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"
41 /* Prototypes for exported functions. */
43 void _initialize_values (void);
45 /* Prototypes for local functions. */
47 static void show_values (char *, int);
49 static void show_convenience (char *, int);
52 /* The value-history records all the values printed
53 by print commands during this session. Each chunk
54 records 60 consecutive values. The first chunk on
55 the chain records the most recent values.
56 The total number of values is in value_history_count. */
58 #define VALUE_HISTORY_CHUNK 60
60 struct value_history_chunk
62 struct value_history_chunk *next;
63 struct value *values[VALUE_HISTORY_CHUNK];
66 /* Chain of chunks now in use. */
68 static struct value_history_chunk *value_history_chain;
70 static int value_history_count; /* Abs number of last entry stored */
72 /* List of all value objects currently allocated
73 (except for those released by calls to release_value)
74 This is so they can be freed after each command. */
76 static struct value *all_values;
78 /* Allocate a value that has the correct length for type TYPE. */
81 allocate_value (struct type *type)
84 struct type *atype = check_typedef (type);
86 val = (struct value *) xmalloc (sizeof (struct value) + TYPE_LENGTH (atype));
87 VALUE_NEXT (val) = all_values;
89 VALUE_TYPE (val) = type;
90 VALUE_ENCLOSING_TYPE (val) = type;
91 VALUE_LVAL (val) = not_lval;
92 VALUE_ADDRESS (val) = 0;
93 VALUE_FRAME_ID (val) = null_frame_id;
94 VALUE_OFFSET (val) = 0;
95 VALUE_BITPOS (val) = 0;
96 VALUE_BITSIZE (val) = 0;
97 VALUE_REGNO (val) = -1;
99 VALUE_OPTIMIZED_OUT (val) = 0;
100 VALUE_BFD_SECTION (val) = NULL;
101 VALUE_EMBEDDED_OFFSET (val) = 0;
102 VALUE_POINTED_TO_OFFSET (val) = 0;
107 /* Allocate a value that has the correct length
108 for COUNT repetitions type TYPE. */
111 allocate_repeat_value (struct type *type, int count)
113 int low_bound = current_language->string_lower_bound; /* ??? */
114 /* FIXME-type-allocation: need a way to free this type when we are
116 struct type *range_type
117 = create_range_type ((struct type *) NULL, builtin_type_int,
118 low_bound, count + low_bound - 1);
119 /* FIXME-type-allocation: need a way to free this type when we are
121 return allocate_value (create_array_type ((struct type *) NULL,
125 /* Return a mark in the value chain. All values allocated after the
126 mark is obtained (except for those released) are subject to being freed
127 if a subsequent value_free_to_mark is passed the mark. */
134 /* Free all values allocated since MARK was obtained by value_mark
135 (except for those released). */
137 value_free_to_mark (struct value *mark)
142 for (val = all_values; val && val != mark; val = next)
144 next = VALUE_NEXT (val);
150 /* Free all the values that have been allocated (except for those released).
151 Called after each command, successful or not. */
154 free_all_values (void)
159 for (val = all_values; val; val = next)
161 next = VALUE_NEXT (val);
168 /* Remove VAL from the chain all_values
169 so it will not be freed automatically. */
172 release_value (struct value *val)
176 if (all_values == val)
178 all_values = val->next;
182 for (v = all_values; v; v = v->next)
192 /* Release all values up to mark */
194 value_release_to_mark (struct value *mark)
199 for (val = next = all_values; next; next = VALUE_NEXT (next))
200 if (VALUE_NEXT (next) == mark)
202 all_values = VALUE_NEXT (next);
203 VALUE_NEXT (next) = 0;
210 /* Return a copy of the value ARG.
211 It contains the same contents, for same memory address,
212 but it's a different block of storage. */
215 value_copy (struct value *arg)
217 struct type *encl_type = VALUE_ENCLOSING_TYPE (arg);
218 struct value *val = allocate_value (encl_type);
219 VALUE_TYPE (val) = VALUE_TYPE (arg);
220 VALUE_LVAL (val) = VALUE_LVAL (arg);
221 VALUE_ADDRESS (val) = VALUE_ADDRESS (arg);
222 VALUE_OFFSET (val) = VALUE_OFFSET (arg);
223 VALUE_BITPOS (val) = VALUE_BITPOS (arg);
224 VALUE_BITSIZE (val) = VALUE_BITSIZE (arg);
225 VALUE_FRAME_ID (val) = VALUE_FRAME_ID (arg);
226 VALUE_REGNO (val) = VALUE_REGNO (arg);
227 VALUE_LAZY (val) = VALUE_LAZY (arg);
228 VALUE_OPTIMIZED_OUT (val) = VALUE_OPTIMIZED_OUT (arg);
229 VALUE_EMBEDDED_OFFSET (val) = VALUE_EMBEDDED_OFFSET (arg);
230 VALUE_POINTED_TO_OFFSET (val) = VALUE_POINTED_TO_OFFSET (arg);
231 VALUE_BFD_SECTION (val) = VALUE_BFD_SECTION (arg);
232 val->modifiable = arg->modifiable;
233 if (!VALUE_LAZY (val))
235 memcpy (VALUE_CONTENTS_ALL_RAW (val), VALUE_CONTENTS_ALL_RAW (arg),
236 TYPE_LENGTH (VALUE_ENCLOSING_TYPE (arg)));
242 /* Access to the value history. */
244 /* Record a new value in the value history.
