gdb/value.h

   1 /* Definitions for values of C expressions, for GDB.
   2
   3    Copyright 1986, 1987, 1988, 1989, 1990, 1991, 1992, 1993, 1994,
   4    1995, 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005
   5    Free Software Foundation, Inc.
   6
   7    This file is part of GDB.
   8
   9    This program is free software; you can redistribute it and/or modify
  10    it under the terms of the GNU General Public License as published by
  11    the Free Software Foundation; either version 2 of the License, or
  12    (at your option) any later version.
  13
  14    This program is distributed in the hope that it will be useful,
  15    but WITHOUT ANY WARRANTY; without even the implied warranty of
  16    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  17    GNU General Public License for more details.
  18
  19    You should have received a copy of the GNU General Public License
  20    along with this program; if not, write to the Free Software
  21    Foundation, Inc., 59 Temple Place - Suite 330,
  22    Boston, MA 02111-1307, USA.  */
  23
  24 #if !defined (VALUE_H)
  25 #define VALUE_H 1
  26
  27 #include "doublest.h"
  28 #include "frame.h"              /* For struct frame_id.  */
  29
  30 struct block;
  31 struct expression;
  32 struct regcache;
  33 struct symbol;
  34 struct type;
  35 struct ui_file;
  36
  37 /* The structure which defines the type of a value.  It should never
  38    be possible for a program lval value to survive over a call to the
  39    inferior (i.e. to be put into the history list or an internal
  40    variable).  */
  41
  42 struct value
  43 {
  44   /* Type of value; either not an lval, or one of the various
  45      different possible kinds of lval.  */
  46   enum lval_type lval;
  47
  48   /* Is it modifiable?  Only relevant if lval != not_lval.  */
  49   int modifiable;
  50
  51   /* Location of value (if lval).  */
  52   union
  53   {
  54     /* If lval == lval_memory, this is the address in the inferior.
  55        If lval == lval_register, this is the byte offset into the
  56        registers structure.  */
  57     CORE_ADDR address;
  58
  59     /* Pointer to internal variable.  */
  60     struct internalvar *internalvar;
  61   } location;
  62
  63   /* Describes offset of a value within lval of a structure in bytes.
  64      If lval == lval_memory, this is an offset to the address.  If
  65      lval == lval_register, this is a further offset from
  66      location.address within the registers structure.  Note also the
  67      member embedded_offset below.  */
  68   int offset;
  69
  70   /* Only used for bitfields; number of bits contained in them.  */
  71   int bitsize;
  72
  73   /* Only used for bitfields; position of start of field.  For
  74      BITS_BIG_ENDIAN=0 targets, it is the position of the LSB.  For
  75      BITS_BIG_ENDIAN=1 targets, it is the position of the MSB. */
  76   int bitpos;
  77
  78   /* Frame register value is relative to.  This will be described in
  79      the lval enum above as "lval_register".  */
  80   struct frame_id frame_id;
  81
  82   /* Type of the value.  */
  83   struct type *type;
  84
  85   /* If a value represents a C++ object, then the `type' field gives
  86      the object's compile-time type.  If the object actually belongs
  87      to some class derived from `type', perhaps with other base
  88      classes and additional members, then `type' is just a subobject
  89      of the real thing, and the full object is probably larger than
  90      `type' would suggest.
  91
  92      If `type' is a dynamic class (i.e. one with a vtable), then GDB
  93      can actually determine the object's run-time type by looking at
  94      the run-time type information in the vtable.  When this
  95      information is available, we may elect to read in the entire
  96      object, for several reasons:
  97
  98      - When printing the value, the user would probably rather see the
  99      full object, not just the limited portion apparent from the
 100      compile-time type.
 101
 102      - If `type' has virtual base classes, then even printing `type'
 103      alone may require reaching outside the `type' portion of the
 104      object to wherever the virtual base class has been stored.
 105
 106      When we store the entire object, `enclosing_type' is the run-time
 107      type -- the complete object -- and `embedded_offset' is the
 108      offset of `type' within that larger type, in bytes.  The
 109      VALUE_CONTENTS macro takes `embedded_offset' into account, so
 110      most GDB code continues to see the `type' portion of the value,
 111      just as the inferior would.
