gdb/frame.h

   1 /* Definitions for dealing with stack frames, for GDB, the GNU debugger.
   2
   3    Copyright (C) 1986-2021 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 #if !defined (FRAME_H)
  21 #define FRAME_H 1
  22
  23 /* The following is the intended naming schema for frame functions.
  24    It isn't 100% consistent, but it is approaching that.  Frame naming
  25    schema:
  26
  27    Prefixes:
  28
  29    get_frame_WHAT...(): Get WHAT from the THIS frame (functionally
  30    equivalent to THIS->next->unwind->what)
  31
  32    frame_unwind_WHAT...(): Unwind THIS frame's WHAT from the NEXT
  33    frame.
  34
  35    frame_unwind_caller_WHAT...(): Unwind WHAT for NEXT stack frame's
  36    real caller.  Any inlined functions in NEXT's stack frame are
  37    skipped.  Use these to ignore any potentially inlined functions,
  38    e.g. inlined into the first instruction of a library trampoline.
  39
  40    get_stack_frame_WHAT...(): Get WHAT for THIS frame, but if THIS is
  41    inlined, skip to the containing stack frame.
  42
  43    put_frame_WHAT...(): Put a value into this frame (unsafe, need to
  44    invalidate the frame / regcache afterwards) (better name more
  45    strongly hinting at its unsafeness)
  46
  47    safe_....(): Safer version of various functions, doesn't throw an
  48    error (leave this for later?).  Returns true / non-NULL if the request
  49    succeeds, false / NULL otherwise.
  50
  51    Suffixes:
  52
  53    void /frame/_WHAT(): Read WHAT's value into the buffer parameter.
  54
  55    ULONGEST /frame/_WHAT_unsigned(): Return an unsigned value (the
  56    alternative is *frame_unsigned_WHAT).
  57
  58    LONGEST /frame/_WHAT_signed(): Return WHAT signed value.
  59
  60    What:
  61
  62    /frame/_memory* (frame, coreaddr, len [, buf]): Extract/return
  63    *memory.
  64
  65    /frame/_register* (frame, regnum [, buf]): extract/return register.
  66
  67    CORE_ADDR /frame/_{pc,sp,...} (frame): Resume address, innner most
  68    stack *address, ...
  69
  70    */
  71
  72 #include "language.h"
  73 #include "cli/cli-option.h"
  74
  75 struct symtab_and_line;
  76 struct frame_unwind;
  77 struct frame_base;
  78 struct block;
  79 struct gdbarch;
  80 struct ui_file;
  81 struct ui_out;
  82 struct frame_print_options;
  83
  84 /* Status of a given frame's stack.  */
  85
  86 enum frame_id_stack_status
  87 {
  88   /* Stack address is invalid.  */
  89   FID_STACK_INVALID = 0,
  90
  91   /* Stack address is valid, and is found in the stack_addr field.  */
  92   FID_STACK_VALID = 1,
  93
  94   /* Sentinel frame.  */
  95   FID_STACK_SENTINEL = 2,
  96
  97   /* Outer frame.  Since a frame's stack address is typically defined as the
  98      value the stack pointer had prior to the activation of the frame, an outer
  99      frame doesn't have a stack address.  The frame ids of frames inlined in the
 100      outer frame are also of this type.  */
 101   FID_STACK_OUTER = 3,
 102
 103   /* Stack address is unavailable.  I.e., there's a valid stack, but
 104      we don't know where it is (because memory or registers we'd
 105      compute it from were not collected).  */
 106   FID_STACK_UNAVAILABLE = -1
 107 };
 108
 109 /* The frame object.  */
 110
 111 struct frame_info;
 112
 113 /* The frame object's ID.  This provides a per-frame unique identifier
 114    that can be used to relocate a `struct frame_info' after a target
 115    resume or a frame cache destruct.  It of course assumes that the
 116    inferior hasn't unwound the stack past that frame.  */
 117
 118 struct frame_id
 119 {
 120   /* The frame's stack address.  This shall be constant through out
 121      the lifetime of a frame.  Note that this requirement applies to
 122      not just the function body, but also the prologue and (in theory
 123      at least) the epilogue.  Since that value needs to fall either on
 124      the boundary, or within the frame's address range, the frame's
 125      outer-most address (the inner-most address of the previous frame)
 126      is used.  Watch out for all the legacy targets that still use the
 127      function pointer register or stack pointer register.  They are
 128      wrong.
 129
 130      This field is valid only if frame_id.stack_status is
 131      FID_STACK_VALID.  It will be 0 for other
 132      FID_STACK_... statuses.  */
 133   CORE_ADDR stack_addr;
 134
 135   /* The frame's code address.  This shall be constant through out the
 136      lifetime of the frame.  While the PC (a.k.a. resume address)
 137      changes as the function is executed, this code address cannot.
 138      Typically, it is set to the address of the entry point of the
 139      frame's function (as returned by get_frame_func).
 140
 141      For inlined functions (INLINE_DEPTH != 0), this is the address of
 142      the first executed instruction in the block corresponding to the
 143      inlined function.
 144
 145      This field is valid only if code_addr_p is true.  Otherwise, this
 146      frame is considered to have a wildcard code address, i.e. one that
 147      matches every address value in frame comparisons.  */
 148   CORE_ADDR code_addr;
 149
 150   /* The frame's special address.  This shall be constant through out the
 151      lifetime of the frame.  This is used for architectures that may have
 152      frames that do not change the stack but are still distinct and have
 153      some form of distinct identifier (e.g. the ia64 which uses a 2nd
 154      stack for registers).  This field is treated as unordered - i.e. will
 155      not be used in frame ordering comparisons.
