gdb/value.h

   1 /* Definitions for values of C expressions, for GDB.
   2
   3    Copyright (C) 1986-2023 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 (VALUE_H)
  21 #define VALUE_H 1
  22
  23 #include "frame.h"              /* For struct frame_id.  */
  24 #include "extension.h"
  25 #include "gdbsupport/gdb_ref_ptr.h"
  26 #include "gmp-utils.h"
  27
  28 struct block;
  29 struct expression;
  30 struct regcache;
  31 struct symbol;
  32 struct type;
  33 struct ui_file;
  34 struct language_defn;
  35 struct value_print_options;
  36
  37 /* Values can be partially 'optimized out' and/or 'unavailable'.
  38    These are distinct states and have different string representations
  39    and related error strings.
  40
  41    'unavailable' has a specific meaning in this context.  It means the
  42    value exists in the program (at the machine level), but GDB has no
  43    means to get to it.  Such a value is normally printed as
  44    <unavailable>.  Examples of how to end up with an unavailable value
  45    would be:
  46
  47     - We're inspecting a traceframe, and the memory or registers the
  48       debug information says the value lives on haven't been collected.
  49
  50     - We're inspecting a core dump, the memory or registers the debug
  51       information says the value lives aren't present in the dump
  52       (that is, we have a partial/trimmed core dump, or we don't fully
  53       understand/handle the core dump's format).
  54
  55     - We're doing live debugging, but the debug API has no means to
  56       get at where the value lives in the machine, like e.g., ptrace
  57       not having access to some register or register set.
  58
  59     - Any other similar scenario.
  60
  61   OTOH, "optimized out" is about what the compiler decided to generate
  62   (or not generate).  A chunk of a value that was optimized out does
  63   not actually exist in the program.  There's no way to get at it
  64   short of compiling the program differently.
  65
  66   A register that has not been saved in a frame is likewise considered
  67   optimized out, except not-saved registers have a different string
  68   representation and related error strings.  E.g., we'll print them as
  69   <not-saved> instead of <optimized out>, as in:
  70
  71     (gdb) p/x $rax
  72     $1 = <not saved>
  73     (gdb) info registers rax
  74     rax            <not saved>
  75
  76   If the debug info describes a variable as being in such a register,
  77   we'll still print the variable as <optimized out>.  IOW, <not saved>
  78   is reserved for inspecting registers at the machine level.
  79
  80   When comparing value contents, optimized out chunks, unavailable
  81   chunks, and valid contents data are all considered different.  See
  82   value_contents_eq for more info.
  83 */
  84
  85 extern bool overload_resolution;
  86
  87 /* The structure which defines the type of a value.  It should never
  88    be possible for a program lval value to survive over a call to the
  89    inferior (i.e. to be put into the history list or an internal
  90    variable).  */
  91
  92 struct value;
  93
  94 /* Increase VAL's reference count.  */
  95
  96 extern void value_incref (struct value *val);
  97
  98 /* Decrease VAL's reference count.  When the reference count drops to
  99    0, VAL will be freed.  */
 100
 101 extern void value_decref (struct value *val);
 102
 103 /* A policy class to interface gdb::ref_ptr with struct value.  */
 104
 105 struct value_ref_policy
 106 {
 107   static void incref (struct value *ptr)
 108   {
 109     value_incref (ptr);
 110   }
 111
 112   static void decref (struct value *ptr)
 113   {
 114     value_decref (ptr);
 115   }
 116 };
 117
 118 /* A gdb:;ref_ptr pointer to a struct value.  */
 119
 120 typedef gdb::ref_ptr<struct value, value_ref_policy> value_ref_ptr;
 121
 122 /* Type of the value.  */
 123
 124 extern struct type *value_type (const struct value *);
 125
 126 /* Return the gdbarch associated with the value. */
 127
 128 extern struct gdbarch *get_value_arch (const struct value *value);
 129
 130 /* This is being used to change the type of an existing value, that
 131    code should instead be creating a new value with the changed type
 132    (but possibly shared content).  */
 133
 134 extern void deprecated_set_value_type (struct value *value,
 135                                        struct type *type);
 136
 137 /* Only used for bitfields; number of bits contained in them.  */
 138
 139 extern LONGEST value_bitsize (const struct value *);
 140 extern void set_value_bitsize (struct value *, LONGEST bit);
 141
 142 /* Only used for bitfields; position of start of field.  For
 143    little-endian targets, it is the position of the LSB.  For
 144    big-endian targets, it is the position of the MSB.  */
 145
 146 extern LONGEST value_bitpos (const struct value *);
 147 extern void set_value_bitpos (struct value *, LONGEST bit);
 148
 149 /* Only used for bitfields; the containing value.  This allows a
 150    single read from the target when displaying multiple
 151    bitfields.  */
 152
 153 struct value *value_parent (const struct value *);
 154 extern void set_value_parent (struct value *value, struct value *parent);
 155
 156 /* Describes offset of a value within lval of a structure in bytes.
 157    If lval == lval_memory, this is an offset to the address.  If lval
 158    == lval_register, this is a further offset from location.address
 159    within the registers structure.  Note also the member
 160    embedded_offset below.  */
 161
 162 extern LONGEST value_offset (const struct value *);
 163 extern void set_value_offset (struct value *, LONGEST offset);
 164
 165 /* The comment from "struct value" reads: ``Is it modifiable?  Only
 166    relevant if lval != not_lval.''.  Shouldn't the value instead be
 167    not_lval and be done with it?  */
 168
 169 extern int deprecated_value_modifiable (const struct value *value);
 170
 171 /* If a value represents a C++ object, then the `type' field gives the
 172    object's compile-time type.  If the object actually belongs to some
 173    class derived from `type', perhaps with other base classes and
 174    additional members, then `type' is just a subobject of the real
 175    thing, and the full object is probably larger than `type' would
 176    suggest.
 177
 178    If `type' is a dynamic class (i.e. one with a vtable), then GDB can
 179    actually determine the object's run-time type by looking at the
 180    run-time type information in the vtable.  When this information is
 181    available, we may elect to read in the entire object, for several
 182    reasons:
 183
 184    - When printing the value, the user would probably rather see the
 185      full object, not just the limited portion apparent from the
 186      compile-time type.