 112
 113      If `type' is a pointer to an object, then `enclosing_type' is a
 114      pointer to the object's run-time type, and `pointed_to_offset' is
 115      the offset in bytes from the full object to the pointed-to object
 116      -- that is, the value `embedded_offset' would have if we followed
 117      the pointer and fetched the complete object.  (I don't really see
 118      the point.  Why not just determine the run-time type when you
 119      indirect, and avoid the special case?  The contents don't matter
 120      until you indirect anyway.)
 121
 122      If we're not doing anything fancy, `enclosing_type' is equal to
 123      `type', and `embedded_offset' is zero, so everything works
 124      normally.  */
 125   struct type *enclosing_type;
 126   int embedded_offset;
 127   int pointed_to_offset;
 128
 129   /* Values are stored in a chain, so that they can be deleted easily
 130      over calls to the inferior.  Values assigned to internal
 131      variables or put into the value history are taken off this
 132      list.  */
 133   struct value *next;
 134
 135   /* Register number if the value is from a register.  */
 136   short regnum;
 137
 138   /* If zero, contents of this value are in the contents field.  If
 139      nonzero, contents are in inferior memory at address in the
 140      location.address field plus the offset field (and the lval field
 141      should be lval_memory).
 142
 143      WARNING: This field is used by the code which handles watchpoints
 144      (see breakpoint.c) to decide whether a particular value can be
 145      watched by hardware watchpoints.  If the lazy flag is set for
 146      some member of a value chain, it is assumed that this member of
 147      the chain doesn't need to be watched as part of watching the
 148      value itself.  This is how GDB avoids watching the entire struct
 149      or array when the user wants to watch a single struct member or
 150      array element.  If you ever change the way lazy flag is set and
 151      reset, be sure to consider this use as well!  */
 152   char lazy;
 153
 154   /* If nonzero, this is the value of a variable which does not
 155      actually exist in the program.  */
 156   char optimized_out;
 157
 158   /* Actual contents of the value.  For use of this value; setting it
 159      uses the stuff above.  Not valid if lazy is nonzero.  Target
 160      byte-order.  We force it to be aligned properly for any possible
 161      value.  Note that a value therefore extends beyond what is
 162      declared here.  */
 163   union
 164   {
 165     bfd_byte contents[1];
 166     DOUBLEST force_doublest_align;
 167     LONGEST force_longest_align;
 168     CORE_ADDR force_core_addr_align;
 169     void *force_pointer_align;
 170   } aligner;
 171   /* Do not add any new members here -- contents above will trash
 172      them.  */
 173 };
 174
 175
 176 extern struct type *value_type (struct value *);
 177 extern int value_bitsize (struct value *);
 178 extern int value_bitpos (struct value *);
 179 extern int value_offset (struct value *);
 180
 181 extern struct type *value_enclosing_type (struct value *);
 182 #define VALUE_LAZY(val) (val)->lazy
 183
 184 /* VALUE_CONTENTS and value_contents_raw() both return the address of
 185    the gdb buffer used to hold a copy of the contents of the lval.
 186    VALUE_CONTENTS is used when the contents of the buffer are needed
 187    -- it uses value_fetch_lazy() to load the buffer from the process
 188    being debugged if it hasn't already been loaded.
 189    value_contents_raw() is used when data is being stored into the
 190    buffer, or when it is certain that the contents of the buffer are
 191    valid.
