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
   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
  62     /* Number of register.  Only used with lval_reg_frame_relative.  */
  63     int regnum;
  64   } location;
  65
  66   /* Describes offset of a value within lval of a structure in bytes.
  67      If lval == lval_memory, this is an offset to the address.
  68      If lval == lval_register, this is a further offset from
  69      location.address within the registers structure.
  70      Note also the member embedded_offset below.  */
  71   int offset;
  72
  73   /* Only used for bitfields; number of bits contained in them.  */
  74   int bitsize;
  75
  76   /* Only used for bitfields; position of start of field.
  77      For BITS_BIG_ENDIAN=0 targets, it is the position of the LSB.
  78      For BITS_BIG_ENDIAN=1 targets, it is the position of the MSB. */
  79     int bitpos;
  80
  81   /* Frame value is relative to.  In practice, this ID is only used if
  82      the value is stored in several registers in other than the
  83      current frame, and these registers have not all been saved at the
  84      same place in memory.  This will be described in the lval enum
  85      above as "lval_reg_frame_relative".  */
  86   struct frame_id frame_id;
  87
  88   /* Type of the value.  */
  89   struct type *type;
  90
  91   /* If a value represents a C++ object, then the `type' field gives
  92      the object's compile-time type.  If the object actually belongs
  93      to some class derived from `type', perhaps with other base
  94      classes and additional members, then `type' is just a subobject
  95      of the real thing, and the full object is probably larger than
  96      `type' would suggest.
  97
  98      If `type' is a dynamic class (i.e. one with a vtable), then GDB
  99      can actually determine the object's run-time type by looking at
 100      the run-time type information in the vtable.  When this
 101      information is available, we may elect to read in the entire
 102      object, for several reasons:
 103
 104      - When printing the value, the user would probably rather see the
 105        full object, not just the limited portion apparent from the
 106        compile-time type.
 107
 108      - If `type' has virtual base classes, then even printing `type'
 109        alone may require reaching outside the `type' portion of the
 110        object to wherever the virtual base class has been stored.
 111
 112      When we store the entire object, `enclosing_type' is the run-time
 113      type -- the complete object -- and `embedded_offset' is the
 114      offset of `type' within that larger type, in bytes.  The
 115      VALUE_CONTENTS macro takes `embedded_offset' into account, so
 116      most GDB code continues to see the `type' portion of the value,
 117      just as the inferior would.
 118
 119      If `type' is a pointer to an object, then `enclosing_type' is a
 120      pointer to the object's run-time type, and `pointed_to_offset' is
 121      the offset in bytes from the full object to the pointed-to object
 122      -- that is, the value `embedded_offset' would have if we
 123      followed the pointer and fetched the complete object.  (I don't
 124      really see the point.  Why not just determine the run-time type
 125      when you indirect, and avoid the special case?  The contents
 126      don't matter until you indirect anyway.)
 127
 128      If we're not doing anything fancy, `enclosing_type' is equal to
 129      `type', and `embedded_offset' is zero, so everything works
 130      normally.  */
 131     struct type *enclosing_type;
 132     int embedded_offset;
 133     int pointed_to_offset;
 134
 135     /* Values are stored in a chain, so that they can be deleted
 136        easily over calls to the inferior.  Values assigned to internal
 137        variables or put into the value history are taken off this
 138        list.  */
 139     struct value *next;
 140
 141     /* Register number if the value is from a register.  */
 142     short regno;
 143
 144     /* If zero, contents of this value are in the contents field.  If
 145        nonzero, contents are in inferior memory at address in the
 146        location.address field plus the offset field (and the lval
 147        field should be lval_memory).
 148
 149        WARNING: This field is used by the code which handles
 150        watchpoints (see breakpoint.c) to decide whether a particular
 151        value can be watched by hardware watchpoints.  If the lazy flag
 152        is set for some member of a value chain, it is assumed that
 153        this member of the chain doesn't need to be watched as part of
 154        watching the value itself.  This is how GDB avoids watching the
 155        entire struct or array when the user wants to watch a single
 156        struct member or array element.  If you ever change the way
 157        lazy flag is set and reset, be sure to consider this use as
 158        well!  */
 159     char lazy;
 160
 161     /* If nonzero, this is the value of a variable which does not
 162        actually exist in the program.  */
 163     char optimized_out;
 164
 165     /* Actual contents of the value.  For use of this value; setting
 166        it uses the stuff above.  Not valid if lazy is nonzero.
