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, 2004, 2005 Free
5 Software Foundation, Inc.
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 val->next = all_values;
90 val->enclosing_type = type;
91 VALUE_LVAL (val) = not_lval;
92 VALUE_ADDRESS (val) = 0;
93 VALUE_FRAME_ID (val) = null_frame_id;
97 VALUE_REGNUM (val) = -1;
99 VALUE_OPTIMIZED_OUT (val) = 0;
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 /* Accessor methods. */
127 value_type (struct value *value)
133 value_offset (struct value *value)
135 return value->offset;
139 value_bitpos (struct value *value)
141 return value->bitpos;
145 value_bitsize (struct value *value)
147 return value->bitsize;
151 value_contents_raw (struct value *value)
153 return value->aligner.contents + value->embedded_offset;
157 value_contents_all_raw (struct value *value)
159 return value->aligner.contents;
163 value_enclosing_type (struct value *value)
165 return value->enclosing_type;
169 value_contents_all (struct value *value)
172 value_fetch_lazy (value);
173 return value->aligner.contents;
177 /* Return a mark in the value chain. All values allocated after the
178 mark is obtained (except for those released) are subject to being freed
179 if a subsequent value_free_to_mark is passed the mark. */
186 /* Free all values allocated since MARK was obtained by value_mark
187 (except for those released). */
189 value_free_to_mark (struct value *mark)
194 for (val = all_values; val && val != mark; val = next)
202 /* Free all the values that have been allocated (except for those released).
203 Called after each command, successful or not. */
206 free_all_values (void)
211 for (val = all_values; val; val = next)
220 /* Remove VAL from the chain all_values
221 so it will not be freed automatically. */
224 release_value (struct value *val)
228 if (all_values == val)
230 all_values = val->next;
234 for (v = all_values; v; v = v->next)
244 /* Release all values up to mark */
246 value_release_to_mark (struct value *mark)
251 for (val = next = all_values; next; next = next->next)
252 if (next->next == mark)
254 all_values = next->next;
262 /* Return a copy of the value ARG.
263 It contains the same contents, for same memory address,
264 but it's a different block of storage. */
267 value_copy (struct value *arg)
269 struct type *encl_type = value_enclosing_type (arg);
270 struct value *val = allocate_value (encl_type);
271 val->type = arg->type;
272 VALUE_LVAL (val) = VALUE_LVAL (arg);
273 VALUE_ADDRESS (val) = VALUE_ADDRESS (arg);
274 val->offset = arg->offset;
275 val->bitpos = arg->bitpos;
276 val->bitsize = arg->bitsize;
277 VALUE_FRAME_ID (val) = VALUE_FRAME_ID (arg);
278 VALUE_REGNUM (val) = VALUE_REGNUM (arg);
279 VALUE_LAZY (val) = VALUE_LAZY (arg);
280 VALUE_OPTIMIZED_OUT (val) = VALUE_OPTIMIZED_OUT (arg);
281 VALUE_EMBEDDED_OFFSET (val) = VALUE_EMBEDDED_OFFSET (arg);
282 VALUE_POINTED_TO_OFFSET (val) = VALUE_POINTED_TO_OFFSET (arg);
283 val->modifiable = arg->modifiable;
284 if (!VALUE_LAZY (val))
286 memcpy (value_contents_all_raw (val), value_contents_all_raw (arg),
287 TYPE_LENGTH (value_enclosing_type (arg)));
293 /* Access to the value history. */
295 /* Record a new value in the value history.
296 Returns the absolute history index of the entry.
297 Result of -1 indicates the value was not saved; otherwise it is the
298 value history index of this new item. */
301 record_latest_value (struct value *val)
305 /* We don't want this value to have anything to do with the inferior anymore.
