gdb/value.h

   1 /* Definitions for values of C expressions, for GDB.
   2
   3    Copyright (C) 1986-2017 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 "doublest.h"
  24 #include "frame.h"              /* For struct frame_id.  */
  25
  26 struct block;
  27 struct expression;
  28 struct regcache;
  29 struct symbol;
  30 struct type;
  31 struct ui_file;
  32 struct language_defn;
  33 struct value_print_options;
  34 struct xmethod_worker;
  35
  36 /* Values can be partially 'optimized out' and/or 'unavailable'.
  37    These are distinct states and have different string representations
  38    and related error strings.
  39
  40    'unavailable' has a specific meaning in this context.  It means the
  41    value exists in the program (at the machine level), but GDB has no
  42    means to get to it.  Such a value is normally printed as
  43    <unavailable>.  Examples of how to end up with an unavailable value
  44    would be:
  45
  46     - We're inspecting a traceframe, and the memory or registers the
  47       debug information says the value lives on haven't been collected.
  48
  49     - We're inspecting a core dump, the memory or registers the debug
  50       information says the value lives aren't present in the dump
  51       (that is, we have a partial/trimmed core dump, or we don't fully
  52       understand/handle the core dump's format).
  53
  54     - We're doing live debugging, but the debug API has no means to
  55       get at where the value lives in the machine, like e.g., ptrace
  56       not having access to some register or register set.
  57
  58     - Any other similar scenario.
  59
  60   OTOH, "optimized out" is about what the compiler decided to generate
  61   (or not generate).  A chunk of a value that was optimized out does
  62   not actually exist in the program.  There's no way to get at it
  63   short of compiling the program differently.
  64
  65   A register that has not been saved in a frame is likewise considered
  66   optimized out, except not-saved registers have a different string
  67   representation and related error strings.  E.g., we'll print them as
  68   <not-saved> instead of <optimized out>, as in:
  69
  70     (gdb) p/x $rax
  71     $1 = <not saved>
  72     (gdb) info registers rax
  73     rax            <not saved>
  74
  75   If the debug info describes a variable as being in such a register,
  76   we'll still print the variable as <optimized out>.  IOW, <not saved>
  77   is reserved for inspecting registers at the machine level.
  78
  79   When comparing value contents, optimized out chunks, unavailable
  80   chunks, and valid contents data are all considered different.  See
  81   value_contents_eq for more info.
  82 */
  83
  84 /* The structure which defines the type of a value.  It should never
  85    be possible for a program lval value to survive over a call to the
  86    inferior (i.e. to be put into the history list or an internal
  87    variable).  */
  88
  89 struct value;
  90
  91 /* Values are stored in a chain, so that they can be deleted easily
  92    over calls to the inferior.  Values assigned to internal variables,
  93    put into the value history or exposed to Python are taken off this
  94    list.  */
  95
  96 struct value *value_next (const struct value *);
  97
  98 /* Type of the value.  */
  99
 100 extern struct type *value_type (const struct value *);
 101
 102 /* Return the gdbarch associated with the value. */
 103
 104 extern struct gdbarch *get_value_arch (const struct value *value);
 105
 106 /* This is being used to change the type of an existing value, that
 107    code should instead be creating a new value with the changed type
 108    (but possibly shared content).  */
 109
 110 extern void deprecated_set_value_type (struct value *value,
 111                                        struct type *type);
 112
 113 /* Only used for bitfields; number of bits contained in them.  */
 114
 115 extern LONGEST value_bitsize (const struct value *);
 116 extern void set_value_bitsize (struct value *, LONGEST bit);
 117
 118 /* Only used for bitfields; position of start of field.  For
 119    gdbarch_bits_big_endian=0 targets, it is the position of the LSB.  For
 120    gdbarch_bits_big_endian=1 targets, it is the position of the MSB.  */
 121
 122 extern LONGEST value_bitpos (const struct value *);
 123 extern void set_value_bitpos (struct value *, LONGEST bit);
 124
 125 /* Only used for bitfields; the containing value.  This allows a
 126    single read from the target when displaying multiple
 127    bitfields.  */
 128
 129 struct value *value_parent (const struct value *);
 130 extern void set_value_parent (struct value *value, struct value *parent);
 131
 132 /* Describes offset of a value within lval of a structure in bytes.
 133    If lval == lval_memory, this is an offset to the address.  If lval
 134    == lval_register, this is a further offset from location.address
 135    within the registers structure.  Note also the member
 136    embedded_offset below.  */
 137
 138 extern LONGEST value_offset (const struct value *);
 139 extern void set_value_offset (struct value *, LONGEST offset);
 140
 141 /* The comment from "struct value" reads: ``Is it modifiable?  Only
 142    relevant if lval != not_lval.''.  Shouldn't the value instead be
 143    not_lval and be done with it?  */
 144
 145 extern int deprecated_value_modifiable (const struct value *value);
 146
 147 /* If a value represents a C++ object, then the `type' field gives the
 148    object's compile-time type.  If the object actually belongs to some
 149    class derived from `type', perhaps with other base classes and
 150    additional members, then `type' is just a subobject of the real
 151    thing, and the full object is probably larger than `type' would
 152    suggest.
 153
 154    If `type' is a dynamic class (i.e. one with a vtable), then GDB can
 155    actually determine the object's run-time type by looking at the
 156    run-time type information in the vtable.  When this information is
 157    available, we may elect to read in the entire object, for several
 158    reasons:
 159
 160    - When printing the value, the user would probably rather see the
 161      full object, not just the limited portion apparent from the
 162      compile-time type.
 163
 164    - If `type' has virtual base classes, then even printing `type'
 165      alone may require reaching outside the `type' portion of the
 166      object to wherever the virtual base class has been stored.