 156
 157      This field is valid only if special_addr_p is true.  Otherwise, this
 158      frame is considered to have a wildcard special address, i.e. one that
 159      matches every address value in frame comparisons.  */
 160   CORE_ADDR special_addr;
 161
 162   /* Flags to indicate the above fields have valid contents.  */
 163   ENUM_BITFIELD(frame_id_stack_status) stack_status : 3;
 164   unsigned int code_addr_p : 1;
 165   unsigned int special_addr_p : 1;
 166
 167   /* It is non-zero for a frame made up by GDB without stack data
 168      representation in inferior, such as INLINE_FRAME or TAILCALL_FRAME.
 169      Caller of inlined function will have it zero, each more inner called frame
 170      will have it increasingly one, two etc.  Similarly for TAILCALL_FRAME.  */
 171   int artificial_depth;
 172 };
 173
 174 /* Save and restore the currently selected frame.  */
 175
 176 class scoped_restore_selected_frame
 177 {
 178 public:
 179   /* Save the currently selected frame.  */
 180   scoped_restore_selected_frame ();
 181
 182   /* Restore the currently selected frame.  */
 183   ~scoped_restore_selected_frame ();
 184
 185   DISABLE_COPY_AND_ASSIGN (scoped_restore_selected_frame);
 186
 187 private:
 188
 189   /* The ID and level of the previously selected frame.  */
 190   struct frame_id m_fid;
 191   int m_level;
 192
 193   /* Save/restore the language as well, because selecting a frame
 194      changes the current language to the frame's language if "set
 195      language auto".  */
 196   enum language m_lang;
 197 };
 198
 199 /* Methods for constructing and comparing Frame IDs.  */
 200
 201 /* For convenience.  All fields are zero.  This means "there is no frame".  */
 202 extern const struct frame_id null_frame_id;
 203
 204 /* Sentinel frame.  */
 205 extern const struct frame_id sentinel_frame_id;
 206
 207 /* This means "there is no frame ID, but there is a frame".  It should be
 208    replaced by best-effort frame IDs for the outermost frame, somehow.
 209    The implementation is only special_addr_p set.  */
 210 extern const struct frame_id outer_frame_id;
 211
 212 /* Flag to control debugging.  */
 213
 214 extern unsigned int frame_debug;
 215
 216 /* Construct a frame ID.  The first parameter is the frame's constant
 217    stack address (typically the outer-bound), and the second the
 218    frame's constant code address (typically the entry point).
 219    The special identifier address is set to indicate a wild card.  */
 220 extern struct frame_id frame_id_build (CORE_ADDR stack_addr,
 221                                        CORE_ADDR code_addr);
 222
 223 /* Construct a special frame ID.  The first parameter is the frame's constant
 224    stack address (typically the outer-bound), the second is the
 225    frame's constant code address (typically the entry point),
 226    and the third parameter is the frame's special identifier address.  */
 227 extern struct frame_id frame_id_build_special (CORE_ADDR stack_addr,
 228                                                CORE_ADDR code_addr,
 229                                                CORE_ADDR special_addr);
 230
 231 /* Construct a frame ID representing a frame where the stack address
 232    exists, but is unavailable.  CODE_ADDR is the frame's constant code
 233    address (typically the entry point).  The special identifier
 234    address is set to indicate a wild card.  */
 235 extern struct frame_id frame_id_build_unavailable_stack (CORE_ADDR code_addr);
 236
 237 /* Construct a frame ID representing a frame where the stack address
 238    exists, but is unavailable.  CODE_ADDR is the frame's constant code
 239    address (typically the entry point).  SPECIAL_ADDR is the special
 240    identifier address.  */
 241 extern struct frame_id
 242   frame_id_build_unavailable_stack_special (CORE_ADDR code_addr,
 243                                             CORE_ADDR special_addr);
 244
 245 /* Construct a wild card frame ID.  The parameter is the frame's constant
 246    stack address (typically the outer-bound).  The code address as well
 247    as the special identifier address are set to indicate wild cards.  */
 248 extern struct frame_id frame_id_build_wild (CORE_ADDR stack_addr);
 249
 250 /* Returns true when L is a valid frame.  */
 251 extern bool frame_id_p (frame_id l);
 252
 253 /* Returns true when L is a valid frame representing a frame made up by GDB
 254    without stack data representation in inferior, such as INLINE_FRAME or
 255    TAILCALL_FRAME.  */
 256 extern bool frame_id_artificial_p (frame_id l);
 257
 258 /* Returns true when L and R identify the same frame.  */
 259 extern bool frame_id_eq (frame_id l, frame_id r);
 260
 261 /* Write the internal representation of a frame ID on the specified
 262    stream.  */
 263 extern void fprint_frame_id (struct ui_file *file, struct frame_id id);
 264
 265
 266 /* Frame types.  Some are real, some are signal trampolines, and some
 267    are completely artificial (dummy).  */
 268
 269 enum frame_type
 270 {
 271   /* A true stack frame, created by the target program during normal
 272      execution.  */
 273   NORMAL_FRAME,
 274   /* A fake frame, created by GDB when performing an inferior function
 275      call.  */
 276   DUMMY_FRAME,
 277   /* A frame representing an inlined function, associated with an
 278      upcoming (prev, outer, older) NORMAL_FRAME.  */
 279   INLINE_FRAME,
 280   /* A virtual frame of a tail call - see dwarf2_tailcall_frame_unwind.  */
 281   TAILCALL_FRAME,
 282   /* In a signal handler, various OSs handle this in various ways.
