1 /* Low level packing and unpacking of values for GDB, the GNU Debugger.
3 Copyright 1986, 1987, 1988, 1989, 1990, 1991, 1992, 1993, 1994,
4 1995, 1996, 1997, 1998, 1999, 2000, 2002, 2003 Free Software
7 This file is part of GDB.
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.
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.
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. */
25 #include "gdb_string.h"
37 #include "gdb_assert.h"
40 /* Prototypes for exported functions. */
42 void _initialize_values (void);
44 /* Prototypes for local functions. */
46 static void show_values (char *, int);
48 static void show_convenience (char *, int);
51 /* The value-history records all the values printed
52 by print commands during this session. Each chunk
53 records 60 consecutive values. The first chunk on
54 the chain records the most recent values.
55 The total number of values is in value_history_count. */
57 #define VALUE_HISTORY_CHUNK 60
59 struct value_history_chunk
61 struct value_history_chunk
*next
;
62 struct value
*values
[VALUE_HISTORY_CHUNK
];
65 /* Chain of chunks now in use. */
67 static struct value_history_chunk
*value_history_chain
;
69 static int value_history_count
; /* Abs number of last entry stored */
71 /* List of all value objects currently allocated
72 (except for those released by calls to release_value)
73 This is so they can be freed after each command. */
75 static struct value
*all_values
;
77 /* Allocate a value that has the correct length for type TYPE. */
80 allocate_value (struct type
*type
)
83 struct type
*atype
= check_typedef (type
);
85 val
= (struct value
*) xmalloc (sizeof (struct value
) + TYPE_LENGTH (atype
));
86 VALUE_NEXT (val
) = all_values
;
88 VALUE_TYPE (val
) = type
;
89 VALUE_ENCLOSING_TYPE (val
) = type
;
90 VALUE_LVAL (val
) = not_lval
;
91 VALUE_ADDRESS (val
) = 0;
92 VALUE_FRAME (val
) = 0;
93 VALUE_OFFSET (val
) = 0;
94 VALUE_BITPOS (val
) = 0;
95 VALUE_BITSIZE (val
) = 0;
96 VALUE_REGNO (val
) = -1;
98 VALUE_OPTIMIZED_OUT (val
) = 0;
99 VALUE_BFD_SECTION (val
) = NULL
;
100 VALUE_EMBEDDED_OFFSET (val
) = 0;
101 VALUE_POINTED_TO_OFFSET (val
) = 0;
106 /* Allocate a value that has the correct length
107 for COUNT repetitions type TYPE. */
110 allocate_repeat_value (struct type
*type
, int count
)
112 int low_bound
= current_language
->string_lower_bound
; /* ??? */
113 /* FIXME-type-allocation: need a way to free this type when we are
115 struct type
*range_type
116 = create_range_type ((struct type
*) NULL
, builtin_type_int
,
117 low_bound
, count
+ low_bound
- 1);
118 /* FIXME-type-allocation: need a way to free this type when we are
120 return allocate_value (create_array_type ((struct type
*) NULL
,
124 /* Return a mark in the value chain. All values allocated after the
125 mark is obtained (except for those released) are subject to being freed
126 if a subsequent value_free_to_mark is passed the mark. */
133 /* Free all values allocated since MARK was obtained by value_mark
134 (except for those released). */
136 value_free_to_mark (struct value
*mark
)
141 for (val
= all_values
; val
&& val
!= mark
; val
= next
)
143 next
= VALUE_NEXT (val
);
149 /* Free all the values that have been allocated (except for those released).
150 Called after each command, successful or not. */
153 free_all_values (void)
158 for (val
= all_values
; val
; val
= next
)
160 next
= VALUE_NEXT (val
);
167 /* Remove VAL from the chain all_values
168 so it will not be freed automatically. */
171 release_value (struct value
*val
)
175 if (all_values
== val
)
177 all_values
= val
->next
;
181 for (v
= all_values
; v
; v
= v
->next
)
191 /* Release all values up to mark */
193 value_release_to_mark (struct value
*mark
)
198 for (val
= next
= all_values
; next
; next
= VALUE_NEXT (next
))
199 if (VALUE_NEXT (next
) == mark
)
201 all_values
= VALUE_NEXT (next
);
202 VALUE_NEXT (next
) = 0;
209 /* Return a copy of the value ARG.
210 It contains the same contents, for same memory address,
211 but it's a different block of storage. */
214 value_copy (struct value
*arg
)
216 register struct type
*encl_type
= VALUE_ENCLOSING_TYPE (arg
);
217 struct value
*val
= allocate_value (encl_type
);
218 VALUE_TYPE (val
) = VALUE_TYPE (arg
);
219 VALUE_LVAL (val
) = VALUE_LVAL (arg
);
220 VALUE_ADDRESS (val
) = VALUE_ADDRESS (arg
);
221 VALUE_OFFSET (val
) = VALUE_OFFSET (arg
);
222 VALUE_BITPOS (val
) = VALUE_BITPOS (arg
);
223 VALUE_BITSIZE (val
) = VALUE_BITSIZE (arg
);
224 VALUE_FRAME (val
) = VALUE_FRAME (arg
);
225 VALUE_REGNO (val
) = VALUE_REGNO (arg
);
226 VALUE_LAZY (val
) = VALUE_LAZY (arg
);
227 VALUE_OPTIMIZED_OUT (val
) = VALUE_OPTIMIZED_OUT (arg
);
228 VALUE_EMBEDDED_OFFSET (val
) = VALUE_EMBEDDED_OFFSET (arg
);
229 VALUE_POINTED_TO_OFFSET (val
) = VALUE_POINTED_TO_OFFSET (arg
);
230 VALUE_BFD_SECTION (val
) = VALUE_BFD_SECTION (arg
);
231 val
->modifiable
= arg
->modifiable
;
232 if (!VALUE_LAZY (val
))
234 memcpy (VALUE_CONTENTS_ALL_RAW (val
), VALUE_CONTENTS_ALL_RAW (arg
),
235 TYPE_LENGTH (VALUE_ENCLOSING_TYPE (arg
)));
241 /* Access to the value history. */
243 /* Record a new value in the value history.