 187
 188    - If `type' has virtual base classes, then even printing `type'
 189      alone may require reaching outside the `type' portion of the
 190      object to wherever the virtual base class has been stored.
 191
 192    When we store the entire object, `enclosing_type' is the run-time
 193    type -- the complete object -- and `embedded_offset' is the offset
 194    of `type' within that larger type, in bytes.  The value_contents()
 195    macro takes `embedded_offset' into account, so most GDB code
 196    continues to see the `type' portion of the value, just as the
 197    inferior would.
 198
 199    If `type' is a pointer to an object, then `enclosing_type' is a
 200    pointer to the object's run-time type, and `pointed_to_offset' is
 201    the offset in bytes from the full object to the pointed-to object
 202    -- that is, the value `embedded_offset' would have if we followed
 203    the pointer and fetched the complete object.  (I don't really see
 204    the point.  Why not just determine the run-time type when you
 205    indirect, and avoid the special case?  The contents don't matter
 206    until you indirect anyway.)
 207
 208    If we're not doing anything fancy, `enclosing_type' is equal to
 209    `type', and `embedded_offset' is zero, so everything works
 210    normally.  */
 211
 212 extern struct type *value_enclosing_type (const struct value *);
 213 extern void set_value_enclosing_type (struct value *val,
 214                                       struct type *new_type);
 215
 216 /* Returns value_type or value_enclosing_type depending on
 217    value_print_options.objectprint.
 218
 219    If RESOLVE_SIMPLE_TYPES is 0 the enclosing type will be resolved
 220    only for pointers and references, else it will be returned
 221    for all the types (e.g. structures).  This option is useful
 222    to prevent retrieving enclosing type for the base classes fields.
 223
 224    REAL_TYPE_FOUND is used to inform whether the real type was found
 225    (or just static type was used).  The NULL may be passed if it is not
 226    necessary. */
 227
 228 extern struct type *value_actual_type (struct value *value,
 229                                        int resolve_simple_types,
 230                                        int *real_type_found);
 231
 232 extern LONGEST value_pointed_to_offset (const struct value *value);
 233 extern void set_value_pointed_to_offset (struct value *value, LONGEST val);
 234 extern LONGEST value_embedded_offset (const struct value *value);
 235 extern void set_value_embedded_offset (struct value *value, LONGEST val);
 236
 237 /* For lval_computed values, this structure holds functions used to
 238    retrieve and set the value (or portions of the value).
 239
 240    For each function, 'V' is the 'this' pointer: an lval_funcs
 241    function F may always assume that the V it receives is an
 242    lval_computed value, and has F in the appropriate slot of its
 243    lval_funcs structure.  */
 244
 245 struct lval_funcs
 246 {
 247   /* Fill in VALUE's contents.  This is used to "un-lazy" values.  If
 248      a problem arises in obtaining VALUE's bits, this function should
 249      call 'error'.  If it is NULL value_fetch_lazy on "un-lazy"
 250      non-optimized-out value is an internal error.  */
 251   void (*read) (struct value *v);
 252
 253   /* Handle an assignment TOVAL = FROMVAL by writing the value of
 254      FROMVAL to TOVAL's location.  The contents of TOVAL have not yet
 255      been updated.  If a problem arises in doing so, this function
 256      should call 'error'.  If it is NULL such TOVAL assignment is an error as
 257      TOVAL is not considered as an lvalue.  */
 258   void (*write) (struct value *toval, struct value *fromval);
 259
 260   /* Return true if any part of V is optimized out, false otherwise.
 261      This will only be called for lazy values -- if the value has been
 262      fetched, then the value's optimized-out bits are consulted
 263      instead.  */
 264   bool (*is_optimized_out) (struct value *v);
 265
 266   /* If non-NULL, this is used to implement pointer indirection for
 267      this value.  This method may return NULL, in which case value_ind
 268      will fall back to ordinary indirection.  */
 269   struct value *(*indirect) (struct value *value);
 270
 271   /* If non-NULL, this is used to implement reference resolving for
 272      this value.  This method may return NULL, in which case coerce_ref
 273      will fall back to ordinary references resolving.  */
 274   struct value *(*coerce_ref) (const struct value *value);
 275
 276   /* If non-NULL, this is used to determine whether the indicated bits
 277      of VALUE are a synthetic pointer.  */
 278   int (*check_synthetic_pointer) (const struct value *value,
 279                                   LONGEST offset, int length);
 280
 281   /* Return a duplicate of VALUE's closure, for use in a new value.
 282      This may simply return the same closure, if VALUE's is
 283      reference-counted or statically allocated.
 284
 285      This may be NULL, in which case VALUE's closure is re-used in the
 286      new value.  */
 287   void *(*copy_closure) (const struct value *v);
 288
 289   /* Drop VALUE's reference to its closure.  Maybe this frees the
 290      closure; maybe this decrements a reference count; maybe the
 291      closure is statically allocated and this does nothing.
 292
 293      This may be NULL, in which case no action is taken to free
 294      VALUE's closure.  */
 295   void (*free_closure) (struct value *v);
 296 };
 297
 298 /* Create a computed lvalue, with type TYPE, function pointers FUNCS,
 299    and closure CLOSURE.  */
 300
 301 extern struct value *allocate_computed_value (struct type *type,
 302                                               const struct lval_funcs *funcs,
 303                                               void *closure);
 304
 305 extern struct value *allocate_optimized_out_value (struct type *type);
 306
 307 /* If VALUE is lval_computed, return its lval_funcs structure.  */
 308
 309 extern const struct lval_funcs *value_computed_funcs (const struct value *);
 310
 311 /* If VALUE is lval_computed, return its closure.  The meaning of the
 312    returned value depends on the functions VALUE uses.  */
 313
 314 extern void *value_computed_closure (const struct value *value);
 315
 316 /* If zero, contents of this value are in the contents field.  If
 317    nonzero, contents are in inferior.  If the lval field is lval_memory,
 318    the contents are in inferior memory at location.address plus offset.
