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
  29 struct block;
  30 struct expression;
  31 struct regcache;
  32 struct symbol;
  33 struct type;
  34 struct ui_file;
  35
  36 /* The structure which defines the type of a value.  It should never
  37    be possible for a program lval value to survive over a call to the
  38    inferior (i.e. to be put into the history list or an internal
  39    variable).  */
  40
  41 struct value
  42 {
  43   /* Type of value; either not an lval, or one of the various
  44      different possible kinds of lval.  */
  45   enum lval_type lval;
  46
  47   /* Is it modifiable?  Only relevant if lval != not_lval.  */
  48   int modifiable;
  49
  50   /* Location of value (if lval).  */
  51   union
  52   {
  53     /* If lval == lval_memory, this is the address in the inferior.
  54        If lval == lval_register, this is the byte offset into the
  55        registers structure.  */
  56     CORE_ADDR address;
  57
  58     /* Pointer to internal variable.  */
  59     struct internalvar *internalvar;
  60
  61     /* Number of register.  Only used with lval_reg_frame_relative.  */
  62     int regnum;
  63   } location;
  64
  65   /* Describes offset of a value within lval of a structure in bytes.
  66      If lval == lval_memory, this is an offset to the address.
  67      If lval == lval_register, this is a further offset from
  68      location.address within the registers structure.
  69      Note also the member embedded_offset below.  */
  70   int offset;
  71
  72   /* Only used for bitfields; number of bits contained in them.  */
  73   int bitsize;
  74
  75   /* Only used for bitfields; position of start of field.
  76      For BITS_BIG_ENDIAN=0 targets, it is the position of the LSB.
  77      For BITS_BIG_ENDIAN=1 targets, it is the position of the MSB. */
  78     int bitpos;
  79
  80   /* Frame value is relative to.  In practice, this address is only
  81      used if the value is stored in several registers in other than
  82      the current frame, and these registers have not all been saved
  83      at the same place in memory.  This will be described in the
  84      lval enum above as "lval_reg_frame_relative".  */
  85   CORE_ADDR frame_addr;
  86
  87   /* Type of the value.  */
  88   struct type *type;
  89
  90   /* If a value represents a C++ object, then the `type' field gives
  91      the object's compile-time type.  If the object actually belongs
  92      to some class derived from `type', perhaps with other base
  93      classes and additional members, then `type' is just a subobject
  94      of the real thing, and the full object is probably larger than
  95      `type' would suggest.
  96
  97      If `type' is a dynamic class (i.e. one with a vtable), then GDB
  98      can actually determine the object's run-time type by looking at
  99      the run-time type information in the vtable.  When this
 100      information is available, we may elect to read in the entire
 101      object, for several reasons:
 102
 103      - When printing the value, the user would probably rather see the
 104        full object, not just the limited portion apparent from the
 105        compile-time type.
 106
 107      - If `type' has virtual base classes, then even printing `type'
 108        alone may require reaching outside the `type' portion of the
 109        object to wherever the virtual base class has been stored.
 110
 111      When we store the entire object, `enclosing_type' is the run-time
 112      type -- the complete object -- and `embedded_offset' is the
 113      offset of `type' within that larger type, in bytes.  The
 114      VALUE_CONTENTS macro takes `embedded_offset' into account, so
 115      most GDB code continues to see the `type' portion of the value,
 116      just as the inferior would.
 117
 118      If `type' is a pointer to an object, then `enclosing_type' is a
 119      pointer to the object's run-time type, and `pointed_to_offset' is
 120      the offset in bytes from the full object to the pointed-to object
 121      -- that is, the value `embedded_offset' would have if we
 122      followed the pointer and fetched the complete object.  (I don't
 123      really see the point.  Why not just determine the run-time type
 124      when you indirect, and avoid the special case?  The contents
 125      don't matter until you indirect anyway.)
