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
  28 #include "doublest.h"
  29
  30 /*
  31  * The structure which defines the type of a value.  It should never
  32  * be possible for a program lval value to survive over a call to the inferior
  33  * (ie to be put into the history list or an internal variable).
  34  */
  35
  36 struct value
  37   {
  38     /* Type of value; either not an lval, or one of the various
  39        different possible kinds of lval.  */
  40     enum lval_type lval;
  41     /* Is it modifiable?  Only relevant if lval != not_lval.  */
  42     int modifiable;
  43     /* Location of value (if lval).  */
  44     union
  45       {
  46         /* If lval == lval_memory, this is the address in the inferior.
  47            If lval == lval_register, this is the byte offset into the
  48            registers structure.  */
  49         CORE_ADDR address;
  50         /* Pointer to internal variable.  */
  51         struct internalvar *internalvar;
  52         /* Number of register.  Only used with
  53            lval_reg_frame_relative.  */
  54         int regnum;
  55       }
  56     location;
  57     /* Describes offset of a value within lval of a structure in bytes.
  58        If lval == lval_memory, this is an offset to the address.
  59        If lval == lval_register, this is a further offset from
  60           location.address within the registers structure.
  61        Note also the member embedded_offset below.  */
  62     int offset;
  63     /* Only used for bitfields; number of bits contained in them.  */
  64     int bitsize;
  65     /* Only used for bitfields; position of start of field.
  66        For BITS_BIG_ENDIAN=0 targets, it is the position of the LSB.
  67        For BITS_BIG_ENDIAN=1 targets, it is the position of the MSB. */
  68     int bitpos;
  69     /* Frame value is relative to.  In practice, this address is only
  70        used if the value is stored in several registers in other than
  71        the current frame, and these registers have not all been saved
  72        at the same place in memory.  This will be described in the
  73        lval enum above as "lval_reg_frame_relative".  */
  74     CORE_ADDR frame_addr;
  75
  76     /* Type of the value.  */
  77     struct type *type;
  78
  79     /* If a value represents a C++ object, then the `type' field gives
  80        the object's compile-time type.  If the object actually belongs
  81        to some class derived from `type', perhaps with other base
  82        classes and additional members, then `type' is just a subobject
  83        of the real thing, and the full object is probably larger than
  84        `type' would suggest.
  85
  86        If `type' is a dynamic class (i.e. one with a vtable), then GDB
  87        can actually determine the object's run-time type by looking at
  88        the run-time type information in the vtable.  When this
  89        information is available, we may elect to read in the entire
  90        object, for several reasons:
  91
  92          - When printing the value, the user would probably rather see
  93            the full object, not just the limited portion apparent from
  94            the compile-time type.
  95
  96          - If `type' has virtual base classes, then even printing
  97            `type' alone may require reaching outside the `type'
  98            portion of the object to wherever the virtual base class
  99            has been stored.
 100
 101        When we store the entire object, `enclosing_type' is the
 102        run-time type --- the complete object --- and `embedded_offset'
 103        is the offset of `type' within that larger type, in bytes.  The
 104        VALUE_CONTENTS macro takes `embedded_offset' into account, so
 105        most GDB code continues to see the `type' portion of the value,
 106        just as the inferior would.
 107
 108        If `type' is a pointer to an object, then `enclosing_type' is a
 109        pointer to the object's run-time type, and `pointed_to_offset'
 110        is the offset in bytes from the full object to the pointed-to
 111        object --- that is, the value `embedded_offset' would have if
 112        we followed the pointer and fetched the complete object.  (I
 113        don't really see the point.  Why not just determine the
 114        run-time type when you indirect, and avoid the special case?
 115        The contents don't matter until you indirect anyway.)
 116
 117        If we're not doing anything fancy, `enclosing_type' is equal to
 118        `type', and `embedded_offset' is zero, so everything works
 119        normally.  */
 120     struct type *enclosing_type;
 121     int embedded_offset;
 122     int pointed_to_offset;
 123
 124     /* Values are stored in a chain, so that they can be deleted
 125        easily over calls to the inferior.  Values assigned to internal
 126        variables or put into the value history are taken off this
 127        list.  */
 128     struct value *next;
 129
 130     /* Register number if the value is from a register.  Is not kept
 131        if you take a field of a structure that is stored in a
 132        register.  Shouldn't it be?  */
 133     short regno;
 134     /* If zero, contents of this value are in the contents field.
 135        If nonzero, contents are in inferior memory at address
 136        in the location.address field plus the offset field
 137        (and the lval field should be lval_memory).
