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 /* NOTE: cagney/2002-12-17: This macro was handling a chill language
 263    problem but that language has gone away.  */
 264 #define COERCE_VARYING_ARRAY(arg, real_arg_type)
 265
 266 /* If ARG is an enum, convert it to an integer.  */
 267
 268 #define COERCE_ENUM(arg) \
 269   do {                                                                  \
 270     if (TYPE_CODE (check_typedef (VALUE_TYPE (arg))) == TYPE_CODE_ENUM) \
 271       arg = value_cast (builtin_type_unsigned_int, arg);                \
 272   } while (0)
 273
 274 /* Internal variables (variables for convenience of use of debugger)
 275    are recorded as a chain of these structures.  */
 276
 277 struct internalvar
 278 {
 279   struct internalvar *next;
 280   char *name;
 281   struct value *value;
 282 };
 283
 284 /* Pointer to member function.  Depends on compiler implementation.  */
 285
 286 #define METHOD_PTR_IS_VIRTUAL(ADDR)  ((ADDR) & 0x80000000)
 287 #define METHOD_PTR_FROM_VOFFSET(OFFSET) (0x80000000 + (OFFSET))
 288 #define METHOD_PTR_TO_VOFFSET(ADDR) (~0x80000000 & (ADDR))
 289 \f
 290
 291 #include "symtab.h"
 292 #include "gdbtypes.h"
 293 #include "expression.h"
 294
 295 struct frame_info;
 296 struct fn_field;
 297
 298 extern void print_address_demangle (CORE_ADDR, struct ui_file *, int);
 299
 300 extern LONGEST value_as_long (struct value *val);
 301 extern DOUBLEST value_as_double (struct value *val);
 302 extern CORE_ADDR value_as_address (struct value *val);
 303
 304 extern LONGEST unpack_long (struct type *type, const char *valaddr);
 305 extern DOUBLEST unpack_double (struct type *type, const char *valaddr,
 306                                int *invp);
 307 extern CORE_ADDR unpack_pointer (struct type *type, const char *valaddr);
 308 extern LONGEST unpack_field_as_long (struct type *type, const char *valaddr,
 309                                      int fieldno);
 310
 311 extern struct value *value_from_longest (struct type *type, LONGEST num);
 312 extern struct value *value_from_pointer (struct type *type, CORE_ADDR addr);
 313 extern struct value *value_from_double (struct type *type, DOUBLEST num);
 314 extern struct value *value_from_string (char *string);
 315
 316 extern struct value *value_at (struct type *type, CORE_ADDR addr,
 317                                asection * sect);
 318 extern struct value *value_at_lazy (struct type *type, CORE_ADDR addr,
 319                                     asection * sect);
 320
 321 extern struct value *value_from_register (struct type *type, int regnum,
 322                                           struct frame_info *frame);
 323
 324 extern struct value *value_of_variable (struct symbol *var, struct block *b);
 325
 326 extern struct value *value_of_register (int regnum,
 327                                         struct frame_info *frame);
 328
 329 extern int symbol_read_needs_frame (struct symbol *);
 330
 331 extern struct value *read_var_value (struct symbol *var,
 332                                      struct frame_info *frame);
 333
 334 extern struct value *locate_var_value (struct symbol *var,
 335                                        struct frame_info *frame);
 336
 337 extern struct value *allocate_value (struct type *type);
 338
 339 extern struct value *allocate_repeat_value (struct type *type, int count);
 340
 341 extern struct value *value_change_enclosing_type (struct value *val,
 342                                                   struct type *new_type);
 343
 344 extern struct value *value_mark (void);
 345
 346 extern void value_free_to_mark (struct value *mark);
 347
 348 extern struct value *value_string (char *ptr, int len);
 349 extern struct value *value_bitstring (char *ptr, int len);
 350
 351 extern struct value *value_array (int lowbound, int highbound,
 352                                   struct value ** elemvec);
 353
 354 extern struct value *value_concat (struct value *arg1, struct value *arg2);
 355
 356 extern struct value *value_binop (struct value *arg1, struct value *arg2,
 357                                   enum exp_opcode op);
 358
 359 extern struct value *value_add (struct value *arg1, struct value *arg2);
 360
 361 extern struct value *value_sub (struct value *arg1, struct value *arg2);
 362
 363 extern struct value *value_coerce_array (struct value *arg1);
 364