245 Returns the absolute history index of the entry.
246 Result of -1 indicates the value was not saved; otherwise it is the
247 value history index of this new item. */
250 record_latest_value (struct value *val)
254 /* We don't want this value to have anything to do with the inferior anymore.
255 In particular, "set $1 = 50" should not affect the variable from which
256 the value was taken, and fast watchpoints should be able to assume that
257 a value on the value history never changes. */
258 if (VALUE_LAZY (val))
259 value_fetch_lazy (val);
260 /* We preserve VALUE_LVAL so that the user can find out where it was fetched
261 from. This is a bit dubious, because then *&$1 does not just return $1
262 but the current contents of that location. c'est la vie... */
266 /* Here we treat value_history_count as origin-zero
267 and applying to the value being stored now. */
269 i = value_history_count % VALUE_HISTORY_CHUNK;
272 struct value_history_chunk *new
273 = (struct value_history_chunk *)
274 xmalloc (sizeof (struct value_history_chunk));
275 memset (new->values, 0, sizeof new->values);
276 new->next = value_history_chain;
277 value_history_chain = new;
280 value_history_chain->values[i] = val;
282 /* Now we regard value_history_count as origin-one
283 and applying to the value just stored. */
285 return ++value_history_count;
288 /* Return a copy of the value in the history with sequence number NUM. */
291 access_value_history (int num)
293 struct value_history_chunk *chunk;
298 absnum += value_history_count;
303 error ("The history is empty.");
305 error ("There is only one value in the history.");
307 error ("History does not go back to $$%d.", -num);
309 if (absnum > value_history_count)
310 error ("History has not yet reached $%d.", absnum);
314 /* Now absnum is always absolute and origin zero. */
316 chunk = value_history_chain;
317 for (i = (value_history_count - 1) / VALUE_HISTORY_CHUNK - absnum / VALUE_HISTORY_CHUNK;
321 return value_copy (chunk->values[absnum % VALUE_HISTORY_CHUNK]);
324 /* Clear the value history entirely.
325 Must be done when new symbol tables are loaded,
326 because the type pointers become invalid. */
329 clear_value_history (void)
331 struct value_history_chunk *next;
335 while (value_history_chain)
337 for (i = 0; i < VALUE_HISTORY_CHUNK; i++)
338 if ((val = value_history_chain->values[i]) != NULL)
340 next = value_history_chain->next;
341 xfree (value_history_chain);
342 value_history_chain = next;
344 value_history_count = 0;
348 show_values (char *num_exp, int from_tty)
356 /* "info history +" should print from the stored position.
357 "info history <exp>" should print around value number <exp>. */
358 if (num_exp[0] != '+' || num_exp[1] != '\0')
359 num = parse_and_eval_long (num_exp) - 5;
363 /* "info history" means print the last 10 values. */
364 num = value_history_count - 9;
370 for (i = num; i < num + 10 && i <= value_history_count; i++)
372 val = access_value_history (i);
373 printf_filtered ("$%d = ", i);
374 value_print (val, gdb_stdout, 0, Val_pretty_default);
375 printf_filtered ("\n");
378 /* The next "info history +" should start after what we just printed. */
381 /* Hitting just return after this command should do the same thing as
382 "info history +". If num_exp is null, this is unnecessary, since
383 "info history +" is not useful after "info history". */
384 if (from_tty && num_exp)
391 /* Internal variables. These are variables within the debugger
392 that hold values assigned by debugger commands.
393 The user refers to them with a '$' prefix
394 that does not appear in the variable names stored internally. */
396 static struct internalvar *internalvars;
398 /* Look up an internal variable with name NAME. NAME should not
399 normally include a dollar sign.