 126
 127      If we're not doing anything fancy, `enclosing_type' is equal to
 128      `type', and `embedded_offset' is zero, so everything works
 129      normally.  */
 130     struct type *enclosing_type;
 131     int embedded_offset;
 132     int pointed_to_offset;
 133
 134     /* Values are stored in a chain, so that they can be deleted
 135        easily over calls to the inferior.  Values assigned to internal
 136        variables or put into the value history are taken off this
 137        list.  */
 138     struct value *next;
 139
 140     /* Register number if the value is from a register.  */
 141     short regno;
 142
 143     /* If zero, contents of this value are in the contents field.  If
 144        nonzero, contents are in inferior memory at address in the
 145        location.address field plus the offset field (and the lval
 146        field should be lval_memory).
 147
 148        WARNING: This field is used by the code which handles
 149        watchpoints (see breakpoint.c) to decide whether a particular
 150        value can be watched by hardware watchpoints.  If the lazy flag
 151        is set for some member of a value chain, it is assumed that
 152        this member of the chain doesn't need to be watched as part of
 153        watching the value itself.  This is how GDB avoids watching the
 154        entire struct or array when the user wants to watch a single
 155        struct member or array element.  If you ever change the way
 156        lazy flag is set and reset, be sure to consider this use as
 157        well!  */
 158     char lazy;
 159
 160     /* If nonzero, this is the value of a variable which does not
 161        actually exist in the program.  */
 162     char optimized_out;
 163
 164     /* The BFD section associated with this value.  */
 165     asection *bfd_section;
 166
 167     /* Actual contents of the value.  For use of this value; setting
 168        it uses the stuff above.  Not valid if lazy is nonzero.
 169        Target byte-order.  We force it to be aligned properly for any
 170        possible value.  Note that a value therefore extends beyond
 171        what is declared here.  */
 172     union
 173     {
 174       long contents[1];
 175       DOUBLEST force_doublest_align;
 176       LONGEST force_longest_align;
 177       CORE_ADDR force_core_addr_align;
 178       void *force_pointer_align;
 179     } aligner;
 180     /* Do not add any new members here -- contents above will trash them.  */
 181 };
 182
 183 #define VALUE_TYPE(val) (val)->type
 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_REGNUM(val) ((val)->location.regnum)
 219 #define VALUE_FRAME(val) ((val)->frame_addr)
 220 #define VALUE_OFFSET(val) (val)->offset
 221 #define VALUE_BITSIZE(val) (val)->bitsize
 222 #define VALUE_BITPOS(val) (val)->bitpos
 223 #define VALUE_NEXT(val) (val)->next
 224 #define VALUE_REGNO(val) (val)->regno
 225 #define VALUE_OPTIMIZED_OUT(val) ((val)->optimized_out)
 226 #define VALUE_EMBEDDED_OFFSET(val) ((val)->embedded_offset)
 227 #define VALUE_POINTED_TO_OFFSET(val) ((val)->pointed_to_offset)
 228 #define VALUE_BFD_SECTION(val) ((val)->bfd_section)
 229
 230 /* Convert a REF to the object referenced.  */
 231
 232 #define COERCE_REF(arg) \
 233   do {                                                                  \
 234     struct type *value_type_arg_tmp = check_typedef (VALUE_TYPE (arg)); \
 235     if (TYPE_CODE (value_type_arg_tmp) == TYPE_CODE_REF)                \
 236       arg = value_at_lazy (TYPE_TARGET_TYPE (value_type_arg_tmp),       \
 237                            unpack_pointer (VALUE_TYPE (arg),            \
 238                                            VALUE_CONTENTS (arg)),       \
 239                                            VALUE_BFD_SECTION (arg));    \
 240   } while (0)
 241
 242 /* If ARG is an array, convert it to a pointer.