 138
 139        WARNING: This field is used by the code which handles
 140        watchpoints (see breakpoint.c) to decide whether a particular
 141        value can be watched by hardware watchpoints.  If the lazy flag
 142        is set for some member of a value chain, it is assumed that
 143        this member of the chain doesn't need to be watched as part of
 144        watching the value itself.  This is how GDB avoids watching the
 145        entire struct or array when the user wants to watch a single
 146        struct member or array element.  If you ever change the way
 147        lazy flag is set and reset, be sure to consider this use as
 148        well!  */
 149     char lazy;
 150     /* If nonzero, this is the value of a variable which does not
 151        actually exist in the program.  */
 152     char optimized_out;
 153     /* The BFD section associated with this value.  */
 154     asection *bfd_section;
 155     /* Actual contents of the value.  For use of this value; setting
 156        it uses the stuff above.  Not valid if lazy is nonzero.
 157        Target byte-order.  We force it to be aligned properly for any
 158        possible value.  Note that a value therefore extends beyond
 159        what is declared here.  */
 160     union
 161       {
 162         long contents[1];
 163         DOUBLEST force_doublest_align;
 164         LONGEST force_longest_align;
 165         CORE_ADDR force_core_addr_align;
 166         void *force_pointer_align;
 167       }
 168     aligner;
 169     /* Do not add any new members here -- contents above will trash them */
 170   };
 171
 172 #define VALUE_TYPE(val) (val)->type
 173 #define VALUE_ENCLOSING_TYPE(val) (val)->enclosing_type
 174 #define VALUE_LAZY(val) (val)->lazy
 175 /* VALUE_CONTENTS and VALUE_CONTENTS_RAW both return the address of
 176    the gdb buffer used to hold a copy of the contents of the lval.
 177    VALUE_CONTENTS is used when the contents of the buffer are needed --
 178    it uses value_fetch_lazy() to load the buffer from the process being
 179    debugged if it hasn't already been loaded.  VALUE_CONTENTS_RAW is
 180    used when data is being stored into the buffer, or when it is
 181    certain that the contents of the buffer are valid.
 182    Note: The contents pointer is adjusted by the offset required to
 183    get to the real subobject, if the value happens to represent
 184    something embedded in a larger run-time object. */
 185
 186 #define VALUE_CONTENTS_RAW(val) ((char *) (val)->aligner.contents + (val)->embedded_offset)
 187 #define VALUE_CONTENTS(val) ((void)(VALUE_LAZY(val) && value_fetch_lazy(val)),\
 188                              VALUE_CONTENTS_RAW(val))
 189
 190 /* The ALL variants of the above two macros do not adjust the returned
 191    pointer by the embedded_offset value. */
 192
 193 #define VALUE_CONTENTS_ALL_RAW(val) ((char *) (val)->aligner.contents)
 194 #define VALUE_CONTENTS_ALL(val) ((void) (VALUE_LAZY(val) && value_fetch_lazy(val)),\
 195                                  VALUE_CONTENTS_ALL_RAW(val))
 196
 197
 198 extern int value_fetch_lazy (struct value *val);
 199
 200 #define VALUE_LVAL(val) (val)->lval
 201 #define VALUE_ADDRESS(val) (val)->location.address
 202 #define VALUE_INTERNALVAR(val) (val)->location.internalvar
 203 #define VALUE_FRAME_REGNUM(val) ((val)->location.regnum)
 204 #define VALUE_FRAME(val) ((val)->frame_addr)
 205 #define VALUE_OFFSET(val) (val)->offset
 206 #define VALUE_BITSIZE(val) (val)->bitsize
 207 #define VALUE_BITPOS(val) (val)->bitpos
 208 #define VALUE_NEXT(val) (val)->next
 209 #define VALUE_REGNO(val) (val)->regno
 210 #define VALUE_OPTIMIZED_OUT(val) ((val)->optimized_out)
 211 #define VALUE_EMBEDDED_OFFSET(val) ((val)->embedded_offset)
 212 #define VALUE_POINTED_TO_OFFSET(val) ((val)->pointed_to_offset)
 213 #define VALUE_BFD_SECTION(val) ((val)->bfd_section)
 214
 215 /* Convert a REF to the object referenced. */
 216
 217 #define COERCE_REF(arg)    \
 218 do { struct type *value_type_arg_tmp = check_typedef (VALUE_TYPE (arg));\
 219      if (TYPE_CODE (value_type_arg_tmp) == TYPE_CODE_REF)               \
 220          arg = value_at_lazy (TYPE_TARGET_TYPE (value_type_arg_tmp),    \
 221                               unpack_pointer (VALUE_TYPE (arg),         \
 222                                               VALUE_CONTENTS (arg)),    \
 223                               VALUE_BFD_SECTION (arg));                 \
 224     } while (0)
 225
 226 /* If ARG is an array, convert it to a pointer.
