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