gdb/value.h

   1 /* Definitions for values of C expressions, for GDB.
   2
   3    Copyright (C) 1986-2016 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 short *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
 649 extern struct value *value_at (struct type *type, CORE_ADDR addr);
 650 extern struct value *value_at_lazy (struct type *type, CORE_ADDR addr);
 651
 652 extern struct value *value_from_contents_and_address_unresolved
 653      (struct type *, const gdb_byte *, CORE_ADDR);
 654 extern struct value *value_from_contents_and_address (struct type *,
 655                                                       const gdb_byte *,
 656                                                       CORE_ADDR);
 657 extern struct value *value_from_contents (struct type *, const gdb_byte *);
 658
 659 extern struct value *default_value_from_register (struct gdbarch *gdbarch,
 660                                                   struct type *type,
 661                                                   int regnum,
 662                                                   struct frame_id frame_id);
 663
 664 extern void read_frame_register_value (struct value *value,
 665                                        struct frame_info *frame);
 666
 667 extern struct value *value_from_register (struct type *type, int regnum,
 668                                           struct frame_info *frame);
 669
 670 extern CORE_ADDR address_from_register (int regnum,
 671                                         struct frame_info *frame);
 672
 673 extern struct value *value_of_variable (struct symbol *var,
 674                                         const struct block *b);
 675
 676 extern struct value *address_of_variable (struct symbol *var,
 677                                           const struct block *b);
 678
 679 extern struct value *value_of_register (int regnum, struct frame_info *frame);
 680
 681 struct value *value_of_register_lazy (struct frame_info *frame, int regnum);
 682
 683 /* Return the symbol's reading requirement.  */
 684
 685 extern enum symbol_needs_kind symbol_read_needs (struct symbol *);
 686
 687 /* Return true if the symbol needs a frame.  This is a wrapper for
 688    symbol_read_needs that simply checks for SYMBOL_NEEDS_FRAME.  */
 689
 690 extern int symbol_read_needs_frame (struct symbol *);
 691
 692 extern struct value *read_var_value (struct symbol *var,
 693                                      const struct block *var_block,
 694                                      struct frame_info *frame);
 695
 696 extern struct value *default_read_var_value (struct symbol *var,
 697                                              const struct block *var_block,
 698                                              struct frame_info *frame);
 699
 700 extern struct value *allocate_value (struct type *type);
 701 extern struct value *allocate_value_lazy (struct type *type);
 702 extern void value_contents_copy (struct value *dst, LONGEST dst_offset,
 703                                  struct value *src, LONGEST src_offset,
 704                                  LONGEST length);
 705 extern void value_contents_copy_raw (struct value *dst, LONGEST dst_offset,
 706                                      struct value *src, LONGEST src_offset,
 707                                      LONGEST length);
 708
 709 extern struct value *allocate_repeat_value (struct type *type, int count);
 710
 711 extern struct value *value_mark (void);
 712
 713 extern void value_free_to_mark (const struct value *mark);
 714
 715 extern struct value *value_cstring (const char *ptr, ssize_t len,
 716                                     struct type *char_type);
 717 extern struct value *value_string (const char *ptr, ssize_t len,
 718                                    struct type *char_type);
 719
 720 extern struct value *value_array (int lowbound, int highbound,
 721                                   struct value **elemvec);
 722
 723 extern struct value *value_concat (struct value *arg1, struct value *arg2);
 724
 725 extern struct value *value_binop (struct value *arg1, struct value *arg2,
 726                                   enum exp_opcode op);
 727
 728 extern struct value *value_ptradd (struct value *arg1, LONGEST arg2);
 729
 730 extern LONGEST value_ptrdiff (struct value *arg1, struct value *arg2);
 731
 732 extern int value_must_coerce_to_target (struct value *arg1);
 733
 734 extern struct value *value_coerce_to_target (struct value *arg1);
 735
 736 extern struct value *value_coerce_array (struct value *arg1);
 737
 738 extern struct value *value_coerce_function (struct value *arg1);
 739
 740 extern struct value *value_ind (struct value *arg1);
 741
 742 extern struct value *value_addr (struct value *arg1);
 743
 744 extern struct value *value_ref (struct value *arg1);
 745
 746 extern struct value *value_assign (struct value *toval,
 747                                    struct value *fromval);
 748
 749 extern struct value *value_pos (struct value *arg1);
 750
 751 extern struct value *value_neg (struct value *arg1);
 752
 753 extern struct value *value_complement (struct value *arg1);
 754
 755 extern struct value *value_struct_elt (struct value **argp,
 756                                        struct value **args,
 757                                        const char *name, int *static_memfuncp,