 283      The main thing is that the frame may be far from normal.  */
 284   SIGTRAMP_FRAME,
 285   /* Fake frame representing a cross-architecture call.  */
 286   ARCH_FRAME,
 287   /* Sentinel or registers frame.  This frame obtains register values
 288      direct from the inferior's registers.  */
 289   SENTINEL_FRAME
 290 };
 291
 292 /* For every stopped thread, GDB tracks two frames: current and
 293    selected.  Current frame is the inner most frame of the selected
 294    thread.  Selected frame is the one being examined by the GDB
 295    CLI (selected using `up', `down', ...).  The frames are created
 296    on-demand (via get_prev_frame()) and then held in a frame cache.  */
 297 /* FIXME: cagney/2002-11-28: Er, there is a lie here.  If you do the
 298    sequence: `thread 1; up; thread 2; thread 1' you lose thread 1's
 299    selected frame.  At present GDB only tracks the selected frame of
 300    the current thread.  But be warned, that might change.  */
 301 /* FIXME: cagney/2002-11-14: At any time, only one thread's selected
 302    and current frame can be active.  Switching threads causes gdb to
 303    discard all that cached frame information.  Ulgh!  Instead, current
 304    and selected frame should be bound to a thread.  */
 305
 306 /* On demand, create the inner most frame using information found in
 307    the inferior.  If the inner most frame can't be created, throw an
 308    error.  */
 309 extern struct frame_info *get_current_frame (void);
 310
 311 /* Does the current target interface have enough state to be able to
 312    query the current inferior for frame info, and is the inferior in a
 313    state where that is possible?  */
 314 extern bool has_stack_frames ();
 315
 316 /* Invalidates the frame cache (this function should have been called
 317    invalidate_cached_frames).
 318
 319    FIXME: cagney/2002-11-28: There should be two methods: one that
 320    reverts the thread's selected frame back to current frame (for when
 321    the inferior resumes) and one that does not (for when the user
 322    modifies the target invalidating the frame cache).  */
 323 extern void reinit_frame_cache (void);
 324
 325 /* Return the selected frame.  Always returns non-NULL.  If there
 326    isn't an inferior sufficient for creating a frame, an error is
 327    thrown.  When MESSAGE is non-NULL, use it for the error message,
 328    otherwise use a generic error message.  */
 329 /* FIXME: cagney/2002-11-28: At present, when there is no selected
 330    frame, this function always returns the current (inner most) frame.
 331    It should instead, when a thread has previously had its frame
 332    selected (but not resumed) and the frame cache invalidated, find
 333    and then return that thread's previously selected frame.  */
 334 extern struct frame_info *get_selected_frame (const char *message = nullptr);
 335
 336 /* Select a specific frame.  NULL implies re-select the inner most
 337    frame.  */
 338 extern void select_frame (struct frame_info *);
 339
 340 /* Save the frame ID and frame level of the selected frame in FRAME_ID
 341    and FRAME_LEVEL, to be restored later with restore_selected_frame.
 342
 343    This is preferred over getting the same info out of
 344    get_selected_frame directly because this function does not create
 345    the selected-frame's frame_info object if it hasn't been created
 346    yet, and thus is more efficient and doesn't throw.  */
 347 extern void save_selected_frame (frame_id *frame_id, int *frame_level)
 348   noexcept;
 349
 350 /* Restore selected frame as saved with save_selected_frame.
 351
 352    Does not try to find the corresponding frame_info object.  Instead
 353    the next call to get_selected_frame will look it up and cache the
 354    result.
 355
 356    This function does not throw.  It is designed to be safe to called
 357    from the destructors of RAII types.  */
 358 extern void restore_selected_frame (frame_id frame_id, int frame_level)
 359   noexcept;
 360
 361 /* Lookup the frame_info object for the selected frame FRAME_ID /
 362    FRAME_LEVEL and cache the result.
 363
 364    If FRAME_LEVEL > 0 and the originally selected frame isn't found,
 365    warn and select the innermost (current) frame.  */
 366 extern void lookup_selected_frame (frame_id frame_id, int frame_level);
 367
 368 /* Given a FRAME, return the next (more inner, younger) or previous
 369    (more outer, older) frame.  */
 370 extern struct frame_info *get_prev_frame (struct frame_info *);
 371 extern struct frame_info *get_next_frame (struct frame_info *);
 372
 373 /* Like get_next_frame(), but allows return of the sentinel frame.  NULL
 374    is never returned.  */
 375 extern struct frame_info *get_next_frame_sentinel_okay (struct frame_info *);
 376
 377 /* Return a "struct frame_info" corresponding to the frame that called
 378    THIS_FRAME.  Returns NULL if there is no such frame.
 379
 380    Unlike get_prev_frame, this function always tries to unwind the
 381    frame.  */
 382 extern struct frame_info *get_prev_frame_always (struct frame_info *);
 383
 384 /* Given a frame's ID, relocate the frame.  Returns NULL if the frame
 385    is not found.  */
 386 extern struct frame_info *frame_find_by_id (struct frame_id id);
 387
 388 /* Given a frame's ID, find the previous frame's ID.  Returns null_frame_id
 389    if the frame is not found.  */
 390 extern struct frame_id get_prev_frame_id_by_id (struct frame_id id);
 391
 392 /* Base attributes of a frame: */
 393
 394 /* The frame's `resume' address.  Where the program will resume in
 395    this frame.