 167
 168    When we store the entire object, `enclosing_type' is the run-time
 169    type -- the complete object -- and `embedded_offset' is the offset
 170    of `type' within that larger type, in bytes.  The value_contents()
 171    macro takes `embedded_offset' into account, so most GDB code
 172    continues to see the `type' portion of the value, just as the
 173    inferior would.
 174
 175    If `type' is a pointer to an object, then `enclosing_type' is a
 176    pointer to the object's run-time type, and `pointed_to_offset' is
 177    the offset in bytes from the full object to the pointed-to object
 178    -- that is, the value `embedded_offset' would have if we followed
 179    the pointer and fetched the complete object.  (I don't really see
 180    the point.  Why not just determine the run-time type when you
 181    indirect, and avoid the special case?  The contents don't matter
 182    until you indirect anyway.)
 183
 184    If we're not doing anything fancy, `enclosing_type' is equal to
 185    `type', and `embedded_offset' is zero, so everything works
 186    normally.  */
 187
 188 extern struct type *value_enclosing_type (const struct value *);
 189 extern void set_value_enclosing_type (struct value *val,
 190                                       struct type *new_type);
 191
 192 /* Returns value_type or value_enclosing_type depending on
 193    value_print_options.objectprint.
 194
 195    If RESOLVE_SIMPLE_TYPES is 0 the enclosing type will be resolved
 196    only for pointers and references, else it will be returned
 197    for all the types (e.g. structures).  This option is useful
 198    to prevent retrieving enclosing type for the base classes fields.
 199
 200    REAL_TYPE_FOUND is used to inform whether the real type was found
 201    (or just static type was used).  The NULL may be passed if it is not
 202    necessary. */
 203
 204 extern struct type *value_actual_type (struct value *value,
 205                                        int resolve_simple_types,
 206                                        int *real_type_found);
 207
 208 extern LONGEST value_pointed_to_offset (const struct value *value);
 209 extern void set_value_pointed_to_offset (struct value *value, LONGEST val);
 210 extern LONGEST value_embedded_offset (const struct value *value);
 211 extern void set_value_embedded_offset (struct value *value, LONGEST val);
 212
 213 /* For lval_computed values, this structure holds functions used to
 214    retrieve and set the value (or portions of the value).
 215
 216    For each function, 'V' is the 'this' pointer: an lval_funcs
 217    function F may always assume that the V it receives is an
 218    lval_computed value, and has F in the appropriate slot of its
 219    lval_funcs structure.  */
 220
 221 struct lval_funcs
 222 {
 223   /* Fill in VALUE's contents.  This is used to "un-lazy" values.  If
 224      a problem arises in obtaining VALUE's bits, this function should
 225      call 'error'.  If it is NULL value_fetch_lazy on "un-lazy"
 226      non-optimized-out value is an internal error.  */
 227   void (*read) (struct value *v);
 228
 229   /* Handle an assignment TOVAL = FROMVAL by writing the value of
 230      FROMVAL to TOVAL's location.  The contents of TOVAL have not yet
 231      been updated.  If a problem arises in doing so, this function
 232      should call 'error'.  If it is NULL such TOVAL assignment is an error as
 233      TOVAL is not considered as an lvalue.  */
 234   void (*write) (struct value *toval, struct value *fromval);
 235
 236   /* If non-NULL, this is used to implement pointer indirection for
 237      this value.  This method may return NULL, in which case value_ind
 238      will fall back to ordinary indirection.  */
 239   struct value *(*indirect) (struct value *value);
 240
 241   /* If non-NULL, this is used to implement reference resolving for
 242      this value.  This method may return NULL, in which case coerce_ref
 243      will fall back to ordinary references resolving.  */
 244   struct value *(*coerce_ref) (const struct value *value);
 245
 246   /* If non-NULL, this is used to determine whether the indicated bits
 247      of VALUE are a synthetic pointer.  */
 248   int (*check_synthetic_pointer) (const struct value *value,
 249                                   LONGEST offset, int length);
 250
 251   /* Return a duplicate of VALUE's closure, for use in a new value.
 252      This may simply return the same closure, if VALUE's is
 253      reference-counted or statically allocated.
 254
 255      This may be NULL, in which case VALUE's closure is re-used in the
 256      new value.  */
 257   void *(*copy_closure) (const struct value *v);
 258
 259   /* Drop VALUE's reference to its closure.  Maybe this frees the
 260      closure; maybe this decrements a reference count; maybe the
 261      closure is statically allocated and this does nothing.
 262
 263      This may be NULL, in which case no action is taken to free
 264      VALUE's closure.  */
 265   void (*free_closure) (struct value *v);
 266 };
 267
 268 /* Create a computed lvalue, with type TYPE, function pointers FUNCS,
 269    and closure CLOSURE.  */
 270
 271 extern struct value *allocate_computed_value (struct type *type,
 272                                               const struct lval_funcs *funcs,
 273                                               void *closure);
 274
 275 /* Helper function to check the validity of some bits of a value.
 276
 277    If TYPE represents some aggregate type (e.g., a structure), return 1.
 278
 279    Otherwise, any of the bytes starting at OFFSET and extending for
 280    TYPE_LENGTH(TYPE) bytes are invalid, print a message to STREAM and
 281    return 0.  The checking is done using FUNCS.
 282
 283    Otherwise, return 1.  */
 284
 285 extern int valprint_check_validity (struct ui_file *stream, struct type *type,
 286                                     LONGEST embedded_offset,
 287                                     const struct value *val);
 288
 289 extern struct value *allocate_optimized_out_value (struct type *type);
 290
 291 /* If VALUE is lval_computed, return its lval_funcs structure.  */
 292
 293 extern const struct lval_funcs *value_computed_funcs (const struct value *);
 294
 295 /* If VALUE is lval_computed, return its closure.  The meaning of the
 296    returned value depends on the functions VALUE uses.  */
 297
 298 extern void *value_computed_closure (const struct value *value);
 299
 300 /* If zero, contents of this value are in the contents field.  If
 301    nonzero, contents are in inferior.  If the lval field is lval_memory,
 302    the contents are in inferior memory at location.address plus offset.
