gdb/value.h

   1 /* Definitions for values of C expressions, for GDB.
   2    Copyright 1986, 1987, 1988, 1989, 1990, 1991, 1992, 1993, 1994,
   3    1995, 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003
   4    Free Software Foundation, Inc.
   5
   6    This file is part of GDB.
   7
   8    This program is free software; you can redistribute it and/or modify
   9    it under the terms of the GNU General Public License as published by
  10    the Free Software Foundation; either version 2 of the License, or
  11    (at your option) any later version.
  12
  13    This program is distributed in the hope that it will be useful,
  14    but WITHOUT ANY WARRANTY; without even the implied warranty of
  15    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16    GNU General Public License for more details.
  17
  18    You should have received a copy of the GNU General Public License
  19    along with this program; if not, write to the Free Software
  20    Foundation, Inc., 59 Temple Place - Suite 330,
  21    Boston, MA 02111-1307, USA.  */
  22
  23 #if !defined (VALUE_H)
  24 #define VALUE_H 1
  25
  26 struct regcache;
  27 struct block;
  28
  29 #include "doublest.h"
  30
  31 /*
  32  * The structure which defines the type of a value.  It should never
  33  * be possible for a program lval value to survive over a call to the inferior
  34  * (ie to be put into the history list or an internal variable).
  35  */
  36
  37 struct value
  38   {
  39     /* Type of value; either not an lval, or one of the various
  40        different possible kinds of lval.  */
  41     enum lval_type lval;
  42     /* Is it modifiable?  Only relevant if lval != not_lval.  */
  43     int modifiable;
  44     /* Location of value (if lval).  */
  45     union
  46       {
  47         /* If lval == lval_memory, this is the address in the inferior.
  48            If lval == lval_register, this is the byte offset into the
  49            registers structure.  */
  50         CORE_ADDR address;
  51         /* Pointer to internal variable.  */
  52         struct internalvar *internalvar;
  53         /* Number of register.  Only used with
  54            lval_reg_frame_relative.  */
  55         int regnum;
  56       }
  57     location;
  58     /* Describes offset of a value within lval of a structure in bytes.
  59        If lval == lval_memory, this is an offset to the address.
  60        If lval == lval_register, this is a further offset from
  61           location.address within the registers structure.
  62        Note also the member embedded_offset below.  */
  63     int offset;
  64     /* Only used for bitfields; number of bits contained in them.  */
  65     int bitsize;
  66     /* Only used for bitfields; position of start of field.
  67        For BITS_BIG_ENDIAN=0 targets, it is the position of the LSB.
  68        For BITS_BIG_ENDIAN=1 targets, it is the position of the MSB. */
  69     int bitpos;
  70     /* Frame value is relative to.  In practice, this address is only
  71        used if the value is stored in several registers in other than
  72        the current frame, and these registers have not all been saved
  73        at the same place in memory.  This will be described in the
  74        lval enum above as "lval_reg_frame_relative".  */
  75     CORE_ADDR frame_addr;
  76
  77     /* Type of the value.  */
  78     struct type *type;
  79
  80     /* If a value represents a C++ object, then the `type' field gives
  81        the object's compile-time type.  If the object actually belongs
  82        to some class derived from `type', perhaps with other base
  83        classes and additional members, then `type' is just a subobject
  84        of the real thing, and the full object is probably larger than
  85        `type' would suggest.
  86
  87        If `type' is a dynamic class (i.e. one with a vtable), then GDB
  88        can actually determine the object's run-time type by looking at
  89        the run-time type information in the vtable.  When this
  90        information is available, we may elect to read in the entire
  91        object, for several reasons:
  92
  93          - When printing the value, the user would probably rather see
  94            the full object, not just the limited portion apparent from
  95            the compile-time type.
  96
  97          - If `type' has virtual base classes, then even printing
  98            `type' alone may require reaching outside the `type'
  99            portion of the object to wherever the virtual base class
 100            has been stored.