244 Returns the absolute history index of the entry.
245 Result of -1 indicates the value was not saved; otherwise it is the
246 value history index of this new item. */
249 record_latest_value (struct value
*val
)
253 /* We don't want this value to have anything to do with the inferior anymore.
254 In particular, "set $1 = 50" should not affect the variable from which
255 the value was taken, and fast watchpoints should be able to assume that
256 a value on the value history never changes. */
257 if (VALUE_LAZY (val
))
258 value_fetch_lazy (val
);
259 /* We preserve VALUE_LVAL so that the user can find out where it was fetched
260 from. This is a bit dubious, because then *&$1 does not just return $1
261 but the current contents of that location. c'est la vie... */
265 /* Here we treat value_history_count as origin-zero
266 and applying to the value being stored now. */
268 i
= value_history_count
% VALUE_HISTORY_CHUNK
;
271 struct value_history_chunk
*new
272 = (struct value_history_chunk
*)
273 xmalloc (sizeof (struct value_history_chunk
));
274 memset (new->values
, 0, sizeof new->values
);
275 new->next
= value_history_chain
;
276 value_history_chain
= new;
279 value_history_chain
->values
[i
] = val
;
281 /* Now we regard value_history_count as origin-one
282 and applying to the value just stored. */
284 return ++value_history_count
;
287 /* Return a copy of the value in the history with sequence number NUM. */
290 access_value_history (int num
)
292 struct value_history_chunk
*chunk
;
294 register int absnum
= num
;
297 absnum
+= value_history_count
;
302 error ("The history is empty.");
304 error ("There is only one value in the history.");
306 error ("History does not go back to $$%d.", -num
);
308 if (absnum
> value_history_count
)
309 error ("History has not yet reached $%d.", absnum
);
313 /* Now absnum is always absolute and origin zero. */
315 chunk
= value_history_chain
;
316 for (i
= (value_history_count
- 1) / VALUE_HISTORY_CHUNK
- absnum
/ VALUE_HISTORY_CHUNK
;
320 return value_copy (chunk
->values
[absnum
% VALUE_HISTORY_CHUNK
]);
323 /* Clear the value history entirely.
324 Must be done when new symbol tables are loaded,
325 because the type pointers become invalid. */
328 clear_value_history (void)
330 struct value_history_chunk
*next
;
334 while (value_history_chain
)
336 for (i
= 0; i
< VALUE_HISTORY_CHUNK
; i
++)
337 if ((val
= value_history_chain
->values
[i
]) != NULL
)
339 next
= value_history_chain
->next
;
340 xfree (value_history_chain
);
341 value_history_chain
= next
;
343 value_history_count
= 0;
347 show_values (char *num_exp
, int from_tty
)
355 /* "info history +" should print from the stored position.
356 "info history <exp>" should print around value number <exp>. */
357 if (num_exp
[0] != '+' || num_exp
[1] != '\0')
358 num
= parse_and_eval_long (num_exp
) - 5;
362 /* "info history" means print the last 10 values. */
363 num
= value_history_count
- 9;
369 for (i
= num
; i
< num
+ 10 && i
<= value_history_count
; i
++)
371 val
= access_value_history (i
);
372 printf_filtered ("$%d = ", i
);
373 value_print (val
, gdb_stdout
, 0, Val_pretty_default
);
374 printf_filtered ("\n");
377 /* The next "info history +" should start after what we just printed. */
380 /* Hitting just return after this command should do the same thing as
381 "info history +". If num_exp is null, this is unnecessary, since
382 "info history +" is not useful after "info history". */
383 if (from_tty
&& num_exp
)
390 /* Internal variables. These are variables within the debugger
391 that hold values assigned by debugger commands.
392 The user refers to them with a '$' prefix
393 that does not appear in the variable names stored internally. */
395 static struct internalvar
*internalvars
;
397 /* Look up an internal variable with name NAME. NAME should not
398 normally include a dollar sign.