306 In particular, "set $1 = 50" should not affect the variable from which
307 the value was taken, and fast watchpoints should be able to assume that
308 a value on the value history never changes. */
309 if (VALUE_LAZY (val))
310 value_fetch_lazy (val);
311 /* We preserve VALUE_LVAL so that the user can find out where it was fetched
312 from. This is a bit dubious, because then *&$1 does not just return $1
313 but the current contents of that location. c'est la vie... */
317 /* Here we treat value_history_count as origin-zero
318 and applying to the value being stored now. */
320 i = value_history_count % VALUE_HISTORY_CHUNK;
323 struct value_history_chunk *new
324 = (struct value_history_chunk *)
325 xmalloc (sizeof (struct value_history_chunk));
326 memset (new->values, 0, sizeof new->values);
327 new->next = value_history_chain;
328 value_history_chain = new;
331 value_history_chain->values[i] = val;
333 /* Now we regard value_history_count as origin-one
334 and applying to the value just stored. */
336 return ++value_history_count;
339 /* Return a copy of the value in the history with sequence number NUM. */
342 access_value_history (int num)
344 struct value_history_chunk *chunk;
349 absnum += value_history_count;
354 error ("The history is empty.");
356 error ("There is only one value in the history.");
358 error ("History does not go back to $$%d.", -num);
360 if (absnum > value_history_count)
361 error ("History has not yet reached $%d.", absnum);
365 /* Now absnum is always absolute and origin zero. */
367 chunk = value_history_chain;
368 for (i = (value_history_count - 1) / VALUE_HISTORY_CHUNK - absnum / VALUE_HISTORY_CHUNK;
372 return value_copy (chunk->values[absnum % VALUE_HISTORY_CHUNK]);
375 /* Clear the value history entirely.
376 Must be done when new symbol tables are loaded,
377 because the type pointers become invalid. */
380 clear_value_history (void)
382 struct value_history_chunk *next;
386 while (value_history_chain)
388 for (i = 0; i < VALUE_HISTORY_CHUNK; i++)
389 if ((val = value_history_chain->values[i]) != NULL)
391 next = value_history_chain->next;
392 xfree (value_history_chain);
393 value_history_chain = next;
395 value_history_count = 0;
399 show_values (char *num_exp, int from_tty)
407 /* "info history +" should print from the stored position.
408 "info history <exp>" should print around value number <exp>. */
409 if (num_exp[0] != '+' || num_exp[1] != '\0')
410 num = parse_and_eval_long (num_exp) - 5;
414 /* "info history" means print the last 10 values. */
415 num = value_history_count - 9;
421 for (i = num; i < num + 10 && i <= value_history_count; i++)
423 val = access_value_history (i);
424 printf_filtered ("$%d = ", i);
425 value_print (val, gdb_stdout, 0, Val_pretty_default);
426 printf_filtered ("\n");
429 /* The next "info history +" should start after what we just printed. */
432 /* Hitting just return after this command should do the same thing as
433 "info history +". If num_exp is null, this is unnecessary, since
434 "info history +" is not useful after "info history". */
435 if (from_tty && num_exp)
442 /* Internal variables. These are variables within the debugger
443 that hold values assigned by debugger commands.
444 The user refers to them with a '$' prefix
445 that does not appear in the variable names stored internally. */
447 static struct internalvar *internalvars;
449 /* Look up an internal variable with name NAME. NAME should not
450 normally include a dollar sign.
452 If the specified internal variable does not exist,
453 one is created, with a void value. */
456 lookup_internalvar (char *name)
458 struct internalvar *var;
460 for (var = internalvars; var; var = var->next)
461 if (strcmp (var->name, name) == 0)
464 var = (struct internalvar *) xmalloc (sizeof (struct internalvar));
465 var->name = concat (name, NULL);
466 var->value = allocate_value (builtin_type_void);
467 release_value (var->value);
468 var->next = internalvars;
474 value_of_internalvar (struct internalvar *var)
478 val = value_copy (var->value);
479 if (VALUE_LAZY (val))
480 value_fetch_lazy (val);
481 VALUE_LVAL (val) = lval_internalvar;
482 VALUE_INTERNALVAR (val) = var;
487 set_internalvar_component (struct internalvar *var, int offset, int bitpos,
488 int bitsize, struct value *newval)
490 char *addr = VALUE_CONTENTS (var->value) + offset;
493 modify_field (addr, value_as_long (newval),
496 memcpy (addr, VALUE_CONTENTS (newval), TYPE_LENGTH (value_type (newval)));
500 set_internalvar (struct internalvar *var, struct value *val)
502 struct value *newval;
504 newval = value_copy (val);
505 newval->modifiable = 1;
507 /* Force the value to be fetched from the target now, to avoid problems
508 later when this internalvar is referenced and the target is gone or
510 if (VALUE_LAZY (newval))
511 value_fetch_lazy (newval);
513 /* Begin code which must not call error(). If var->value points to
514 something free'd, an error() obviously leaves a dangling pointer.