 319    The lval field may also be lval_register.
 320
 321    WARNING: This field is used by the code which handles watchpoints
 322    (see breakpoint.c) to decide whether a particular value can be
 323    watched by hardware watchpoints.  If the lazy flag is set for some
 324    member of a value chain, it is assumed that this member of the
 325    chain doesn't need to be watched as part of watching the value
 326    itself.  This is how GDB avoids watching the entire struct or array
 327    when the user wants to watch a single struct member or array
 328    element.  If you ever change the way lazy flag is set and reset, be
 329    sure to consider this use as well!  */
 330
 331 extern int value_lazy (const struct value *);
 332 extern void set_value_lazy (struct value *value, int val);
 333
 334 extern int value_stack (const struct value *);
 335 extern void set_value_stack (struct value *value, int val);
 336
 337 /* Throw an error complaining that the value has been optimized
 338    out.  */
 339
 340 extern void error_value_optimized_out (void);
 341
 342 /* value_contents() and value_contents_raw() both return the address
 343    of the gdb buffer used to hold a copy of the contents of the lval.
 344    value_contents() is used when the contents of the buffer are needed
 345    -- it uses value_fetch_lazy() to load the buffer from the process
 346    being debugged if it hasn't already been loaded
 347    (value_contents_writeable() is used when a writeable but fetched
 348    buffer is required)..  value_contents_raw() is used when data is
 349    being stored into the buffer, or when it is certain that the
 350    contents of the buffer are valid.
 351
 352    Note: The contents pointer is adjusted by the offset required to
 353    get to the real subobject, if the value happens to represent
 354    something embedded in a larger run-time object.  */
 355
 356 extern gdb::array_view<gdb_byte> value_contents_raw (struct value *);
 357
 358 /* Actual contents of the value.  For use of this value; setting it
 359    uses the stuff above.  Not valid if lazy is nonzero.  Target
 360    byte-order.  We force it to be aligned properly for any possible
 361    value.  Note that a value therefore extends beyond what is
 362    declared here.  */
 363
 364 extern gdb::array_view<const gdb_byte> value_contents (struct value *);
 365 extern gdb::array_view<gdb_byte> value_contents_writeable (struct value *);
 366
 367 /* The ALL variants of the above two macros do not adjust the returned
 368    pointer by the embedded_offset value.  */
 369
 370 extern gdb::array_view<gdb_byte> value_contents_all_raw (struct value *);
 371 extern gdb::array_view<const gdb_byte> value_contents_all (struct value *);
 372
 373 /* Like value_contents_all, but does not require that the returned
 374    bits be valid.  This should only be used in situations where you
 375    plan to check the validity manually.  */
 376 extern gdb::array_view<const gdb_byte> value_contents_for_printing (struct value *value);
 377
 378 /* Like value_contents_for_printing, but accepts a constant value
 379    pointer.  Unlike value_contents_for_printing however, the pointed
 380    value must _not_ be lazy.  */
 381 extern gdb::array_view<const gdb_byte>
 382   value_contents_for_printing_const (const struct value *value);
 383
 384 extern void value_fetch_lazy (struct value *val);
 385
 386 /* If nonzero, this is the value of a variable which does not actually
 387    exist in the program, at least partially.  If the value is lazy,
 388    this may fetch it now.  */
 389 extern int value_optimized_out (struct value *value);
 390
 391 /* Given a value, return true if any of the contents bits starting at
 392    OFFSET and extending for LENGTH bits is optimized out, false
 393    otherwise.  */
 394
 395 extern int value_bits_any_optimized_out (const struct value *value,
 396                                          int bit_offset, int bit_length);
 397
 398 /* Like value_optimized_out, but return true iff the whole value is
 399    optimized out.  */
 400 extern int value_entirely_optimized_out (struct value *value);
 401
 402 /* Mark VALUE's content bytes starting at OFFSET and extending for
 403    LENGTH bytes as optimized out.  */
 404
 405 extern void mark_value_bytes_optimized_out (struct value *value,
 406                                             int offset, int length);
 407
 408 /* Mark VALUE's content bits starting at OFFSET and extending for
 409    LENGTH bits as optimized out.  */
 410
 411 extern void mark_value_bits_optimized_out (struct value *value,
 412                                            LONGEST offset, LONGEST length);
 413
 414 /* Set or return field indicating whether a variable is initialized or
 415    not, based on debugging information supplied by the compiler.
 416    1 = initialized; 0 = uninitialized.  */
 417 extern int value_initialized (const struct value *);
 418 extern void set_value_initialized (struct value *, int);
 419
 420 /* Set COMPONENT's location as appropriate for a component of WHOLE
 421    --- regardless of what kind of lvalue WHOLE is.  */
 422 extern void set_value_component_location (struct value *component,
 423                                           const struct value *whole);
 424
 425 /* While the following fields are per- VALUE .CONTENT .PIECE (i.e., a
 426    single value might have multiple LVALs), this hacked interface is
 427    limited to just the first PIECE.  Expect further change.  */
 428 /* Type of value; either not an lval, or one of the various different
 429    possible kinds of lval.  */
 430 extern enum lval_type *deprecated_value_lval_hack (struct value *);
 431 #define VALUE_LVAL(val) (*deprecated_value_lval_hack (val))
 432
 433 /* Like VALUE_LVAL, except the parameter can be const.  */
 434 extern enum lval_type value_lval_const (const struct value *value);
 435
 436 /* If lval == lval_memory, return the address in the inferior.  If
 437    lval == lval_register, return the byte offset into the registers
 438    structure.  Otherwise, return 0.  The returned address
 439    includes the offset, if any.  */
 440 extern CORE_ADDR value_address (const struct value *);
 441
 442 /* Like value_address, except the result does not include value's
 443    offset.  */
 444 extern CORE_ADDR value_raw_address (const struct value *);
 445
 446 /* Set the address of a value.  */
 447 extern void set_value_address (struct value *, CORE_ADDR);
 448
 449 /* Pointer to internal variable.  */
 450 extern struct internalvar **deprecated_value_internalvar_hack (struct value *);
 451 #define VALUE_INTERNALVAR(val) (*deprecated_value_internalvar_hack (val))
 452
 453 /* Frame ID of "next" frame to which a register value is relative.  A
 454    register value is indicated by VALUE_LVAL being set to lval_register.