 396
 397    This replaced: frame->pc; */
 398 extern CORE_ADDR get_frame_pc (struct frame_info *);
 399
 400 /* Same as get_frame_pc, but return a boolean indication of whether
 401    the PC is actually available, instead of throwing an error.  */
 402
 403 extern bool get_frame_pc_if_available (frame_info *frame, CORE_ADDR *pc);
 404
 405 /* An address (not necessarily aligned to an instruction boundary)
 406    that falls within THIS frame's code block.
 407
 408    When a function call is the last statement in a block, the return
 409    address for the call may land at the start of the next block.
 410    Similarly, if a no-return function call is the last statement in
 411    the function, the return address may end up pointing beyond the
 412    function, and possibly at the start of the next function.
 413
 414    These methods make an allowance for this.  For call frames, this
 415    function returns the frame's PC-1 which "should" be an address in
 416    the frame's block.  */
 417
 418 extern CORE_ADDR get_frame_address_in_block (struct frame_info *this_frame);
 419
 420 /* Same as get_frame_address_in_block, but returns a boolean
 421    indication of whether the frame address is determinable (when the
 422    PC is unavailable, it will not be), instead of possibly throwing an
 423    error trying to read an unavailable PC.  */
 424
 425 extern bool get_frame_address_in_block_if_available (frame_info *this_frame,
 426                                                      CORE_ADDR *pc);
 427
 428 /* The frame's inner-most bound.  AKA the stack-pointer.  Confusingly
 429    known as top-of-stack.  */
 430
 431 extern CORE_ADDR get_frame_sp (struct frame_info *);
 432
 433 /* Following on from the `resume' address.  Return the entry point
 434    address of the function containing that resume address, or zero if
 435    that function isn't known.  */
 436 extern CORE_ADDR get_frame_func (struct frame_info *fi);
 437
 438 /* Same as get_frame_func, but returns a boolean indication of whether
 439    the frame function is determinable (when the PC is unavailable, it
 440    will not be), instead of possibly throwing an error trying to read
 441    an unavailable PC.  */
 442
 443 extern bool get_frame_func_if_available (frame_info *fi, CORE_ADDR *);
 444
 445 /* Closely related to the resume address, various symbol table
 446    attributes that are determined by the PC.  Note that for a normal
 447    frame, the PC refers to the resume address after the return, and
 448    not the call instruction.  In such a case, the address is adjusted
 449    so that it (approximately) identifies the call site (and not the
 450    return site).
 451
 452    NOTE: cagney/2002-11-28: The frame cache could be used to cache the
 453    computed value.  Working on the assumption that the bottle-neck is
 454    in the single step code, and that code causes the frame cache to be
 455    constantly flushed, caching things in a frame is probably of little
 456    benefit.  As they say `show us the numbers'.
 457
 458    NOTE: cagney/2002-11-28: Plenty more where this one came from:
 459    find_frame_block(), find_frame_partial_function(),
 460    find_frame_symtab(), find_frame_function().  Each will need to be
 461    carefully considered to determine if the real intent was for it to
 462    apply to the PC or the adjusted PC.  */
 463 extern symtab_and_line find_frame_sal (frame_info *frame);
 464
 465 /* Set the current source and line to the location given by frame
 466    FRAME, if possible.  */
 467
 468 void set_current_sal_from_frame (struct frame_info *);
 469
 470 /* Return the frame base (what ever that is) (DEPRECATED).
 471
 472    Old code was trying to use this single method for two conflicting
 473    purposes.  Such code needs to be updated to use either of:
 474
 475    get_frame_id: A low level frame unique identifier, that consists of
 476    both a stack and a function address, that can be used to uniquely
 477    identify a frame.  This value is determined by the frame's
 478    low-level unwinder, the stack part [typically] being the
 479    top-of-stack of the previous frame, and the function part being the
 480    function's start address.  Since the correct identification of a
 481    frameless function requires both a stack and function address,
 482    the old get_frame_base method was not sufficient.
 483
 484    get_frame_base_address: get_frame_locals_address:
 485    get_frame_args_address: A set of high-level debug-info dependant
 486    addresses that fall within the frame.  These addresses almost
 487    certainly will not match the stack address part of a frame ID (as
 488    returned by get_frame_base).