515 But we also get a danling pointer if var->value points to
516 something in the value chain (i.e., before release_value is
517 called), because after the error free_all_values will get called before
521 release_value (newval);
522 /* End code which must not call error(). */
526 internalvar_name (struct internalvar *var)
531 /* Free all internalvars. Done when new symtabs are loaded,
532 because that makes the values invalid. */
535 clear_internalvars (void)
537 struct internalvar *var;
542 internalvars = var->next;
550 show_convenience (char *ignore, int from_tty)
552 struct internalvar *var;
555 for (var = internalvars; var; var = var->next)
561 printf_filtered ("$%s = ", var->name);
562 value_print (var->value, gdb_stdout, 0, Val_pretty_default);
563 printf_filtered ("\n");
566 printf_unfiltered ("No debugger convenience variables now defined.\n\
567 Convenience variables have names starting with \"$\";\n\
568 use \"set\" as in \"set $foo = 5\" to define them.\n");
571 /* Extract a value as a C number (either long or double).
572 Knows how to convert fixed values to double, or
573 floating values to long.
574 Does not deallocate the value. */
577 value_as_long (struct value *val)
579 /* This coerces arrays and functions, which is necessary (e.g.
580 in disassemble_command). It also dereferences references, which
581 I suspect is the most logical thing to do. */
582 val = coerce_array (val);
583 return unpack_long (value_type (val), VALUE_CONTENTS (val));
587 value_as_double (struct value *val)
592 foo = unpack_double (value_type (val), VALUE_CONTENTS (val), &inv);
594 error ("Invalid floating value found in program.");
597 /* Extract a value as a C pointer. Does not deallocate the value.
598 Note that val's type may not actually be a pointer; value_as_long
599 handles all the cases. */
601 value_as_address (struct value *val)
603 /* Assume a CORE_ADDR can fit in a LONGEST (for now). Not sure
604 whether we want this to be true eventually. */
606 /* ADDR_BITS_REMOVE is wrong if we are being called for a
607 non-address (e.g. argument to "signal", "info break", etc.), or
608 for pointers to char, in which the low bits *are* significant. */
609 return ADDR_BITS_REMOVE (value_as_long (val));
612 /* There are several targets (IA-64, PowerPC, and others) which
613 don't represent pointers to functions as simply the address of
614 the function's entry point. For example, on the IA-64, a
615 function pointer points to a two-word descriptor, generated by
616 the linker, which contains the function's entry point, and the
617 value the IA-64 "global pointer" register should have --- to
618 support position-independent code. The linker generates
619 descriptors only for those functions whose addresses are taken.
621 On such targets, it's difficult for GDB to convert an arbitrary
622 function address into a function pointer; it has to either find
623 an existing descriptor for that function, or call malloc and
624 build its own. On some targets, it is impossible for GDB to
625 build a descriptor at all: the descriptor must contain a jump
626 instruction; data memory cannot be executed; and code memory
629 Upon entry to this function, if VAL is a value of type `function'
630 (that is, TYPE_CODE (VALUE_TYPE (val)) == TYPE_CODE_FUNC), then
631 VALUE_ADDRESS (val) is the address of the function. This is what
632 you'll get if you evaluate an expression like `main'. The call
633 to COERCE_ARRAY below actually does all the usual unary
634 conversions, which includes converting values of type `function'
635 to `pointer to function'. This is the challenging conversion
636 discussed above. Then, `unpack_long' will convert that pointer
637 back into an address.
639 So, suppose the user types `disassemble foo' on an architecture
640 with a strange function pointer representation, on which GDB
641 cannot build its own descriptors, and suppose further that `foo'
642 has no linker-built descriptor. The address->pointer conversion
643 will signal an error and prevent the command from running, even
644 though the next step would have been to convert the pointer
645 directly back into the same address.