 758                                        const char *err);
 759
 760 extern struct value *value_struct_elt_bitpos (struct value **argp,
 761                                               int bitpos,
 762                                               struct type *field_type,
 763                                               const char *err);
 764
 765 extern struct value *value_aggregate_elt (struct type *curtype,
 766                                           const char *name,
 767                                           struct type *expect_type,
 768                                           int want_address,
 769                                           enum noside noside);
 770
 771 extern struct value *value_static_field (struct type *type, int fieldno);
 772
 773 enum oload_search_type { NON_METHOD, METHOD, BOTH };
 774
 775 extern int find_overload_match (struct value **args, int nargs,
 776                                 const char *name,
 777                                 enum oload_search_type method,
 778                                 struct value **objp, struct symbol *fsym,
 779                                 struct value **valp, struct symbol **symp,
 780                                 int *staticp, const int no_adl,
 781                                 enum noside noside);
 782
 783 extern struct value *value_field (struct value *arg1, int fieldno);
 784
 785 extern struct value *value_primitive_field (struct value *arg1, LONGEST offset,
 786                                             int fieldno,
 787                                             struct type *arg_type);
 788
 789
 790 extern struct type *value_rtti_indirect_type (struct value *, int *, LONGEST *,
 791                                               int *);
 792
 793 extern struct value *value_full_object (struct value *, struct type *, int,
 794                                         int, int);
 795
 796 extern struct value *value_cast_pointers (struct type *, struct value *, int);
 797
 798 extern struct value *value_cast (struct type *type, struct value *arg2);
 799
 800 extern struct value *value_reinterpret_cast (struct type *type,
 801                                              struct value *arg);
 802
 803 extern struct value *value_dynamic_cast (struct type *type, struct value *arg);
 804
 805 extern struct value *value_zero (struct type *type, enum lval_type lv);
 806
 807 extern struct value *value_one (struct type *type);
 808
 809 extern struct value *value_repeat (struct value *arg1, int count);
 810
 811 extern struct value *value_subscript (struct value *array, LONGEST index);
 812
 813 extern struct value *value_bitstring_subscript (struct type *type,
 814                                                 struct value *bitstring,
 815                                                 LONGEST index);
 816
 817 extern struct value *register_value_being_returned (struct type *valtype,
 818                                                     struct regcache *retbuf);
 819
 820 extern int value_in (struct value *element, struct value *set);
 821
 822 extern int value_bit_index (struct type *type, const gdb_byte *addr,
 823                             int index);
 824
 825 extern enum return_value_convention
 826 struct_return_convention (struct gdbarch *gdbarch, struct value *function,
 827                           struct type *value_type);
 828
 829 extern int using_struct_return (struct gdbarch *gdbarch,
 830                                 struct value *function,
 831                                 struct type *value_type);
 832
 833 extern struct value *evaluate_expression (struct expression *exp);
 834
 835 extern struct value *evaluate_type (struct expression *exp);
 836
 837 extern struct value *evaluate_subexp (struct type *expect_type,
 838                                       struct expression *exp,
 839                                       int *pos, enum noside noside);
 840
 841 extern struct value *evaluate_subexpression_type (struct expression *exp,
 842                                                   int subexp);
 843
 844 extern void fetch_subexp_value (struct expression *exp, int *pc,
 845                                 struct value **valp, struct value **resultp,
 846                                 struct value **val_chain,
 847                                 int preserve_errors);
 848
 849 extern char *extract_field_op (struct expression *exp, int *subexp);
 850
 851 extern struct value *evaluate_subexp_with_coercion (struct expression *,
 852                                                     int *, enum noside);
 853
 854 extern struct value *parse_and_eval (const char *exp);
 855
 856 extern struct value *parse_to_comma_and_eval (const char **expp);
 857
 858 extern struct type *parse_and_eval_type (char *p, int length);
 859
 860 extern CORE_ADDR parse_and_eval_address (const char *exp);
 861
 862 extern LONGEST parse_and_eval_long (const char *exp);
 863
 864 extern void unop_promote (const struct language_defn *language,
 865                           struct gdbarch *gdbarch,
 866                           struct value **arg1);
 867
 868 extern void binop_promote (const struct language_defn *language,
 869                            struct gdbarch *gdbarch,
 870                            struct value **arg1, struct value **arg2);
 871