400 If the specified internal variable does not exist,
401 one is created, with a void value. */
404 lookup_internalvar (char *name
)
406 register struct internalvar
*var
;
408 for (var
= internalvars
; var
; var
= var
->next
)
409 if (STREQ (var
->name
, name
))
412 var
= (struct internalvar
*) xmalloc (sizeof (struct internalvar
));
413 var
->name
= concat (name
, NULL
);
414 var
->value
= allocate_value (builtin_type_void
);
415 release_value (var
->value
);
416 var
->next
= internalvars
;
422 value_of_internalvar (struct internalvar
*var
)
426 #ifdef IS_TRAPPED_INTERNALVAR
427 if (IS_TRAPPED_INTERNALVAR (var
->name
))
428 return VALUE_OF_TRAPPED_INTERNALVAR (var
);
431 val
= value_copy (var
->value
);
432 if (VALUE_LAZY (val
))
433 value_fetch_lazy (val
);
434 VALUE_LVAL (val
) = lval_internalvar
;
435 VALUE_INTERNALVAR (val
) = var
;
440 set_internalvar_component (struct internalvar
*var
, int offset
, int bitpos
,
441 int bitsize
, struct value
*newval
)
443 register char *addr
= VALUE_CONTENTS (var
->value
) + offset
;
445 #ifdef IS_TRAPPED_INTERNALVAR
446 if (IS_TRAPPED_INTERNALVAR (var
->name
))
447 SET_TRAPPED_INTERNALVAR (var
, newval
, bitpos
, bitsize
, offset
);
451 modify_field (addr
, value_as_long (newval
),
454 memcpy (addr
, VALUE_CONTENTS (newval
), TYPE_LENGTH (VALUE_TYPE (newval
)));
458 set_internalvar (struct internalvar
*var
, struct value
*val
)
460 struct value
*newval
;
462 #ifdef IS_TRAPPED_INTERNALVAR
463 if (IS_TRAPPED_INTERNALVAR (var
->name
))
464 SET_TRAPPED_INTERNALVAR (var
, val
, 0, 0, 0);
467 newval
= value_copy (val
);
468 newval
->modifiable
= 1;
470 /* Force the value to be fetched from the target now, to avoid problems
471 later when this internalvar is referenced and the target is gone or
473 if (VALUE_LAZY (newval
))
474 value_fetch_lazy (newval
);
476 /* Begin code which must not call error(). If var->value points to
477 something free'd, an error() obviously leaves a dangling pointer.
478 But we also get a danling pointer if var->value points to
479 something in the value chain (i.e., before release_value is
480 called), because after the error free_all_values will get called before
484 release_value (newval
);
485 /* End code which must not call error(). */
489 internalvar_name (struct internalvar
*var
)
494 /* Free all internalvars. Done when new symtabs are loaded,
495 because that makes the values invalid. */
498 clear_internalvars (void)
500 register struct internalvar
*var
;
505 internalvars
= var
->next
;
513 show_convenience (char *ignore
, int from_tty
)
515 register struct internalvar
*var
;
518 for (var
= internalvars
; var
; var
= var
->next
)
520 #ifdef IS_TRAPPED_INTERNALVAR
521 if (IS_TRAPPED_INTERNALVAR (var
->name
))
528 printf_filtered ("$%s = ", var
->name
);
529 value_print (var
->value
, gdb_stdout
, 0, Val_pretty_default
);
530 printf_filtered ("\n");
533 printf_unfiltered ("No debugger convenience variables now defined.\n\
534 Convenience variables have names starting with \"$\";\n\
535 use \"set\" as in \"set $foo = 5\" to define them.\n");
538 /* Extract a value as a C number (either long or double).
539 Knows how to convert fixed values to double, or
540 floating values to long.
541 Does not deallocate the value. */
544 value_as_long (struct value
*val
)
546 /* This coerces arrays and functions, which is necessary (e.g.
547 in disassemble_command). It also dereferences references, which
548 I suspect is the most logical thing to do. */
550 return unpack_long (VALUE_TYPE (val
), VALUE_CONTENTS (val
));
554 value_as_double (struct value
*val
)
559 foo
= unpack_double (VALUE_TYPE (val
), VALUE_CONTENTS (val
), &inv
);
561 error ("Invalid floating value found in program.");
564 /* Extract a value as a C pointer. Does not deallocate the value.
565 Note that val's type may not actually be a pointer; value_as_long
566 handles all the cases. */
568 value_as_address (struct value
*val
)
570 /* Assume a CORE_ADDR can fit in a LONGEST (for now). Not sure
571 whether we want this to be true eventually. */
573 /* ADDR_BITS_REMOVE is wrong if we are being called for a
574 non-address (e.g. argument to "signal", "info break", etc.), or
575 for pointers to char, in which the low bits *are* significant. */
576 return ADDR_BITS_REMOVE (value_as_long (val
));
579 /* There are several targets (IA-64, PowerPC, and others) which
580 don't represent pointers to functions as simply the address of
581 the function's entry point. For example, on the IA-64, a
582 function pointer points to a two-word descriptor, generated by
583 the linker, which contains the function's entry point, and the
584 value the IA-64 "global pointer" register should have --- to
585 support position-independent code. The linker generates
586 descriptors only for those functions whose addresses are taken.
588 On such targets, it's difficult for GDB to convert an arbitrary
589 function address into a function pointer; it has to either find
590 an existing descriptor for that function, or call malloc and
591 build its own. On some targets, it is impossible for GDB to
592 build a descriptor at all: the descriptor must contain a jump
593 instruction; data memory cannot be executed; and code memory
596 Upon entry to this function, if VAL is a value of type `function'
597 (that is, TYPE_CODE (VALUE_TYPE (val)) == TYPE_CODE_FUNC), then
598 VALUE_ADDRESS (val) is the address of the function. This is what
599 you'll get if you evaluate an expression like `main'. The call
600 to COERCE_ARRAY below actually does all the usual unary
601 conversions, which includes converting values of type `function'
602 to `pointer to function'. This is the challenging conversion
603 discussed above. Then, `unpack_long' will convert that pointer
604 back into an address.
