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     /* The BFD section associated with this value.  */
 166     asection *bfd_section;
 167
 168     /* Actual contents of the value.  For use of this value; setting
 169        it uses the stuff above.  Not valid if lazy is nonzero.
 170        Target byte-order.  We force it to be aligned properly for any
 171        possible value.  Note that a value therefore extends beyond
 172        what is declared here.  */
 173     union
 174     {
 175       long contents[1];
 176       DOUBLEST force_doublest_align;
 177       LONGEST force_longest_align;
 178       CORE_ADDR force_core_addr_align;
 179       void *force_pointer_align;
 180     } aligner;
 181     /* Do not add any new members here -- contents above will trash them.  */
 182 };
 183
 184 #define VALUE_TYPE(val) (val)->type
 185 #define VALUE_ENCLOSING_TYPE(val) (val)->enclosing_type
 186 #define VALUE_LAZY(val) (val)->lazy
 187
 188 /* VALUE_CONTENTS and VALUE_CONTENTS_RAW both return the address of
 189    the gdb buffer used to hold a copy of the contents of the lval.
 190    VALUE_CONTENTS is used when the contents of the buffer are needed
 191    -- it uses value_fetch_lazy() to load the buffer from the process
 192    being debugged if it hasn't already been loaded.
 193    VALUE_CONTENTS_RAW is used when data is being stored into the
 194    buffer, or when it is certain that the contents of the buffer are
 195    valid.
 196
 197    Note: The contents pointer is adjusted by the offset required to
 198    get to the real subobject, if the value happens to represent
 199    something embedded in a larger run-time object.  */
 200
 201 #define VALUE_CONTENTS_RAW(val) \
 202  ((char *) (val)->aligner.contents + (val)->embedded_offset)
 203 #define VALUE_CONTENTS(val) \
 204  ((void)(VALUE_LAZY(val) && value_fetch_lazy(val)), VALUE_CONTENTS_RAW(val))
 205
 206 /* The ALL variants of the above two macros do not adjust the returned
 207    pointer by the embedded_offset value.  */
 208
 209 #define VALUE_CONTENTS_ALL_RAW(val) ((char *) (val)->aligner.contents)
 210 #define VALUE_CONTENTS_ALL(val) \
 211   ((void) (VALUE_LAZY(val) && value_fetch_lazy(val)), \
 212    VALUE_CONTENTS_ALL_RAW(val))
 213
 214 extern int value_fetch_lazy (struct value *val);
 215
 216 #define VALUE_LVAL(val) (val)->lval
 217 #define VALUE_ADDRESS(val) (val)->location.address
 218 #define VALUE_INTERNALVAR(val) (val)->location.internalvar
 219 #define VALUE_FRAME_REGNUM(val) ((val)->location.regnum)
 220 #define VALUE_FRAME_ID(val) ((val)->frame_id)
 221 #define VALUE_OFFSET(val) (val)->offset
 222 #define VALUE_BITSIZE(val) (val)->bitsize
 223 #define VALUE_BITPOS(val) (val)->bitpos
 224 #define VALUE_NEXT(val) (val)->next
 225 #define VALUE_REGNO(val) (val)->regno
 226 #define VALUE_OPTIMIZED_OUT(val) ((val)->optimized_out)
 227 #define VALUE_EMBEDDED_OFFSET(val) ((val)->embedded_offset)
 228 #define VALUE_POINTED_TO_OFFSET(val) ((val)->pointed_to_offset)
 229 #define VALUE_BFD_SECTION(val) ((val)->bfd_section)
 230
 231 /* Convert a REF to the object referenced.  */
 232
 233 #define COERCE_REF(arg) \
 234   do {                                                                  \
 235     struct type *value_type_arg_tmp = check_typedef (VALUE_TYPE (arg)); \
 236     if (TYPE_CODE (value_type_arg_tmp) == TYPE_CODE_REF)                \
 237       arg = value_at_lazy (TYPE_TARGET_TYPE (value_type_arg_tmp),       \
 238                            unpack_pointer (VALUE_TYPE (arg),            \
 239                                            VALUE_CONTENTS (arg)),       \
 240                                            VALUE_BFD_SECTION (arg));    \
 241   } while (0)
 242
 243 /* If ARG is an array, convert it to a pointer.