 101
 102        When we store the entire object, `enclosing_type' is the
 103        run-time type --- the complete object --- and `embedded_offset'
 104        is the offset of `type' within that larger type, in bytes.  The
 105        VALUE_CONTENTS macro takes `embedded_offset' into account, so
 106        most GDB code continues to see the `type' portion of the value,
 107        just as the inferior would.
 108
 109        If `type' is a pointer to an object, then `enclosing_type' is a
 110        pointer to the object's run-time type, and `pointed_to_offset'
 111        is the offset in bytes from the full object to the pointed-to
 112        object --- that is, the value `embedded_offset' would have if
 113        we followed the pointer and fetched the complete object.  (I
 114        don't really see the point.  Why not just determine the
 115        run-time type when you indirect, and avoid the special case?
 116        The contents don't matter until you indirect anyway.)
 117
 118        If we're not doing anything fancy, `enclosing_type' is equal to
 119        `type', and `embedded_offset' is zero, so everything works
 120        normally.  */
 121     struct type *enclosing_type;
 122     int embedded_offset;
 123     int pointed_to_offset;
 124
 125     /* Values are stored in a chain, so that they can be deleted
 126        easily over calls to the inferior.  Values assigned to internal
 127        variables or put into the value history are taken off this
 128        list.  */
 129     struct value *next;
 130
 131     /* Register number if the value is from a register.  Is not kept
 132        if you take a field of a structure that is stored in a
 133        register.  Shouldn't it be?  */
 134     short regno;
 135     /* If zero, contents of this value are in the contents field.
 136        If nonzero, contents are in inferior memory at address
 137        in the location.address field plus the offset field
 138        (and the lval field should be lval_memory).
 139
 140        WARNING: This field is used by the code which handles
 141        watchpoints (see breakpoint.c) to decide whether a particular
 142        value can be watched by hardware watchpoints.  If the lazy flag
 143        is set for some member of a value chain, it is assumed that
 144        this member of the chain doesn't need to be watched as part of
 145        watching the value itself.  This is how GDB avoids watching the
 146        entire struct or array when the user wants to watch a single
 147        struct member or array element.  If you ever change the way
 148        lazy flag is set and reset, be sure to consider this use as
 149        well!  */
 150     char lazy;
 151     /* If nonzero, this is the value of a variable which does not
 152        actually exist in the program.  */
 153     char optimized_out;
 154     /* The BFD section associated with this value.  */
 155     asection *bfd_section;
 156     /* Actual contents of the value.  For use of this value; setting
 157        it uses the stuff above.  Not valid if lazy is nonzero.
 158        Target byte-order.  We force it to be aligned properly for any
 159        possible value.  Note that a value therefore extends beyond
 160        what is declared here.  */
 161     union
 162       {
 163         long contents[1];
 164         DOUBLEST force_doublest_align;
 165         LONGEST force_longest_align;
 166         CORE_ADDR force_core_addr_align;
 167         void *force_pointer_align;
 168       }
 169     aligner;
 170     /* Do not add any new members here -- contents above will trash them */
 171   };
 172
 173 #define VALUE_TYPE(val) (val)->type
 174 #define VALUE_ENCLOSING_TYPE(val) (val)->enclosing_type
 175 #define VALUE_LAZY(val) (val)->lazy
 176 /* VALUE_CONTENTS and VALUE_CONTENTS_RAW both return the address of
 177    the gdb buffer used to hold a copy of the contents of the lval.
 178    VALUE_CONTENTS is used when the contents of the buffer are needed --
 179    it uses value_fetch_lazy() to load the buffer from the process being
 180    debugged if it hasn't already been loaded.  VALUE_CONTENTS_RAW is
 181    used when data is being stored into the buffer, or when it is
 182    certain that the contents of the buffer are valid.