 455    So, if the register value is found relative to frame F, then the
 456    frame id of F->next will be stored in VALUE_NEXT_FRAME_ID.  */
 457 extern struct frame_id *deprecated_value_next_frame_id_hack (struct value *);
 458 #define VALUE_NEXT_FRAME_ID(val) (*deprecated_value_next_frame_id_hack (val))
 459
 460 /* Register number if the value is from a register.  */
 461 extern int *deprecated_value_regnum_hack (struct value *);
 462 #define VALUE_REGNUM(val) (*deprecated_value_regnum_hack (val))
 463
 464 /* Return value after lval_funcs->coerce_ref (after check_typedef).  Return
 465    NULL if lval_funcs->coerce_ref is not applicable for whatever reason.  */
 466
 467 extern struct value *coerce_ref_if_computed (const struct value *arg);
 468
 469 /* Setup a new value type and enclosing value type for dereferenced value VALUE.
 470    ENC_TYPE is the new enclosing type that should be set.  ORIGINAL_TYPE and
 471    ORIGINAL_VAL are the type and value of the original reference or
 472    pointer.  ORIGINAL_VALUE_ADDRESS is the address within VALUE, that is
 473    the address that was dereferenced.
 474
 475    Note, that VALUE is modified by this function.
 476
 477    It is a common implementation for coerce_ref and value_ind.  */
 478
 479 extern struct value * readjust_indirect_value_type (struct value *value,
 480                                                     struct type *enc_type,
 481                                                     const struct type *original_type,
 482                                                     struct value *original_val,
 483                                                     CORE_ADDR original_value_address);
 484
 485 /* Convert a REF to the object referenced.  */
 486
 487 extern struct value *coerce_ref (struct value *value);
 488
 489 /* If ARG is an array, convert it to a pointer.
 490    If ARG is a function, convert it to a function pointer.
 491
 492    References are dereferenced.  */
 493
 494 extern struct value *coerce_array (struct value *value);
 495
 496 /* Given a value, determine whether the bits starting at OFFSET and
 497    extending for LENGTH bits are a synthetic pointer.  */
 498
 499 extern int value_bits_synthetic_pointer (const struct value *value,
 500                                          LONGEST offset, LONGEST length);
 501
 502 /* Given a value, determine whether the contents bytes starting at
 503    OFFSET and extending for LENGTH bytes are available.  This returns
 504    nonzero if all bytes in the given range are available, zero if any
 505    byte is unavailable.  */
 506
 507 extern int value_bytes_available (const struct value *value,
 508                                   LONGEST offset, LONGEST length);
 509
 510 /* Given a value, determine whether the contents bits starting at
 511    OFFSET and extending for LENGTH bits are available.  This returns
 512    nonzero if all bits in the given range are available, zero if any
 513    bit is unavailable.  */
 514
 515 extern int value_bits_available (const struct value *value,
 516                                  LONGEST offset, LONGEST length);
 517
 518 /* Like value_bytes_available, but return false if any byte in the
 519    whole object is unavailable.  */
 520 extern int value_entirely_available (struct value *value);
 521
 522 /* Like value_entirely_available, but return false if any byte in the
 523    whole object is available.  */
 524 extern int value_entirely_unavailable (struct value *value);
 525
 526 /* Mark VALUE's content bytes starting at OFFSET and extending for
 527    LENGTH bytes as unavailable.  */
 528
 529 extern void mark_value_bytes_unavailable (struct value *value,
 530                                           LONGEST offset, LONGEST length);
 531
 532 /* Mark VALUE's content bits starting at OFFSET and extending for
 533    LENGTH bits as unavailable.  */
 534
 535 extern void mark_value_bits_unavailable (struct value *value,
 536                                          LONGEST offset, LONGEST length);
 537
 538 /* Compare LENGTH bytes of VAL1's contents starting at OFFSET1 with
 539    LENGTH bytes of VAL2's contents starting at OFFSET2.
 540
 541    Note that "contents" refers to the whole value's contents
 542    (value_contents_all), without any embedded offset adjustment.  For
 543    example, to compare a complete object value with itself, including
 544    its enclosing type chunk, you'd do:
 545
 546      int len = check_typedef (value_enclosing_type (val))->length ();
 547      value_contents_eq (val, 0, val, 0, len);
 548
 549    Returns true iff the set of available/valid contents match.
 550
 551    Optimized-out contents are equal to optimized-out contents, and are
 552    not equal to non-optimized-out contents.
 553
 554    Unavailable contents are equal to unavailable contents, and are not
 555    equal to non-unavailable contents.