 167        Target byte-order.  We force it to be aligned properly for any
 168        possible value.  Note that a value therefore extends beyond
 169        what is declared here.  */
 170     union
 171     {
 172       long contents[1];
 173       DOUBLEST force_doublest_align;
 174       LONGEST force_longest_align;
 175       CORE_ADDR force_core_addr_align;
 176       void *force_pointer_align;
 177     } aligner;
 178     /* Do not add any new members here -- contents above will trash them.  */
 179 };
 180
 181 #define VALUE_TYPE(val) (val)->type
 182 #define VALUE_ENCLOSING_TYPE(val) (val)->enclosing_type
 183 #define VALUE_LAZY(val) (val)->lazy
 184
 185 /* VALUE_CONTENTS and VALUE_CONTENTS_RAW both return the address of
 186    the gdb buffer used to hold a copy of the contents of the lval.
 187    VALUE_CONTENTS is used when the contents of the buffer are needed
 188    -- it uses value_fetch_lazy() to load the buffer from the process
 189    being debugged if it hasn't already been loaded.
 190    VALUE_CONTENTS_RAW is used when data is being stored into the
 191    buffer, or when it is certain that the contents of the buffer are
 192    valid.
 193
 194    Note: The contents pointer is adjusted by the offset required to
 195    get to the real subobject, if the value happens to represent
 196    something embedded in a larger run-time object.  */
 197
 198 #define VALUE_CONTENTS_RAW(val) \
 199  ((char *) (val)->aligner.contents + (val)->embedded_offset)
 200 #define VALUE_CONTENTS(val) \
 201  ((void)(VALUE_LAZY(val) && value_fetch_lazy(val)), VALUE_CONTENTS_RAW(val))
 202
 203 /* The ALL variants of the above two macros do not adjust the returned
 204    pointer by the embedded_offset value.  */
 205
 206 #define VALUE_CONTENTS_ALL_RAW(val) ((char *) (val)->aligner.contents)
 207 #define VALUE_CONTENTS_ALL(val) \
 208   ((void) (VALUE_LAZY(val) && value_fetch_lazy(val)), \
 209    VALUE_CONTENTS_ALL_RAW(val))
 210
 211 extern int value_fetch_lazy (struct value *val);
 212
 213 #define VALUE_LVAL(val) (val)->lval
 214 #define VALUE_ADDRESS(val) (val)->location.address
 215 #define VALUE_INTERNALVAR(val) (val)->location.internalvar
 216 #define VALUE_FRAME_REGNUM(val) ((val)->location.regnum)
 217 #define VALUE_FRAME_ID(val) ((val)->frame_id)
 218 #define VALUE_OFFSET(val) (val)->offset
 219 #define VALUE_BITSIZE(val) (val)->bitsize
 220 #define VALUE_BITPOS(val) (val)->bitpos
 221 #define VALUE_NEXT(val) (val)->next
 222 #define VALUE_REGNO(val) (val)->regno
 223 #define VALUE_OPTIMIZED_OUT(val) ((val)->optimized_out)
 224 #define VALUE_EMBEDDED_OFFSET(val) ((val)->embedded_offset)
 225 #define VALUE_POINTED_TO_OFFSET(val) ((val)->pointed_to_offset)
 226
 227 /* Convert a REF to the object referenced.  */
 228
 229 #define COERCE_REF(arg) \
 230   do {                                                                  \
 231     struct type *value_type_arg_tmp = check_typedef (VALUE_TYPE (arg)); \
 232     if (TYPE_CODE (value_type_arg_tmp) == TYPE_CODE_REF)                \
 233       arg = value_at_lazy (TYPE_TARGET_TYPE (value_type_arg_tmp),       \
 234                            unpack_pointer (VALUE_TYPE (arg),            \
 235                                            VALUE_CONTENTS (arg)));      \
 236   } while (0)
 237
 238 /* If ARG is an array, convert it to a pointer.