 872 extern struct value *access_value_history (int num);
 873
 874 extern struct value *value_of_internalvar (struct gdbarch *gdbarch,
 875                                            struct internalvar *var);
 876
 877 extern int get_internalvar_integer (struct internalvar *var, LONGEST *l);
 878
 879 extern void set_internalvar (struct internalvar *var, struct value *val);
 880
 881 extern void set_internalvar_integer (struct internalvar *var, LONGEST l);
 882
 883 extern void set_internalvar_string (struct internalvar *var,
 884                                     const char *string);
 885
 886 extern void clear_internalvar (struct internalvar *var);
 887
 888 extern void set_internalvar_component (struct internalvar *var,
 889                                        LONGEST offset,
 890                                        LONGEST bitpos, LONGEST bitsize,
 891                                        struct value *newvalue);
 892
 893 extern struct internalvar *lookup_only_internalvar (const char *name);
 894
 895 extern struct internalvar *create_internalvar (const char *name);
 896
 897 extern VEC (char_ptr) *complete_internalvar (const char *name);
 898
 899 /* An internalvar can be dynamically computed by supplying a vector of
 900    function pointers to perform various operations.  */
 901
 902 struct internalvar_funcs
 903 {
 904   /* Compute the value of the variable.  The DATA argument passed to
 905      the function is the same argument that was passed to
 906      `create_internalvar_type_lazy'.  */
 907
 908   struct value *(*make_value) (struct gdbarch *arch,
 909                                struct internalvar *var,
 910                                void *data);
 911
 912   /* Update the agent expression EXPR with bytecode to compute the
 913      value.  VALUE is the agent value we are updating.  The DATA
 914      argument passed to this function is the same argument that was
 915      passed to `create_internalvar_type_lazy'.  If this pointer is
 916      NULL, then the internalvar cannot be compiled to an agent
 917      expression.  */
 918
 919   void (*compile_to_ax) (struct internalvar *var,
 920                          struct agent_expr *expr,
 921                          struct axs_value *value,
 922                          void *data);
 923
 924   /* If non-NULL, this is called to destroy DATA.  The DATA argument
 925      passed to this function is the same argument that was passed to
 926      `create_internalvar_type_lazy'.  */
 927
 928   void (*destroy) (void *data);
 929 };
 930
 931 extern struct internalvar *create_internalvar_type_lazy (const char *name,
 932                                 const struct internalvar_funcs *funcs,
 933                                 void *data);
 934
 935 /* Compile an internal variable to an agent expression.  VAR is the
 936    variable to compile; EXPR and VALUE are the agent expression we are
 937    updating.  This will return 0 if there is no known way to compile
 938    VAR, and 1 if VAR was successfully compiled.  It may also throw an
 939    exception on error.  */
 940
 941 extern int compile_internalvar_to_ax (struct internalvar *var,
 942                                       struct agent_expr *expr,
 943                                       struct axs_value *value);
 944
 945 extern struct internalvar *lookup_internalvar (const char *name);
 946
 947 extern int value_equal (struct value *arg1, struct value *arg2);
 948
 949 extern int value_equal_contents (struct value *arg1, struct value *arg2);
 950
 951 extern int value_less (struct value *arg1, struct value *arg2);
 952
 953 extern int value_logical_not (struct value *arg1);
 954
 955 /* C++ */
 956
 957 extern struct value *value_of_this (const struct language_defn *lang);
 958
 959 extern struct value *value_of_this_silent (const struct language_defn *lang);
 960
 961 extern struct value *value_x_binop (struct value *arg1, struct value *arg2,
 962                                     enum exp_opcode op,
 963                                     enum exp_opcode otherop,
 964                                     enum noside noside);
 965
 966 extern struct value *value_x_unop (struct value *arg1, enum exp_opcode op,
 967                                    enum noside noside);
 968
 969 extern struct value *value_fn_field (struct value **arg1p, struct fn_field *f,
 970                                      int j, struct type *type, LONGEST offset);
 971
 972 extern int binop_types_user_defined_p (enum exp_opcode op,
 973                                        struct type *type1,
 974                                        struct type *type2);
 975
 976 extern int binop_user_defined_p (enum exp_opcode op, struct value *arg1,
 977                                  struct value *arg2);
 978
 979 extern int unop_user_defined_p (enum exp_opcode op, struct value *arg1);
 980
 981 extern int destructor_name_p (const char *name, struct type *type);
 982
 983 extern void value_incref (struct value *val);
 984
 985 extern void value_free (struct value *val);
 986
 987 extern void free_all_values (void);
 988
 989 extern void free_value_chain (struct value *v);
 990
 991 extern void release_value (struct value *val);
 992
 993 extern void release_value_or_incref (struct value *val);
 994
 995 extern int record_latest_value (struct value *val);
 996