 303    The lval field may also be lval_register.
 304
 305    WARNING: This field is used by the code which handles watchpoints
 306    (see breakpoint.c) to decide whether a particular value can be
 307    watched by hardware watchpoints.  If the lazy flag is set for some
 308    member of a value chain, it is assumed that this member of the
 309    chain doesn't need to be watched as part of watching the value
 310    itself.  This is how GDB avoids watching the entire struct or array
 311    when the user wants to watch a single struct member or array
 312    element.  If you ever change the way lazy flag is set and reset, be
 313    sure to consider this use as well!  */
 314
 315 extern int value_lazy (const struct value *);
 316 extern void set_value_lazy (struct value *value, int val);
 317
 318 extern int value_stack (const struct value *);
 319 extern void set_value_stack (struct value *value, int val);
 320
 321 /* Throw an error complaining that the value has been optimized
 322    out.  */
 323
 324 extern void error_value_optimized_out (void);
 325
 326 /* value_contents() and value_contents_raw() both return the address
 327    of the gdb buffer used to hold a copy of the contents of the lval.
 328    value_contents() is used when the contents of the buffer are needed
 329    -- it uses value_fetch_lazy() to load the buffer from the process
 330    being debugged if it hasn't already been loaded
 331    (value_contents_writeable() is used when a writeable but fetched
 332    buffer is required)..  value_contents_raw() is used when data is
 333    being stored into the buffer, or when it is certain that the
 334    contents of the buffer are valid.
 335
 336    Note: The contents pointer is adjusted by the offset required to
 337    get to the real subobject, if the value happens to represent
 338    something embedded in a larger run-time object.  */
 339
 340 extern gdb_byte *value_contents_raw (struct value *);
 341
 342 /* Actual contents of the value.  For use of this value; setting it
 343    uses the stuff above.  Not valid if lazy is nonzero.  Target
 344    byte-order.  We force it to be aligned properly for any possible
 345    value.  Note that a value therefore extends beyond what is
 346    declared here.  */
 347
 348 extern const gdb_byte *value_contents (struct value *);
 349 extern gdb_byte *value_contents_writeable (struct value *);
 350
 351 /* The ALL variants of the above two macros do not adjust the returned
 352    pointer by the embedded_offset value.  */
 353
 354 extern gdb_byte *value_contents_all_raw (struct value *);
 355 extern const gdb_byte *value_contents_all (struct value *);
 356
 357 /* Like value_contents_all, but does not require that the returned
 358    bits be valid.  This should only be used in situations where you
 359    plan to check the validity manually.  */
 360 extern const gdb_byte *value_contents_for_printing (struct value *value);
 361
 362 /* Like value_contents_for_printing, but accepts a constant value
 363    pointer.  Unlike value_contents_for_printing however, the pointed
 364    value must _not_ be lazy.  */
 365 extern const gdb_byte *
 366   value_contents_for_printing_const (const struct value *value);
 367
 368 extern void value_fetch_lazy (struct value *val);
 369
 370 /* If nonzero, this is the value of a variable which does not actually
 371    exist in the program, at least partially.  If the value is lazy,
 372    this may fetch it now.  */
 373 extern int value_optimized_out (struct value *value);
 374
 375 /* Given a value, return true if any of the contents bits starting at
 376    OFFSET and extending for LENGTH bits is optimized out, false
 377    otherwise.  */
 378
 379 extern int value_bits_any_optimized_out (const struct value *value,
 380                                          int bit_offset, int bit_length);
 381
 382 /* Like value_optimized_out, but return true iff the whole value is
 383    optimized out.  */
 384 extern int value_entirely_optimized_out (struct value *value);
 385
 386 /* Mark VALUE's content bytes starting at OFFSET and extending for
 387    LENGTH bytes as optimized out.  */
 388
 389 extern void mark_value_bytes_optimized_out (struct value *value,
 390                                             int offset, int length);
 391
 392 /* Mark VALUE's content bits starting at OFFSET and extending for
 393    LENGTH bits as optimized out.  */
 394
 395 extern void mark_value_bits_optimized_out (struct value *value,
 396                                            LONGEST offset, LONGEST length);
 397
 398 /* Set or return field indicating whether a variable is initialized or
 399    not, based on debugging information supplied by the compiler.
 400    1 = initialized; 0 = uninitialized.  */
 401 extern int value_initialized (const struct value *);
 402 extern void set_value_initialized (struct value *, int);
 403
 404 /* Set COMPONENT's location as appropriate for a component of WHOLE
 405    --- regardless of what kind of lvalue WHOLE is.  */
 406 extern void set_value_component_location (struct value *component,
 407                                           const struct value *whole);
 408
 409 /* While the following fields are per- VALUE .CONTENT .PIECE (i.e., a
 410    single value might have multiple LVALs), this hacked interface is
 411    limited to just the first PIECE.  Expect further change.  */
 412 /* Type of value; either not an lval, or one of the various different
 413    possible kinds of lval.  */
 414 extern enum lval_type *deprecated_value_lval_hack (struct value *);
 415 #define VALUE_LVAL(val) (*deprecated_value_lval_hack (val))
 416
 417 /* Like VALUE_LVAL, except the parameter can be const.  */
 418 extern enum lval_type value_lval_const (const struct value *value);
 419
 420 /* If lval == lval_memory, return the address in the inferior.  If
 421    lval == lval_register, return the byte offset into the registers
 422    structure.  Otherwise, return 0.  The returned address
 423    includes the offset, if any.  */
 424 extern CORE_ADDR value_address (const struct value *);
 425
 426 /* Like value_address, except the result does not include value's
 427    offset.  */
 428 extern CORE_ADDR value_raw_address (const struct value *);
 429
 430 /* Set the address of a value.  */
 431 extern void set_value_address (struct value *, CORE_ADDR);
 432
 433 /* Pointer to internal variable.  */
 434 extern struct internalvar **deprecated_value_internalvar_hack (struct value *);
 435 #define VALUE_INTERNALVAR(val) (*deprecated_value_internalvar_hack (val))
 436
 437 /* Frame ID of "next" frame to which a register value is relative.  A
 438    register value is indicated by VALUE_LVAL being set to lval_register.