647 The following shortcut avoids this whole mess. If VAL is a
648 function, just return its address directly. */
649 if (TYPE_CODE (value_type (val)) == TYPE_CODE_FUNC
650 || TYPE_CODE (value_type (val)) == TYPE_CODE_METHOD)
651 return VALUE_ADDRESS (val);
653 val = coerce_array (val);
655 /* Some architectures (e.g. Harvard), map instruction and data
656 addresses onto a single large unified address space. For
657 instance: An architecture may consider a large integer in the
658 range 0x10000000 .. 0x1000ffff to already represent a data
659 addresses (hence not need a pointer to address conversion) while
660 a small integer would still need to be converted integer to
661 pointer to address. Just assume such architectures handle all
662 integer conversions in a single function. */
666 I think INTEGER_TO_ADDRESS is a good idea as proposed --- but we
667 must admonish GDB hackers to make sure its behavior matches the
668 compiler's, whenever possible.
670 In general, I think GDB should evaluate expressions the same way
671 the compiler does. When the user copies an expression out of
672 their source code and hands it to a `print' command, they should
673 get the same value the compiler would have computed. Any
674 deviation from this rule can cause major confusion and annoyance,
675 and needs to be justified carefully. In other words, GDB doesn't
676 really have the freedom to do these conversions in clever and
679 AndrewC pointed out that users aren't complaining about how GDB
680 casts integers to pointers; they are complaining that they can't
681 take an address from a disassembly listing and give it to `x/i'.
682 This is certainly important.
684 Adding an architecture method like integer_to_address() certainly
685 makes it possible for GDB to "get it right" in all circumstances
686 --- the target has complete control over how things get done, so
687 people can Do The Right Thing for their target without breaking
688 anyone else. The standard doesn't specify how integers get
689 converted to pointers; usually, the ABI doesn't either, but
690 ABI-specific code is a more reasonable place to handle it. */
692 if (TYPE_CODE (value_type (val)) != TYPE_CODE_PTR
693 && TYPE_CODE (value_type (val)) != TYPE_CODE_REF
694 && gdbarch_integer_to_address_p (current_gdbarch))
695 return gdbarch_integer_to_address (current_gdbarch, value_type (val),
696 VALUE_CONTENTS (val));
698 return unpack_long (value_type (val), VALUE_CONTENTS (val));
702 /* Unpack raw data (copied from debugee, target byte order) at VALADDR
703 as a long, or as a double, assuming the raw data is described
704 by type TYPE. Knows how to convert different sizes of values
705 and can convert between fixed and floating point. We don't assume
706 any alignment for the raw data. Return value is in host byte order.
708 If you want functions and arrays to be coerced to pointers, and
709 references to be dereferenced, call value_as_long() instead.
711 C++: It is assumed that the front-end has taken care of
712 all matters concerning pointers to members. A pointer
713 to member which reaches here is considered to be equivalent
714 to an INT (or some size). After all, it is only an offset. */
717 unpack_long (struct type *type, const char *valaddr)
719 enum type_code code = TYPE_CODE (type);
720 int len = TYPE_LENGTH (type);
721 int nosign = TYPE_UNSIGNED (type);
723 if (current_language->la_language == language_scm
724 && is_scmvalue_type (type))
725 return scm_unpack (type, valaddr, TYPE_CODE_INT);
729 case TYPE_CODE_TYPEDEF:
730 return unpack_long (check_typedef (type), valaddr);
735 case TYPE_CODE_RANGE:
737 return extract_unsigned_integer (valaddr, len);
739 return extract_signed_integer (valaddr, len);
742 return extract_typed_floating (valaddr, type);
746 /* Assume a CORE_ADDR can fit in a LONGEST (for now). Not sure
747 whether we want this to be true eventually. */
748 return extract_typed_address (valaddr, type);
750 case TYPE_CODE_MEMBER:
751 error ("not implemented: member types in unpack_long");
754 error ("Value can't be converted to integer.");
756 return 0; /* Placate lint. */
759 /* Return a double value from the specified type and address.