606 So, suppose the user types `disassemble foo' on an architecture
607 with a strange function pointer representation, on which GDB
608 cannot build its own descriptors, and suppose further that `foo'
609 has no linker-built descriptor. The address->pointer conversion
610 will signal an error and prevent the command from running, even
611 though the next step would have been to convert the pointer
612 directly back into the same address.
614 The following shortcut avoids this whole mess. If VAL is a
615 function, just return its address directly. */
616 if (TYPE_CODE (VALUE_TYPE (val
)) == TYPE_CODE_FUNC
617 || TYPE_CODE (VALUE_TYPE (val
)) == TYPE_CODE_METHOD
)
618 return VALUE_ADDRESS (val
);
622 /* Some architectures (e.g. Harvard), map instruction and data
623 addresses onto a single large unified address space. For
624 instance: An architecture may consider a large integer in the
625 range 0x10000000 .. 0x1000ffff to already represent a data
626 addresses (hence not need a pointer to address conversion) while
627 a small integer would still need to be converted integer to
628 pointer to address. Just assume such architectures handle all
629 integer conversions in a single function. */
633 I think INTEGER_TO_ADDRESS is a good idea as proposed --- but we
634 must admonish GDB hackers to make sure its behavior matches the
635 compiler's, whenever possible.
637 In general, I think GDB should evaluate expressions the same way
638 the compiler does. When the user copies an expression out of
639 their source code and hands it to a `print' command, they should
640 get the same value the compiler would have computed. Any
641 deviation from this rule can cause major confusion and annoyance,
642 and needs to be justified carefully. In other words, GDB doesn't
643 really have the freedom to do these conversions in clever and
646 AndrewC pointed out that users aren't complaining about how GDB
647 casts integers to pointers; they are complaining that they can't
648 take an address from a disassembly listing and give it to `x/i'.
649 This is certainly important.
651 Adding an architecture method like INTEGER_TO_ADDRESS certainly
652 makes it possible for GDB to "get it right" in all circumstances
653 --- the target has complete control over how things get done, so
654 people can Do The Right Thing for their target without breaking
655 anyone else. The standard doesn't specify how integers get
656 converted to pointers; usually, the ABI doesn't either, but
657 ABI-specific code is a more reasonable place to handle it. */
659 if (TYPE_CODE (VALUE_TYPE (val
)) != TYPE_CODE_PTR
660 && TYPE_CODE (VALUE_TYPE (val
)) != TYPE_CODE_REF
661 && INTEGER_TO_ADDRESS_P ())
662 return INTEGER_TO_ADDRESS (VALUE_TYPE (val
), VALUE_CONTENTS (val
));
664 return unpack_long (VALUE_TYPE (val
), VALUE_CONTENTS (val
));
668 /* Unpack raw data (copied from debugee, target byte order) at VALADDR
669 as a long, or as a double, assuming the raw data is described
670 by type TYPE. Knows how to convert different sizes of values
671 and can convert between fixed and floating point. We don't assume
672 any alignment for the raw data. Return value is in host byte order.
674 If you want functions and arrays to be coerced to pointers, and
675 references to be dereferenced, call value_as_long() instead.
677 C++: It is assumed that the front-end has taken care of
678 all matters concerning pointers to members. A pointer
679 to member which reaches here is considered to be equivalent
680 to an INT (or some size). After all, it is only an offset. */
683 unpack_long (struct type
*type
, const char *valaddr
)
685 register enum type_code code
= TYPE_CODE (type
);
686 register int len
= TYPE_LENGTH (type
);
687 register int nosign
= TYPE_UNSIGNED (type
);
689 if (current_language
->la_language
== language_scm
690 && is_scmvalue_type (type
))
691 return scm_unpack (type
, valaddr
, TYPE_CODE_INT
);
695 case TYPE_CODE_TYPEDEF
:
696 return unpack_long (check_typedef (type
), valaddr
);
701 case TYPE_CODE_RANGE
:
703 return extract_unsigned_integer (valaddr
, len
);
705 return extract_signed_integer (valaddr
, len
);
708 return extract_typed_floating (valaddr
, type
);
712 /* Assume a CORE_ADDR can fit in a LONGEST (for now). Not sure
713 whether we want this to be true eventually. */
714 return extract_typed_address (valaddr
, type
);
716 case TYPE_CODE_MEMBER
:
717 error ("not implemented: member types in unpack_long");
720 error ("Value can't be converted to integer.");
722 return 0; /* Placate lint. */
725 /* Return a double value from the specified type and address.
726 INVP points to an int which is set to 0 for valid value,
727 1 for invalid value (bad float format). In either case,
728 the returned double is OK to use. Argument is in target
729 format, result is in host format. */
732 unpack_double (struct type
*type
, const char *valaddr
, int *invp
)
738 *invp
= 0; /* Assume valid. */
739 CHECK_TYPEDEF (type
);
740 code
= TYPE_CODE (type
);
741 len
= TYPE_LENGTH (type
);
742 nosign
= TYPE_UNSIGNED (type
);
743 if (code
== TYPE_CODE_FLT
)
745 /* NOTE: cagney/2002-02-19: There was a test here to see if the
746 floating-point value was valid (using the macro
747 INVALID_FLOAT). That test/macro have been removed.
749 It turns out that only the VAX defined this macro and then
750 only in a non-portable way. Fixing the portability problem
751 wouldn't help since the VAX floating-point code is also badly
752 bit-rotten. The target needs to add definitions for the
753 methods TARGET_FLOAT_FORMAT and TARGET_DOUBLE_FORMAT - these
754 exactly describe the target floating-point format. The
755 problem here is that the corresponding floatformat_vax_f and
756 floatformat_vax_d values these methods should be set to are
757 also not defined either. Oops!