 439    So, if the register value is found relative to frame F, then the
 440    frame id of F->next will be stored in VALUE_NEXT_FRAME_ID.  */
 441 extern struct frame_id *deprecated_value_next_frame_id_hack (struct value *);
 442 #define VALUE_NEXT_FRAME_ID(val) (*deprecated_value_next_frame_id_hack (val))
 443
 444 /* Frame ID of frame to which a register value is relative.  This is
 445    similar to VALUE_NEXT_FRAME_ID, above, but may not be assigned to.
 446    Note that VALUE_FRAME_ID effectively undoes the "next" operation
 447    that was performed during the assignment to VALUE_NEXT_FRAME_ID.  */
 448 #define VALUE_FRAME_ID(val) (get_prev_frame_id_by_id (VALUE_NEXT_FRAME_ID (val)))
 449
 450 /* Register number if the value is from a register.  */
 451 extern int *deprecated_value_regnum_hack (struct value *);
 452 #define VALUE_REGNUM(val) (*deprecated_value_regnum_hack (val))
 453
 454 /* Return value after lval_funcs->coerce_ref (after check_typedef).  Return
 455    NULL if lval_funcs->coerce_ref is not applicable for whatever reason.  */
 456
 457 extern struct value *coerce_ref_if_computed (const struct value *arg);
 458
 459 /* Setup a new value type and enclosing value type for dereferenced value VALUE.
 460    ENC_TYPE is the new enclosing type that should be set.  ORIGINAL_TYPE and
 461    ORIGINAL_VAL are the type and value of the original reference or pointer.
 462
 463    Note, that VALUE is modified by this function.
 464
 465    It is a common implementation for coerce_ref and value_ind.  */
 466
 467 extern struct value * readjust_indirect_value_type (struct value *value,
 468                                                     struct type *enc_type,
 469                                                     const struct type *original_type,
 470                                                     const struct value *original_val);
 471
 472 /* Convert a REF to the object referenced.  */
 473
 474 extern struct value *coerce_ref (struct value *value);
 475
 476 /* If ARG is an array, convert it to a pointer.
 477    If ARG is a function, convert it to a function pointer.
 478
 479    References are dereferenced.  */
 480
 481 extern struct value *coerce_array (struct value *value);
 482
 483 /* Given a value, determine whether the bits starting at OFFSET and
 484    extending for LENGTH bits are a synthetic pointer.  */
 485
 486 extern int value_bits_synthetic_pointer (const struct value *value,
 487                                          LONGEST offset, LONGEST length);
 488
 489 /* Given a value, determine whether the contents bytes starting at
 490    OFFSET and extending for LENGTH bytes are available.  This returns
 491    nonzero if all bytes in the given range are available, zero if any
 492    byte is unavailable.  */
 493
 494 extern int value_bytes_available (const struct value *value,
 495                                   LONGEST offset, LONGEST length);
 496
 497 /* Given a value, determine whether the contents bits starting at
 498    OFFSET and extending for LENGTH bits are available.  This returns
 499    nonzero if all bits in the given range are available, zero if any
 500    bit is unavailable.  */
 501
 502 extern int value_bits_available (const struct value *value,
 503                                  LONGEST offset, LONGEST length);
 504
 505 /* Like value_bytes_available, but return false if any byte in the
 506    whole object is unavailable.  */
 507 extern int value_entirely_available (struct value *value);
 508
 509 /* Like value_entirely_available, but return false if any byte in the
 510    whole object is available.  */
 511 extern int value_entirely_unavailable (struct value *value);
 512
 513 /* Mark VALUE's content bytes starting at OFFSET and extending for
 514    LENGTH bytes as unavailable.  */
 515
 516 extern void mark_value_bytes_unavailable (struct value *value,
 517                                           LONGEST offset, LONGEST length);
 518
 519 /* Mark VALUE's content bits starting at OFFSET and extending for
 520    LENGTH bits as unavailable.  */
 521
 522 extern void mark_value_bits_unavailable (struct value *value,
 523                                          LONGEST offset, LONGEST length);
 524
 525 /* Compare LENGTH bytes of VAL1's contents starting at OFFSET1 with
 526    LENGTH bytes of VAL2's contents starting at OFFSET2.
 527
 528    Note that "contents" refers to the whole value's contents
 529    (value_contents_all), without any embedded offset adjustment.  For
 530    example, to compare a complete object value with itself, including
 531    its enclosing type chunk, you'd do:
 532
 533      int len = TYPE_LENGTH (check_typedef (value_enclosing_type (val)));
 534      value_contents_eq (val, 0, val, 0, len);
 535
 536    Returns true iff the set of available/valid contents match.
 537
 538    Optimized-out contents are equal to optimized-out contents, and are
 539    not equal to non-optimized-out contents.
 540
 541    Unavailable contente are equal to unavailable contents, and are not
 542    equal to non-unavailable contents.