 556
 557    For example, if 'x's represent an unavailable byte, and 'V' and 'Z'
 558    represent different available/valid bytes, in a value with length
 559    16:
 560
 561      offset:   0   4   8   12  16
 562      contents: xxxxVVVVxxxxVVZZ
 563
 564    then:
 565
 566      value_contents_eq(val, 0, val, 8, 6) => true
 567      value_contents_eq(val, 0, val, 4, 4) => false
 568      value_contents_eq(val, 0, val, 8, 8) => false
 569      value_contents_eq(val, 4, val, 12, 2) => true
 570      value_contents_eq(val, 4, val, 12, 4) => true
 571      value_contents_eq(val, 3, val, 4, 4) => true
 572
 573    If 'x's represent an unavailable byte, 'o' represents an optimized
 574    out byte, in a value with length 8:
 575
 576      offset:   0   4   8
 577      contents: xxxxoooo
 578
 579    then:
 580
 581      value_contents_eq(val, 0, val, 2, 2) => true
 582      value_contents_eq(val, 4, val, 6, 2) => true
 583      value_contents_eq(val, 0, val, 4, 4) => true
 584
 585    We only know whether a value chunk is unavailable or optimized out
 586    if we've tried to read it.  As this routine is used by printing
 587    routines, which may be printing values in the value history, long
 588    after the inferior is gone, it works with const values.  Therefore,
 589    this routine must not be called with lazy values.  */
 590
 591 extern bool value_contents_eq (const struct value *val1, LONGEST offset1,
 592                                const struct value *val2, LONGEST offset2,
 593                                LONGEST length);
 594
 595 /* An overload of value_contents_eq that compares the entirety of both
 596    values.  */
 597
 598 extern bool value_contents_eq (const struct value *val1,
 599                                const struct value *val2);
 600
 601 /* Read LENGTH addressable memory units starting at MEMADDR into BUFFER,
 602    which is (or will be copied to) VAL's contents buffer offset by
 603    BIT_OFFSET bits.  Marks value contents ranges as unavailable if
 604    the corresponding memory is likewise unavailable.  STACK indicates
 605    whether the memory is known to be stack memory.  */
 606
 607 extern void read_value_memory (struct value *val, LONGEST bit_offset,
 608                                int stack, CORE_ADDR memaddr,
 609                                gdb_byte *buffer, size_t length);
 610
 611 /* Cast SCALAR_VALUE to the element type of VECTOR_TYPE, then replicate
 612    into each element of a new vector value with VECTOR_TYPE.  */
 613
 614 struct value *value_vector_widen (struct value *scalar_value,
 615                                   struct type *vector_type);
 616
 617 \f
 618
 619 #include "symtab.h"
 620 #include "gdbtypes.h"
 621 #include "expression.h"
 622
 623 class frame_info_ptr;
 624 struct fn_field;
 625
 626 extern int print_address_demangle (const struct value_print_options *,
 627                                    struct gdbarch *, CORE_ADDR,
 628                                    struct ui_file *, int);
 629
 630 /* Returns true if VAL is of floating-point type.  In addition,
 631    throws an error if the value is an invalid floating-point value.  */
 632 extern bool is_floating_value (struct value *val);
 633
 634 extern LONGEST value_as_long (struct value *val);
 635 extern CORE_ADDR value_as_address (struct value *val);
 636
 637 extern LONGEST unpack_long (struct type *type, const gdb_byte *valaddr);
 638 extern CORE_ADDR unpack_pointer (struct type *type, const gdb_byte *valaddr);
 639
 640 extern LONGEST unpack_field_as_long (struct type *type,
 641                                      const gdb_byte *valaddr,
 642                                      int fieldno);
 643
 644 /* Unpack a bitfield of the specified FIELD_TYPE, from the object at
 645    VALADDR, and store the result in *RESULT.
 646    The bitfield starts at BITPOS bits and contains BITSIZE bits; if
 647    BITSIZE is zero, then the length is taken from FIELD_TYPE.
 648
 649    Extracting bits depends on endianness of the machine.  Compute the
 650    number of least significant bits to discard.  For big endian machines,
 651    we compute the total number of bits in the anonymous object, subtract
 652    off the bit count from the MSB of the object to the MSB of the
 653    bitfield, then the size of the bitfield, which leaves the LSB discard
 654    count.  For little endian machines, the discard count is simply the
 655    number of bits from the LSB of the anonymous object to the LSB of the
 656    bitfield.
 657
 658    If the field is signed, we also do sign extension.  */
 659
 660 extern LONGEST unpack_bits_as_long (struct type *field_type,
 661                                     const gdb_byte *valaddr,
 662                                     LONGEST bitpos, LONGEST bitsize);
 663
 664 extern int unpack_value_field_as_long (struct type *type, const gdb_byte *valaddr,
 665                                 LONGEST embedded_offset, int fieldno,
 666                                 const struct value *val, LONGEST *result);
 667
 668 extern void unpack_value_bitfield (struct value *dest_val,
 669                                    LONGEST bitpos, LONGEST bitsize,
 670                                    const gdb_byte *valaddr,
 671                                    LONGEST embedded_offset,
 672                                    const struct value *val);
 673
 674 extern struct value *value_field_bitfield (struct type *type, int fieldno,
 675                                            const gdb_byte *valaddr,
 676                                            LONGEST embedded_offset,
 677                                            const struct value *val);
 678
 679 extern void pack_long (gdb_byte *buf, struct type *type, LONGEST num);
 680
 681 extern struct value *value_from_longest (struct type *type, LONGEST num);
 682 extern struct value *value_from_ulongest (struct type *type, ULONGEST num);
 683 extern struct value *value_from_pointer (struct type *type, CORE_ADDR addr);
 684 extern struct value *value_from_host_double (struct type *type, double d);
 685 extern struct value *value_from_history_ref (const char *, const char **);
 686 extern struct value *value_from_component (struct value *, struct type *,
 687                                            LONGEST);
 688
 689
 690 /* Create a new value by extracting it from WHOLE.  TYPE is the type
 691    of the new value.  BIT_OFFSET and BIT_LENGTH describe the offset
 692    and field width of the value to extract from WHOLE -- BIT_LENGTH
 693    may differ from TYPE's length in the case where WHOLE's type is
 694    packed.
 695
 696    When the value does come from a non-byte-aligned offset or field
 697    width, it will be marked non_lval.  */
 698
 699 extern struct value *value_from_component_bitsize (struct value *whole,
 700                                                    struct type *type,
 701                                                    LONGEST bit_offset,
 702                                                    LONGEST bit_length);
 703
 704 extern struct value *value_at (struct type *type, CORE_ADDR addr);
 705 extern struct value *value_at_lazy (struct type *type, CORE_ADDR addr);
 706
 707 /* Like value_at, but ensures that the result is marked not_lval.