760 INVP points to an int which is set to 0 for valid value,
761 1 for invalid value (bad float format). In either case,
762 the returned double is OK to use. Argument is in target
763 format, result is in host format. */
766 unpack_double (struct type *type, const char *valaddr, int *invp)
772 *invp = 0; /* Assume valid. */
773 CHECK_TYPEDEF (type);
774 code = TYPE_CODE (type);
775 len = TYPE_LENGTH (type);
776 nosign = TYPE_UNSIGNED (type);
777 if (code == TYPE_CODE_FLT)
779 /* NOTE: cagney/2002-02-19: There was a test here to see if the
780 floating-point value was valid (using the macro
781 INVALID_FLOAT). That test/macro have been removed.
783 It turns out that only the VAX defined this macro and then
784 only in a non-portable way. Fixing the portability problem
785 wouldn't help since the VAX floating-point code is also badly
786 bit-rotten. The target needs to add definitions for the
787 methods TARGET_FLOAT_FORMAT and TARGET_DOUBLE_FORMAT - these
788 exactly describe the target floating-point format. The
789 problem here is that the corresponding floatformat_vax_f and
790 floatformat_vax_d values these methods should be set to are
791 also not defined either. Oops!
793 Hopefully someone will add both the missing floatformat
794 definitions and the new cases for floatformat_is_valid (). */
796 if (!floatformat_is_valid (floatformat_from_type (type), valaddr))
802 return extract_typed_floating (valaddr, type);
806 /* Unsigned -- be sure we compensate for signed LONGEST. */
807 return (ULONGEST) unpack_long (type, valaddr);
811 /* Signed -- we are OK with unpack_long. */
812 return unpack_long (type, valaddr);
816 /* Unpack raw data (copied from debugee, target byte order) at VALADDR
817 as a CORE_ADDR, assuming the raw data is described by type TYPE.
818 We don't assume any alignment for the raw data. Return value is in
821 If you want functions and arrays to be coerced to pointers, and
822 references to be dereferenced, call value_as_address() instead.
824 C++: It is assumed that the front-end has taken care of
825 all matters concerning pointers to members. A pointer
826 to member which reaches here is considered to be equivalent
827 to an INT (or some size). After all, it is only an offset. */
830 unpack_pointer (struct type *type, const char *valaddr)
832 /* Assume a CORE_ADDR can fit in a LONGEST (for now). Not sure
833 whether we want this to be true eventually. */
834 return unpack_long (type, valaddr);
838 /* Get the value of the FIELDN'th field (which must be static) of
839 TYPE. Return NULL if the field doesn't exist or has been
843 value_static_field (struct type *type, int fieldno)
845 struct value *retval;
847 if (TYPE_FIELD_STATIC_HAS_ADDR (type, fieldno))
849 retval = value_at (TYPE_FIELD_TYPE (type, fieldno),
850 TYPE_FIELD_STATIC_PHYSADDR (type, fieldno));
854 char *phys_name = TYPE_FIELD_STATIC_PHYSNAME (type, fieldno);
855 struct symbol *sym = lookup_symbol (phys_name, 0, VAR_DOMAIN, 0, NULL);
858 /* With some compilers, e.g. HP aCC, static data members are reported
859 as non-debuggable symbols */
860 struct minimal_symbol *msym = lookup_minimal_symbol (phys_name, NULL, NULL);
865 retval = value_at (TYPE_FIELD_TYPE (type, fieldno),
866 SYMBOL_VALUE_ADDRESS (msym));
871 /* SYM should never have a SYMBOL_CLASS which will require
872 read_var_value to use the FRAME parameter. */
873 if (symbol_read_needs_frame (sym))
874 warning ("static field's value depends on the current "
875 "frame - bad debug info?");
876 retval = read_var_value (sym, NULL);
878 if (retval && VALUE_LVAL (retval) == lval_memory)
879 SET_FIELD_PHYSADDR (TYPE_FIELD (type, fieldno),
880 VALUE_ADDRESS (retval));
885 /* Change the enclosing type of a value object VAL to NEW_ENCL_TYPE.