401 If the specified internal variable does not exist,
402 one is created, with a void value. */
405 lookup_internalvar (char *name)
407 struct internalvar *var;
409 for (var = internalvars; var; var = var->next)
410 if (strcmp (var->name, name) == 0)
413 var = (struct internalvar *) xmalloc (sizeof (struct internalvar));
414 var->name = concat (name, NULL);
415 var->value = allocate_value (builtin_type_void);
416 release_value (var->value);
417 var->next = internalvars;
423 value_of_internalvar (struct internalvar *var)
427 val = value_copy (var->value);
428 if (VALUE_LAZY (val))
429 value_fetch_lazy (val);
430 VALUE_LVAL (val) = lval_internalvar;
431 VALUE_INTERNALVAR (val) = var;
436 set_internalvar_component (struct internalvar *var, int offset, int bitpos,
437 int bitsize, struct value *newval)
439 char *addr = VALUE_CONTENTS (var->value) + offset;
442 modify_field (addr, value_as_long (newval),
445 memcpy (addr, VALUE_CONTENTS (newval), TYPE_LENGTH (VALUE_TYPE (newval)));
449 set_internalvar (struct internalvar *var, struct value *val)
451 struct value *newval;
453 newval = value_copy (val);
454 newval->modifiable = 1;
456 /* Force the value to be fetched from the target now, to avoid problems
457 later when this internalvar is referenced and the target is gone or
459 if (VALUE_LAZY (newval))
460 value_fetch_lazy (newval);
462 /* Begin code which must not call error(). If var->value points to
463 something free'd, an error() obviously leaves a dangling pointer.
464 But we also get a danling pointer if var->value points to
465 something in the value chain (i.e., before release_value is
466 called), because after the error free_all_values will get called before
470 release_value (newval);
471 /* End code which must not call error(). */
475 internalvar_name (struct internalvar *var)
480 /* Free all internalvars. Done when new symtabs are loaded,
481 because that makes the values invalid. */
484 clear_internalvars (void)
486 struct internalvar *var;
491 internalvars = var->next;
499 show_convenience (char *ignore, int from_tty)
501 struct internalvar *var;
504 for (var = internalvars; var; var = var->next)
510 printf_filtered ("$%s = ", var->name);
511 value_print (var->value, gdb_stdout, 0, Val_pretty_default);
512 printf_filtered ("\n");
515 printf_unfiltered ("No debugger convenience variables now defined.\n\
516 Convenience variables have names starting with \"$\";\n\
517 use \"set\" as in \"set $foo = 5\" to define them.\n");
520 /* Extract a value as a C number (either long or double).
521 Knows how to convert fixed values to double, or
522 floating values to long.
523 Does not deallocate the value. */
526 value_as_long (struct value *val)
528 /* This coerces arrays and functions, which is necessary (e.g.
529 in disassemble_command). It also dereferences references, which
530 I suspect is the most logical thing to do. */
532 return unpack_long (VALUE_TYPE (val), VALUE_CONTENTS (val));
536 value_as_double (struct value *val)
541 foo = unpack_double (VALUE_TYPE (val), VALUE_CONTENTS (val), &inv);
543 error ("Invalid floating value found in program.");
546 /* Extract a value as a C pointer. Does not deallocate the value.
547 Note that val's type may not actually be a pointer; value_as_long
548 handles all the cases. */
550 value_as_address (struct value *val)
552 /* Assume a CORE_ADDR can fit in a LONGEST (for now). Not sure
553 whether we want this to be true eventually. */
555 /* ADDR_BITS_REMOVE is wrong if we are being called for a
556 non-address (e.g. argument to "signal", "info break", etc.), or
557 for pointers to char, in which the low bits *are* significant. */
558 return ADDR_BITS_REMOVE (value_as_long (val));
561 /* There are several targets (IA-64, PowerPC, and others) which
562 don't represent pointers to functions as simply the address of
563 the function's entry point. For example, on the IA-64, a
564 function pointer points to a two-word descriptor, generated by
565 the linker, which contains the function's entry point, and the
566 value the IA-64 "global pointer" register should have --- to
567 support position-independent code. The linker generates
568 descriptors only for those functions whose addresses are taken.
570 On such targets, it's difficult for GDB to convert an arbitrary
571 function address into a function pointer; it has to either find
572 an existing descriptor for that function, or call malloc and
573 build its own. On some targets, it is impossible for GDB to
574 build a descriptor at all: the descriptor must contain a jump
575 instruction; data memory cannot be executed; and code memory
578 Upon entry to this function, if VAL is a value of type `function'
579 (that is, TYPE_CODE (VALUE_TYPE (val)) == TYPE_CODE_FUNC), then
580 VALUE_ADDRESS (val) is the address of the function. This is what
581 you'll get if you evaluate an expression like `main'. The call
582 to COERCE_ARRAY below actually does all the usual unary
583 conversions, which includes converting values of type `function'
584 to `pointer to function'. This is the challenging conversion
585 discussed above. Then, `unpack_long' will convert that pointer
586 back into an address.