 708    This can be important if the memory is "volatile".  */
 709 extern struct value *value_at_non_lval (struct type *type, CORE_ADDR addr);
 710
 711 extern struct value *value_from_contents_and_address_unresolved
 712      (struct type *, const gdb_byte *, CORE_ADDR);
 713 extern struct value *value_from_contents_and_address (struct type *,
 714                                                       const gdb_byte *,
 715                                                       CORE_ADDR);
 716 extern struct value *value_from_contents (struct type *, const gdb_byte *);
 717
 718 extern struct value *default_value_from_register (struct gdbarch *gdbarch,
 719                                                   struct type *type,
 720                                                   int regnum,
 721                                                   struct frame_id frame_id);
 722
 723 extern void read_frame_register_value (struct value *value,
 724                                        frame_info_ptr frame);
 725
 726 extern struct value *value_from_register (struct type *type, int regnum,
 727                                           frame_info_ptr frame);
 728
 729 extern CORE_ADDR address_from_register (int regnum,
 730                                         frame_info_ptr frame);
 731
 732 extern struct value *value_of_variable (struct symbol *var,
 733                                         const struct block *b);
 734
 735 extern struct value *address_of_variable (struct symbol *var,
 736                                           const struct block *b);
 737
 738 extern struct value *value_of_register (int regnum, frame_info_ptr frame);
 739
 740 struct value *value_of_register_lazy (frame_info_ptr frame, int regnum);
 741
 742 /* Return the symbol's reading requirement.  */
 743
 744 extern enum symbol_needs_kind symbol_read_needs (struct symbol *);
 745
 746 /* Return true if the symbol needs a frame.  This is a wrapper for
 747    symbol_read_needs that simply checks for SYMBOL_NEEDS_FRAME.  */
 748
 749 extern int symbol_read_needs_frame (struct symbol *);
 750
 751 extern struct value *read_var_value (struct symbol *var,
 752                                      const struct block *var_block,
 753                                      frame_info_ptr frame);
 754
 755 extern struct value *allocate_value (struct type *type);
 756 extern struct value *allocate_value_lazy (struct type *type);
 757 extern void value_contents_copy (struct value *dst, LONGEST dst_offset,
 758                                  struct value *src, LONGEST src_offset,
 759                                  LONGEST length);
 760
 761 extern struct value *allocate_repeat_value (struct type *type, int count);
 762
 763 extern struct value *value_mark (void);
 764
 765 extern void value_free_to_mark (const struct value *mark);
 766
 767 /* A helper class that uses value_mark at construction time and calls
 768    value_free_to_mark in the destructor.  This is used to clear out
 769    temporary values created during the lifetime of this object.  */
 770 class scoped_value_mark
 771 {
 772  public:
 773
 774   scoped_value_mark ()
 775     : m_value (value_mark ())
 776   {
 777   }
 778
 779   ~scoped_value_mark ()
 780   {
 781     free_to_mark ();
 782   }
 783
 784   scoped_value_mark (scoped_value_mark &&other) = default;
 785
 786   DISABLE_COPY_AND_ASSIGN (scoped_value_mark);
 787
 788   /* Free the values currently on the value stack.  */
 789   void free_to_mark ()
 790   {
 791     if (m_value != NULL)
 792       {
 793         value_free_to_mark (m_value);
 794         m_value = NULL;
 795       }
 796   }
 797
 798  private:
 799
 800   const struct value *m_value;
 801 };
 802
 803 extern struct value *value_cstring (const char *ptr, ssize_t len,
 804                                     struct type *char_type);
 805 extern struct value *value_string (const char *ptr, ssize_t len,
 806                                    struct type *char_type);
 807
 808 extern struct value *value_array (int lowbound, int highbound,
 809                                   struct value **elemvec);
 810
 811 extern struct value *value_concat (struct value *arg1, struct value *arg2);
 812
 813 extern struct value *value_binop (struct value *arg1, struct value *arg2,
 814                                   enum exp_opcode op);
 815
 816 extern struct value *value_ptradd (struct value *arg1, LONGEST arg2);
 817
 818 extern LONGEST value_ptrdiff (struct value *arg1, struct value *arg2);
 819
 820 /* Return true if VAL does not live in target memory, but should in order
 821    to operate on it.  Otherwise return false.  */
 822
 823 extern bool value_must_coerce_to_target (struct value *arg1);
 824
 825 extern struct value *value_coerce_to_target (struct value *arg1);
 826
 827 extern struct value *value_coerce_array (struct value *arg1);
 828
 829 extern struct value *value_coerce_function (struct value *arg1);
 830
 831 extern struct value *value_ind (struct value *arg1);
 832
 833 extern struct value *value_addr (struct value *arg1);
 834
 835 extern struct value *value_ref (struct value *arg1, enum type_code refcode);
 836
 837 extern struct value *value_assign (struct value *toval,
 838                                    struct value *fromval);
 839
 840 extern struct value *value_pos (struct value *arg1);
 841
 842 extern struct value *value_neg (struct value *arg1);
 843
 844 extern struct value *value_complement (struct value *arg1);
 845
 846 extern struct value *value_struct_elt (struct value **argp,
 847                                        gdb::optional<gdb::array_view <value *>> args,
 848                                        const char *name, int *static_memfuncp,
 849                                        const char *err);
 850
 851 extern struct value *value_struct_elt_bitpos (struct value **argp,
 852                                               int bitpos,
 853                                               struct type *field_type,
 854                                               const char *err);
 855
 856 extern struct value *value_aggregate_elt (struct type *curtype,
 857                                           const char *name,
 858                                           struct type *expect_type,
 859                                           int want_address,
 860                                           enum noside noside);
 861
 862 extern struct value *value_static_field (struct type *type, int fieldno);
 863
 864 enum oload_search_type { NON_METHOD, METHOD, BOTH };
 865
 866 extern int find_overload_match (gdb::array_view<value *> args,
 867                                 const char *name,
 868                                 enum oload_search_type method,
 869                                 struct value **objp, struct symbol *fsym,
 870                                 struct value **valp, struct symbol **symp,
 871                                 int *staticp, const int no_adl,
 872                                 enum noside noside);
 873
 874 extern struct value *value_field (struct value *arg1, int fieldno);
 875
 876 extern struct value *value_primitive_field (struct value *arg1, LONGEST offset,
 877                                             int fieldno,
 878                                             struct type *arg_type);
 879
 880
 881 extern struct type *value_rtti_indirect_type (struct value *, int *, LONGEST *,
 882                                               int *);
 883
 884 extern struct value *value_full_object (struct value *, struct type *, int,
 885                                         int, int);
 886