 489
 490    This replaced: frame->frame; */
 491
 492 extern CORE_ADDR get_frame_base (struct frame_info *);
 493
 494 /* Return the per-frame unique identifer.  Can be used to relocate a
 495    frame after a frame cache flush (and other similar operations).  If
 496    FI is NULL, return the null_frame_id.
 497
 498    NOTE: kettenis/20040508: These functions return a structure.  On
 499    platforms where structures are returned in static storage (vax,
 500    m68k), this may trigger compiler bugs in code like:
 501
 502    if (frame_id_eq (get_frame_id (l), get_frame_id (r)))
 503
 504    where the return value from the first get_frame_id (l) gets
 505    overwritten by the second get_frame_id (r).  Please avoid writing
 506    code like this.  Use code like:
 507
 508    struct frame_id id = get_frame_id (l);
 509    if (frame_id_eq (id, get_frame_id (r)))
 510
 511    instead, since that avoids the bug.  */
 512 extern struct frame_id get_frame_id (struct frame_info *fi);
 513 extern struct frame_id get_stack_frame_id (struct frame_info *fi);
 514 extern struct frame_id frame_unwind_caller_id (struct frame_info *next_frame);
 515
 516 /* Assuming that a frame is `normal', return its base-address, or 0 if
 517    the information isn't available.  NOTE: This address is really only
 518    meaningful to the frame's high-level debug info.  */
 519 extern CORE_ADDR get_frame_base_address (struct frame_info *);
 520
 521 /* Assuming that a frame is `normal', return the base-address of the
 522    local variables, or 0 if the information isn't available.  NOTE:
 523    This address is really only meaningful to the frame's high-level
 524    debug info.  Typically, the argument and locals share a single
 525    base-address.  */
 526 extern CORE_ADDR get_frame_locals_address (struct frame_info *);
 527
 528 /* Assuming that a frame is `normal', return the base-address of the
 529    parameter list, or 0 if that information isn't available.  NOTE:
 530    This address is really only meaningful to the frame's high-level
 531    debug info.  Typically, the argument and locals share a single
 532    base-address.  */
 533 extern CORE_ADDR get_frame_args_address (struct frame_info *);
 534
 535 /* The frame's level: 0 for innermost, 1 for its caller, ...; or -1
 536    for an invalid frame).  */
 537 extern int frame_relative_level (struct frame_info *fi);
 538
 539 /* Return the frame's type.  */
 540
 541 extern enum frame_type get_frame_type (struct frame_info *);
 542
 543 /* Return the frame's program space.  */
 544 extern struct program_space *get_frame_program_space (struct frame_info *);
 545
 546 /* Unwind THIS frame's program space from the NEXT frame.  */
 547 extern struct program_space *frame_unwind_program_space (struct frame_info *);
 548
 549 class address_space;
 550
 551 /* Return the frame's address space.  */
 552 extern const address_space *get_frame_address_space (struct frame_info *);
 553
 554 /* For frames where we can not unwind further, describe why.  */
 555
 556 enum unwind_stop_reason
 557   {
 558 #define SET(name, description) name,
 559 #define FIRST_ENTRY(name) UNWIND_FIRST = name,
 560 #define LAST_ENTRY(name) UNWIND_LAST = name,
 561 #define FIRST_ERROR(name) UNWIND_FIRST_ERROR = name,
 562
 563 #include "unwind_stop_reasons.def"
 564 #undef SET
 565 #undef FIRST_ENTRY
 566 #undef LAST_ENTRY
 567 #undef FIRST_ERROR
 568   };
 569
 570 /* Return the reason why we can't unwind past this frame.  */
 571
 572 enum unwind_stop_reason get_frame_unwind_stop_reason (struct frame_info *);
 573
 574 /* Translate a reason code to an informative string.  This converts the
 575    generic stop reason codes into a generic string describing the code.
 576    For a possibly frame specific string explaining the stop reason, use
 577    FRAME_STOP_REASON_STRING instead.  */
 578
 579 const char *unwind_stop_reason_to_string (enum unwind_stop_reason);
 580
 581 /* Return a possibly frame specific string explaining why the unwind
 582    stopped here.  E.g., if unwinding tripped on a memory error, this
 583    will return the error description string, which includes the address
 584    that we failed to access.  If there's no specific reason stored for
 585    a frame then a generic reason string will be returned.
 586
 587    Should only be called for frames that don't have a previous frame.  */
 588
 589 const char *frame_stop_reason_string (struct frame_info *);
 590
 591 /* Unwind the stack frame so that the value of REGNUM, in the previous
 592    (up, older) frame is returned.  If VALUEP is NULL, don't
 593    fetch/compute the value.  Instead just return the location of the
 594    value.  */
 595 extern void frame_register_unwind (frame_info *frame, int regnum,
 596                                    int *optimizedp, int *unavailablep,
 597                                    enum lval_type *lvalp,
 598                                    CORE_ADDR *addrp, int *realnump,
 599                                    gdb_byte *valuep);
 600
 601 /* Fetch a register from this, or unwind a register from the next
 602    frame.  Note that the get_frame methods are wrappers to
 603    frame->next->unwind.  They all [potentially] throw an error if the
 604    fetch fails.  The value methods never return NULL, but usually
 605    do return a lazy value.  */
 606
 607 extern void frame_unwind_register (frame_info *next_frame,
 608                                    int regnum, gdb_byte *buf);
 609 extern void get_frame_register (struct frame_info *frame,
 610                                 int regnum, gdb_byte *buf);
 611
 612 struct value *frame_unwind_register_value (frame_info *next_frame,
 613                                            int regnum);
 614 struct value *get_frame_register_value (struct frame_info *frame,
 615                                         int regnum);
 616
 617 extern LONGEST frame_unwind_register_signed (frame_info *next_frame,
 618                                              int regnum);