 239    If ARG is an enum, convert it to an integer.
 240    If ARG is a function, convert it to a function pointer.
 241
 242    References are dereferenced.  */
 243
 244 #define COERCE_ARRAY(arg) \
 245   do {                                                                  \
 246     COERCE_REF(arg);                                                    \
 247     if (current_language->c_style_arrays                                \
 248         && TYPE_CODE (VALUE_TYPE (arg)) == TYPE_CODE_ARRAY)             \
 249       arg = value_coerce_array (arg);                                   \
 250     if (TYPE_CODE (VALUE_TYPE (arg)) == TYPE_CODE_FUNC)                 \
 251       arg = value_coerce_function (arg);                                \
 252   } while (0)
 253
 254 #define COERCE_NUMBER(arg) \
 255   do { COERCE_ARRAY(arg); COERCE_ENUM(arg); } while (0)
 256
 257 /* If ARG is an enum, convert it to an integer.  */
 258
 259 #define COERCE_ENUM(arg) \
 260   do {                                                                  \
 261     if (TYPE_CODE (check_typedef (VALUE_TYPE (arg))) == TYPE_CODE_ENUM) \
 262       arg = value_cast (builtin_type_unsigned_int, arg);                \
 263   } while (0)
 264
 265 /* Internal variables (variables for convenience of use of debugger)
 266    are recorded as a chain of these structures.  */
 267
 268 struct internalvar
 269 {
 270   struct internalvar *next;
 271   char *name;
 272   struct value *value;
 273 };
 274
 275 /* Pointer to member function.  Depends on compiler implementation.  */
 276
 277 #define METHOD_PTR_IS_VIRTUAL(ADDR)  ((ADDR) & 0x80000000)
 278 #define METHOD_PTR_FROM_VOFFSET(OFFSET) (0x80000000 + (OFFSET))
 279 #define METHOD_PTR_TO_VOFFSET(ADDR) (~0x80000000 & (ADDR))
 280 \f
 281
 282 #include "symtab.h"
 283 #include "gdbtypes.h"
 284 #include "expression.h"
 285
 286 struct frame_info;
 287 struct fn_field;
 288
 289 extern void print_address_demangle (CORE_ADDR, struct ui_file *, int);
 290
 291 extern LONGEST value_as_long (struct value *val);
 292 extern DOUBLEST value_as_double (struct value *val);
 293 extern CORE_ADDR value_as_address (struct value *val);
 294
 295 extern LONGEST unpack_long (struct type *type, const char *valaddr);
 296 extern DOUBLEST unpack_double (struct type *type, const char *valaddr,
 297                                int *invp);
 298 extern CORE_ADDR unpack_pointer (struct type *type, const char *valaddr);
 299 extern LONGEST unpack_field_as_long (struct type *type, const char *valaddr,
 300                                      int fieldno);
 301
 302 extern struct value *value_from_longest (struct type *type, LONGEST num);
 303 extern struct value *value_from_pointer (struct type *type, CORE_ADDR addr);
 304 extern struct value *value_from_double (struct type *type, DOUBLEST num);
 305 extern struct value *value_from_string (char *string);
 306
 307 extern struct value *value_at (struct type *type, CORE_ADDR addr);
 308 extern struct value *value_at_lazy (struct type *type, CORE_ADDR addr);
 309
 310 extern struct value *value_from_register (struct type *type, int regnum,
 311                                           struct frame_info *frame);
 312
 313 extern struct value *value_of_variable (struct symbol *var, struct block *b);
 314
 315 extern struct value *value_of_register (int regnum,
 316                                         struct frame_info *frame);
 317
 318 extern int symbol_read_needs_frame (struct symbol *);
 319
 320 extern struct value *read_var_value (struct symbol *var,
 321                                      struct frame_info *frame);
 322
 323 extern struct value *locate_var_value (struct symbol *var,
 324                                        struct frame_info *frame);
 325
 326 extern struct value *allocate_value (struct type *type);
 327
 328 extern struct value *allocate_repeat_value (struct type *type, int count);
 329
 330 extern struct value *value_change_enclosing_type (struct value *val,
 331                                                   struct type *new_type);
 332
 333 extern struct value *value_mark (void);
 334
 335 extern void value_free_to_mark (struct value *mark);
 336
 337 extern struct value *value_string (char *ptr, int len);
 338 extern struct value *value_bitstring (char *ptr, int len);
 339
 340 extern struct value *value_array (int lowbound, int highbound,
 341                                   struct value ** elemvec);
 342