588 So, suppose the user types `disassemble foo' on an architecture
589 with a strange function pointer representation, on which GDB
590 cannot build its own descriptors, and suppose further that `foo'
591 has no linker-built descriptor. The address->pointer conversion
592 will signal an error and prevent the command from running, even
593 though the next step would have been to convert the pointer
594 directly back into the same address.
596 The following shortcut avoids this whole mess. If VAL is a
597 function, just return its address directly. */
598 if (TYPE_CODE (VALUE_TYPE (val)) == TYPE_CODE_FUNC
599 || TYPE_CODE (VALUE_TYPE (val)) == TYPE_CODE_METHOD)
600 return VALUE_ADDRESS (val);
604 /* Some architectures (e.g. Harvard), map instruction and data
605 addresses onto a single large unified address space. For
606 instance: An architecture may consider a large integer in the
607 range 0x10000000 .. 0x1000ffff to already represent a data
608 addresses (hence not need a pointer to address conversion) while
609 a small integer would still need to be converted integer to
610 pointer to address. Just assume such architectures handle all
611 integer conversions in a single function. */
615 I think INTEGER_TO_ADDRESS is a good idea as proposed --- but we
616 must admonish GDB hackers to make sure its behavior matches the
617 compiler's, whenever possible.
619 In general, I think GDB should evaluate expressions the same way
620 the compiler does. When the user copies an expression out of
621 their source code and hands it to a `print' command, they should
622 get the same value the compiler would have computed. Any
623 deviation from this rule can cause major confusion and annoyance,
624 and needs to be justified carefully. In other words, GDB doesn't
625 really have the freedom to do these conversions in clever and
628 AndrewC pointed out that users aren't complaining about how GDB
629 casts integers to pointers; they are complaining that they can't
630 take an address from a disassembly listing and give it to `x/i'.
631 This is certainly important.
633 Adding an architecture method like INTEGER_TO_ADDRESS certainly
634 makes it possible for GDB to "get it right" in all circumstances
635 --- the target has complete control over how things get done, so
636 people can Do The Right Thing for their target without breaking
637 anyone else. The standard doesn't specify how integers get
638 converted to pointers; usually, the ABI doesn't either, but
639 ABI-specific code is a more reasonable place to handle it. */
641 if (TYPE_CODE (VALUE_TYPE (val)) != TYPE_CODE_PTR
642 && TYPE_CODE (VALUE_TYPE (val)) != TYPE_CODE_REF
643 && INTEGER_TO_ADDRESS_P ())
644 return INTEGER_TO_ADDRESS (VALUE_TYPE (val), VALUE_CONTENTS (val));
646 return unpack_long (VALUE_TYPE (val), VALUE_CONTENTS (val));
650 /* Unpack raw data (copied from debugee, target byte order) at VALADDR
651 as a long, or as a double, assuming the raw data is described
652 by type TYPE. Knows how to convert different sizes of values
653 and can convert between fixed and floating point. We don't assume
654 any alignment for the raw data. Return value is in host byte order.
656 If you want functions and arrays to be coerced to pointers, and
657 references to be dereferenced, call value_as_long() instead.
659 C++: It is assumed that the front-end has taken care of
660 all matters concerning pointers to members. A pointer
661 to member which reaches here is considered to be equivalent
662 to an INT (or some size). After all, it is only an offset. */
665 unpack_long (struct type *type, const char *valaddr)
667 enum type_code code = TYPE_CODE (type);
668 int len = TYPE_LENGTH (type);
669 int nosign = TYPE_UNSIGNED (type);
671 if (current_language->la_language == language_scm
672 && is_scmvalue_type (type))
673 return scm_unpack (type, valaddr, TYPE_CODE_INT);
677 case TYPE_CODE_TYPEDEF:
678 return unpack_long (check_typedef (type), valaddr);
683 case TYPE_CODE_RANGE:
685 return extract_unsigned_integer (valaddr, len);
687 return extract_signed_integer (valaddr, len);
690 return extract_typed_floating (valaddr, type);
694 /* Assume a CORE_ADDR can fit in a LONGEST (for now). Not sure
695 whether we want this to be true eventually. */
696 return extract_typed_address (valaddr, type);
698 case TYPE_CODE_MEMBER:
699 error ("not implemented: member types in unpack_long");
702 error ("Value can't be converted to integer.");
704 return 0; /* Placate lint. */
707 /* Return a double value from the specified type and address.