759 Hopefully someone will add both the missing floatformat
760 definitions and floatformat_is_invalid() function. */
761 return extract_typed_floating (valaddr
, type
);
765 /* Unsigned -- be sure we compensate for signed LONGEST. */
766 return (ULONGEST
) unpack_long (type
, valaddr
);
770 /* Signed -- we are OK with unpack_long. */
771 return unpack_long (type
, valaddr
);
775 /* Unpack raw data (copied from debugee, target byte order) at VALADDR
776 as a CORE_ADDR, assuming the raw data is described by type TYPE.
777 We don't assume any alignment for the raw data. Return value is in
780 If you want functions and arrays to be coerced to pointers, and
781 references to be dereferenced, call value_as_address() instead.
783 C++: It is assumed that the front-end has taken care of
784 all matters concerning pointers to members. A pointer
785 to member which reaches here is considered to be equivalent
786 to an INT (or some size). After all, it is only an offset. */
789 unpack_pointer (struct type
*type
, const char *valaddr
)
791 /* Assume a CORE_ADDR can fit in a LONGEST (for now). Not sure
792 whether we want this to be true eventually. */
793 return unpack_long (type
, valaddr
);
797 /* Get the value of the FIELDN'th field (which must be static) of
798 TYPE. Return NULL if the field doesn't exist or has been
802 value_static_field (struct type
*type
, int fieldno
)
804 struct value
*retval
;
806 if (TYPE_FIELD_STATIC_HAS_ADDR (type
, fieldno
))
808 retval
= value_at (TYPE_FIELD_TYPE (type
, fieldno
),
809 TYPE_FIELD_STATIC_PHYSADDR (type
, fieldno
),
814 char *phys_name
= TYPE_FIELD_STATIC_PHYSNAME (type
, fieldno
);
815 struct symbol
*sym
= lookup_symbol (phys_name
, 0, VAR_NAMESPACE
, 0, NULL
);
818 /* With some compilers, e.g. HP aCC, static data members are reported
819 as non-debuggable symbols */
820 struct minimal_symbol
*msym
= lookup_minimal_symbol (phys_name
, NULL
, NULL
);
825 retval
= value_at (TYPE_FIELD_TYPE (type
, fieldno
),
826 SYMBOL_VALUE_ADDRESS (msym
),
827 SYMBOL_BFD_SECTION (msym
));
832 /* SYM should never have a SYMBOL_CLASS which will require
833 read_var_value to use the FRAME parameter. */
834 if (symbol_read_needs_frame (sym
))
835 warning ("static field's value depends on the current "
836 "frame - bad debug info?");
837 retval
= read_var_value (sym
, NULL
);
839 if (retval
&& VALUE_LVAL (retval
) == lval_memory
)
840 SET_FIELD_PHYSADDR (TYPE_FIELD (type
, fieldno
),
841 VALUE_ADDRESS (retval
));
846 /* Change the enclosing type of a value object VAL to NEW_ENCL_TYPE.
847 You have to be careful here, since the size of the data area for the value
848 is set by the length of the enclosing type. So if NEW_ENCL_TYPE is bigger
849 than the old enclosing type, you have to allocate more space for the data.
850 The return value is a pointer to the new version of this value structure. */
853 value_change_enclosing_type (struct value
*val
, struct type
*new_encl_type
)
855 if (TYPE_LENGTH (new_encl_type
) <= TYPE_LENGTH (VALUE_ENCLOSING_TYPE (val
)))
857 VALUE_ENCLOSING_TYPE (val
) = new_encl_type
;
862 struct value
*new_val
;
865 new_val
= (struct value
*) xrealloc (val
, sizeof (struct value
) + TYPE_LENGTH (new_encl_type
));
867 VALUE_ENCLOSING_TYPE (new_val
) = new_encl_type
;
869 /* We have to make sure this ends up in the same place in the value
870 chain as the original copy, so it's clean-up behavior is the same.
871 If the value has been released, this is a waste of time, but there
872 is no way to tell that in advance, so... */
874 if (val
!= all_values
)
876 for (prev
= all_values
; prev
!= NULL
; prev
= prev
->next
)
878 if (prev
->next
== val
)
880 prev
->next
= new_val
;
890 /* Given a value ARG1 (offset by OFFSET bytes)
891 of a struct or union type ARG_TYPE,
892 extract and return the value of one of its (non-static) fields.