 183    Note: The contents pointer is adjusted by the offset required to
 184    get to the real subobject, if the value happens to represent
 185    something embedded in a larger run-time object. */
 186
 187 #define VALUE_CONTENTS_RAW(val) ((char *) (val)->aligner.contents + (val)->embedded_offset)
 188 #define VALUE_CONTENTS(val) ((void)(VALUE_LAZY(val) && value_fetch_lazy(val)),\
 189                              VALUE_CONTENTS_RAW(val))
 190
 191 /* The ALL variants of the above two macros do not adjust the returned
 192    pointer by the embedded_offset value. */
 193
 194 #define VALUE_CONTENTS_ALL_RAW(val) ((char *) (val)->aligner.contents)
 195 #define VALUE_CONTENTS_ALL(val) ((void) (VALUE_LAZY(val) && value_fetch_lazy(val)),\
 196                                  VALUE_CONTENTS_ALL_RAW(val))
 197
 198
 199 extern int value_fetch_lazy (struct value *val);
 200
 201 #define VALUE_LVAL(val) (val)->lval
 202 #define VALUE_ADDRESS(val) (val)->location.address
 203 #define VALUE_INTERNALVAR(val) (val)->location.internalvar
 204 #define VALUE_FRAME_REGNUM(val) ((val)->location.regnum)
 205 #define VALUE_FRAME(val) ((val)->frame_addr)
 206 #define VALUE_OFFSET(val) (val)->offset
 207 #define VALUE_BITSIZE(val) (val)->bitsize
 208 #define VALUE_BITPOS(val) (val)->bitpos
 209 #define VALUE_NEXT(val) (val)->next
 210 #define VALUE_REGNO(val) (val)->regno
 211 #define VALUE_OPTIMIZED_OUT(val) ((val)->optimized_out)
 212 #define VALUE_EMBEDDED_OFFSET(val) ((val)->embedded_offset)
 213 #define VALUE_POINTED_TO_OFFSET(val) ((val)->pointed_to_offset)
 214 #define VALUE_BFD_SECTION(val) ((val)->bfd_section)
 215
 216 /* Convert a REF to the object referenced. */
 217
 218 #define COERCE_REF(arg)    \
 219 do { struct type *value_type_arg_tmp = check_typedef (VALUE_TYPE (arg));\
 220      if (TYPE_CODE (value_type_arg_tmp) == TYPE_CODE_REF)               \
 221          arg = value_at_lazy (TYPE_TARGET_TYPE (value_type_arg_tmp),    \
 222                               unpack_pointer (VALUE_TYPE (arg),         \
 223                                               VALUE_CONTENTS (arg)),    \
 224                               VALUE_BFD_SECTION (arg));                 \
 225     } while (0)
 226
 227 /* If ARG is an array, convert it to a pointer.
 228    If ARG is an enum, convert it to an integer.
 229    If ARG is a function, convert it to a function pointer.
 230
 231    References are dereferenced.  */
 232
 233 #define COERCE_ARRAY(arg)    \
 234 do { COERCE_REF(arg);                                                   \
 235   if (current_language->c_style_arrays                                  \
 236       && TYPE_CODE (VALUE_TYPE (arg)) == TYPE_CODE_ARRAY)               \
 237     arg = value_coerce_array (arg);                                     \
 238   if (TYPE_CODE (VALUE_TYPE (arg)) == TYPE_CODE_FUNC)                   \
 239     arg = value_coerce_function (arg);                                  \
 240 } while (0)
 241
 242 #define COERCE_NUMBER(arg)  \
 243   do { COERCE_ARRAY(arg);  COERCE_ENUM(arg); } while (0)
 244
 245 /* NOTE: cagney/2002-12-17: This macro was handling a chill language
 246    problem but that language has gone away.  */
 247 #define COERCE_VARYING_ARRAY(arg, real_arg_type)
 248
 249 /* If ARG is an enum, convert it to an integer.  */
 250
 251 #define COERCE_ENUM(arg)   { \
 252   if (TYPE_CODE (check_typedef (VALUE_TYPE (arg))) == TYPE_CODE_ENUM)   \
 253     arg = value_cast (builtin_type_unsigned_int, arg);                  \
 254 }
 255
 256 /* Internal variables (variables for convenience of use of debugger)
 257    are recorded as a chain of these structures.  */
 258
 259 struct internalvar
 260   {
 261     struct internalvar *next;
 262     char *name;
 263     struct value *value;
 264   };
 265
 266 /* Pointer to member function.  Depends on compiler implementation. */
 267
 268 #define METHOD_PTR_IS_VIRTUAL(ADDR)  ((ADDR) & 0x80000000)
 269 #define METHOD_PTR_FROM_VOFFSET(OFFSET) (0x80000000 + (OFFSET))
 270 #define METHOD_PTR_TO_VOFFSET(ADDR) (~0x80000000 & (ADDR))
 271 \f
 272
 273 #include "symtab.h"
 274 #include "gdbtypes.h"