 543
 544    For example, if 'x's represent an unavailable byte, and 'V' and 'Z'
 545    represent different available/valid bytes, in a value with length
 546    16:
 547
 548      offset:   0   4   8   12  16
 549      contents: xxxxVVVVxxxxVVZZ
 550
 551    then:
 552
 553      value_contents_eq(val, 0, val, 8, 6) => 1
 554      value_contents_eq(val, 0, val, 4, 4) => 0
 555      value_contents_eq(val, 0, val, 8, 8) => 0
 556      value_contents_eq(val, 4, val, 12, 2) => 1
 557      value_contents_eq(val, 4, val, 12, 4) => 0
 558      value_contents_eq(val, 3, val, 4, 4) => 0
 559
 560    If 'x's represent an unavailable byte, 'o' represents an optimized
 561    out byte, in a value with length 8:
 562
 563      offset:   0   4   8
 564      contents: xxxxoooo
 565
 566    then:
 567
 568      value_contents_eq(val, 0, val, 2, 2) => 1
 569      value_contents_eq(val, 4, val, 6, 2) => 1
 570      value_contents_eq(val, 0, val, 4, 4) => 0
 571
 572    We only know whether a value chunk is unavailable or optimized out
 573    if we've tried to read it.  As this routine is used by printing
 574    routines, which may be printing values in the value history, long
 575    after the inferior is gone, it works with const values.  Therefore,
 576    this routine must not be called with lazy values.  */
 577
 578 extern int value_contents_eq (const struct value *val1, LONGEST offset1,
 579                               const struct value *val2, LONGEST offset2,
 580                               LONGEST length);
 581
 582 /* Read LENGTH addressable memory units starting at MEMADDR into BUFFER,
 583    which is (or will be copied to) VAL's contents buffer offset by
 584    EMBEDDED_OFFSET (that is, to &VAL->contents[EMBEDDED_OFFSET]).
 585    Marks value contents ranges as unavailable if the corresponding
 586    memory is likewise unavailable.  STACK indicates whether the memory
 587    is known to be stack memory.  */
 588
 589 extern void read_value_memory (struct value *val, LONGEST embedded_offset,
 590                                int stack, CORE_ADDR memaddr,
 591                                gdb_byte *buffer, size_t length);
 592
 593 /* Cast SCALAR_VALUE to the element type of VECTOR_TYPE, then replicate
 594    into each element of a new vector value with VECTOR_TYPE.  */
 595
 596 struct value *value_vector_widen (struct value *scalar_value,
 597                                   struct type *vector_type);
 598
 599 \f
 600
 601 #include "symtab.h"
 602 #include "gdbtypes.h"
 603 #include "expression.h"
 604
 605 struct frame_info;
 606 struct fn_field;
 607
 608 extern int print_address_demangle (const struct value_print_options *,
 609                                    struct gdbarch *, CORE_ADDR,
 610                                    struct ui_file *, int);
 611
 612 extern LONGEST value_as_long (struct value *val);
 613 extern DOUBLEST value_as_double (struct value *val);
 614 extern CORE_ADDR value_as_address (struct value *val);
 615
 616 extern LONGEST unpack_long (struct type *type, const gdb_byte *valaddr);
 617 extern DOUBLEST unpack_double (struct type *type, const gdb_byte *valaddr,
 618                                int *invp);
 619 extern CORE_ADDR unpack_pointer (struct type *type, const gdb_byte *valaddr);
 620
 621 extern LONGEST unpack_field_as_long (struct type *type,
 622                                      const gdb_byte *valaddr,
 623                                      int fieldno);
 624 extern int unpack_value_field_as_long (struct type *type, const gdb_byte *valaddr,
 625                                 LONGEST embedded_offset, int fieldno,
 626                                 const struct value *val, LONGEST *result);
 627
 628 extern void unpack_value_bitfield (struct value *dest_val,
 629                                    LONGEST bitpos, LONGEST bitsize,
 630                                    const gdb_byte *valaddr,
 631                                    LONGEST embedded_offset,
 632                                    const struct value *val);
 633
 634 extern struct value *value_field_bitfield (struct type *type, int fieldno,
 635                                            const gdb_byte *valaddr,
 636                                            LONGEST embedded_offset,
 637                                            const struct value *val);
 638
 639 extern void pack_long (gdb_byte *buf, struct type *type, LONGEST num);
 640
 641 extern struct value *value_from_longest (struct type *type, LONGEST num);
 642 extern struct value *value_from_ulongest (struct type *type, ULONGEST num);
 643 extern struct value *value_from_pointer (struct type *type, CORE_ADDR addr);
 644 extern struct value *value_from_double (struct type *type, DOUBLEST num);
 645 extern struct value *value_from_decfloat (struct type *type,
 646                                           const gdb_byte *decbytes);
 647 extern struct value *value_from_history_ref (const char *, const char **);
 648 extern struct value *value_from_component (struct value *, struct type *,
 649                                            LONGEST);
 650
 651 extern struct value *value_at (struct type *type, CORE_ADDR addr);
 652 extern struct value *value_at_lazy (struct type *type, CORE_ADDR addr);
 653
 654 extern struct value *value_from_contents_and_address_unresolved
 655      (struct type *, const gdb_byte *, CORE_ADDR);
 656 extern struct value *value_from_contents_and_address (struct type *,
 657                                                       const gdb_byte *,
 658                                                       CORE_ADDR);
 659 extern struct value *value_from_contents (struct type *, const gdb_byte *);
 660
 661 extern struct value *default_value_from_register (struct gdbarch *gdbarch,
 662                                                   struct type *type,
 663                                                   int regnum,
 664                                                   struct frame_id frame_id);
 665
 666 extern void read_frame_register_value (struct value *value,
 667                                        struct frame_info *frame);
 668
 669 extern struct value *value_from_register (struct type *type, int regnum,
 670                                           struct frame_info *frame);
 671
 672 extern CORE_ADDR address_from_register (int regnum,
 673                                         struct frame_info *frame);
 674
 675 extern struct value *value_of_variable (struct symbol *var,
 676                                         const struct block *b);
 677
 678 extern struct value *address_of_variable (struct symbol *var,
 679                                           const struct block *b);
 680
 681 extern struct value *value_of_register (int regnum, struct frame_info *frame);