 192
 193    Note: The contents pointer is adjusted by the offset required to
 194    get to the real subobject, if the value happens to represent
 195    something embedded in a larger run-time object.  */
 196
 197 extern bfd_byte *value_contents_raw (struct value *);
 198 #define VALUE_CONTENTS(val) \
 199  ((void)(VALUE_LAZY(val) && value_fetch_lazy(val)), \
 200   (val)->aligner.contents)
 201
 202 /* The ALL variants of the above two macros do not adjust the returned
 203    pointer by the embedded_offset value.  */
 204
 205 extern bfd_byte *value_contents_all_raw (struct value *);
 206 extern const bfd_byte *value_contents_all (struct value *);
 207
 208 extern int value_fetch_lazy (struct value *val);
 209
 210 #define VALUE_LVAL(val) (val)->lval
 211 #define VALUE_ADDRESS(val) (val)->location.address
 212 #define VALUE_INTERNALVAR(val) (val)->location.internalvar
 213 #define VALUE_FRAME_ID(val) ((val)->frame_id)
 214 #define VALUE_REGNUM(val) (val)->regnum
 215 #define VALUE_OPTIMIZED_OUT(val) ((val)->optimized_out)
 216 #define VALUE_EMBEDDED_OFFSET(val) ((val)->embedded_offset)
 217 #define VALUE_POINTED_TO_OFFSET(val) ((val)->pointed_to_offset)
 218
 219 /* Convert a REF to the object referenced.  */
 220
 221 extern struct value *coerce_ref (struct value *value);
 222
 223 /* If ARG is an array, convert it to a pointer.
 224    If ARG is an enum, convert it to an integer.
 225    If ARG is a function, convert it to a function pointer.
 226
 227    References are dereferenced.  */
 228
 229 extern struct value *coerce_array (struct value *value);
 230 extern struct value *coerce_number (struct value *value);
 231
 232 /* If ARG is an enum, convert it to an integer.  */
 233
 234 extern struct value *coerce_enum (struct value *value);
 235
 236 /* Internal variables (variables for convenience of use of debugger)
 237    are recorded as a chain of these structures.  */
 238
 239 struct internalvar
 240 {
 241   struct internalvar *next;
 242   char *name;
 243   struct value *value;
 244 };
 245
 246 /* Pointer to member function.  Depends on compiler implementation.  */
 247
 248 #define METHOD_PTR_IS_VIRTUAL(ADDR)  ((ADDR) & 0x80000000)
 249 #define METHOD_PTR_FROM_VOFFSET(OFFSET) (0x80000000 + (OFFSET))
 250 #define METHOD_PTR_TO_VOFFSET(ADDR) (~0x80000000 & (ADDR))
 251 \f
 252
 253 #include "symtab.h"
 254 #include "gdbtypes.h"
 255 #include "expression.h"
 256
 257 struct frame_info;
 258 struct fn_field;
 259
 260 extern void print_address_demangle (CORE_ADDR, struct ui_file *, int);
 261
 262 extern LONGEST value_as_long (struct value *val);
 263 extern DOUBLEST value_as_double (struct value *val);
 264 extern CORE_ADDR value_as_address (struct value *val);
 265
 266 extern LONGEST unpack_long (struct type *type, const char *valaddr);
 267 extern DOUBLEST unpack_double (struct type *type, const char *valaddr,
 268                                int *invp);
 269 extern CORE_ADDR unpack_pointer (struct type *type, const char *valaddr);
 270 extern LONGEST unpack_field_as_long (struct type *type, const char *valaddr,
 271                                      int fieldno);
 272
 273 extern struct value *value_from_longest (struct type *type, LONGEST num);
 274 extern struct value *value_from_pointer (struct type *type, CORE_ADDR addr);
 275 extern struct value *value_from_double (struct type *type, DOUBLEST num);
 276 extern struct value *value_from_string (char *string);
 277
 278 extern struct value *value_at (struct type *type, CORE_ADDR addr);
 279 extern struct value *value_at_lazy (struct type *type, CORE_ADDR addr);
 280
 281 extern struct value *value_from_register (struct type *type, int regnum,
 282                                           struct frame_info *frame);
 283
 284 extern struct value *value_of_variable (struct symbol *var, struct block *b);
 285
 286 extern struct value *value_of_register (int regnum, struct frame_info *frame);
 287
 288 extern int symbol_read_needs_frame (struct symbol *);
 289
 290 extern struct value *read_var_value (struct symbol *var,
 291                                      struct frame_info *frame);
 292
 293 extern struct value *locate_var_value (struct symbol *var,
 294                                        struct frame_info *frame);
 295
 296 extern struct value *allocate_value (struct type *type);
 297
 298 extern struct value *allocate_repeat_value (struct type *type, int count);
 299
 300 extern struct value *value_change_enclosing_type (struct value *val,
 301                                                   struct type *new_type);
 302
 303 extern struct value *value_mark (void);
 304