 243    If ARG is an enum, convert it to an integer.
 244    If ARG is a function, convert it to a function pointer.
 245
 246    References are dereferenced.  */
 247
 248 #define COERCE_ARRAY(arg) \
 249   do {                                                                  \
 250     COERCE_REF(arg);                                                    \
 251     if (current_language->c_style_arrays                                \
 252         && TYPE_CODE (VALUE_TYPE (arg)) == TYPE_CODE_ARRAY)             \
 253       arg = value_coerce_array (arg);                                   \
 254     if (TYPE_CODE (VALUE_TYPE (arg)) == TYPE_CODE_FUNC)                 \
 255       arg = value_coerce_function (arg);                                \
 256   } while (0)
 257
 258 #define COERCE_NUMBER(arg) \
 259   do { COERCE_ARRAY(arg); COERCE_ENUM(arg); } while (0)
 260
 261 /* NOTE: cagney/2002-12-17: This macro was handling a chill language
 262    problem but that language has gone away.  */
 263 #define COERCE_VARYING_ARRAY(arg, real_arg_type)
 264
 265 /* If ARG is an enum, convert it to an integer.  */
 266
 267 #define COERCE_ENUM(arg) \
 268   do {                                                                  \
 269     if (TYPE_CODE (check_typedef (VALUE_TYPE (arg))) == TYPE_CODE_ENUM) \
 270       arg = value_cast (builtin_type_unsigned_int, arg);                \
 271   } while (0)
 272
 273 /* Internal variables (variables for convenience of use of debugger)
 274    are recorded as a chain of these structures.  */
 275
 276 struct internalvar
 277 {
 278   struct internalvar *next;
 279   char *name;
 280   struct value *value;
 281 };
 282
 283 /* Pointer to member function.  Depends on compiler implementation.  */
 284
 285 #define METHOD_PTR_IS_VIRTUAL(ADDR)  ((ADDR) & 0x80000000)
 286 #define METHOD_PTR_FROM_VOFFSET(OFFSET) (0x80000000 + (OFFSET))
 287 #define METHOD_PTR_TO_VOFFSET(ADDR) (~0x80000000 & (ADDR))
 288 \f
 289
 290 #include "symtab.h"
 291 #include "gdbtypes.h"
 292 #include "expression.h"
 293
 294 struct frame_info;
 295 struct fn_field;
 296
 297 extern void print_address_demangle (CORE_ADDR, struct ui_file *, int);
 298
 299 extern LONGEST value_as_long (struct value *val);
 300 extern DOUBLEST value_as_double (struct value *val);
 301 extern CORE_ADDR value_as_address (struct value *val);
 302
 303 extern LONGEST unpack_long (struct type *type, const char *valaddr);
 304 extern DOUBLEST unpack_double (struct type *type, const char *valaddr,
 305                                int *invp);
 306 extern CORE_ADDR unpack_pointer (struct type *type, const char *valaddr);
 307 extern LONGEST unpack_field_as_long (struct type *type, const char *valaddr,
 308                                      int fieldno);
 309
 310 extern struct value *value_from_longest (struct type *type, LONGEST num);
 311 extern struct value *value_from_pointer (struct type *type, CORE_ADDR addr);
 312 extern struct value *value_from_double (struct type *type, DOUBLEST num);
 313 extern struct value *value_from_string (char *string);
 314
 315 extern struct value *value_at (struct type *type, CORE_ADDR addr,
 316                                asection * sect);
 317 extern struct value *value_at_lazy (struct type *type, CORE_ADDR addr,
 318                                     asection * sect);
 319
 320 extern struct value *value_from_register (struct type *type, int regnum,
 321                                           struct frame_info *frame);
 322
 323 extern struct value *value_of_variable (struct symbol *var, struct block *b);
 324
 325 extern struct value *value_of_register (int regnum,
 326                                         struct frame_info *frame);
 327
 328 extern int symbol_read_needs_frame (struct symbol *);
 329
 330 extern struct value *read_var_value (struct symbol *var,
 331                                      struct frame_info *frame);
 332
 333 extern struct value *locate_var_value (struct symbol *var,
 334                                        struct frame_info *frame);
 335
 336 extern struct value *allocate_value (struct type *type);
 337
 338 extern struct value *allocate_repeat_value (struct type *type, int count);
 339
 340 extern struct value *value_change_enclosing_type (struct value *val,
 341                                                   struct type *new_type);
 342
 343 extern struct value *value_mark (void);
 344
 345 extern void value_free_to_mark (struct value *mark);
 346
 347 extern struct value *value_string (char *ptr, int len);
 348 extern struct value *value_bitstring (char *ptr, int len);
 349
 350 extern struct value *value_array (int lowbound, int highbound,
 351                                   struct value ** elemvec);
 352