708 INVP points to an int which is set to 0 for valid value,
709 1 for invalid value (bad float format). In either case,
710 the returned double is OK to use. Argument is in target
711 format, result is in host format. */
714 unpack_double (struct type *type, const char *valaddr, int *invp)
720 *invp = 0; /* Assume valid. */
721 CHECK_TYPEDEF (type);
722 code = TYPE_CODE (type);
723 len = TYPE_LENGTH (type);
724 nosign = TYPE_UNSIGNED (type);
725 if (code == TYPE_CODE_FLT)
727 /* NOTE: cagney/2002-02-19: There was a test here to see if the
728 floating-point value was valid (using the macro
729 INVALID_FLOAT). That test/macro have been removed.
731 It turns out that only the VAX defined this macro and then
732 only in a non-portable way. Fixing the portability problem
733 wouldn't help since the VAX floating-point code is also badly
734 bit-rotten. The target needs to add definitions for the
735 methods TARGET_FLOAT_FORMAT and TARGET_DOUBLE_FORMAT - these
736 exactly describe the target floating-point format. The
737 problem here is that the corresponding floatformat_vax_f and
738 floatformat_vax_d values these methods should be set to are
739 also not defined either. Oops!
741 Hopefully someone will add both the missing floatformat
742 definitions and the new cases for floatformat_is_valid (). */
744 if (!floatformat_is_valid (floatformat_from_type (type), valaddr))
750 return extract_typed_floating (valaddr, type);
754 /* Unsigned -- be sure we compensate for signed LONGEST. */
755 return (ULONGEST) unpack_long (type, valaddr);
759 /* Signed -- we are OK with unpack_long. */
760 return unpack_long (type, valaddr);
764 /* Unpack raw data (copied from debugee, target byte order) at VALADDR
765 as a CORE_ADDR, assuming the raw data is described by type TYPE.
766 We don't assume any alignment for the raw data. Return value is in
769 If you want functions and arrays to be coerced to pointers, and
770 references to be dereferenced, call value_as_address() instead.
772 C++: It is assumed that the front-end has taken care of
773 all matters concerning pointers to members. A pointer
774 to member which reaches here is considered to be equivalent
775 to an INT (or some size). After all, it is only an offset. */
778 unpack_pointer (struct type *type, const char *valaddr)
780 /* Assume a CORE_ADDR can fit in a LONGEST (for now). Not sure
781 whether we want this to be true eventually. */
782 return unpack_long (type, valaddr);
786 /* Get the value of the FIELDN'th field (which must be static) of
787 TYPE. Return NULL if the field doesn't exist or has been
791 value_static_field (struct type *type, int fieldno)
793 struct value *retval;
795 if (TYPE_FIELD_STATIC_HAS_ADDR (type, fieldno))
797 retval = value_at (TYPE_FIELD_TYPE (type, fieldno),
798 TYPE_FIELD_STATIC_PHYSADDR (type, fieldno),
803 char *phys_name = TYPE_FIELD_STATIC_PHYSNAME (type, fieldno);
804 struct symbol *sym = lookup_symbol (phys_name, 0, VAR_DOMAIN, 0, NULL);
807 /* With some compilers, e.g. HP aCC, static data members are reported
808 as non-debuggable symbols */
809 struct minimal_symbol *msym = lookup_minimal_symbol (phys_name, NULL, NULL);
814 retval = value_at (TYPE_FIELD_TYPE (type, fieldno),
815 SYMBOL_VALUE_ADDRESS (msym),
816 SYMBOL_BFD_SECTION (msym));
821 /* SYM should never have a SYMBOL_CLASS which will require
822 read_var_value to use the FRAME parameter. */
823 if (symbol_read_needs_frame (sym))
824 warning ("static field's value depends on the current "
825 "frame - bad debug info?");
826 retval = read_var_value (sym, NULL);
828 if (retval && VALUE_LVAL (retval) == lval_memory)
829 SET_FIELD_PHYSADDR (TYPE_FIELD (type, fieldno),
830 VALUE_ADDRESS (retval));
835 /* Change the enclosing type of a value object VAL to NEW_ENCL_TYPE.
836 You have to be careful here, since the size of the data area for the value
837 is set by the length of the enclosing type. So if NEW_ENCL_TYPE is bigger
838 than the old enclosing type, you have to allocate more space for the data.
839 The return value is a pointer to the new version of this value structure. */
842 value_change_enclosing_type (struct value *val, struct type *new_encl_type)
844 if (TYPE_LENGTH (new_encl_type) <= TYPE_LENGTH (VALUE_ENCLOSING_TYPE (val)))
846 VALUE_ENCLOSING_TYPE (val) = new_encl_type;
851 struct value *new_val;
854 new_val = (struct value *) xrealloc (val, sizeof (struct value) + TYPE_LENGTH (new_encl_type));
856 VALUE_ENCLOSING_TYPE (new_val) = new_encl_type;
858 /* We have to make sure this ends up in the same place in the value
859 chain as the original copy, so it's clean-up behavior is the same.