 305 extern void value_free_to_mark (struct value *mark);
 306
 307 extern struct value *value_string (char *ptr, int len);
 308 extern struct value *value_bitstring (char *ptr, int len);
 309
 310 extern struct value *value_array (int lowbound, int highbound,
 311                                   struct value **elemvec);
 312
 313 extern struct value *value_concat (struct value *arg1, struct value *arg2);
 314
 315 extern struct value *value_binop (struct value *arg1, struct value *arg2,
 316                                   enum exp_opcode op);
 317
 318 extern struct value *value_add (struct value *arg1, struct value *arg2);
 319
 320 extern struct value *value_sub (struct value *arg1, struct value *arg2);
 321
 322 extern struct value *value_coerce_array (struct value *arg1);
 323
 324 extern struct value *value_coerce_function (struct value *arg1);
 325
 326 extern struct value *value_ind (struct value *arg1);
 327
 328 extern struct value *value_addr (struct value *arg1);
 329
 330 extern struct value *value_assign (struct value *toval,
 331                                    struct value *fromval);
 332
 333 extern struct value *value_neg (struct value *arg1);
 334
 335 extern struct value *value_complement (struct value *arg1);
 336
 337 extern struct value *value_struct_elt (struct value **argp,
 338                                        struct value **args,
 339                                        char *name, int *static_memfuncp,
 340                                        char *err);
 341
 342 extern struct value *value_aggregate_elt (struct type *curtype,
 343                                           char *name, enum noside noside);
 344
 345 extern struct value *value_static_field (struct type *type, int fieldno);
 346
 347 extern struct fn_field *value_find_oload_method_list (struct value **, char *,
 348                                                       int, int *,
 349                                                       struct type **, int *);
 350
 351 extern int find_overload_match (struct type **arg_types, int nargs,
 352                                 char *name, int method, int lax,
 353                                 struct value **objp, struct symbol *fsym,
 354                                 struct value **valp, struct symbol **symp,
 355                                 int *staticp);
 356
 357 extern struct value *value_field (struct value *arg1, int fieldno);
 358
 359 extern struct value *value_primitive_field (struct value *arg1, int offset,
 360                                             int fieldno,
 361                                             struct type *arg_type);
 362
 363
 364 extern struct type *value_rtti_target_type (struct value *, int *, int *,
 365                                             int *);
 366
 367 extern struct value *value_full_object (struct value *, struct type *, int,
 368                                         int, int);
 369
 370 extern struct value *value_cast (struct type *type, struct value *arg2);
 371
 372 extern struct value *value_zero (struct type *type, enum lval_type lv);
 373
 374 extern struct value *value_repeat (struct value *arg1, int count);
 375
 376 extern struct value *value_subscript (struct value *array, struct value *idx);
 377
 378 extern struct value *register_value_being_returned (struct type *valtype,
 379                                                     struct regcache *retbuf);
 380
 381 extern struct value *value_in (struct value *element, struct value *set);
 382
 383 extern int value_bit_index (struct type *type, const bfd_byte *addr,
 384                             int index);
 385
 386 extern int using_struct_return (struct type *value_type, int gcc_p);
 387
 388 extern struct value *evaluate_expression (struct expression *exp);
 389
 390 extern struct value *evaluate_type (struct expression *exp);
 391
 392 extern struct value *evaluate_subexp_with_coercion (struct expression *,
 393                                                     int *, enum noside);
 394
 395 extern struct value *parse_and_eval (char *exp);
 396
 397 extern struct value *parse_to_comma_and_eval (char **expp);
 398
 399 extern struct type *parse_and_eval_type (char *p, int length);
 400
 401 extern CORE_ADDR parse_and_eval_address (char *exp);
 402
 403 extern CORE_ADDR parse_and_eval_address_1 (char **expptr);
 404
 405 extern LONGEST parse_and_eval_long (char *exp);
 406
 407 extern struct value *access_value_history (int num);
 408
 409 extern struct value *value_of_internalvar (struct internalvar *var);
 410
 411 extern void set_internalvar (struct internalvar *var, struct value *val);
 412