886 You have to be careful here, since the size of the data area for the value
887 is set by the length of the enclosing type. So if NEW_ENCL_TYPE is bigger
888 than the old enclosing type, you have to allocate more space for the data.
889 The return value is a pointer to the new version of this value structure. */
892 value_change_enclosing_type (struct value *val, struct type *new_encl_type)
894 if (TYPE_LENGTH (new_encl_type) <= TYPE_LENGTH (value_enclosing_type (val)))
896 val->enclosing_type = new_encl_type;
901 struct value *new_val;
904 new_val = (struct value *) xrealloc (val, sizeof (struct value) + TYPE_LENGTH (new_encl_type));
906 new_val->enclosing_type = new_encl_type;
908 /* We have to make sure this ends up in the same place in the value
909 chain as the original copy, so it's clean-up behavior is the same.
910 If the value has been released, this is a waste of time, but there
911 is no way to tell that in advance, so... */
913 if (val != all_values)
915 for (prev = all_values; prev != NULL; prev = prev->next)
917 if (prev->next == val)
919 prev->next = new_val;
929 /* Given a value ARG1 (offset by OFFSET bytes)
930 of a struct or union type ARG_TYPE,
931 extract and return the value of one of its (non-static) fields.
932 FIELDNO says which field. */
935 value_primitive_field (struct value *arg1, int offset,
936 int fieldno, struct type *arg_type)
941 CHECK_TYPEDEF (arg_type);
942 type = TYPE_FIELD_TYPE (arg_type, fieldno);
944 /* Handle packed fields */
946 if (TYPE_FIELD_BITSIZE (arg_type, fieldno))
948 v = value_from_longest (type,
949 unpack_field_as_long (arg_type,
950 VALUE_CONTENTS (arg1)
953 v->bitpos = TYPE_FIELD_BITPOS (arg_type, fieldno) % 8;
954 v->bitsize = TYPE_FIELD_BITSIZE (arg_type, fieldno);
955 v->offset = value_offset (arg1) + offset
956 + TYPE_FIELD_BITPOS (arg_type, fieldno) / 8;
958 else if (fieldno < TYPE_N_BASECLASSES (arg_type))
960 /* This field is actually a base subobject, so preserve the
961 entire object's contents for later references to virtual
963 v = allocate_value (value_enclosing_type (arg1));
965 if (VALUE_LAZY (arg1))
968 memcpy (value_contents_all_raw (v), value_contents_all_raw (arg1),
969 TYPE_LENGTH (value_enclosing_type (arg1)));
970 v->offset = value_offset (arg1);
971 VALUE_EMBEDDED_OFFSET (v)
973 VALUE_EMBEDDED_OFFSET (arg1) +
974 TYPE_FIELD_BITPOS (arg_type, fieldno) / 8;
978 /* Plain old data member */
979 offset += TYPE_FIELD_BITPOS (arg_type, fieldno) / 8;
980 v = allocate_value (type);
981 if (VALUE_LAZY (arg1))
984 memcpy (value_contents_raw (v),
985 value_contents_raw (arg1) + offset,
987 v->offset = (value_offset (arg1) + offset
988 + VALUE_EMBEDDED_OFFSET (arg1));
990 VALUE_LVAL (v) = VALUE_LVAL (arg1);
991 if (VALUE_LVAL (arg1) == lval_internalvar)
992 VALUE_LVAL (v) = lval_internalvar_component;
993 VALUE_ADDRESS (v) = VALUE_ADDRESS (arg1);
994 VALUE_REGNUM (v) = VALUE_REGNUM (arg1);
995 VALUE_FRAME_ID (v) = VALUE_FRAME_ID (arg1);
996 /* VALUE_OFFSET (v) = VALUE_OFFSET (arg1) + offset
997 + TYPE_FIELD_BITPOS (arg_type, fieldno) / 8; */
1001 /* Given a value ARG1 of a struct or union type,
1002 extract and return the value of one of its (non-static) fields.
1003 FIELDNO says which field. */
1006 value_field (struct value *arg1, int fieldno)
1008 return value_primitive_field (arg1, 0, fieldno, value_type (arg1));
1011 /* Return a non-virtual function as a value.