 343 extern struct value *value_concat (struct value *arg1, struct value *arg2);
 344
 345 extern struct value *value_binop (struct value *arg1, struct value *arg2,
 346                                   enum exp_opcode op);
 347
 348 extern struct value *value_add (struct value *arg1, struct value *arg2);
 349
 350 extern struct value *value_sub (struct value *arg1, struct value *arg2);
 351
 352 extern struct value *value_coerce_array (struct value *arg1);
 353
 354 extern struct value *value_coerce_function (struct value *arg1);
 355
 356 extern struct value *value_ind (struct value *arg1);
 357
 358 extern struct value *value_addr (struct value *arg1);
 359
 360 extern struct value *value_assign (struct value *toval, struct value *fromval);
 361
 362 extern struct value *value_neg (struct value *arg1);
 363
 364 extern struct value *value_complement (struct value *arg1);
 365
 366 extern struct value *value_struct_elt (struct value **argp,
 367                                        struct value **args,
 368                                        char *name, int *static_memfuncp,
 369                                        char *err);
 370
 371 extern struct value *value_aggregate_elt (struct type *curtype,
 372                                           char *name,
 373                                           enum noside noside);
 374
 375 extern struct value *value_static_field (struct type *type, int fieldno);
 376
 377 extern struct fn_field *value_find_oload_method_list (struct value **, char *,
 378                                                       int, int *,
 379                                                       struct type **, int *);
 380
 381 extern int find_overload_match (struct type **arg_types, int nargs,
 382                                 char *name, int method, int lax,
 383                                 struct value **objp, struct symbol *fsym,
 384                                 struct value **valp, struct symbol **symp,
 385                                 int *staticp);
 386
 387 extern struct value *value_field (struct value *arg1, int fieldno);
 388
 389 extern struct value *value_primitive_field (struct value *arg1, int offset,
 390                                             int fieldno,
 391                                             struct type *arg_type);
 392
 393
 394 extern struct type *value_rtti_target_type (struct value *, int *, int *,
 395                                             int *);
 396
 397 extern struct value *value_full_object (struct value *, struct type *, int,
 398                                         int, int);
 399
 400 extern struct value *value_cast (struct type *type, struct value *arg2);
 401
 402 extern struct value *value_zero (struct type *type, enum lval_type lv);
 403
 404 extern struct value *value_repeat (struct value *arg1, int count);
 405
 406 extern struct value *value_subscript (struct value *array, struct value *idx);
 407
 408 extern struct value *register_value_being_returned (struct type *valtype,
 409                                                     struct regcache *retbuf);
 410
 411 extern struct value *value_in (struct value *element, struct value *set);
 412
 413 extern int value_bit_index (struct type *type, char *addr, int index);
 414
 415 extern int using_struct_return (struct type *value_type, int gcc_p);
 416
 417 extern struct value *evaluate_expression (struct expression *exp);
 418
 419 extern struct value *evaluate_type (struct expression *exp);
 420
 421 extern struct value *evaluate_subexp_with_coercion (struct expression *,
 422                                                     int *, enum noside);
 423
 424 extern struct value *parse_and_eval (char *exp);
 425
 426 extern struct value *parse_to_comma_and_eval (char **expp);
 427
 428 extern struct type *parse_and_eval_type (char *p, int length);
 429
 430 extern CORE_ADDR parse_and_eval_address (char *exp);
 431
 432 extern CORE_ADDR parse_and_eval_address_1 (char **expptr);
 433
 434 extern LONGEST parse_and_eval_long (char *exp);
 435
 436 extern struct value *access_value_history (int num);
 437
 438 extern struct value *value_of_internalvar (struct internalvar *var);
 439
 440 extern void set_internalvar (struct internalvar *var, struct value *val);
 441
 442 extern void set_internalvar_component (struct internalvar *var,
 443                                        int offset,
 444                                        int bitpos, int bitsize,