 413 extern void set_internalvar_component (struct internalvar *var,
 414                                        int offset,
 415                                        int bitpos, int bitsize,
 416                                        struct value *newvalue);
 417
 418 extern struct internalvar *lookup_internalvar (char *name);
 419
 420 extern int value_equal (struct value *arg1, struct value *arg2);
 421
 422 extern int value_less (struct value *arg1, struct value *arg2);
 423
 424 extern int value_logical_not (struct value *arg1);
 425
 426 /* C++ */
 427
 428 extern struct value *value_of_this (int complain);
 429
 430 extern struct value *value_x_binop (struct value *arg1, struct value *arg2,
 431                                     enum exp_opcode op,
 432                                     enum exp_opcode otherop,
 433                                     enum noside noside);
 434
 435 extern struct value *value_x_unop (struct value *arg1, enum exp_opcode op,
 436                                    enum noside noside);
 437
 438 extern struct value *value_fn_field (struct value **arg1p, struct fn_field *f,
 439                                      int j, struct type *type, int offset);
 440
 441 extern int binop_user_defined_p (enum exp_opcode op, struct value *arg1,
 442                                  struct value *arg2);
 443
 444 extern int unop_user_defined_p (enum exp_opcode op, struct value *arg1);
 445
 446 extern int destructor_name_p (const char *name, const struct type *type);
 447
 448 #define value_free(val) xfree (val)
 449
 450 extern void free_all_values (void);
 451
 452 extern void release_value (struct value *val);
 453
 454 extern int record_latest_value (struct value *val);
 455
 456 extern void modify_field (char *addr, LONGEST fieldval, int bitpos,
 457                           int bitsize);
 458
 459 extern void type_print (struct type *type, char *varstring,
 460                         struct ui_file *stream, int show);
 461
 462 extern char *baseclass_addr (struct type *type, int index, char *valaddr,
 463                              struct value **valuep, int *errp);
 464
 465 extern void print_longest (struct ui_file *stream, int format,
 466                            int use_local, LONGEST val);
 467
 468 extern void print_floating (const bfd_byte *valaddr, struct type *type,
 469                             struct ui_file *stream);
 470
 471 extern int value_print (struct value *val, struct ui_file *stream, int format,
 472                         enum val_prettyprint pretty);
 473
 474 extern void value_print_array_elements (struct value *val,
 475                                         struct ui_file *stream, int format,
 476                                         enum val_prettyprint pretty);
 477
 478 extern struct value *value_release_to_mark (struct value *mark);
 479
 480 extern int val_print (struct type *type, const bfd_byte *valaddr,
 481                       int embedded_offset, CORE_ADDR address,
 482                       struct ui_file *stream, int format,
 483                       int deref_ref, int recurse,
 484                       enum val_prettyprint pretty);
 485
 486 extern int val_print_string (CORE_ADDR addr, int len, int width,
 487                              struct ui_file *stream);
 488
 489 extern void print_variable_value (struct symbol *var,
 490                                   struct frame_info *frame,
 491                                   struct ui_file *stream);
 492
 493 extern int check_field (struct value *, const char *);
 494
 495 extern void typedef_print (struct type *type, struct symbol *news,
 496                            struct ui_file *stream);
 497
 498 extern char *internalvar_name (struct internalvar *var);
 499
 500 extern void clear_value_history (void);
 501
 502 extern void clear_internalvars (void);
 503
 504 /* From values.c */
 505
 506 extern struct value *value_copy (struct value *);
 507
 508 /* From valops.c */
 509
 510 extern struct value *varying_to_slice (struct value *);
 511
 512 extern struct value *value_slice (struct value *, int, int);
 513
 514 extern struct value *value_literal_complex (struct value *, struct value *,
 515                                             struct type *);
 516
 517 extern void find_rt_vbase_offset (struct type *, struct type *,
 518                                   const bfd_byte *, int, int *, int *);
 519
 520 extern struct value *find_function_in_inferior (const char *);
 521
 522 extern struct value *value_allocate_space_in_inferior (int);
 523
 524 extern struct value *value_of_local (const char *name, int complain);
 525
 526 #endif /* !defined (VALUE_H) */