 244    If ARG is an enum, convert it to an integer.
 245    If ARG is a function, convert it to a function pointer.
 246
 247    References are dereferenced.  */
 248
 249 #define COERCE_ARRAY(arg) \
 250   do {                                                                  \
 251     COERCE_REF(arg);                                                    \
 252     if (current_language->c_style_arrays                                \
 253         && TYPE_CODE (VALUE_TYPE (arg)) == TYPE_CODE_ARRAY)             \
 254       arg = value_coerce_array (arg);                                   \
 255     if (TYPE_CODE (VALUE_TYPE (arg)) == TYPE_CODE_FUNC)                 \
 256       arg = value_coerce_function (arg);                                \
 257   } while (0)
 258
 259 #define COERCE_NUMBER(arg) \
 260   do { COERCE_ARRAY(arg); COERCE_ENUM(arg); } while (0)
 261
 262 /* If ARG is an enum, convert it to an integer.  */
 263
 264 #define COERCE_ENUM(arg) \
 265   do {                                                                  \
 266     if (TYPE_CODE (check_typedef (VALUE_TYPE (arg))) == TYPE_CODE_ENUM) \
 267       arg = value_cast (builtin_type_unsigned_int, arg);                \
 268   } while (0)
 269
 270 /* Internal variables (variables for convenience of use of debugger)
 271    are recorded as a chain of these structures.  */
 272
 273 struct internalvar
 274 {
 275   struct internalvar *next;
 276   char *name;
 277   struct value *value;
 278 };
 279
 280 /* Pointer to member function.  Depends on compiler implementation.  */
 281
 282 #define METHOD_PTR_IS_VIRTUAL(ADDR)  ((ADDR) & 0x80000000)
 283 #define METHOD_PTR_FROM_VOFFSET(OFFSET) (0x80000000 + (OFFSET))
 284 #define METHOD_PTR_TO_VOFFSET(ADDR) (~0x80000000 & (ADDR))
 285 \f
 286
 287 #include "symtab.h"
 288 #include "gdbtypes.h"
 289 #include "expression.h"
 290
 291 struct frame_info;
 292 struct fn_field;
 293
 294 extern void print_address_demangle (CORE_ADDR, struct ui_file *, int);
 295
 296 extern LONGEST value_as_long (struct value *val);
 297 extern DOUBLEST value_as_double (struct value *val);
 298 extern CORE_ADDR value_as_address (struct value *val);
 299
 300 extern LONGEST unpack_long (struct type *type, const char *valaddr);
 301 extern DOUBLEST unpack_double (struct type *type, const char *valaddr,
 302                                int *invp);
 303 extern CORE_ADDR unpack_pointer (struct type *type, const char *valaddr);
 304 extern LONGEST unpack_field_as_long (struct type *type, const char *valaddr,
 305                                      int fieldno);
 306
 307 extern struct value *value_from_longest (struct type *type, LONGEST num);
 308 extern struct value *value_from_pointer (struct type *type, CORE_ADDR addr);
 309 extern struct value *value_from_double (struct type *type, DOUBLEST num);
 310 extern struct value *value_from_string (char *string);
 311
 312 extern struct value *value_at (struct type *type, CORE_ADDR addr,
 313                                asection * sect);
 314 extern struct value *value_at_lazy (struct type *type, CORE_ADDR addr,
 315                                     asection * sect);
 316
 317 extern struct value *value_from_register (struct type *type, int regnum,
 318                                           struct frame_info *frame);
 319
 320 extern struct value *value_of_variable (struct symbol *var, struct block *b);
 321
 322 extern struct value *value_of_register (int regnum,
 323                                         struct frame_info *frame);
 324
 325 extern int symbol_read_needs_frame (struct symbol *);
 326
 327 extern struct value *read_var_value (struct symbol *var,
 328                                      struct frame_info *frame);
 329
 330 extern struct value *locate_var_value (struct symbol *var,
 331                                        struct frame_info *frame);
 332
 333 extern struct value *allocate_value (struct type *type);
 334
 335 extern struct value *allocate_repeat_value (struct type *type, int count);
 336
 337 extern struct value *value_change_enclosing_type (struct value *val,
 338                                                   struct type *new_type);
 339
 340 extern struct value *value_mark (void);
 341
 342 extern void value_free_to_mark (struct value *mark);
 343
 344 extern struct value *value_string (char *ptr, int len);
 345 extern struct value *value_bitstring (char *ptr, int len);
 346
 347 extern struct value *value_array (int lowbound, int highbound,