 619 extern LONGEST get_frame_register_signed (struct frame_info *frame,
 620                                           int regnum);
 621 extern ULONGEST frame_unwind_register_unsigned (frame_info *frame,
 622                                                 int regnum);
 623 extern ULONGEST get_frame_register_unsigned (struct frame_info *frame,
 624                                              int regnum);
 625
 626 /* Read a register from this, or unwind a register from the next
 627    frame.  Note that the read_frame methods are wrappers to
 628    get_frame_register_value, that do not throw if the result is
 629    optimized out or unavailable.  */
 630
 631 extern bool read_frame_register_unsigned (frame_info *frame,
 632                                           int regnum, ULONGEST *val);
 633
 634 /* Get the value of the register that belongs to this FRAME.  This
 635    function is a wrapper to the call sequence ``frame_register_unwind
 636    (get_next_frame (FRAME))''.  As per frame_register_unwind(), if
 637    VALUEP is NULL, the registers value is not fetched/computed.  */
 638
 639 extern void frame_register (struct frame_info *frame, int regnum,
 640                             int *optimizedp, int *unavailablep,
 641                             enum lval_type *lvalp,
 642                             CORE_ADDR *addrp, int *realnump,
 643                             gdb_byte *valuep);
 644
 645 /* The reverse.  Store a register value relative to the specified
 646    frame.  Note: this call makes the frame's state undefined.  The
 647    register and frame caches must be flushed.  */
 648 extern void put_frame_register (struct frame_info *frame, int regnum,
 649                                 const gdb_byte *buf);
 650
 651 /* Read LEN bytes from one or multiple registers starting with REGNUM
 652    in frame FRAME, starting at OFFSET, into BUF.  If the register
 653    contents are optimized out or unavailable, set *OPTIMIZEDP,
 654    *UNAVAILABLEP accordingly.  */
 655 extern bool get_frame_register_bytes (frame_info *frame, int regnum,
 656                                       CORE_ADDR offset,
 657                                       gdb::array_view<gdb_byte> buffer,
 658                                       int *optimizedp, int *unavailablep);
 659
 660 /* Write bytes from BUFFER to one or multiple registers starting with REGNUM
 661    in frame FRAME, starting at OFFSET.  */
 662 extern void put_frame_register_bytes (struct frame_info *frame, int regnum,
 663                                       CORE_ADDR offset,
 664                                       gdb::array_view<const gdb_byte> buffer);
 665
 666 /* Unwind the PC.  Strictly speaking return the resume address of the
 667    calling frame.  For GDB, `pc' is the resume address and not a
 668    specific register.  */
 669
 670 extern CORE_ADDR frame_unwind_caller_pc (struct frame_info *frame);
 671
 672 /* Discard the specified frame.  Restoring the registers to the state
 673    of the caller.  */
 674 extern void frame_pop (struct frame_info *frame);
 675
 676 /* Return memory from the specified frame.  A frame knows its thread /
 677    LWP and hence can find its way down to a target.  The assumption
 678    here is that the current and previous frame share a common address
 679    space.
 680
 681    If the memory read fails, these methods throw an error.
 682
 683    NOTE: cagney/2003-06-03: Should there be unwind versions of these
 684    methods?  That isn't clear.  Can code, for instance, assume that
 685    this and the previous frame's memory or architecture are identical?
 686    If architecture / memory changes are always separated by special
 687    adaptor frames this should be ok.  */
 688
 689 extern void get_frame_memory (struct frame_info *this_frame, CORE_ADDR addr,
 690                               gdb::array_view<gdb_byte> buffer);
 691 extern LONGEST get_frame_memory_signed (struct frame_info *this_frame,
 692                                         CORE_ADDR memaddr, int len);
 693 extern ULONGEST get_frame_memory_unsigned (struct frame_info *this_frame,
 694                                            CORE_ADDR memaddr, int len);
 695
 696 /* Same as above, but return true zero when the entire memory read
 697    succeeds, false otherwise.  */
 698 extern bool safe_frame_unwind_memory (frame_info *this_frame, CORE_ADDR addr,
 699                                       gdb::array_view<gdb_byte> buffer);
 700
 701 /* Return this frame's architecture.  */
 702 extern struct gdbarch *get_frame_arch (struct frame_info *this_frame);
 703
 704 /* Return the previous frame's architecture.  */
 705 extern struct gdbarch *frame_unwind_arch (frame_info *next_frame);
 706
 707 /* Return the previous frame's architecture, skipping inline functions.  */
 708 extern struct gdbarch *frame_unwind_caller_arch (struct frame_info *frame);
 709
 710
 711 /* Values for the source flag to be used in print_frame_info ().
 712    For all the cases below, the address is never printed if
 713    'set print address' is off.  When 'set print address' is on,
 714    the address is printed if the program counter is not at the
 715    beginning of the source line of the frame
 716    and PRINT_WHAT is != LOC_AND_ADDRESS.  */
 717 enum print_what
 718   {
 719     /* Print only the address, source line, like in stepi.  */
 720     SRC_LINE = -1,
 721     /* Print only the location, i.e. level, address,
 722        function, args (as controlled by 'set print frame-arguments'),
 723        file, line, line num.  */
 724     LOCATION,
 725     /* Print both of the above.  */
 726     SRC_AND_LOC,
 727     /* Print location only, print the address even if the program counter
 728        is at the beginning of the source line.  */
 729     LOC_AND_ADDRESS,
 730     /* Print only level and function,
 731        i.e. location only, without address, file, line, line num.  */
 732     SHORT_LOCATION
 733   };
 734
 735 /* Allocate zero initialized memory from the frame cache obstack.