 353 extern struct value *value_concat (struct value *arg1, struct value *arg2);
 354
 355 extern struct value *value_binop (struct value *arg1, struct value *arg2,
 356                                   enum exp_opcode op);
 357
 358 extern struct value *value_add (struct value *arg1, struct value *arg2);
 359
 360 extern struct value *value_sub (struct value *arg1, struct value *arg2);
 361
 362 extern struct value *value_coerce_array (struct value *arg1);
 363
 364 extern struct value *value_coerce_function (struct value *arg1);
 365
 366 extern struct value *value_ind (struct value *arg1);
 367
 368 extern struct value *value_addr (struct value *arg1);
 369
 370 extern struct value *value_assign (struct value *toval, struct value *fromval);
 371
 372 extern struct value *value_neg (struct value *arg1);
 373
 374 extern struct value *value_complement (struct value *arg1);
 375
 376 extern struct value *value_struct_elt (struct value **argp,
 377                                        struct value **args,
 378                                        char *name, int *static_memfuncp,
 379                                        char *err);
 380
 381 extern struct value *value_struct_elt_for_reference (struct type *domain,
 382                                                      int offset,
 383                                                      struct type *curtype,
 384                                                      char *name,
 385                                                      struct type *intype);
 386
 387 extern struct value *value_static_field (struct type *type, int fieldno);
 388
 389 extern struct fn_field *value_find_oload_method_list (struct value **, char *,
 390                                                       int, int *,
 391                                                       struct type **, int *);
 392
 393 extern int find_overload_match (struct type **arg_types, int nargs,
 394                                 char *name, int method, int lax,
 395                                 struct value **objp, struct symbol *fsym,
 396                                 struct value **valp, struct symbol **symp,
 397                                 int *staticp);
 398
 399 extern struct value *value_field (struct value *arg1, int fieldno);
 400
 401 extern struct value *value_primitive_field (struct value *arg1, int offset,
 402                                             int fieldno,
 403                                             struct type *arg_type);
 404
 405
 406 extern struct type *value_rtti_target_type (struct value *, int *, int *,
 407                                             int *);
 408
 409 extern struct value *value_full_object (struct value *, struct type *, int,
 410                                         int, int);
 411
 412 extern struct value *value_cast (struct type *type, struct value *arg2);
 413
 414 extern struct value *value_zero (struct type *type, enum lval_type lv);
 415
 416 extern struct value *value_repeat (struct value *arg1, int count);
 417
 418 extern struct value *value_subscript (struct value *array, struct value *idx);
 419
 420 extern struct value *value_being_returned (struct type *valtype,
 421                                            struct regcache *retbuf,
 422                                            int struct_return);
 423
 424 extern struct value *value_in (struct value *element, struct value *set);
 425
 426 extern int value_bit_index (struct type *type, char *addr, int index);
 427
 428 extern int using_struct_return (struct value *function, CORE_ADDR funcaddr,
 429                                 struct type *value_type, int gcc_p);
 430
 431 extern void set_return_value (struct value *val);
 432
 433 extern struct value *evaluate_expression (struct expression *exp);
 434
 435 extern struct value *evaluate_type (struct expression *exp);
 436
 437 extern struct value *evaluate_subexp_with_coercion (struct expression *,
 438                                                     int *, enum noside);
 439
 440 extern struct value *parse_and_eval (char *exp);
 441
 442 extern struct value *parse_to_comma_and_eval (char **expp);
 443
 444 extern struct type *parse_and_eval_type (char *p, int length);
 445
 446 extern CORE_ADDR parse_and_eval_address (char *exp);
 447
 448 extern CORE_ADDR parse_and_eval_address_1 (char **expptr);
 449
 450 extern LONGEST parse_and_eval_long (char *exp);
 451
 452 extern struct value *access_value_history (int num);
 453
 454 extern struct value *value_of_internalvar (struct internalvar *var);
 455
 456 extern void set_internalvar (struct internalvar *var, struct value *val);
 457
 458 extern void set_internalvar_component (struct internalvar *var,
 459                                        int offset,