893 FIELDNO says which field. */
896 value_primitive_field (struct value
*arg1
, int offset
,
897 register int fieldno
, register struct type
*arg_type
)
900 register struct type
*type
;
902 CHECK_TYPEDEF (arg_type
);
903 type
= TYPE_FIELD_TYPE (arg_type
, fieldno
);
905 /* Handle packed fields */
907 if (TYPE_FIELD_BITSIZE (arg_type
, fieldno
))
909 v
= value_from_longest (type
,
910 unpack_field_as_long (arg_type
,
911 VALUE_CONTENTS (arg1
)
914 VALUE_BITPOS (v
) = TYPE_FIELD_BITPOS (arg_type
, fieldno
) % 8;
915 VALUE_BITSIZE (v
) = TYPE_FIELD_BITSIZE (arg_type
, fieldno
);
916 VALUE_OFFSET (v
) = VALUE_OFFSET (arg1
) + offset
917 + TYPE_FIELD_BITPOS (arg_type
, fieldno
) / 8;
919 else if (fieldno
< TYPE_N_BASECLASSES (arg_type
))
921 /* This field is actually a base subobject, so preserve the
922 entire object's contents for later references to virtual
924 v
= allocate_value (VALUE_ENCLOSING_TYPE (arg1
));
925 VALUE_TYPE (v
) = type
;
926 if (VALUE_LAZY (arg1
))
929 memcpy (VALUE_CONTENTS_ALL_RAW (v
), VALUE_CONTENTS_ALL_RAW (arg1
),
930 TYPE_LENGTH (VALUE_ENCLOSING_TYPE (arg1
)));
931 VALUE_OFFSET (v
) = VALUE_OFFSET (arg1
);
932 VALUE_EMBEDDED_OFFSET (v
)
934 VALUE_EMBEDDED_OFFSET (arg1
) +
935 TYPE_FIELD_BITPOS (arg_type
, fieldno
) / 8;
939 /* Plain old data member */
940 offset
+= TYPE_FIELD_BITPOS (arg_type
, fieldno
) / 8;
941 v
= allocate_value (type
);
942 if (VALUE_LAZY (arg1
))
945 memcpy (VALUE_CONTENTS_RAW (v
),
946 VALUE_CONTENTS_RAW (arg1
) + offset
,
948 VALUE_OFFSET (v
) = VALUE_OFFSET (arg1
) + offset
949 + VALUE_EMBEDDED_OFFSET (arg1
);
951 VALUE_LVAL (v
) = VALUE_LVAL (arg1
);
952 if (VALUE_LVAL (arg1
) == lval_internalvar
)
953 VALUE_LVAL (v
) = lval_internalvar_component
;
954 VALUE_ADDRESS (v
) = VALUE_ADDRESS (arg1
);
955 VALUE_REGNO (v
) = VALUE_REGNO (arg1
);
956 /* VALUE_OFFSET (v) = VALUE_OFFSET (arg1) + offset
957 + TYPE_FIELD_BITPOS (arg_type, fieldno) / 8; */
961 /* Given a value ARG1 of a struct or union type,
962 extract and return the value of one of its (non-static) fields.
963 FIELDNO says which field. */
966 value_field (struct value
*arg1
, register int fieldno
)
968 return value_primitive_field (arg1
, 0, fieldno
, VALUE_TYPE (arg1
));
971 /* Return a non-virtual function as a value.
972 F is the list of member functions which contains the desired method.
973 J is an index into F which provides the desired method.
975 We only use the symbol for its address, so be happy with either a
976 full symbol or a minimal symbol.
980 value_fn_field (struct value
**arg1p
, struct fn_field
*f
, int j
, struct type
*type
,
984 register struct type
*ftype
= TYPE_FN_FIELD_TYPE (f
, j
);
985 char *physname
= TYPE_FN_FIELD_PHYSNAME (f
, j
);
987 struct minimal_symbol
*msym
;
989 sym
= lookup_symbol (physname
, 0, VAR_NAMESPACE
, 0, NULL
);
996 gdb_assert (sym
== NULL
);
997 msym
= lookup_minimal_symbol (physname
, NULL
, NULL
);
1002 v
= allocate_value (ftype
);
1005 VALUE_ADDRESS (v
) = BLOCK_START (SYMBOL_BLOCK_VALUE (sym
));
1009 VALUE_ADDRESS (v
) = SYMBOL_VALUE_ADDRESS (msym
);
1014 if (type
!= VALUE_TYPE (*arg1p
))
1015 *arg1p
= value_ind (value_cast (lookup_pointer_type (type
),
1016 value_addr (*arg1p
)));
1018 /* Move the `this' pointer according to the offset.
1019 VALUE_OFFSET (*arg1p) += offset;
1027 /* Unpack a field FIELDNO of the specified TYPE, from the anonymous object at
1030 Extracting bits depends on endianness of the machine. Compute the
1031 number of least significant bits to discard. For big endian machines,
1032 we compute the total number of bits in the anonymous object, subtract
1033 off the bit count from the MSB of the object to the MSB of the
1034 bitfield, then the size of the bitfield, which leaves the LSB discard
1035 count. For little endian machines, the discard count is simply the
1036 number of bits from the LSB of the anonymous object to the LSB of the
1039 If the field is signed, we also do sign extension. */
1042 unpack_field_as_long (struct type
*type
, const char *valaddr
, int fieldno
)
1046 int bitpos
= TYPE_FIELD_BITPOS (type
, fieldno
);
1047 int bitsize
= TYPE_FIELD_BITSIZE (type
, fieldno
);
1049 struct type
*field_type
;
1051 val
= extract_unsigned_integer (valaddr
+ bitpos
/ 8, sizeof (val
));
1052 field_type
= TYPE_FIELD_TYPE (type
, fieldno
);
1053 CHECK_TYPEDEF (field_type
);
1055 /* Extract bits. See comment above. */
1057 if (BITS_BIG_ENDIAN
)
1058 lsbcount
= (sizeof val
* 8 - bitpos
% 8 - bitsize
);
1060 lsbcount
= (bitpos
% 8);
1063 /* If the field does not entirely fill a LONGEST, then zero the sign bits.