 227    If ARG is an enum, convert it to an integer.
 228    If ARG is a function, convert it to a function pointer.
 229
 230    References are dereferenced.  */
 231
 232 #define COERCE_ARRAY(arg)    \
 233 do { COERCE_REF(arg);                                                   \
 234   if (current_language->c_style_arrays                                  \
 235       && TYPE_CODE (VALUE_TYPE (arg)) == TYPE_CODE_ARRAY)               \
 236     arg = value_coerce_array (arg);                                     \
 237   if (TYPE_CODE (VALUE_TYPE (arg)) == TYPE_CODE_FUNC)                   \
 238     arg = value_coerce_function (arg);                                  \
 239 } while (0)
 240
 241 #define COERCE_NUMBER(arg)  \
 242   do { COERCE_ARRAY(arg);  COERCE_ENUM(arg); } while (0)
 243
 244 /* NOTE: cagney/2002-12-17: This macro was handling a chill language
 245    problem but that language has gone away.  */
 246 #define COERCE_VARYING_ARRAY(arg, real_arg_type)
 247
 248 /* If ARG is an enum, convert it to an integer.  */
 249
 250 #define COERCE_ENUM(arg)   { \
 251   if (TYPE_CODE (check_typedef (VALUE_TYPE (arg))) == TYPE_CODE_ENUM)   \
 252     arg = value_cast (builtin_type_unsigned_int, arg);                  \
 253 }
 254
 255 /* Internal variables (variables for convenience of use of debugger)
 256    are recorded as a chain of these structures.  */
 257
 258 struct internalvar
 259   {
 260     struct internalvar *next;
 261     char *name;
 262     struct value *value;
 263   };
 264
 265 /* Pointer to member function.  Depends on compiler implementation. */
 266
 267 #define METHOD_PTR_IS_VIRTUAL(ADDR)  ((ADDR) & 0x80000000)
 268 #define METHOD_PTR_FROM_VOFFSET(OFFSET) (0x80000000 + (OFFSET))
 269 #define METHOD_PTR_TO_VOFFSET(ADDR) (~0x80000000 & (ADDR))
 270 \f
 271
 272 #include "symtab.h"
 273 #include "gdbtypes.h"
 274 #include "expression.h"
 275
 276 struct frame_info;
 277 struct fn_field;
 278
 279 extern void print_address_demangle (CORE_ADDR, struct ui_file *, int);
 280
 281 extern LONGEST value_as_long (struct value *val);
 282
 283 extern DOUBLEST value_as_double (struct value *val);
 284
 285 extern CORE_ADDR value_as_address (struct value *val);
 286
 287 extern LONGEST unpack_long (struct type *type, const char *valaddr);
 288
 289 extern DOUBLEST unpack_double (struct type *type, const char *valaddr,
 290                                int *invp);
 291
 292 extern CORE_ADDR unpack_pointer (struct type *type, const char *valaddr);
 293
 294 extern LONGEST unpack_field_as_long (struct type *type, const char *valaddr,
 295                                      int fieldno);
 296
 297 extern struct value *value_from_longest (struct type *type, LONGEST num);
 298
 299 extern struct value *value_from_pointer (struct type *type, CORE_ADDR addr);
 300
 301 extern struct value *value_from_double (struct type *type, DOUBLEST num);
 302
 303 extern struct value *value_from_string (char *string);
 304
 305 extern struct value *value_at (struct type *type, CORE_ADDR addr,
 306                                asection * sect);
 307
 308 extern struct value *value_at_lazy (struct type *type, CORE_ADDR addr,
 309                                     asection * sect);
 310
 311 extern struct value *value_from_register (struct type *type, int regnum,
 312                                           struct frame_info *frame);
 313
 314 extern struct value *value_of_variable (struct symbol *var, struct block *b);
 315
 316 extern struct value *value_of_register (int regnum,
 317                                         struct frame_info *frame);
 318
 319 extern int symbol_read_needs_frame (struct symbol *);
 320
 321 extern struct value *read_var_value (struct symbol *var,
 322                                      struct frame_info *frame);
 323
 324 extern struct value *locate_var_value (struct symbol *var,
 325                                        struct frame_info *frame);
 326
 327 extern struct value *allocate_value (struct type *type);
 328
 329 extern struct value *allocate_repeat_value (struct type *type, int count);
 330
 331 extern struct value *value_change_enclosing_type (struct value *val,
 332                                                   struct type *new_type);
 333
 334 extern struct value *value_mark (void);
 335
 336 extern void value_free_to_mark (struct value *mark);
 337
 338 extern struct value *value_string (char *ptr, int len);
 339 extern struct value *value_bitstring (char *ptr, int len);
 340
 341 extern struct value *value_array (int lowbound, int highbound,
 342                                   struct value ** elemvec);
 343
 344 extern struct value *value_concat (struct value *arg1, struct value *arg2);