 460                                        int bitpos, int bitsize,
 461                                        struct value *newvalue);
 462
 463 extern struct internalvar *lookup_internalvar (char *name);
 464
 465 extern int value_equal (struct value *arg1, struct value *arg2);
 466
 467 extern int value_less (struct value *arg1, struct value *arg2);
 468
 469 extern int value_logical_not (struct value *arg1);
 470
 471 /* C++ */
 472
 473 extern struct value *value_of_this (int complain);
 474
 475 extern struct value *value_x_binop (struct value *arg1, struct value *arg2,
 476                                     enum exp_opcode op,
 477                                     enum exp_opcode otherop,
 478                                     enum noside noside);
 479
 480 extern struct value *value_x_unop (struct value *arg1, enum exp_opcode op,
 481                                    enum noside noside);
 482
 483 extern struct value *value_fn_field (struct value ** arg1p, struct fn_field *f,
 484                                      int j, struct type *type, int offset);
 485
 486 extern int binop_user_defined_p (enum exp_opcode op, struct value *arg1,
 487                                  struct value *arg2);
 488
 489 extern int unop_user_defined_p (enum exp_opcode op, struct value *arg1);
 490
 491 extern int destructor_name_p (const char *name, const struct type *type);
 492
 493 #define value_free(val) xfree (val)
 494
 495 extern void free_all_values (void);
 496
 497 extern void release_value (struct value *val);
 498
 499 extern int record_latest_value (struct value *val);
 500
 501 extern void modify_field (char *addr, LONGEST fieldval, int bitpos,
 502                           int bitsize);
 503
 504 extern void type_print (struct type * type, char *varstring,
 505                         struct ui_file * stream, int show);
 506
 507 extern char *baseclass_addr (struct type *type, int index, char *valaddr,
 508                              struct value **valuep, int *errp);
 509
 510 extern void print_longest (struct ui_file * stream, int format,
 511                            int use_local, LONGEST val);
 512
 513 extern void print_floating (char *valaddr, struct type * type,
 514                             struct ui_file * stream);
 515
 516 extern int value_print (struct value *val, struct ui_file *stream, int format,
 517                         enum val_prettyprint pretty);
 518
 519 extern void value_print_array_elements (struct value *val,
 520                                         struct ui_file *stream, int format,
 521                                         enum val_prettyprint pretty);
 522
 523 extern struct value *value_release_to_mark (struct value *mark);
 524
 525 extern int val_print (struct type * type, char *valaddr,
 526                       int embedded_offset, CORE_ADDR address,
 527                       struct ui_file * stream, int format,
 528                       int deref_ref, int recurse,
 529                       enum val_prettyprint pretty);
 530
 531 extern int val_print_string (CORE_ADDR addr, int len, int width, struct ui_file *stream);
 532
 533 extern void print_variable_value (struct symbol * var,
 534                                   struct frame_info * frame,
 535                                   struct ui_file *stream);
 536
 537 extern int check_field (struct value *, const char *);
 538
 539 extern void typedef_print (struct type * type, struct symbol * news,
 540                              struct ui_file * stream);
 541
 542 extern char *internalvar_name (struct internalvar *var);
 543
 544 extern void clear_value_history (void);
 545
 546 extern void clear_internalvars (void);
 547
 548 /* From values.c */
 549
 550 extern struct value *value_copy (struct value *);
 551
 552 /* From valops.c */
 553
 554 extern struct value *varying_to_slice (struct value *);
 555
 556 extern struct value *value_slice (struct value *, int, int);
 557
 558 extern struct value *value_literal_complex (struct value *, struct value *,
 559                                             struct type *);
 560
 561 extern void find_rt_vbase_offset (struct type *, struct type *, char *, int,
 562                                   int *, int *);
 563
 564 extern struct value *find_function_in_inferior (const char *);
 565
 566 extern struct value *value_allocate_space_in_inferior (int);
 567
 568 extern CORE_ADDR legacy_push_arguments (int nargs, struct value ** args,
 569                                         CORE_ADDR sp, int struct_return,
 570                                         CORE_ADDR struct_addr);
 571
 572 extern struct value *value_of_local (const char *name, int complain);
 573
 574 #endif /* !defined (VALUE_H) */