 365 extern struct value *value_coerce_function (struct value *arg1);
 366
 367 extern struct value *value_ind (struct value *arg1);
 368
 369 extern struct value *value_addr (struct value *arg1);
 370
 371 extern struct value *value_assign (struct value *toval, struct value *fromval);
 372
 373 extern struct value *value_neg (struct value *arg1);
 374
 375 extern struct value *value_complement (struct value *arg1);
 376
 377 extern struct value *value_struct_elt (struct value **argp,
 378                                        struct value **args,
 379                                        char *name, int *static_memfuncp,
 380                                        char *err);
 381
 382 extern struct value *value_aggregate_elt (struct type *curtype,
 383                                           char *name,
 384                                           enum noside noside);
 385
 386 extern struct value *value_static_field (struct type *type, int fieldno);
 387
 388 extern struct fn_field *value_find_oload_method_list (struct value **, char *,
 389                                                       int, int *,
 390                                                       struct type **, int *);
 391
 392 extern int find_overload_match (struct type **arg_types, int nargs,
 393                                 char *name, int method, int lax,
 394                                 struct value **objp, struct symbol *fsym,
 395                                 struct value **valp, struct symbol **symp,
 396                                 int *staticp);
 397
 398 extern struct value *value_field (struct value *arg1, int fieldno);
 399
 400 extern struct value *value_primitive_field (struct value *arg1, int offset,
 401                                             int fieldno,
 402                                             struct type *arg_type);
 403
 404
 405 extern struct type *value_rtti_target_type (struct value *, int *, int *,
 406                                             int *);
 407
 408 extern struct value *value_full_object (struct value *, struct type *, int,
 409                                         int, int);
 410
 411 extern struct value *value_cast (struct type *type, struct value *arg2);
 412
 413 extern struct value *value_zero (struct type *type, enum lval_type lv);
 414
 415 extern struct value *value_repeat (struct value *arg1, int count);
 416
 417 extern struct value *value_subscript (struct value *array, struct value *idx);
 418
 419 extern struct value *value_being_returned (struct type *valtype,
 420                                            struct regcache *retbuf,
 421                                            int struct_return);
 422
 423 extern struct value *value_in (struct value *element, struct value *set);
 424
 425 extern int value_bit_index (struct type *type, char *addr, int index);
 426
 427 extern int using_struct_return (struct type *value_type, int gcc_p);
 428
 429 extern void set_return_value (struct value *val);
 430
 431 extern struct value *evaluate_expression (struct expression *exp);
 432
 433 extern struct value *evaluate_type (struct expression *exp);
 434
 435 extern struct value *evaluate_subexp_with_coercion (struct expression *,
 436                                                     int *, enum noside);
 437
 438 extern struct value *parse_and_eval (char *exp);
 439
 440 extern struct value *parse_to_comma_and_eval (char **expp);
 441
 442 extern struct type *parse_and_eval_type (char *p, int length);
 443
 444 extern CORE_ADDR parse_and_eval_address (char *exp);
 445
 446 extern CORE_ADDR parse_and_eval_address_1 (char **expptr);
 447
 448 extern LONGEST parse_and_eval_long (char *exp);
 449
 450 extern struct value *access_value_history (int num);
 451
 452 extern struct value *value_of_internalvar (struct internalvar *var);
 453
 454 extern void set_internalvar (struct internalvar *var, struct value *val);
 455
 456 extern void set_internalvar_component (struct internalvar *var,
 457                                        int offset,
 458                                        int bitpos, int bitsize,
 459                                        struct value *newvalue);
 460
 461 extern struct internalvar *lookup_internalvar (char *name);
 462
 463 extern int value_equal (struct value *arg1, struct value *arg2);
 464
 465 extern int value_less (struct value *arg1, struct value *arg2);