 275 #include "expression.h"
 276
 277 struct frame_info;
 278 struct fn_field;
 279
 280 extern void print_address_demangle (CORE_ADDR, struct ui_file *, int);
 281
 282 extern LONGEST value_as_long (struct value *val);
 283
 284 extern DOUBLEST value_as_double (struct value *val);
 285
 286 extern CORE_ADDR value_as_address (struct value *val);
 287
 288 extern LONGEST unpack_long (struct type *type, const char *valaddr);
 289
 290 extern DOUBLEST unpack_double (struct type *type, const char *valaddr,
 291                                int *invp);
 292
 293 extern CORE_ADDR unpack_pointer (struct type *type, const char *valaddr);
 294
 295 extern LONGEST unpack_field_as_long (struct type *type, const char *valaddr,
 296                                      int fieldno);
 297
 298 extern struct value *value_from_longest (struct type *type, LONGEST num);
 299
 300 extern struct value *value_from_pointer (struct type *type, CORE_ADDR addr);
 301
 302 extern struct value *value_from_double (struct type *type, DOUBLEST num);
 303
 304 extern struct value *value_from_string (char *string);
 305
 306 extern struct value *value_at (struct type *type, CORE_ADDR addr,
 307                                asection * sect);
 308
 309 extern struct value *value_at_lazy (struct type *type, CORE_ADDR addr,
 310                                     asection * sect);
 311
 312 extern struct value *value_from_register (struct type *type, int regnum,
 313                                           struct frame_info *frame);
 314
 315 extern struct value *value_of_variable (struct symbol *var, struct block *b);
 316
 317 extern struct value *value_of_register (int regnum,
 318                                         struct frame_info *frame);
 319
 320 extern int symbol_read_needs_frame (struct symbol *);
 321
 322 extern struct value *read_var_value (struct symbol *var,
 323                                      struct frame_info *frame);
 324
 325 extern struct value *locate_var_value (struct symbol *var,
 326                                        struct frame_info *frame);
 327
 328 extern struct value *allocate_value (struct type *type);
 329
 330 extern struct value *allocate_repeat_value (struct type *type, int count);
 331
 332 extern struct value *value_change_enclosing_type (struct value *val,
 333                                                   struct type *new_type);
 334
 335 extern struct value *value_mark (void);
 336
 337 extern void value_free_to_mark (struct value *mark);
 338
 339 extern struct value *value_string (char *ptr, int len);
 340 extern struct value *value_bitstring (char *ptr, int len);
 341
 342 extern struct value *value_array (int lowbound, int highbound,
 343                                   struct value ** elemvec);
 344
 345 extern struct value *value_concat (struct value *arg1, struct value *arg2);
 346
 347 extern struct value *value_binop (struct value *arg1, struct value *arg2,
 348                                   enum exp_opcode op);
 349
 350 extern struct value *value_add (struct value *arg1, struct value *arg2);
 351
 352 extern struct value *value_sub (struct value *arg1, struct value *arg2);
 353
 354 extern struct value *value_coerce_array (struct value *arg1);
 355
 356 extern struct value *value_coerce_function (struct value *arg1);
 357
 358 extern struct value *value_ind (struct value *arg1);
 359
 360 extern struct value *value_addr (struct value *arg1);
 361
 362 extern struct value *value_assign (struct value *toval, struct value *fromval);
 363
 364 extern struct value *value_neg (struct value *arg1);
 365
 366 extern struct value *value_complement (struct value *arg1);
 367
 368 extern struct value *value_struct_elt (struct value **argp,
 369                                        struct value **args,
 370                                        char *name, int *static_memfuncp,
 371                                        char *err);
 372
 373 extern struct value *value_struct_elt_for_reference (struct type *domain,
 374                                                      int offset,
 375                                                      struct type *curtype,