 445                                        struct value *newvalue);
 446
 447 extern struct internalvar *lookup_internalvar (char *name);
 448
 449 extern int value_equal (struct value *arg1, struct value *arg2);
 450
 451 extern int value_less (struct value *arg1, struct value *arg2);
 452
 453 extern int value_logical_not (struct value *arg1);
 454
 455 /* C++ */
 456
 457 extern struct value *value_of_this (int complain);
 458
 459 extern struct value *value_x_binop (struct value *arg1, struct value *arg2,
 460                                     enum exp_opcode op,
 461                                     enum exp_opcode otherop,
 462                                     enum noside noside);
 463
 464 extern struct value *value_x_unop (struct value *arg1, enum exp_opcode op,
 465                                    enum noside noside);
 466
 467 extern struct value *value_fn_field (struct value ** arg1p, struct fn_field *f,
 468                                      int j, struct type *type, int offset);
 469
 470 extern int binop_user_defined_p (enum exp_opcode op, struct value *arg1,
 471                                  struct value *arg2);
 472
 473 extern int unop_user_defined_p (enum exp_opcode op, struct value *arg1);
 474
 475 extern int destructor_name_p (const char *name, const struct type *type);
 476
 477 #define value_free(val) xfree (val)
 478
 479 extern void free_all_values (void);
 480
 481 extern void release_value (struct value *val);
 482
 483 extern int record_latest_value (struct value *val);
 484
 485 extern void modify_field (char *addr, LONGEST fieldval, int bitpos,
 486                           int bitsize);
 487
 488 extern void type_print (struct type * type, char *varstring,
 489                         struct ui_file * stream, int show);
 490
 491 extern char *baseclass_addr (struct type *type, int index, char *valaddr,
 492                              struct value **valuep, int *errp);
 493
 494 extern void print_longest (struct ui_file * stream, int format,
 495                            int use_local, LONGEST val);
 496
 497 extern void print_floating (char *valaddr, struct type * type,
 498                             struct ui_file * stream);
 499
 500 extern int value_print (struct value *val, struct ui_file *stream, int format,
 501                         enum val_prettyprint pretty);
 502
 503 extern void value_print_array_elements (struct value *val,
 504                                         struct ui_file *stream, int format,
 505                                         enum val_prettyprint pretty);
 506
 507 extern struct value *value_release_to_mark (struct value *mark);
 508
 509 extern int val_print (struct type * type, char *valaddr,
 510                       int embedded_offset, CORE_ADDR address,
 511                       struct ui_file * stream, int format,
 512                       int deref_ref, int recurse,
 513                       enum val_prettyprint pretty);
 514
 515 extern int val_print_string (CORE_ADDR addr, int len, int width, struct ui_file *stream);
 516
 517 extern void print_variable_value (struct symbol * var,
 518                                   struct frame_info * frame,
 519                                   struct ui_file *stream);
 520
 521 extern int check_field (struct value *, const char *);
 522
 523 extern void typedef_print (struct type * type, struct symbol * news,
 524                              struct ui_file * stream);
 525
 526 extern char *internalvar_name (struct internalvar *var);
 527
 528 extern void clear_value_history (void);
 529
 530 extern void clear_internalvars (void);
 531
 532 /* From values.c */
 533
 534 extern struct value *value_copy (struct value *);
 535
 536 /* From valops.c */
 537
 538 extern struct value *varying_to_slice (struct value *);
 539
 540 extern struct value *value_slice (struct value *, int, int);
 541
 542 extern struct value *value_literal_complex (struct value *, struct value *,
 543                                             struct type *);
 544
 545 extern void find_rt_vbase_offset (struct type *, struct type *, char *, int,
 546                                   int *, int *);
 547
 548 extern struct value *find_function_in_inferior (const char *);
 549
 550 extern struct value *value_allocate_space_in_inferior (int);
 551
 552 extern struct value *value_of_local (const char *name, int complain);
 553
 554 #endif /* !defined (VALUE_H) */