 682
 683 struct value *value_of_register_lazy (struct frame_info *frame, int regnum);
 684
 685 /* Return the symbol's reading requirement.  */
 686
 687 extern enum symbol_needs_kind symbol_read_needs (struct symbol *);
 688
 689 /* Return true if the symbol needs a frame.  This is a wrapper for
 690    symbol_read_needs that simply checks for SYMBOL_NEEDS_FRAME.  */
 691
 692 extern int symbol_read_needs_frame (struct symbol *);
 693
 694 extern struct value *read_var_value (struct symbol *var,
 695                                      const struct block *var_block,
 696                                      struct frame_info *frame);
 697
 698 extern struct value *default_read_var_value (struct symbol *var,
 699                                              const struct block *var_block,
 700                                              struct frame_info *frame);
 701
 702 extern struct value *allocate_value (struct type *type);
 703 extern struct value *allocate_value_lazy (struct type *type);
 704 extern void value_contents_copy (struct value *dst, LONGEST dst_offset,
 705                                  struct value *src, LONGEST src_offset,
 706                                  LONGEST length);
 707 extern void value_contents_copy_raw (struct value *dst, LONGEST dst_offset,
 708                                      struct value *src, LONGEST src_offset,
 709                                      LONGEST length);
 710
 711 extern struct value *allocate_repeat_value (struct type *type, int count);
 712
 713 extern struct value *value_mark (void);
 714
 715 extern void value_free_to_mark (const struct value *mark);
 716
 717 /* A helper class that uses value_mark at construction time and calls
 718    value_free_to_mark in the destructor.  This is used to clear out
 719    temporary values created during the lifetime of this object.  */
 720 class scoped_value_mark
 721 {
 722  public:
 723
 724   scoped_value_mark ()
 725     : m_value (value_mark ())
 726   {
 727   }
 728
 729   ~scoped_value_mark ()
 730   {
 731     free_to_mark ();
 732   }
 733
 734   /* Free the values currently on the value stack.  */
 735   void free_to_mark ()
 736   {
 737     if (m_value != NULL)
 738       {
 739         value_free_to_mark (m_value);
 740         m_value = NULL;
 741       }
 742   }
 743
 744  private:
 745
 746   const struct value *m_value;
 747 };
 748
 749 extern struct value *value_cstring (const char *ptr, ssize_t len,
 750                                     struct type *char_type);
 751 extern struct value *value_string (const char *ptr, ssize_t len,
 752                                    struct type *char_type);
 753
 754 extern struct value *value_array (int lowbound, int highbound,
 755                                   struct value **elemvec);
 756
 757 extern struct value *value_concat (struct value *arg1, struct value *arg2);
 758
 759 extern struct value *value_binop (struct value *arg1, struct value *arg2,
 760                                   enum exp_opcode op);
 761
 762 extern struct value *value_ptradd (struct value *arg1, LONGEST arg2);
 763
 764 extern LONGEST value_ptrdiff (struct value *arg1, struct value *arg2);
 765
 766 extern int value_must_coerce_to_target (struct value *arg1);
 767
 768 extern struct value *value_coerce_to_target (struct value *arg1);
 769
 770 extern struct value *value_coerce_array (struct value *arg1);
 771
 772 extern struct value *value_coerce_function (struct value *arg1);
 773
 774 extern struct value *value_ind (struct value *arg1);
 775
 776 extern struct value *value_addr (struct value *arg1);
 777
 778 extern struct value *value_ref (struct value *arg1, enum type_code refcode);
 779
 780 extern struct value *value_assign (struct value *toval,
 781                                    struct value *fromval);
 782
 783 extern struct value *value_pos (struct value *arg1);
 784
 785 extern struct value *value_neg (struct value *arg1);
 786
 787 extern struct value *value_complement (struct value *arg1);
 788
 789 extern struct value *value_struct_elt (struct value **argp,
 790                                        struct value **args,
 791                                        const char *name, int *static_memfuncp,
 792                                        const char *err);
 793
 794 extern struct value *value_struct_elt_bitpos (struct value **argp,
 795                                               int bitpos,
 796                                               struct type *field_type,
 797                                               const char *err);
 798
 799 extern struct value *value_aggregate_elt (struct type *curtype,
 800                                           const char *name,
 801                                           struct type *expect_type,
 802                                           int want_address,
 803                                           enum noside noside);
 804
 805 extern struct value *value_static_field (struct type *type, int fieldno);
 806
 807 enum oload_search_type { NON_METHOD, METHOD, BOTH };
 808
 809 extern int find_overload_match (struct value **args, int nargs,
 810                                 const char *name,
 811                                 enum oload_search_type method,
 812                                 struct value **objp, struct symbol *fsym,
 813                                 struct value **valp, struct symbol **symp,
 814                                 int *staticp, const int no_adl,
 815                                 enum noside noside);
 816
 817 extern struct value *value_field (struct value *arg1, int fieldno);
 818
 819 extern struct value *value_primitive_field (struct value *arg1, LONGEST offset,
 820                                             int fieldno,
 821                                             struct type *arg_type);
 822
 823
 824 extern struct type *value_rtti_indirect_type (struct value *, int *, LONGEST *,
 825                                               int *);
 826
 827 extern struct value *value_full_object (struct value *, struct type *, int,
 828                                         int, int);
 829
 830 extern struct value *value_cast_pointers (struct type *, struct value *, int);
 831
 832 extern struct value *value_cast (struct type *type, struct value *arg2);
 833
 834 extern struct value *value_reinterpret_cast (struct type *type,
 835                                              struct value *arg);
 836
 837 extern struct value *value_dynamic_cast (struct type *type, struct value *arg);
 838
 839 extern struct value *value_zero (struct type *type, enum lval_type lv);
 840
 841 extern struct value *value_one (struct type *type);
 842
 843 extern struct value *value_repeat (struct value *arg1, int count);