 887 extern struct value *value_cast_pointers (struct type *, struct value *, int);
 888
 889 extern struct value *value_cast (struct type *type, struct value *arg2);
 890
 891 extern struct value *value_reinterpret_cast (struct type *type,
 892                                              struct value *arg);
 893
 894 extern struct value *value_dynamic_cast (struct type *type, struct value *arg);
 895
 896 extern struct value *value_zero (struct type *type, enum lval_type lv);
 897
 898 extern struct value *value_one (struct type *type);
 899
 900 extern struct value *value_repeat (struct value *arg1, int count);
 901
 902 extern struct value *value_subscript (struct value *array, LONGEST index);
 903
 904 extern struct value *value_bitstring_subscript (struct type *type,
 905                                                 struct value *bitstring,
 906                                                 LONGEST index);
 907
 908 extern struct value *register_value_being_returned (struct type *valtype,
 909                                                     struct regcache *retbuf);
 910
 911 extern int value_in (struct value *element, struct value *set);
 912
 913 extern int value_bit_index (struct type *type, const gdb_byte *addr,
 914                             int index);
 915
 916 extern enum return_value_convention
 917 struct_return_convention (struct gdbarch *gdbarch, struct value *function,
 918                           struct type *value_type);
 919
 920 extern int using_struct_return (struct gdbarch *gdbarch,
 921                                 struct value *function,
 922                                 struct type *value_type);
 923
 924 /* Evaluate the expression EXP.  If set, EXPECT_TYPE is passed to the
 925    outermost operation's evaluation.  This is ignored by most
 926    operations, but may be used, e.g., to determine the type of an
 927    otherwise untyped symbol.  The caller should not assume that the
 928    returned value has this type.  */
 929
 930 extern struct value *evaluate_expression (struct expression *exp,
 931                                           struct type *expect_type = nullptr);
 932
 933 extern struct value *evaluate_type (struct expression *exp);
 934
 935 extern value *evaluate_var_value (enum noside noside, const block *blk,
 936                                   symbol *var);
 937
 938 extern value *evaluate_var_msym_value (enum noside noside,
 939                                        struct objfile *objfile,
 940                                        minimal_symbol *msymbol);
 941
 942 namespace expr { class operation; };
 943 extern void fetch_subexp_value (struct expression *exp,
 944                                 expr::operation *op,
 945                                 struct value **valp, struct value **resultp,
 946                                 std::vector<value_ref_ptr> *val_chain,
 947                                 bool preserve_errors);
 948
 949 extern struct value *parse_and_eval (const char *exp);
 950
 951 extern struct value *parse_to_comma_and_eval (const char **expp);
 952
 953 extern struct type *parse_and_eval_type (const char *p, int length);
 954
 955 extern CORE_ADDR parse_and_eval_address (const char *exp);
 956
 957 extern LONGEST parse_and_eval_long (const char *exp);
 958
 959 extern void unop_promote (const struct language_defn *language,
 960                           struct gdbarch *gdbarch,
 961                           struct value **arg1);
 962
 963 extern void binop_promote (const struct language_defn *language,
 964                            struct gdbarch *gdbarch,
 965                            struct value **arg1, struct value **arg2);
 966
 967 extern struct value *access_value_history (int num);
 968
 969 /* Return the number of items in the value history.  */
 970
 971 extern ULONGEST value_history_count ();
 972
 973 extern struct value *value_of_internalvar (struct gdbarch *gdbarch,
 974                                            struct internalvar *var);
 975
 976 extern int get_internalvar_integer (struct internalvar *var, LONGEST *l);
 977
 978 extern void set_internalvar (struct internalvar *var, struct value *val);
 979
 980 extern void set_internalvar_integer (struct internalvar *var, LONGEST l);
 981
 982 extern void set_internalvar_string (struct internalvar *var,
 983                                     const char *string);
 984
 985 extern void clear_internalvar (struct internalvar *var);
 986
 987 extern void set_internalvar_component (struct internalvar *var,
 988                                        LONGEST offset,
 989                                        LONGEST bitpos, LONGEST bitsize,
 990                                        struct value *newvalue);
 991
 992 extern struct internalvar *lookup_only_internalvar (const char *name);
 993
 994 extern struct internalvar *create_internalvar (const char *name);
 995
 996 extern void complete_internalvar (completion_tracker &tracker,
 997                                   const char *name);
 998
 999 /* An internalvar can be dynamically computed by supplying a vector of
1000    function pointers to perform various operations.  */
1001
1002 struct internalvar_funcs
1003 {
1004   /* Compute the value of the variable.  The DATA argument passed to
1005      the function is the same argument that was passed to
1006      `create_internalvar_type_lazy'.  */
1007
1008   struct value *(*make_value) (struct gdbarch *arch,
1009                                struct internalvar *var,
1010                                void *data);
1011
1012   /* Update the agent expression EXPR with bytecode to compute the
1013      value.  VALUE is the agent value we are updating.  The DATA
1014      argument passed to this function is the same argument that was
1015      passed to `create_internalvar_type_lazy'.  If this pointer is
1016      NULL, then the internalvar cannot be compiled to an agent
1017      expression.  */
1018
1019   void (*compile_to_ax) (struct internalvar *var,
1020                          struct agent_expr *expr,
1021                          struct axs_value *value,
1022                          void *data);
1023 };
1024
1025 extern struct internalvar *create_internalvar_type_lazy (const char *name,
1026                                 const struct internalvar_funcs *funcs,
1027                                 void *data);
1028
1029 /* Compile an internal variable to an agent expression.  VAR is the
1030    variable to compile; EXPR and VALUE are the agent expression we are
1031    updating.  This will return 0 if there is no known way to compile
1032    VAR, and 1 if VAR was successfully compiled.  It may also throw an
1033    exception on error.  */
1034
1035 extern int compile_internalvar_to_ax (struct internalvar *var,
1036                                       struct agent_expr *expr,
1037                                       struct axs_value *value);
1038
1039 extern struct internalvar *lookup_internalvar (const char *name);
1040
1041 extern int value_equal (struct value *arg1, struct value *arg2);
1042
1043 extern int value_equal_contents (struct value *arg1, struct value *arg2);
1044
1045 extern int value_less (struct value *arg1, struct value *arg2);
1046
1047 /* Simulate the C operator ! -- return true if ARG1 contains zero.  */
1048 extern bool value_logical_not (struct value *arg1);
1049
1050 /* Returns true if the value VAL represents a true value.  */
1051 static inline bool
1052 value_true (struct value *val)
1053 {
1054   return !value_logical_not (val);
1055 }
1056
1057 /* C++ */
1058
1059 extern struct value *value_of_this (const struct language_defn *lang);
1060
1061 extern struct value *value_of_this_silent (const struct language_defn *lang);