860 If the value has been released, this is a waste of time, but there
861 is no way to tell that in advance, so... */
863 if (val != all_values)
865 for (prev = all_values; prev != NULL; prev = prev->next)
867 if (prev->next == val)
869 prev->next = new_val;
879 /* Given a value ARG1 (offset by OFFSET bytes)
880 of a struct or union type ARG_TYPE,
881 extract and return the value of one of its (non-static) fields.
882 FIELDNO says which field. */
885 value_primitive_field (struct value *arg1, int offset,
886 int fieldno, struct type *arg_type)
891 CHECK_TYPEDEF (arg_type);
892 type = TYPE_FIELD_TYPE (arg_type, fieldno);
894 /* Handle packed fields */
896 if (TYPE_FIELD_BITSIZE (arg_type, fieldno))
898 v = value_from_longest (type,
899 unpack_field_as_long (arg_type,
900 VALUE_CONTENTS (arg1)
903 VALUE_BITPOS (v) = TYPE_FIELD_BITPOS (arg_type, fieldno) % 8;
904 VALUE_BITSIZE (v) = TYPE_FIELD_BITSIZE (arg_type, fieldno);
905 VALUE_OFFSET (v) = VALUE_OFFSET (arg1) + offset
906 + TYPE_FIELD_BITPOS (arg_type, fieldno) / 8;
908 else if (fieldno < TYPE_N_BASECLASSES (arg_type))
910 /* This field is actually a base subobject, so preserve the
911 entire object's contents for later references to virtual
913 v = allocate_value (VALUE_ENCLOSING_TYPE (arg1));
914 VALUE_TYPE (v) = type;
915 if (VALUE_LAZY (arg1))
918 memcpy (VALUE_CONTENTS_ALL_RAW (v), VALUE_CONTENTS_ALL_RAW (arg1),
919 TYPE_LENGTH (VALUE_ENCLOSING_TYPE (arg1)));
920 VALUE_OFFSET (v) = VALUE_OFFSET (arg1);
921 VALUE_EMBEDDED_OFFSET (v)
923 VALUE_EMBEDDED_OFFSET (arg1) +
924 TYPE_FIELD_BITPOS (arg_type, fieldno) / 8;
928 /* Plain old data member */
929 offset += TYPE_FIELD_BITPOS (arg_type, fieldno) / 8;
930 v = allocate_value (type);
931 if (VALUE_LAZY (arg1))
934 memcpy (VALUE_CONTENTS_RAW (v),
935 VALUE_CONTENTS_RAW (arg1) + offset,
937 VALUE_OFFSET (v) = VALUE_OFFSET (arg1) + offset
938 + VALUE_EMBEDDED_OFFSET (arg1);
940 VALUE_LVAL (v) = VALUE_LVAL (arg1);
941 if (VALUE_LVAL (arg1) == lval_internalvar)
942 VALUE_LVAL (v) = lval_internalvar_component;
943 VALUE_ADDRESS (v) = VALUE_ADDRESS (arg1);
944 VALUE_REGNO (v) = VALUE_REGNO (arg1);
945 /* VALUE_OFFSET (v) = VALUE_OFFSET (arg1) + offset
946 + TYPE_FIELD_BITPOS (arg_type, fieldno) / 8; */
950 /* Given a value ARG1 of a struct or union type,
951 extract and return the value of one of its (non-static) fields.
952 FIELDNO says which field. */
955 value_field (struct value *arg1, int fieldno)
957 return value_primitive_field (arg1, 0, fieldno, VALUE_TYPE (arg1));
960 /* Return a non-virtual function as a value.
961 F is the list of member functions which contains the desired method.
962 J is an index into F which provides the desired method.
964 We only use the symbol for its address, so be happy with either a
965 full symbol or a minimal symbol.
969 value_fn_field (struct value **arg1p, struct fn_field *f, int j, struct type *type,
973 struct type *ftype = TYPE_FN_FIELD_TYPE (f, j);
974 char *physname = TYPE_FN_FIELD_PHYSNAME (f, j);
976 struct minimal_symbol *msym;
978 sym = lookup_symbol (physname, 0, VAR_DOMAIN, 0, NULL);
985 gdb_assert (sym == NULL);
986 msym = lookup_minimal_symbol (physname, NULL, NULL);
991 v = allocate_value (ftype);
994 VALUE_ADDRESS (v) = BLOCK_START (SYMBOL_BLOCK_VALUE (sym));
998 VALUE_ADDRESS (v) = SYMBOL_VALUE_ADDRESS (msym);
1003 if (type != VALUE_TYPE (*arg1p))
1004 *arg1p = value_ind (value_cast (lookup_pointer_type (type),
1005 value_addr (*arg1p)));
1007 /* Move the `this' pointer according to the offset.