 844
 845 extern struct value *value_subscript (struct value *array, LONGEST index);
 846
 847 extern struct value *value_bitstring_subscript (struct type *type,
 848                                                 struct value *bitstring,
 849                                                 LONGEST index);
 850
 851 extern struct value *register_value_being_returned (struct type *valtype,
 852                                                     struct regcache *retbuf);
 853
 854 extern int value_in (struct value *element, struct value *set);
 855
 856 extern int value_bit_index (struct type *type, const gdb_byte *addr,
 857                             int index);
 858
 859 extern enum return_value_convention
 860 struct_return_convention (struct gdbarch *gdbarch, struct value *function,
 861                           struct type *value_type);
 862
 863 extern int using_struct_return (struct gdbarch *gdbarch,
 864                                 struct value *function,
 865                                 struct type *value_type);
 866
 867 extern struct value *evaluate_expression (struct expression *exp);
 868
 869 extern struct value *evaluate_type (struct expression *exp);
 870
 871 extern struct value *evaluate_subexp (struct type *expect_type,
 872                                       struct expression *exp,
 873                                       int *pos, enum noside noside);
 874
 875 extern struct value *evaluate_subexpression_type (struct expression *exp,
 876                                                   int subexp);
 877
 878 extern void fetch_subexp_value (struct expression *exp, int *pc,
 879                                 struct value **valp, struct value **resultp,
 880                                 struct value **val_chain,
 881                                 int preserve_errors);
 882
 883 extern char *extract_field_op (struct expression *exp, int *subexp);
 884
 885 extern struct value *evaluate_subexp_with_coercion (struct expression *,
 886                                                     int *, enum noside);
 887
 888 extern struct value *parse_and_eval (const char *exp);
 889
 890 extern struct value *parse_to_comma_and_eval (const char **expp);
 891
 892 extern struct type *parse_and_eval_type (char *p, int length);
 893
 894 extern CORE_ADDR parse_and_eval_address (const char *exp);
 895
 896 extern LONGEST parse_and_eval_long (const char *exp);
 897
 898 extern void unop_promote (const struct language_defn *language,
 899                           struct gdbarch *gdbarch,
 900                           struct value **arg1);
 901
 902 extern void binop_promote (const struct language_defn *language,
 903                            struct gdbarch *gdbarch,
 904                            struct value **arg1, struct value **arg2);
 905
 906 extern struct value *access_value_history (int num);
 907
 908 extern struct value *value_of_internalvar (struct gdbarch *gdbarch,
 909                                            struct internalvar *var);
 910
 911 extern int get_internalvar_integer (struct internalvar *var, LONGEST *l);
 912
 913 extern void set_internalvar (struct internalvar *var, struct value *val);
 914
 915 extern void set_internalvar_integer (struct internalvar *var, LONGEST l);
 916
 917 extern void set_internalvar_string (struct internalvar *var,
 918                                     const char *string);
 919
 920 extern void clear_internalvar (struct internalvar *var);
 921
 922 extern void set_internalvar_component (struct internalvar *var,
 923                                        LONGEST offset,
 924                                        LONGEST bitpos, LONGEST bitsize,
 925                                        struct value *newvalue);
 926
 927 extern struct internalvar *lookup_only_internalvar (const char *name);
 928
 929 extern struct internalvar *create_internalvar (const char *name);
 930
 931 extern VEC (char_ptr) *complete_internalvar (const char *name);
 932
 933 /* An internalvar can be dynamically computed by supplying a vector of
 934    function pointers to perform various operations.  */
 935
 936 struct internalvar_funcs
 937 {
 938   /* Compute the value of the variable.  The DATA argument passed to
 939      the function is the same argument that was passed to
 940      `create_internalvar_type_lazy'.  */
 941
 942   struct value *(*make_value) (struct gdbarch *arch,
 943                                struct internalvar *var,
 944                                void *data);
 945
 946   /* Update the agent expression EXPR with bytecode to compute the
 947      value.  VALUE is the agent value we are updating.  The DATA
 948      argument passed to this function is the same argument that was
 949      passed to `create_internalvar_type_lazy'.  If this pointer is
 950      NULL, then the internalvar cannot be compiled to an agent
 951      expression.  */
 952
 953   void (*compile_to_ax) (struct internalvar *var,
 954                          struct agent_expr *expr,
 955                          struct axs_value *value,
 956                          void *data);
 957
 958   /* If non-NULL, this is called to destroy DATA.  The DATA argument
 959      passed to this function is the same argument that was passed to
 960      `create_internalvar_type_lazy'.  */
 961
 962   void (*destroy) (void *data);
 963 };
 964
 965 extern struct internalvar *create_internalvar_type_lazy (const char *name,
 966                                 const struct internalvar_funcs *funcs,
 967                                 void *data);
 968
 969 /* Compile an internal variable to an agent expression.  VAR is the
 970    variable to compile; EXPR and VALUE are the agent expression we are
 971    updating.  This will return 0 if there is no known way to compile
 972    VAR, and 1 if VAR was successfully compiled.  It may also throw an
 973    exception on error.  */
 974
 975 extern int compile_internalvar_to_ax (struct internalvar *var,
 976                                       struct agent_expr *expr,
 977                                       struct axs_value *value);
 978
 979 extern struct internalvar *lookup_internalvar (const char *name);
 980
 981 extern int value_equal (struct value *arg1, struct value *arg2);
 982
 983 extern int value_equal_contents (struct value *arg1, struct value *arg2);
 984
 985 extern int value_less (struct value *arg1, struct value *arg2);
 986
 987 extern int value_logical_not (struct value *arg1);
 988
 989 /* C++ */
 990
 991 extern struct value *value_of_this (const struct language_defn *lang);
 992
 993 extern struct value *value_of_this_silent (const struct language_defn *lang);
 994
 995 extern struct value *value_x_binop (struct value *arg1, struct value *arg2,