1064 If the field is signed, and is negative, then sign extend. */
1066 if ((bitsize
> 0) && (bitsize
< 8 * (int) sizeof (val
)))
1068 valmask
= (((ULONGEST
) 1) << bitsize
) - 1;
1070 if (!TYPE_UNSIGNED (field_type
))
1072 if (val
& (valmask
^ (valmask
>> 1)))
1081 /* Modify the value of a bitfield. ADDR points to a block of memory in
1082 target byte order; the bitfield starts in the byte pointed to. FIELDVAL
1083 is the desired value of the field, in host byte order. BITPOS and BITSIZE
1084 indicate which bits (in target bit order) comprise the bitfield. */
1087 modify_field (char *addr
, LONGEST fieldval
, int bitpos
, int bitsize
)
1091 /* If a negative fieldval fits in the field in question, chop
1092 off the sign extension bits. */
1093 if (bitsize
< (8 * (int) sizeof (fieldval
))
1094 && (~fieldval
& ~((1 << (bitsize
- 1)) - 1)) == 0)
1095 fieldval
= fieldval
& ((1 << bitsize
) - 1);
1097 /* Warn if value is too big to fit in the field in question. */
1098 if (bitsize
< (8 * (int) sizeof (fieldval
))
1099 && 0 != (fieldval
& ~((1 << bitsize
) - 1)))
1101 /* FIXME: would like to include fieldval in the message, but
1102 we don't have a sprintf_longest. */
1103 warning ("Value does not fit in %d bits.", bitsize
);
1105 /* Truncate it, otherwise adjoining fields may be corrupted. */
1106 fieldval
= fieldval
& ((1 << bitsize
) - 1);
1109 oword
= extract_signed_integer (addr
, sizeof oword
);
1111 /* Shifting for bit field depends on endianness of the target machine. */
1112 if (BITS_BIG_ENDIAN
)
1113 bitpos
= sizeof (oword
) * 8 - bitpos
- bitsize
;
1115 /* Mask out old value, while avoiding shifts >= size of oword */
1116 if (bitsize
< 8 * (int) sizeof (oword
))
1117 oword
&= ~(((((ULONGEST
) 1) << bitsize
) - 1) << bitpos
);
1119 oword
&= ~((~(ULONGEST
) 0) << bitpos
);
1120 oword
|= fieldval
<< bitpos
;
1122 store_signed_integer (addr
, sizeof oword
, oword
);
1125 /* Convert C numbers into newly allocated values */
1128 value_from_longest (struct type
*type
, register LONGEST num
)
1130 struct value
*val
= allocate_value (type
);
1131 register enum type_code code
;
1134 code
= TYPE_CODE (type
);
1135 len
= TYPE_LENGTH (type
);
1139 case TYPE_CODE_TYPEDEF
:
1140 type
= check_typedef (type
);
1143 case TYPE_CODE_CHAR
:
1144 case TYPE_CODE_ENUM
:
1145 case TYPE_CODE_BOOL
:
1146 case TYPE_CODE_RANGE
:
1147 store_signed_integer (VALUE_CONTENTS_RAW (val
), len
, num
);
1152 store_typed_address (VALUE_CONTENTS_RAW (val
), type
, (CORE_ADDR
) num
);
1156 error ("Unexpected type (%d) encountered for integer constant.", code
);
1162 /* Create a value representing a pointer of type TYPE to the address
1165 value_from_pointer (struct type
*type
, CORE_ADDR addr
)
1167 struct value
*val
= allocate_value (type
);
1168 store_typed_address (VALUE_CONTENTS_RAW (val
), type
, addr
);
1173 /* Create a value for a string constant to be stored locally
1174 (not in the inferior's memory space, but in GDB memory).
1175 This is analogous to value_from_longest, which also does not
1176 use inferior memory. String shall NOT contain embedded nulls. */
1179 value_from_string (char *ptr
)
1182 int len
= strlen (ptr
);
1183 int lowbound
= current_language
->string_lower_bound
;
1184 struct type
*rangetype
=
1185 create_range_type ((struct type
*) NULL
,
1187 lowbound
, len
+ lowbound
- 1);
1188 struct type
*stringtype
=
1189 create_array_type ((struct type
*) NULL
,
1190 *current_language
->string_char_type
,
1193 val
= allocate_value (stringtype
);
1194 memcpy (VALUE_CONTENTS_RAW (val
), ptr
, len
);
1199 value_from_double (struct type
*type
, DOUBLEST num
)
1201 struct value
*val
= allocate_value (type
);
1202 struct type
*base_type
= check_typedef (type
);
1203 register enum type_code code
= TYPE_CODE (base_type
);
1204 register int len
= TYPE_LENGTH (base_type
);
1206 if (code
== TYPE_CODE_FLT
)
1208 store_typed_floating (VALUE_CONTENTS_RAW (val
), base_type
, num
);
1211 error ("Unexpected type encountered for floating constant.");
1216 /* Deal with the value that is "about to be returned". */
1218 /* Return the value that a function returning now
1219 would be returning to its caller, assuming its type is VALTYPE.