 348                                   struct value ** elemvec);
 349
 350 extern struct value *value_concat (struct value *arg1, struct value *arg2);
 351
 352 extern struct value *value_binop (struct value *arg1, struct value *arg2,
 353                                   enum exp_opcode op);
 354
 355 extern struct value *value_add (struct value *arg1, struct value *arg2);
 356
 357 extern struct value *value_sub (struct value *arg1, struct value *arg2);
 358
 359 extern struct value *value_coerce_array (struct value *arg1);
 360
 361 extern struct value *value_coerce_function (struct value *arg1);
 362
 363 extern struct value *value_ind (struct value *arg1);
 364
 365 extern struct value *value_addr (struct value *arg1);
 366
 367 extern struct value *value_assign (struct value *toval, struct value *fromval);
 368
 369 extern struct value *value_neg (struct value *arg1);
 370
 371 extern struct value *value_complement (struct value *arg1);
 372
 373 extern struct value *value_struct_elt (struct value **argp,
 374                                        struct value **args,
 375                                        char *name, int *static_memfuncp,
 376                                        char *err);
 377
 378 extern struct value *value_aggregate_elt (struct type *curtype,
 379                                           char *name,
 380                                           enum noside noside);
 381
 382 extern struct value *value_static_field (struct type *type, int fieldno);
 383
 384 extern struct fn_field *value_find_oload_method_list (struct value **, char *,
 385                                                       int, int *,
 386                                                       struct type **, int *);
 387
 388 extern int find_overload_match (struct type **arg_types, int nargs,
 389                                 char *name, int method, int lax,
 390                                 struct value **objp, struct symbol *fsym,
 391                                 struct value **valp, struct symbol **symp,
 392                                 int *staticp);
 393
 394 extern struct value *value_field (struct value *arg1, int fieldno);
 395
 396 extern struct value *value_primitive_field (struct value *arg1, int offset,
 397                                             int fieldno,
 398                                             struct type *arg_type);
 399
 400
 401 extern struct type *value_rtti_target_type (struct value *, int *, int *,
 402                                             int *);
 403
 404 extern struct value *value_full_object (struct value *, struct type *, int,
 405                                         int, int);
 406
 407 extern struct value *value_cast (struct type *type, struct value *arg2);
 408
 409 extern struct value *value_zero (struct type *type, enum lval_type lv);
 410
 411 extern struct value *value_repeat (struct value *arg1, int count);
 412
 413 extern struct value *value_subscript (struct value *array, struct value *idx);
 414
 415 extern struct value *register_value_being_returned (struct type *valtype,
 416                                                     struct regcache *retbuf);
 417
 418 extern struct value *value_in (struct value *element, struct value *set);
 419
 420 extern int value_bit_index (struct type *type, char *addr, int index);
 421
 422 extern int using_struct_return (struct type *value_type, int gcc_p);
 423
 424 extern struct value *evaluate_expression (struct expression *exp);
 425
 426 extern struct value *evaluate_type (struct expression *exp);
 427
 428 extern struct value *evaluate_subexp_with_coercion (struct expression *,
 429                                                     int *, enum noside);
 430
 431 extern struct value *parse_and_eval (char *exp);
 432
 433 extern struct value *parse_to_comma_and_eval (char **expp);
 434
 435 extern struct type *parse_and_eval_type (char *p, int length);
 436
 437 extern CORE_ADDR parse_and_eval_address (char *exp);
 438
 439 extern CORE_ADDR parse_and_eval_address_1 (char **expptr);
 440
 441 extern LONGEST parse_and_eval_long (char *exp);
 442
 443 extern struct value *access_value_history (int num);
 444
 445 extern struct value *value_of_internalvar (struct internalvar *var);
 446
 447 extern void set_internalvar (struct internalvar *var, struct value *val);
 448
 449 extern void set_internalvar_component (struct internalvar *var,
 450                                        int offset,