 345
 346 extern struct value *value_binop (struct value *arg1, struct value *arg2,
 347                                   enum exp_opcode op);
 348
 349 extern struct value *value_add (struct value *arg1, struct value *arg2);
 350
 351 extern struct value *value_sub (struct value *arg1, struct value *arg2);
 352
 353 extern struct value *value_coerce_array (struct value *arg1);
 354
 355 extern struct value *value_coerce_function (struct value *arg1);
 356
 357 extern struct value *value_ind (struct value *arg1);
 358
 359 extern struct value *value_addr (struct value *arg1);
 360
 361 extern struct value *value_assign (struct value *toval, struct value *fromval);
 362
 363 extern struct value *value_neg (struct value *arg1);
 364
 365 extern struct value *value_complement (struct value *arg1);
 366
 367 extern struct value *value_struct_elt (struct value **argp,
 368                                        struct value **args,
 369                                        char *name, int *static_memfuncp,
 370                                        char *err);
 371
 372 extern struct value *value_struct_elt_for_reference (struct type *domain,
 373                                                      int offset,
 374                                                      struct type *curtype,
 375                                                      char *name,
 376                                                      struct type *intype);
 377
 378 extern struct value *value_static_field (struct type *type, int fieldno);
 379
 380 extern struct fn_field *value_find_oload_method_list (struct value **, char *,
 381                                                       int, int *,
 382                                                       struct type **, int *);
 383
 384 extern int find_overload_match (struct type **arg_types, int nargs,
 385                                 char *name, int method, int lax,
 386                                 struct value **objp, struct symbol *fsym,
 387                                 struct value **valp, struct symbol **symp,
 388                                 int *staticp);
 389
 390 extern struct value *value_field (struct value *arg1, int fieldno);
 391
 392 extern struct value *value_primitive_field (struct value *arg1, int offset,
 393                                             int fieldno,
 394                                             struct type *arg_type);
 395
 396
 397 extern struct type *value_rtti_target_type (struct value *, int *, int *,
 398                                             int *);
 399
 400 extern struct value *value_full_object (struct value *, struct type *, int,
 401                                         int, int);
 402
 403 extern struct value *value_cast (struct type *type, struct value *arg2);
 404
 405 extern struct value *value_zero (struct type *type, enum lval_type lv);
 406
 407 extern struct value *value_repeat (struct value *arg1, int count);
 408
 409 extern struct value *value_subscript (struct value *array, struct value *idx);
 410
 411 extern struct value *value_being_returned (struct type *valtype,
 412                                            struct regcache *retbuf,
 413                                            int struct_return);
 414
 415 extern struct value *value_in (struct value *element, struct value *set);
 416
 417 extern int value_bit_index (struct type *type, char *addr, int index);
 418
 419 extern int using_struct_return (struct value *function, CORE_ADDR funcaddr,
 420                                 struct type *value_type, int gcc_p);
 421
 422 extern void set_return_value (struct value *val);
 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
 493 modify_field (char *addr, LONGEST fieldval, int bitpos, 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 *call_function_by_hand (struct value *, int,
 550                                             struct value **);
 551
 552 extern struct value *value_literal_complex (struct value *, struct value *,
 553                                             struct type *);
 554
 555 extern void find_rt_vbase_offset (struct type *, struct type *, char *, int,
 556                                   int *, int *);
 557
 558 extern struct value *find_function_in_inferior (const char *);
 559
 560 extern struct value *value_allocate_space_in_inferior (int);
 561
 562 extern CORE_ADDR default_push_arguments (int nargs, struct value ** args,
 563                                          CORE_ADDR sp, int struct_return,
 564                                          CORE_ADDR struct_addr);
 565
 566 extern struct value *value_of_local (const char *name, int complain);
 567
 568 #endif /* !defined (VALUE_H) */