 466
 467 extern int value_logical_not (struct value *arg1);
 468
 469 /* C++ */
 470
 471 extern struct value *value_of_this (int complain);
 472
 473 extern struct value *value_x_binop (struct value *arg1, struct value *arg2,
 474                                     enum exp_opcode op,
 475                                     enum exp_opcode otherop,
 476                                     enum noside noside);
 477
 478 extern struct value *value_x_unop (struct value *arg1, enum exp_opcode op,
 479                                    enum noside noside);
 480
 481 extern struct value *value_fn_field (struct value ** arg1p, struct fn_field *f,
 482                                      int j, struct type *type, int offset);
 483
 484 extern int binop_user_defined_p (enum exp_opcode op, struct value *arg1,
 485                                  struct value *arg2);
 486
 487 extern int unop_user_defined_p (enum exp_opcode op, struct value *arg1);
 488
 489 extern int destructor_name_p (const char *name, const struct type *type);
 490
 491 #define value_free(val) xfree (val)
 492
 493 extern void free_all_values (void);
 494
 495 extern void release_value (struct value *val);
 496
 497 extern int record_latest_value (struct value *val);
 498
 499 extern void modify_field (char *addr, LONGEST fieldval, int bitpos,
 500                           int bitsize);
 501
 502 extern void type_print (struct type * type, char *varstring,
 503                         struct ui_file * stream, int show);
 504
 505 extern char *baseclass_addr (struct type *type, int index, char *valaddr,
 506                              struct value **valuep, int *errp);
 507
 508 extern void print_longest (struct ui_file * stream, int format,
 509                            int use_local, LONGEST val);
 510
 511 extern void print_floating (char *valaddr, struct type * type,
 512                             struct ui_file * stream);
 513
 514 extern int value_print (struct value *val, struct ui_file *stream, int format,
 515                         enum val_prettyprint pretty);
 516
 517 extern void value_print_array_elements (struct value *val,
 518                                         struct ui_file *stream, int format,
 519                                         enum val_prettyprint pretty);
 520
 521 extern struct value *value_release_to_mark (struct value *mark);
 522
 523 extern int val_print (struct type * type, char *valaddr,
 524                       int embedded_offset, CORE_ADDR address,
 525                       struct ui_file * stream, int format,
 526                       int deref_ref, int recurse,
 527                       enum val_prettyprint pretty);
 528
 529 extern int val_print_string (CORE_ADDR addr, int len, int width, struct ui_file *stream);
 530
 531 extern void print_variable_value (struct symbol * var,
 532                                   struct frame_info * frame,
 533                                   struct ui_file *stream);
 534
 535 extern int check_field (struct value *, const char *);
 536
 537 extern void typedef_print (struct type * type, struct symbol * news,
 538                              struct ui_file * stream);
 539
 540 extern char *internalvar_name (struct internalvar *var);
 541
 542 extern void clear_value_history (void);
 543
 544 extern void clear_internalvars (void);
 545
 546 /* From values.c */
 547
 548 extern struct value *value_copy (struct value *);
 549
 550 /* From valops.c */
 551
 552 extern struct value *varying_to_slice (struct value *);
 553
 554 extern struct value *value_slice (struct value *, int, int);
 555
 556 extern struct value *value_literal_complex (struct value *, struct value *,
 557                                             struct type *);
 558
 559 extern void find_rt_vbase_offset (struct type *, struct type *, char *, int,
 560                                   int *, int *);
 561
 562 extern struct value *find_function_in_inferior (const char *);
 563
 564 extern struct value *value_allocate_space_in_inferior (int);
 565
 566 extern CORE_ADDR legacy_push_arguments (int nargs, struct value ** args,
 567                                         CORE_ADDR sp, int struct_return,
 568                                         CORE_ADDR struct_addr);
 569
 570 extern struct value *value_of_local (const char *name, int complain);
 571
 572 #endif /* !defined (VALUE_H) */