1008 VALUE_OFFSET (*arg1p) += offset;
1016 /* Unpack a field FIELDNO of the specified TYPE, from the anonymous object at
1019 Extracting bits depends on endianness of the machine. Compute the
1020 number of least significant bits to discard. For big endian machines,
1021 we compute the total number of bits in the anonymous object, subtract
1022 off the bit count from the MSB of the object to the MSB of the
1023 bitfield, then the size of the bitfield, which leaves the LSB discard
1024 count. For little endian machines, the discard count is simply the
1025 number of bits from the LSB of the anonymous object to the LSB of the
1028 If the field is signed, we also do sign extension. */
1031 unpack_field_as_long (struct type *type, const char *valaddr, int fieldno)
1035 int bitpos = TYPE_FIELD_BITPOS (type, fieldno);
1036 int bitsize = TYPE_FIELD_BITSIZE (type, fieldno);
1038 struct type *field_type;
1040 val = extract_unsigned_integer (valaddr + bitpos / 8, sizeof (val));
1041 field_type = TYPE_FIELD_TYPE (type, fieldno);
1042 CHECK_TYPEDEF (field_type);
1044 /* Extract bits. See comment above. */
1046 if (BITS_BIG_ENDIAN)
1047 lsbcount = (sizeof val * 8 - bitpos % 8 - bitsize);
1049 lsbcount = (bitpos % 8);
1052 /* If the field does not entirely fill a LONGEST, then zero the sign bits.
1053 If the field is signed, and is negative, then sign extend. */
1055 if ((bitsize > 0) && (bitsize < 8 * (int) sizeof (val)))
1057 valmask = (((ULONGEST) 1) << bitsize) - 1;
1059 if (!TYPE_UNSIGNED (field_type))
1061 if (val & (valmask ^ (valmask >> 1)))
1070 /* Modify the value of a bitfield. ADDR points to a block of memory in
1071 target byte order; the bitfield starts in the byte pointed to. FIELDVAL
1072 is the desired value of the field, in host byte order. BITPOS and BITSIZE
1073 indicate which bits (in target bit order) comprise the bitfield. */
1076 modify_field (char *addr, LONGEST fieldval, int bitpos, int bitsize)
1080 /* If a negative fieldval fits in the field in question, chop
1081 off the sign extension bits. */
1082 if (bitsize < (8 * (int) sizeof (fieldval))
1083 && (~fieldval & ~((1 << (bitsize - 1)) - 1)) == 0)
1084 fieldval = fieldval & ((1 << bitsize) - 1);
1086 /* Warn if value is too big to fit in the field in question. */
1087 if (bitsize < (8 * (int) sizeof (fieldval))
1088 && 0 != (fieldval & ~((1 << bitsize) - 1)))
1090 /* FIXME: would like to include fieldval in the message, but
1091 we don't have a sprintf_longest. */
1092 warning ("Value does not fit in %d bits.", bitsize);
1094 /* Truncate it, otherwise adjoining fields may be corrupted. */
1095 fieldval = fieldval & ((1 << bitsize) - 1);
1098 oword = extract_signed_integer (addr, sizeof oword);
1100 /* Shifting for bit field depends on endianness of the target machine. */
1101 if (BITS_BIG_ENDIAN)
1102 bitpos = sizeof (oword) * 8 - bitpos - bitsize;
1104 /* Mask out old value, while avoiding shifts >= size of oword */
1105 if (bitsize < 8 * (int) sizeof (oword))
1106 oword &= ~(((((ULONGEST) 1) << bitsize) - 1) << bitpos);
1108 oword &= ~((~(ULONGEST) 0) << bitpos);
1109 oword |= fieldval << bitpos;
1111 store_signed_integer (addr, sizeof oword, oword);
1114 /* Convert C numbers into newly allocated values */
1117 value_from_longest (struct type *type, LONGEST num)
1119 struct value *val = allocate_value (type);
1120 enum type_code code;
1123 code = TYPE_CODE (type);
1124 len = TYPE_LENGTH (type);
1128 case TYPE_CODE_TYPEDEF:
1129 type = check_typedef (type);
1132 case TYPE_CODE_CHAR:
1133 case TYPE_CODE_ENUM:
1134 case TYPE_CODE_BOOL:
1135 case TYPE_CODE_RANGE:
1136 store_signed_integer (VALUE_CONTENTS_RAW (val), len, num);
1141 store_typed_address (VALUE_CONTENTS_RAW (val), type, (CORE_ADDR) num);
1145 error ("Unexpected type (%d) encountered for integer constant.", code);
1151 /* Create a value representing a pointer of type TYPE to the address
1154 value_from_pointer (struct type *type, CORE_ADDR addr)
1156 struct value *val = allocate_value (type);
1157 store_typed_address (VALUE_CONTENTS_RAW (val), type, addr);
1162 /* Create a value for a string constant to be stored locally
1163 (not in the inferior's memory space, but in GDB memory).