1062
1063 extern struct value *value_x_binop (struct value *arg1, struct value *arg2,
1064                                     enum exp_opcode op,
1065                                     enum exp_opcode otherop,
1066                                     enum noside noside);
1067
1068 extern struct value *value_x_unop (struct value *arg1, enum exp_opcode op,
1069                                    enum noside noside);
1070
1071 extern struct value *value_fn_field (struct value **arg1p, struct fn_field *f,
1072                                      int j, struct type *type, LONGEST offset);
1073
1074 extern int binop_types_user_defined_p (enum exp_opcode op,
1075                                        struct type *type1,
1076                                        struct type *type2);
1077
1078 extern int binop_user_defined_p (enum exp_opcode op, struct value *arg1,
1079                                  struct value *arg2);
1080
1081 extern int unop_user_defined_p (enum exp_opcode op, struct value *arg1);
1082
1083 extern int destructor_name_p (const char *name, struct type *type);
1084
1085 extern value_ref_ptr release_value (struct value *val);
1086
1087 extern int record_latest_value (struct value *val);
1088
1089 extern void modify_field (struct type *type, gdb_byte *addr,
1090                           LONGEST fieldval, LONGEST bitpos, LONGEST bitsize);
1091
1092 extern void type_print (struct type *type, const char *varstring,
1093                         struct ui_file *stream, int show);
1094
1095 extern std::string type_to_string (struct type *type);
1096
1097 extern gdb_byte *baseclass_addr (struct type *type, int index,
1098                                  gdb_byte *valaddr,
1099                                  struct value **valuep, int *errp);
1100
1101 extern void print_longest (struct ui_file *stream, int format,
1102                            int use_local, LONGEST val);
1103
1104 extern void print_floating (const gdb_byte *valaddr, struct type *type,
1105                             struct ui_file *stream);
1106
1107 extern void value_print (struct value *val, struct ui_file *stream,
1108                          const struct value_print_options *options);
1109
1110 /* Release values from the value chain and return them.  Values
1111    created after MARK are released.  If MARK is nullptr, or if MARK is
1112    not found on the value chain, then all values are released.  Values
1113    are returned in reverse order of creation; that is, newest
1114    first.  */
1115
1116 extern std::vector<value_ref_ptr> value_release_to_mark
1117     (const struct value *mark);
1118
1119 extern void common_val_print (struct value *val,
1120                               struct ui_file *stream, int recurse,
1121                               const struct value_print_options *options,
1122                               const struct language_defn *language);
1123
1124 extern int val_print_string (struct type *elttype, const char *encoding,
1125                              CORE_ADDR addr, int len,
1126                              struct ui_file *stream,
1127                              const struct value_print_options *options);
1128
1129 extern void print_variable_and_value (const char *name,
1130                                       struct symbol *var,
1131                                       frame_info_ptr frame,
1132                                       struct ui_file *stream,
1133                                       int indent);
1134
1135 extern void typedef_print (struct type *type, struct symbol *news,
1136                            struct ui_file *stream);
1137
1138 extern const char *internalvar_name (const struct internalvar *var);
1139
1140 extern void preserve_values (struct objfile *);
1141
1142 /* From values.c */
1143
1144 extern struct value *value_copy (const value *);
1145
1146 extern struct value *value_non_lval (struct value *);
1147
1148 extern void value_force_lval (struct value *, CORE_ADDR);
1149
1150 extern struct value *make_cv_value (int, int, struct value *);
1151
1152 extern void preserve_one_value (struct value *, struct objfile *, htab_t);
1153
1154 /* From valops.c */
1155
1156 extern struct value *varying_to_slice (struct value *);
1157
1158 extern struct value *value_slice (struct value *, int, int);
1159
1160 /* Create a complex number.  The type is the complex type; the values
1161    are cast to the underlying scalar type before the complex number is
1162    created.  */
1163
1164 extern struct value *value_literal_complex (struct value *, struct value *,
1165                                             struct type *);
1166
1167 /* Return the real part of a complex value.  */
1168
1169 extern struct value *value_real_part (struct value *value);
1170
1171 /* Return the imaginary part of a complex value.  */
1172
1173 extern struct value *value_imaginary_part (struct value *value);
1174
1175 extern struct value *find_function_in_inferior (const char *,
1176                                                 struct objfile **);
1177
1178 extern struct value *value_allocate_space_in_inferior (int);
1179
1180 /* User function handler.  */
1181
1182 typedef struct value *(*internal_function_fn) (struct gdbarch *gdbarch,
1183                                                const struct language_defn *language,
1184                                                void *cookie,
1185                                                int argc,
1186                                                struct value **argv);
1187
1188 /* Add a new internal function.  NAME is the name of the function; DOC
1189    is a documentation string describing the function.  HANDLER is
1190    called when the function is invoked.  COOKIE is an arbitrary
1191    pointer which is passed to HANDLER and is intended for "user
1192    data".  */
1193
1194 extern void add_internal_function (const char *name, const char *doc,
1195                                    internal_function_fn handler,
1196                                    void *cookie);
1197
1198 /* This overload takes an allocated documentation string.  */
1199
1200 extern void add_internal_function (gdb::unique_xmalloc_ptr<char> &&name,
1201                                    gdb::unique_xmalloc_ptr<char> &&doc,
1202                                    internal_function_fn handler,
1203                                    void *cookie);
1204
1205 struct value *call_internal_function (struct gdbarch *gdbarch,
1206                                       const struct language_defn *language,
1207                                       struct value *function,
1208                                       int argc, struct value **argv);
1209
1210 const char *value_internal_function_name (struct value *);
1211
1212 /* Build a value wrapping and representing WORKER.  The value takes ownership
1213    of the xmethod_worker object.  */
1214
1215 extern struct value *value_from_xmethod (xmethod_worker_up &&worker);
1216
1217 extern struct type *result_type_of_xmethod (struct value *method,
1218                                             gdb::array_view<value *> argv);
1219
1220 extern struct value *call_xmethod (struct value *method,
1221                                    gdb::array_view<value *> argv);
1222
1223 /* Destroy the values currently allocated.  This is called when GDB is
1224    exiting (e.g., on quit_force).  */
1225 extern void finalize_values ();
1226
1227 /* Convert VALUE to a gdb_mpq.  The caller must ensure that VALUE is
1228    of floating-point, fixed-point, or integer type.  */
1229 extern gdb_mpq value_to_gdb_mpq (struct value *value);
1230
1231 #endif /* !defined (VALUE_H) */