1220 RETBUF is where we look for what ought to be the contents
1221 of the registers (in raw form). This is because it is often
1222 desirable to restore old values to those registers
1223 after saving the contents of interest, and then call
1224 this function using the saved values.
1225 struct_return is non-zero when the function in question is
1226 using the structure return conventions on the machine in question;
1227 0 when it is using the value returning conventions (this often
1228 means returning pointer to where structure is vs. returning value). */
1232 value_being_returned (struct type
*valtype
, struct regcache
*retbuf
,
1238 /* If this is not defined, just use EXTRACT_RETURN_VALUE instead. */
1239 if (EXTRACT_STRUCT_VALUE_ADDRESS_P ())
1242 addr
= EXTRACT_STRUCT_VALUE_ADDRESS (retbuf
);
1244 error ("Function return value unknown.");
1245 return value_at (valtype
, addr
, NULL
);
1248 /* If this is not defined, just use EXTRACT_RETURN_VALUE instead. */
1249 if (DEPRECATED_EXTRACT_STRUCT_VALUE_ADDRESS_P ())
1252 char *buf
= deprecated_grub_regcache_for_registers (retbuf
);
1253 addr
= DEPRECATED_EXTRACT_STRUCT_VALUE_ADDRESS (buf
);
1255 error ("Function return value unknown.");
1256 return value_at (valtype
, addr
, NULL
);
1259 val
= allocate_value (valtype
);
1260 CHECK_TYPEDEF (valtype
);
1261 EXTRACT_RETURN_VALUE (valtype
, retbuf
, VALUE_CONTENTS_RAW (val
));
1266 /* Should we use EXTRACT_STRUCT_VALUE_ADDRESS instead of
1267 EXTRACT_RETURN_VALUE? GCC_P is true if compiled with gcc
1268 and TYPE is the type (which is known to be struct, union or array).
1270 On most machines, the struct convention is used unless we are
1271 using gcc and the type is of a special size. */
1272 /* As of about 31 Mar 93, GCC was changed to be compatible with the
1273 native compiler. GCC 2.3.3 was the last release that did it the
1274 old way. Since gcc2_compiled was not changed, we have no
1275 way to correctly win in all cases, so we just do the right thing
1276 for gcc1 and for gcc2 after this change. Thus it loses for gcc
1277 2.0-2.3.3. This is somewhat unfortunate, but changing gcc2_compiled
1278 would cause more chaos than dealing with some struct returns being
1282 generic_use_struct_convention (int gcc_p
, struct type
*value_type
)
1284 return !((gcc_p
== 1)
1285 && (TYPE_LENGTH (value_type
) == 1
1286 || TYPE_LENGTH (value_type
) == 2
1287 || TYPE_LENGTH (value_type
) == 4
1288 || TYPE_LENGTH (value_type
) == 8));
1291 /* Return true if the function specified is using the structure returning
1292 convention on this machine to return arguments, or 0 if it is using
1293 the value returning convention. FUNCTION is the value representing
1294 the function, FUNCADDR is the address of the function, and VALUE_TYPE
1295 is the type returned by the function. GCC_P is nonzero if compiled
1300 using_struct_return (struct value
*function
, CORE_ADDR funcaddr
,
1301 struct type
*value_type
, int gcc_p
)
1303 register enum type_code code
= TYPE_CODE (value_type
);
1305 if (code
== TYPE_CODE_ERROR
)
1306 error ("Function return type unknown.");
1308 if (code
== TYPE_CODE_STRUCT
1309 || code
== TYPE_CODE_UNION
1310 || code
== TYPE_CODE_ARRAY
1311 || RETURN_VALUE_ON_STACK (value_type
))
1312 return USE_STRUCT_CONVENTION (gcc_p
, value_type
);
1317 /* Store VAL so it will be returned if a function returns now.
1318 Does not verify that VAL's type matches what the current
1319 function wants to return. */
1322 set_return_value (struct value
*val
)
1324 struct type
*type
= check_typedef (VALUE_TYPE (val
));
1325 register enum type_code code
= TYPE_CODE (type
);
1327 if (code
== TYPE_CODE_ERROR
)
1328 error ("Function return type unknown.");
1330 if (code
== TYPE_CODE_STRUCT
1331 || code
== TYPE_CODE_UNION
) /* FIXME, implement struct return. */
1332 error ("GDB does not support specifying a struct or union return value.");
1334 STORE_RETURN_VALUE (type
, current_regcache
, VALUE_CONTENTS (val
));
1338 _initialize_values (void)
1340 add_cmd ("convenience", no_class
, show_convenience
,
1341 "Debugger convenience (\"$foo\") variables.\n\
1342 These variables are created when you assign them values;\n\
1343 thus, \"print $foo=1\" gives \"$foo\" the value 1. Values may be any type.\n\n\
1344 A few convenience variables are given values automatically:\n\
1345 \"$_\"holds the last address examined with \"x\" or \"info lines\",\n\
1346 \"$__\" holds the contents of the last address examined with \"x\".",
1349 add_cmd ("values", no_class
, show_values
,
1350 "Elements of value history around item number IDX (or last ten).",