 736    Appendices to the frame info (such as the unwind cache) should
 737    allocate memory using this method.  */
 738
 739 extern void *frame_obstack_zalloc (unsigned long size);
 740 #define FRAME_OBSTACK_ZALLOC(TYPE) \
 741   ((TYPE *) frame_obstack_zalloc (sizeof (TYPE)))
 742 #define FRAME_OBSTACK_CALLOC(NUMBER,TYPE) \
 743   ((TYPE *) frame_obstack_zalloc ((NUMBER) * sizeof (TYPE)))
 744
 745 class readonly_detached_regcache;
 746 /* Create a regcache, and copy the frame's registers into it.  */
 747 std::unique_ptr<readonly_detached_regcache> frame_save_as_regcache
 748     (struct frame_info *this_frame);
 749
 750 extern const struct block *get_frame_block (struct frame_info *,
 751                                             CORE_ADDR *addr_in_block);
 752
 753 /* Return the `struct block' that belongs to the selected thread's
 754    selected frame.  If the inferior has no state, return NULL.
 755
 756    NOTE: cagney/2002-11-29:
 757
 758    No state?  Does the inferior have any execution state (a core file
 759    does, an executable does not).  At present the code tests
 760    `target_has_stack' but I'm left wondering if it should test
 761    `target_has_registers' or, even, a merged target_has_state.
 762
 763    Should it look at the most recently specified SAL?  If the target
 764    has no state, should this function try to extract a block from the
 765    most recently selected SAL?  That way `list foo' would give it some
 766    sort of reference point.  Then again, perhaps that would confuse
 767    things.
 768
 769    Calls to this function can be broken down into two categories: Code
 770    that uses the selected block as an additional, but optional, data
 771    point; Code that uses the selected block as a prop, when it should
 772    have the relevant frame/block/pc explicitly passed in.
 773
 774    The latter can be eliminated by correctly parameterizing the code,
 775    the former though is more interesting.  Per the "address" command,
 776    it occurs in the CLI code and makes it possible for commands to
 777    work, even when the inferior has no state.  */
 778
 779 extern const struct block *get_selected_block (CORE_ADDR *addr_in_block);
 780
 781 extern struct symbol *get_frame_function (struct frame_info *);
 782
 783 extern CORE_ADDR get_pc_function_start (CORE_ADDR);
 784
 785 extern struct frame_info *find_relative_frame (struct frame_info *, int *);
 786
 787 /* Wrapper over print_stack_frame modifying current_uiout with UIOUT for
 788    the function call.  */
 789
 790 extern void print_stack_frame_to_uiout (struct ui_out *uiout,
 791                                         struct frame_info *, int print_level,
 792                                         enum print_what print_what,
 793                                         int set_current_sal);
 794
 795 extern void print_stack_frame (struct frame_info *, int print_level,
 796                                enum print_what print_what,
 797                                int set_current_sal);
 798
 799 extern void print_frame_info (const frame_print_options &fp_opts,
 800                               struct frame_info *, int print_level,
 801                               enum print_what print_what, int args,
 802                               int set_current_sal);
 803
 804 extern struct frame_info *block_innermost_frame (const struct block *);
 805
 806 extern bool deprecated_frame_register_read (frame_info *frame, int regnum,
 807                                             gdb_byte *buf);
 808
 809 /* From stack.c.  */
 810
 811 /* The possible choices of "set print frame-arguments".  */
 812 extern const char print_frame_arguments_all[];
 813 extern const char print_frame_arguments_scalars[];
 814 extern const char print_frame_arguments_none[];
 815
 816 /* The possible choices of "set print frame-info".  */
 817 extern const char print_frame_info_auto[];
 818 extern const char print_frame_info_source_line[];
 819 extern const char print_frame_info_location[];
 820 extern const char print_frame_info_source_and_location[];
 821 extern const char print_frame_info_location_and_address[];
 822 extern const char print_frame_info_short_location[];
 823
 824 /* The possible choices of "set print entry-values".  */
 825 extern const char print_entry_values_no[];
 826 extern const char print_entry_values_only[];
 827 extern const char print_entry_values_preferred[];
 828 extern const char print_entry_values_if_needed[];
 829 extern const char print_entry_values_both[];
 830 extern const char print_entry_values_compact[];
 831 extern const char print_entry_values_default[];
 832
 833 /* Data for the frame-printing "set print" settings exposed as command
 834    options.  */
 835
 836 struct frame_print_options
 837 {
 838   const char *print_frame_arguments = print_frame_arguments_scalars;
 839   const char *print_frame_info = print_frame_info_auto;
 840   const char *print_entry_values = print_entry_values_default;
 841
 842   /* If true, don't invoke pretty-printers for frame
 843      arguments.  */
 844   bool print_raw_frame_arguments;
 845 };
 846
 847 /* The values behind the global "set print ..." settings.  */
 848 extern frame_print_options user_frame_print_options;
 849
 850 /* Inferior function parameter value read in from a frame.  */
 851
 852 struct frame_arg
 853 {
 854   /* Symbol for this parameter used for example for its name.  */
 855   struct symbol *sym = nullptr;
 856
 857   /* Value of the parameter.  It is NULL if ERROR is not NULL; if both VAL and
 858      ERROR are NULL this parameter's value should not be printed.  */
 859   struct value *val = nullptr;
 860
 861   /* String containing the error message, it is more usually NULL indicating no
 862      error occured reading this parameter.  */
 863   gdb::unique_xmalloc_ptr<char> error;
 864
 865   /* One of the print_entry_values_* entries as appropriate specifically for
 866      this frame_arg.  It will be different from print_entry_values.  With
 867      print_entry_values_no this frame_arg should be printed as a normal
 868      parameter.  print_entry_values_only says it should be printed as entry
 869      value parameter.  print_entry_values_compact says it should be printed as
 870      both as a normal parameter and entry values parameter having the same
 871      value - print_entry_values_compact is not permitted fi ui_out_is_mi_like_p
 872      (in such case print_entry_values_no and print_entry_values_only is used
 873      for each parameter kind specifically.  */
 874   const char *entry_kind = nullptr;
 875 };
 876
 877 extern void read_frame_arg (const frame_print_options &fp_opts,
 878                             symbol *sym, frame_info *frame,
 879                             struct frame_arg *argp,
 880                             struct frame_arg *entryargp);
 881 extern void read_frame_local (struct symbol *sym, struct frame_info *frame,
 882                               struct frame_arg *argp);
 883
 884 extern void info_args_command (const char *, int);
 885
 886 extern void info_locals_command (const char *, int);
 887
 888 extern void return_command (const char *, int);
 889
 890 /* Set FRAME's unwinder temporarily, so that we can call a sniffer.