 996                                     enum exp_opcode op,
 997                                     enum exp_opcode otherop,
 998                                     enum noside noside);
 999
1000 extern struct value *value_x_unop (struct value *arg1, enum exp_opcode op,
1001                                    enum noside noside);
1002
1003 extern struct value *value_fn_field (struct value **arg1p, struct fn_field *f,
1004                                      int j, struct type *type, LONGEST offset);
1005
1006 extern int binop_types_user_defined_p (enum exp_opcode op,
1007                                        struct type *type1,
1008                                        struct type *type2);
1009
1010 extern int binop_user_defined_p (enum exp_opcode op, struct value *arg1,
1011                                  struct value *arg2);
1012
1013 extern int unop_user_defined_p (enum exp_opcode op, struct value *arg1);
1014
1015 extern int destructor_name_p (const char *name, struct type *type);
1016
1017 extern void value_incref (struct value *val);
1018
1019 extern void value_free (struct value *val);
1020
1021 extern void free_all_values (void);
1022
1023 extern void free_value_chain (struct value *v);
1024
1025 extern void release_value (struct value *val);
1026
1027 extern void release_value_or_incref (struct value *val);
1028
1029 extern int record_latest_value (struct value *val);
1030
1031 extern void modify_field (struct type *type, gdb_byte *addr,
1032                           LONGEST fieldval, LONGEST bitpos, LONGEST bitsize);
1033
1034 extern void type_print (struct type *type, const char *varstring,
1035                         struct ui_file *stream, int show);
1036
1037 extern std::string type_to_string (struct type *type);
1038
1039 extern gdb_byte *baseclass_addr (struct type *type, int index,
1040                                  gdb_byte *valaddr,
1041                                  struct value **valuep, int *errp);
1042
1043 extern void print_longest (struct ui_file *stream, int format,
1044                            int use_local, LONGEST val);
1045
1046 extern void print_floating (const gdb_byte *valaddr, struct type *type,
1047                             struct ui_file *stream);
1048
1049 extern void print_decimal_floating (const gdb_byte *valaddr, struct type *type,
1050                                     struct ui_file *stream);
1051
1052 extern void value_print (struct value *val, struct ui_file *stream,
1053                          const struct value_print_options *options);
1054
1055 extern void value_print_array_elements (struct value *val,
1056                                         struct ui_file *stream, int format,
1057                                         enum val_prettyformat pretty);
1058
1059 extern struct value *value_release_to_mark (const struct value *mark);
1060
1061 extern void val_print (struct type *type,
1062                        LONGEST embedded_offset, CORE_ADDR address,
1063                        struct ui_file *stream, int recurse,
1064                        struct value *val,
1065                        const struct value_print_options *options,
1066                        const struct language_defn *language);
1067
1068 extern void common_val_print (struct value *val,
1069                               struct ui_file *stream, int recurse,
1070                               const struct value_print_options *options,
1071                               const struct language_defn *language);
1072
1073 extern int val_print_string (struct type *elttype, const char *encoding,
1074                              CORE_ADDR addr, int len,
1075                              struct ui_file *stream,
1076                              const struct value_print_options *options);
1077
1078 extern void print_variable_and_value (const char *name,
1079                                       struct symbol *var,
1080                                       struct frame_info *frame,
1081                                       struct ui_file *stream,
1082                                       int indent);
1083
1084 extern void typedef_print (struct type *type, struct symbol *news,
1085                            struct ui_file *stream);
1086
1087 extern char *internalvar_name (const struct internalvar *var);
1088
1089 extern void preserve_values (struct objfile *);
1090
1091 /* From values.c */
1092
1093 extern struct value *value_copy (struct value *);
1094
1095 extern struct value *value_non_lval (struct value *);
1096
1097 extern void value_force_lval (struct value *, CORE_ADDR);
1098
1099 extern struct value *make_cv_value (int, int, struct value *);
1100
1101 extern void preserve_one_value (struct value *, struct objfile *, htab_t);
1102
1103 /* From valops.c */
1104
1105 extern struct value *varying_to_slice (struct value *);
1106
1107 extern struct value *value_slice (struct value *, int, int);
1108
1109 extern struct value *value_literal_complex (struct value *, struct value *,
1110                                             struct type *);
1111
1112 extern struct value *find_function_in_inferior (const char *,
1113                                                 struct objfile **);
1114
1115 extern struct value *value_allocate_space_in_inferior (int);
1116
1117 extern struct value *value_subscripted_rvalue (struct value *array,
1118                                                LONGEST index, int lowerbound);
1119
1120 /* User function handler.  */
1121
1122 typedef struct value *(*internal_function_fn) (struct gdbarch *gdbarch,
1123                                                const struct language_defn *language,
1124                                                void *cookie,
1125                                                int argc,
1126                                                struct value **argv);
1127
1128 void add_internal_function (const char *name, const char *doc,
1129                             internal_function_fn handler,
1130                             void *cookie);
1131
1132 struct value *call_internal_function (struct gdbarch *gdbarch,
1133                                       const struct language_defn *language,
1134                                       struct value *function,
1135                                       int argc, struct value **argv);
1136
1137 char *value_internal_function_name (struct value *);
1138
1139 extern struct value *value_of_xmethod (struct xmethod_worker *);
1140
1141 extern struct type *result_type_of_xmethod (struct value *method,
1142                                             int argc, struct value **argv);
1143
1144 extern struct value *call_xmethod (struct value *method,
1145                                    int argc, struct value **argv);
1146
1147 #endif /* !defined (VALUE_H) */