;
 952 }
 953
 954 /* Default method for gdbarch_addressable_memory_unit_size.  By default, a memory byte has
 955    a size of 1 octet.  */
 956
 957 int
 958 default_addressable_memory_unit_size (struct gdbarch *gdbarch)
 959 {
 960   return 1;
 961 }
 962
 963 void
 964 default_guess_tracepoint_registers (struct gdbarch *gdbarch,
 965                                     struct regcache *regcache,
 966                                     CORE_ADDR addr)
 967 {
 968   int pc_regno = gdbarch_pc_regnum (gdbarch);
 969   gdb_byte *regs;
 970
 971   /* This guessing code below only works if the PC register isn't
 972      a pseudo-register.  The value of a pseudo-register isn't stored
 973      in the (non-readonly) regcache -- instead it's recomputed
 974      (probably from some other cached raw register) whenever the
 975      register is read.  In this case, a custom method implementation
 976      should be used by the architecture.  */
 977   if (pc_regno < 0 || pc_regno >= gdbarch_num_regs (gdbarch))
 978     return;
 979
 980   regs = (gdb_byte *) alloca (register_size (gdbarch, pc_regno));
 981   store_unsigned_integer (regs, register_size (gdbarch, pc_regno),
 982                           gdbarch_byte_order (gdbarch), addr);
 983   regcache->raw_supply (pc_regno, regs);
 984 }
 985
 986 int
 987 default_print_insn (bfd_vma memaddr, disassemble_info *info)
 988 {
 989   disassembler_ftype disassemble_fn;
 990
 991   disassemble_fn = disassembler (info->arch, info->endian == BFD_ENDIAN_BIG,
 992                                  info->mach, exec_bfd);
 993
 994   gdb_assert (disassemble_fn != NULL);
 995   return (*disassemble_fn) (memaddr, info);
 996 }
 997
 998 /* See arch-utils.h.  */
 999
1000 CORE_ADDR
1001 gdbarch_skip_prologue_noexcept (gdbarch *gdbarch, CORE_ADDR pc) noexcept
1002 {
1003   CORE_ADDR new_pc = pc;
1004
1005   try
1006     {
1007       new_pc = gdbarch_skip_prologue (gdbarch, pc);
1008     }
1009   catch (const gdb_exception &ex)
1010     {}
1011
1012   return new_pc;
1013 }
1014
1015 /* See arch-utils.h.  */
1016
1017 bool
1018 default_in_indirect_branch_thunk (gdbarch *gdbarch, CORE_ADDR pc)
1019 {
1020   return false;
1021 }
1022
1023 /* See arch-utils.h.  */
1024
1025 ULONGEST
1026 default_type_align (struct gdbarch *gdbarch, struct type *type)
1027 {
1028   return 0;
1029 }
1030
1031 /* See arch-utils.h.  */
1032
1033 std::string
1034 default_get_pc_address_flags (frame_info *frame, CORE_ADDR pc)
1035 {
1036   return "";
1037 }
1038
1039 void _initialize_gdbarch_utils ();
1040 void
1041 _initialize_gdbarch_utils ()
1042 {
1043   add_setshow_enum_cmd ("endian", class_support,
1044                         endian_enum, &set_endian_string,
1045                         _("Set endianness of target."),
1046                         _("Show endianness of target."),
1047                         NULL, set_endian, show_endian,
1048                         &setlist, &showlist);
1049 }