 997 extern void modify_field (struct type *type, gdb_byte *addr,
 998                           LONGEST fieldval, LONGEST bitpos, LONGEST bitsize);
 999
1000 extern void type_print (struct type *type, const char *varstring,
1001                         struct ui_file *stream, int show);
1002
1003 extern std::string type_to_string (struct type *type);
1004
1005 extern gdb_byte *baseclass_addr (struct type *type, int index,
1006                                  gdb_byte *valaddr,
1007                                  struct value **valuep, int *errp);
1008
1009 extern void print_longest (struct ui_file *stream, int format,
1010                            int use_local, LONGEST val);
1011
1012 extern void print_floating (const gdb_byte *valaddr, struct type *type,
1013                             struct ui_file *stream);
1014
1015 extern void print_decimal_floating (const gdb_byte *valaddr, struct type *type,
1016                                     struct ui_file *stream);
1017
1018 extern void value_print (struct value *val, struct ui_file *stream,
1019                          const struct value_print_options *options);
1020
1021 extern void value_print_array_elements (struct value *val,
1022                                         struct ui_file *stream, int format,
1023                                         enum val_prettyformat pretty);
1024
1025 extern struct value *value_release_to_mark (const struct value *mark);
1026
1027 extern void val_print (struct type *type,
1028                        LONGEST embedded_offset, CORE_ADDR address,
1029                        struct ui_file *stream, int recurse,
1030                        struct value *val,
1031                        const struct value_print_options *options,
1032                        const struct language_defn *language);
1033
1034 extern void common_val_print (struct value *val,
1035                               struct ui_file *stream, int recurse,
1036                               const struct value_print_options *options,
1037                               const struct language_defn *language);
1038
1039 extern int val_print_string (struct type *elttype, const char *encoding,
1040                              CORE_ADDR addr, int len,
1041                              struct ui_file *stream,
1042                              const struct value_print_options *options);
1043
1044 extern void print_variable_and_value (const char *name,
1045                                       struct symbol *var,
1046                                       struct frame_info *frame,
1047                                       struct ui_file *stream,
1048                                       int indent);
1049
1050 extern void typedef_print (struct type *type, struct symbol *news,
1051                            struct ui_file *stream);
1052
1053 extern char *internalvar_name (const struct internalvar *var);
1054
1055 extern void preserve_values (struct objfile *);
1056
1057 /* From values.c */
1058
1059 extern struct value *value_copy (struct value *);
1060
1061 extern struct value *value_non_lval (struct value *);
1062
1063 extern void value_force_lval (struct value *, CORE_ADDR);
1064
1065 extern struct value *make_cv_value (int, int, struct value *);
1066
1067 extern void preserve_one_value (struct value *, struct objfile *, htab_t);
1068
1069 /* From valops.c */
1070
1071 extern struct value *varying_to_slice (struct value *);
1072
1073 extern struct value *value_slice (struct value *, int, int);
1074
1075 extern struct value *value_literal_complex (struct value *, struct value *,
1076                                             struct type *);
1077
1078 extern struct value *find_function_in_inferior (const char *,
1079                                                 struct objfile **);
1080
1081 extern struct value *value_allocate_space_in_inferior (int);
1082
1083 extern struct value *value_subscripted_rvalue (struct value *array,
1084                                                LONGEST index, int lowerbound);
1085
1086 /* User function handler.  */
1087
1088 typedef struct value *(*internal_function_fn) (struct gdbarch *gdbarch,
1089                                                const struct language_defn *language,
1090                                                void *cookie,
1091                                                int argc,
1092                                                struct value **argv);
1093
1094 void add_internal_function (const char *name, const char *doc,
1095                             internal_function_fn handler,
1096                             void *cookie);
1097
1098 struct value *call_internal_function (struct gdbarch *gdbarch,
1099                                       const struct language_defn *language,
1100                                       struct value *function,
1101                                       int argc, struct value **argv);
1102
1103 char *value_internal_function_name (struct value *);
1104
1105 extern struct value *value_of_xmethod (struct xmethod_worker *);
1106
1107 extern struct type *result_type_of_xmethod (struct value *method,
1108                                             int argc, struct value **argv);
1109
1110 extern struct value *call_xmethod (struct value *method,
1111                                    int argc, struct value **argv);
1112
1113 #endif /* !defined (VALUE_H) */