1164 This is analogous to value_from_longest, which also does not
1165 use inferior memory. String shall NOT contain embedded nulls. */
1168 value_from_string (char *ptr)
1171 int len = strlen (ptr);
1172 int lowbound = current_language->string_lower_bound;
1173 struct type *rangetype =
1174 create_range_type ((struct type *) NULL,
1176 lowbound, len + lowbound - 1);
1177 struct type *stringtype =
1178 create_array_type ((struct type *) NULL,
1179 *current_language->string_char_type,
1182 val = allocate_value (stringtype);
1183 memcpy (VALUE_CONTENTS_RAW (val), ptr, len);
1188 value_from_double (struct type *type, DOUBLEST num)
1190 struct value *val = allocate_value (type);
1191 struct type *base_type = check_typedef (type);
1192 enum type_code code = TYPE_CODE (base_type);
1193 int len = TYPE_LENGTH (base_type);
1195 if (code == TYPE_CODE_FLT)
1197 store_typed_floating (VALUE_CONTENTS_RAW (val), base_type, num);
1200 error ("Unexpected type encountered for floating constant.");
1206 /* Should we use DEPRECATED_EXTRACT_STRUCT_VALUE_ADDRESS instead of
1207 EXTRACT_RETURN_VALUE? GCC_P is true if compiled with gcc and TYPE
1208 is the type (which is known to be struct, union or array).
1210 On most machines, the struct convention is used unless we are
1211 using gcc and the type is of a special size. */
1212 /* As of about 31 Mar 93, GCC was changed to be compatible with the
1213 native compiler. GCC 2.3.3 was the last release that did it the
1214 old way. Since gcc2_compiled was not changed, we have no
1215 way to correctly win in all cases, so we just do the right thing
1216 for gcc1 and for gcc2 after this change. Thus it loses for gcc
1217 2.0-2.3.3. This is somewhat unfortunate, but changing gcc2_compiled
1218 would cause more chaos than dealing with some struct returns being
1220 /* NOTE: cagney/2004-06-13: Deleted check for "gcc_p". GCC 1.x is
1224 generic_use_struct_convention (int gcc_p, struct type *value_type)
1226 return !(TYPE_LENGTH (value_type) == 1
1227 || TYPE_LENGTH (value_type) == 2
1228 || TYPE_LENGTH (value_type) == 4
1229 || TYPE_LENGTH (value_type) == 8);
1232 /* Return true if the function returning the specified type is using
1233 the convention of returning structures in memory (passing in the
1234 address as a hidden first parameter). GCC_P is nonzero if compiled
1238 using_struct_return (struct type *value_type, int gcc_p)
1240 enum type_code code = TYPE_CODE (value_type);
1242 if (code == TYPE_CODE_ERROR)
1243 error ("Function return type unknown.");
1245 if (code == TYPE_CODE_VOID)
1246 /* A void return value is never in memory. See also corresponding
1247 code in "print_return_value". */
1250 if (!gdbarch_return_value_p (current_gdbarch))
1252 /* FIXME: cagney/2003-10-01: The below is dead. Instead an
1253 architecture should implement "gdbarch_return_value". Using
1254 that new function it is possible to exactly specify the ABIs
1255 "struct return" vs "register return" conventions. */
1256 if (code == TYPE_CODE_STRUCT
1257 || code == TYPE_CODE_UNION
1258 || code == TYPE_CODE_ARRAY)
1259 return DEPRECATED_USE_STRUCT_CONVENTION (gcc_p, value_type);
1264 /* Probe the architecture for the return-value convention. */
1265 return (gdbarch_return_value (current_gdbarch, value_type,
1267 != RETURN_VALUE_REGISTER_CONVENTION);
1271 _initialize_values (void)
1273 add_cmd ("convenience", no_class, show_convenience,
1274 "Debugger convenience (\"$foo\") variables.\n\
1275 These variables are created when you assign them values;\n\
1276 thus, \"print $foo=1\" gives \"$foo\" the value 1. Values may be any type.\n\n\
1277 A few convenience variables are given values automatically:\n\
1278 \"$_\"holds the last address examined with \"x\" or \"info lines\",\n\
1279 \"$__\" holds the contents of the last address examined with \"x\".",
1282 add_cmd ("values", no_class, show_values,
1283 "Elements of value history around item number IDX (or last ten).",