 376                                                      char *name,
 377                                                      struct type *intype);
 378
 379 extern struct value *value_static_field (struct type *type, int fieldno);
 380
 381 extern struct fn_field *value_find_oload_method_list (struct value **, char *,
 382                                                       int, int *,
 383                                                       struct type **, int *);
 384
 385 extern int find_overload_match (struct type **arg_types, int nargs,
 386                                 char *name, int method, int lax,
 387                                 struct value **objp, struct symbol *fsym,
 388                                 struct value **valp, struct symbol **symp,
 389                                 int *staticp);
 390
 391 extern struct value *value_field (struct value *arg1, int fieldno);
 392
 393 extern struct value *value_primitive_field (struct value *arg1, int offset,
 394                                             int fieldno,
 395                                             struct type *arg_type);
 396
 397
 398 extern struct type *value_rtti_target_type (struct value *, int *, int *,
 399                                             int *);
 400
 401 extern struct value *value_full_object (struct value *, struct type *, int,
 402                                         int, int);
 403
 404 extern struct value *value_cast (struct type *type, struct value *arg2);
 405
 406 extern struct value *value_zero (struct type *type, enum lval_type lv);
 407
 408 extern struct value *value_repeat (struct value *arg1, int count);
 409
 410 extern struct value *value_subscript (struct value *array, struct value *idx);
 411
 412 extern struct value *value_being_returned (struct type *valtype,
 413                                            struct regcache *retbuf,
 414                                            int struct_return);
 415
 416 extern struct value *value_in (struct value *element, struct value *set);
 417
 418 extern int value_bit_index (struct type *type, char *addr, int index);
 419
 420 extern int using_struct_return (struct value *function, CORE_ADDR funcaddr,
 421                                 struct type *value_type, int gcc_p);
 422
 423 extern void set_return_value (struct value *val);
 424
 425 extern struct value *evaluate_expression (struct expression *exp);
 426
 427 extern struct value *evaluate_type (struct expression *exp);
 428
 429 extern struct value *evaluate_subexp_with_coercion (struct expression *,
 430                                                     int *, enum noside);
 431
 432 extern struct value *parse_and_eval (char *exp);
 433
 434 extern struct value *parse_to_comma_and_eval (char **expp);
 435
 436 extern struct type *parse_and_eval_type (char *p, int length);
 437
 438 extern CORE_ADDR parse_and_eval_address (char *exp);
 439
 440 extern CORE_ADDR parse_and_eval_address_1 (char **expptr);
 441
 442 extern LONGEST parse_and_eval_long (char *exp);
 443
 444 extern struct value *access_value_history (int num);
 445
 446 extern struct value *value_of_internalvar (struct internalvar *var);
 447
 448 extern void set_internalvar (struct internalvar *var, struct value *val);
 449
 450 extern void set_internalvar_component (struct internalvar *var,
 451                                        int offset,
 452                                        int bitpos, int bitsize,
 453                                        struct value *newvalue);
 454
 455 extern struct internalvar *lookup_internalvar (char *name);
 456
 457 extern int value_equal (struct value *arg1, struct value *arg2);
 458
 459 extern int value_less (struct value *arg1, struct value *arg2);
 460
 461 extern int value_logical_not (struct value *arg1);
 462
 463 /* C++ */
 464
 465 extern struct value *value_of_this (int complain);
 466
 467 extern struct value *value_x_binop (struct value *arg1, struct value *arg2,
 468                                     enum exp_opcode op,
 469                                     enum exp_opcode otherop,