 451                                        int bitpos, int bitsize,
 452                                        struct value *newvalue);
 453
 454 extern struct internalvar *lookup_internalvar (char *name);
 455
 456 extern int value_equal (struct value *arg1, struct value *arg2);
 457
 458 extern int value_less (struct value *arg1, struct value *arg2);
 459
 460 extern int value_logical_not (struct value *arg1);
 461
 462 /* C++ */
 463
 464 extern struct value *value_of_this (int complain);
 465
 466 extern struct value *value_x_binop (struct value *arg1, struct value *arg2,
 467                                     enum exp_opcode op,
 468                                     enum exp_opcode otherop,
 469                                     enum noside noside);
 470
 471 extern struct value *value_x_unop (struct value *arg1, enum exp_opcode op,
 472                                    enum noside noside);
 473
 474 extern struct value *value_fn_field (struct value ** arg1p, struct fn_field *f,
 475                                      int j, struct type *type, int offset);
 476
 477 extern int binop_user_defined_p (enum exp_opcode op, struct value *arg1,
 478                                  struct value *arg2);
 479
 480 extern int unop_user_defined_p (enum exp_opcode op, struct value *arg1);
 481
 482 extern int destructor_name_p (const char *name, const struct type *type);
 483
 484 #define value_free(val) xfree (val)
 485
 486 extern void free_all_values (void);
 487
 488 extern void release_value (struct value *val);
 489
 490 extern int record_latest_value (struct value *val);
 491
 492 extern void modify_field (char *addr, LONGEST fieldval, int bitpos,
 493                           int bitsize);
 494
 495 extern void type_print (struct type * type, char *varstring,
 496                         struct ui_file * stream, int show);
 497
 498 extern char *baseclass_addr (struct type *type, int index, char *valaddr,
 499                              struct value **valuep, int *errp);
 500
 501 extern void print_longest (struct ui_file * stream, int format,
 502                            int use_local, LONGEST val);
 503
 504 extern void print_floating (char *valaddr, struct type * type,
 505                             struct ui_file * stream);
 506
 507 extern int value_print (struct value *val, struct ui_file *stream, int format,
 508                         enum val_prettyprint pretty);
 509
 510 extern void value_print_array_elements (struct value *val,
 511                                         struct ui_file *stream, int format,
 512                                         enum val_prettyprint pretty);
 513
 514 extern struct value *value_release_to_mark (struct value *mark);
 515
 516 extern int val_print (struct type * type, char *valaddr,
 517                       int embedded_offset, CORE_ADDR address,
 518                       struct ui_file * stream, int format,
 519                       int deref_ref, int recurse,
 520                       enum val_prettyprint pretty);
 521
 522 extern int val_print_string (CORE_ADDR addr, int len, int width, struct ui_file *stream);
 523
 524 extern void print_variable_value (struct symbol * var,
 525                                   struct frame_info * frame,
 526                                   struct ui_file *stream);
 527
 528 extern int check_field (struct value *, const char *);
 529
 530 extern void typedef_print (struct type * type, struct symbol * news,
 531                              struct ui_file * stream);
 532
 533 extern char *internalvar_name (struct internalvar *var);
 534
 535 extern void clear_value_history (void);
 536
 537 extern void clear_internalvars (void);
 538
 539 /* From values.c */
 540
 541 extern struct value *value_copy (struct value *);
 542
 543 /* From valops.c */
 544
 545 extern struct value *varying_to_slice (struct value *);
 546
 547 extern struct value *value_slice (struct value *, int, int);
 548
 549 extern struct value *value_literal_complex (struct value *, struct value *,
 550                                             struct type *);
 551
 552 extern void find_rt_vbase_offset (struct type *, struct type *, char *, int,
 553                                   int *, int *);
 554
 555 extern struct value *find_function_in_inferior (const char *);
 556
 557 extern struct value *value_allocate_space_in_inferior (int);
 558
 559 extern struct value *value_of_local (const char *name, int complain);
 560
 561 #endif /* !defined (VALUE_H) */