 891    If sniffing fails, the caller should be sure to call
 892    frame_cleanup_after_sniffer.  */
 893
 894 extern void frame_prepare_for_sniffer (struct frame_info *frame,
 895                                        const struct frame_unwind *unwind);
 896
 897 /* Clean up after a failed (wrong unwinder) attempt to unwind past
 898    FRAME.  */
 899
 900 extern void frame_cleanup_after_sniffer (struct frame_info *frame);
 901
 902 /* Notes (cagney/2002-11-27, drow/2003-09-06):
 903
 904    You might think that calls to this function can simply be replaced by a
 905    call to get_selected_frame().
 906
 907    Unfortunately, it isn't that easy.
 908
 909    The relevant code needs to be audited to determine if it is
 910    possible (or practical) to instead pass the applicable frame in as a
 911    parameter.  For instance, DEPRECATED_DO_REGISTERS_INFO() relied on
 912    the deprecated_selected_frame global, while its replacement,
 913    PRINT_REGISTERS_INFO(), is parameterized with the selected frame.
 914    The only real exceptions occur at the edge (in the CLI code) where
 915    user commands need to pick up the selected frame before proceeding.
 916
 917    There are also some functions called with a NULL frame meaning either "the
 918    program is not running" or "use the selected frame".
 919
 920    This is important.  GDB is trying to stamp out the hack:
 921
 922    saved_frame = deprecated_safe_get_selected_frame ();
 923    select_frame (...);
 924    hack_using_global_selected_frame ();
 925    select_frame (saved_frame);
 926
 927    Take care!
 928
 929    This function calls get_selected_frame if the inferior should have a
 930    frame, or returns NULL otherwise.  */
 931
 932 extern struct frame_info *deprecated_safe_get_selected_frame (void);
 933
 934 /* Create a frame using the specified BASE and PC.  */
 935
 936 extern struct frame_info *create_new_frame (CORE_ADDR base, CORE_ADDR pc);
 937
 938 /* Return true if the frame unwinder for frame FI is UNWINDER; false
 939    otherwise.  */
 940
 941 extern bool frame_unwinder_is (frame_info *fi, const frame_unwind *unwinder);
 942
 943 /* Return the language of FRAME.  */
 944
 945 extern enum language get_frame_language (struct frame_info *frame);
 946
 947 /* Return the first non-tailcall frame above FRAME or FRAME if it is not a
 948    tailcall frame.  Return NULL if FRAME is the start of a tailcall-only
 949    chain.  */
 950
 951 extern struct frame_info *skip_tailcall_frames (struct frame_info *frame);
 952
 953 /* Return the first frame above FRAME or FRAME of which the code is
 954    writable.  */
 955
 956 extern struct frame_info *skip_unwritable_frames (struct frame_info *frame);
 957
 958 /* Data for the "set backtrace" settings.  */
 959
 960 struct set_backtrace_options
 961 {
 962   /* Flag to indicate whether backtraces should continue past
 963      main.  */
 964   bool backtrace_past_main = false;
 965
 966   /* Flag to indicate whether backtraces should continue past
 967      entry.  */
 968   bool backtrace_past_entry = false;
 969
 970   /* Upper bound on the number of backtrace levels.  Note this is not
 971      exposed as a command option, because "backtrace" and "frame
 972      apply" already have other means to set a frame count limit.  */
 973   unsigned int backtrace_limit = UINT_MAX;
 974 };
 975
 976 /* The corresponding option definitions.  */
 977 extern const gdb::option::option_def set_backtrace_option_defs[2];
 978
 979 /* The values behind the global "set backtrace ..." settings.  */
 980 extern set_backtrace_options user_set_backtrace_options;
 981
 982 /* Get the number of calls to reinit_frame_cache.  */
 983
 984 unsigned int get_frame_cache_generation ();
 985
 986 /* Mark that the PC value is masked for the previous frame.  */
 987
 988 extern void set_frame_previous_pc_masked (struct frame_info *frame);
 989
 990 /* Get whether the PC value is masked for the given frame.  */
 991
 992 extern bool get_frame_pc_masked (const struct frame_info *frame);
 993
 994
 995 #endif /* !defined (FRAME_H)  */