 470                                     enum noside noside);
 471
 472 extern struct value *value_x_unop (struct value *arg1, enum exp_opcode op,
 473                                    enum noside noside);
 474
 475 extern struct value *value_fn_field (struct value ** arg1p, struct fn_field *f,
 476                                      int j, struct type *type, int offset);
 477
 478 extern int binop_user_defined_p (enum exp_opcode op, struct value *arg1,
 479                                  struct value *arg2);
 480
 481 extern int unop_user_defined_p (enum exp_opcode op, struct value *arg1);
 482
 483 extern int destructor_name_p (const char *name, const struct type *type);
 484
 485 #define value_free(val) xfree (val)
 486
 487 extern void free_all_values (void);
 488
 489 extern void release_value (struct value *val);
 490
 491 extern int record_latest_value (struct value *val);
 492
 493 extern void modify_field (char *addr, LONGEST fieldval, int bitpos,
 494                           int bitsize);
 495
 496 extern void type_print (struct type * type, char *varstring,
 497                         struct ui_file * stream, int show);
 498
 499 extern char *baseclass_addr (struct type *type, int index, char *valaddr,
 500                              struct value **valuep, int *errp);
 501
 502 extern void print_longest (struct ui_file * stream, int format,
 503                            int use_local, LONGEST val);
 504
 505 extern void print_floating (char *valaddr, struct type * type,
 506                             struct ui_file * stream);
 507
 508 extern int value_print (struct value *val, struct ui_file *stream, int format,
 509                         enum val_prettyprint pretty);
 510
 511 extern void value_print_array_elements (struct value *val,
 512                                         struct ui_file *stream, int format,
 513                                         enum val_prettyprint pretty);
 514
 515 extern struct value *value_release_to_mark (struct value *mark);
 516
 517 extern int val_print (struct type * type, char *valaddr,
 518                       int embedded_offset, CORE_ADDR address,
 519                       struct ui_file * stream, int format,
 520                       int deref_ref, int recurse,
 521                       enum val_prettyprint pretty);
 522
 523 extern int val_print_string (CORE_ADDR addr, int len, int width, struct ui_file *stream);
 524
 525 extern void print_variable_value (struct symbol * var,
 526                                   struct frame_info * frame,
 527                                   struct ui_file *stream);
 528
 529 extern int check_field (struct value *, const char *);
 530
 531 extern void typedef_print (struct type * type, struct symbol * news,
 532                              struct ui_file * stream);
 533
 534 extern char *internalvar_name (struct internalvar *var);
 535
 536 extern void clear_value_history (void);
 537
 538 extern void clear_internalvars (void);
 539
 540 /* From values.c */
 541
 542 extern struct value *value_copy (struct value *);
 543
 544 /* From valops.c */
 545
 546 extern struct value *varying_to_slice (struct value *);
 547
 548 extern struct value *value_slice (struct value *, int, int);
 549
 550 extern struct value *call_function_by_hand (struct value *, int,
 551                                             struct value **);
 552
 553 extern struct value *value_literal_complex (struct value *, struct value *,
 554                                             struct type *);
 555
 556 extern void find_rt_vbase_offset (struct type *, struct type *, char *, int,
 557                                   int *, int *);
 558
 559 extern struct value *find_function_in_inferior (const char *);
 560
 561 extern struct value *value_allocate_space_in_inferior (int);
 562
 563 extern CORE_ADDR default_push_arguments (int nargs, struct value ** args,
 564                                          CORE_ADDR sp, int struct_return,
 565                                          CORE_ADDR struct_addr);
 566
 567 extern struct value *value_of_local (const char *name, int complain);
 568
 569 #endif /* !defined (VALUE_H) */