1012 F is the list of member functions which contains the desired method.
1013 J is an index into F which provides the desired method.
1015 We only use the symbol for its address, so be happy with either a
1016 full symbol or a minimal symbol.
1020 value_fn_field (struct value **arg1p, struct fn_field *f, int j, struct type *type,
1024 struct type *ftype = TYPE_FN_FIELD_TYPE (f, j);
1025 char *physname = TYPE_FN_FIELD_PHYSNAME (f, j);
1027 struct minimal_symbol *msym;
1029 sym = lookup_symbol (physname, 0, VAR_DOMAIN, 0, NULL);
1036 gdb_assert (sym == NULL);
1037 msym = lookup_minimal_symbol (physname, NULL, NULL);
1042 v = allocate_value (ftype);
1045 VALUE_ADDRESS (v) = BLOCK_START (SYMBOL_BLOCK_VALUE (sym));
1049 VALUE_ADDRESS (v) = SYMBOL_VALUE_ADDRESS (msym);
1054 if (type != value_type (*arg1p))
1055 *arg1p = value_ind (value_cast (lookup_pointer_type (type),
1056 value_addr (*arg1p)));
1058 /* Move the `this' pointer according to the offset.
1059 VALUE_OFFSET (*arg1p) += offset;
1067 /* Unpack a field FIELDNO of the specified TYPE, from the anonymous object at
1070 Extracting bits depends on endianness of the machine. Compute the
1071 number of least significant bits to discard. For big endian machines,
1072 we compute the total number of bits in the anonymous object, subtract
1073 off the bit count from the MSB of the object to the MSB of the
1074 bitfield, then the size of the bitfield, which leaves the LSB discard
1075 count. For little endian machines, the discard count is simply the
1076 number of bits from the LSB of the anonymous object to the LSB of the
1079 If the field is signed, we also do sign extension. */
1082 unpack_field_as_long (struct type *type, const char *valaddr, int fieldno)
1086 int bitpos = TYPE_FIELD_BITPOS (type, fieldno);
1087 int bitsize = TYPE_FIELD_BITSIZE (type, fieldno);
1089 struct type *field_type;
1091 val = extract_unsigned_integer (valaddr + bitpos / 8, sizeof (val));
1092 field_type = TYPE_FIELD_TYPE (type, fieldno);
1093 CHECK_TYPEDEF (field_type);
1095 /* Extract bits. See comment above. */
1097 if (BITS_BIG_ENDIAN)
1098 lsbcount = (sizeof val * 8 - bitpos % 8 - bitsize);
1100 lsbcount = (bitpos % 8);
1103 /* If the field does not entirely fill a LONGEST, then zero the sign bits.
1104 If the field is signed, and is negative, then sign extend. */
1106 if ((bitsize > 0) && (bitsize < 8 * (int) sizeof (val)))
1108 valmask = (((ULONGEST) 1) << bitsize) - 1;
1110 if (!TYPE_UNSIGNED (field_type))
1112 if (val & (valmask ^ (valmask >> 1)))
1121 /* Modify the value of a bitfield. ADDR points to a block of memory in
1122 target byte order; the bitfield starts in the byte pointed to. FIELDVAL
1123 is the desired value of the field, in host byte order. BITPOS and BITSIZE
1124 indicate which bits (in target bit order) comprise the bitfield.
1125 Requires 0 < BITSIZE <= lbits, 0 <= BITPOS+BITSIZE <= lbits, and
1126 0 <= BITPOS, where lbits is the size of a LONGEST in bits. */
1129 modify_field (char *addr, LONGEST fieldval, int bitpos, int bitsize)
1132 ULONGEST mask = (ULONGEST) -1 >> (8 * sizeof (ULONGEST) - bitsize);
1134 /* If a negative fieldval fits in the field in question, chop
1135 off the sign extension bits. */
1136 if ((~fieldval & ~(mask >> 1)) == 0)
1139 /* Warn if value is too big to fit in the field in question. */
1140 if (0 != (fieldval & ~mask))
1142 /* FIXME: would like to include fieldval in the message, but
1143 we don't have a sprintf_longest. */
1144 warning ("Value does not fit in %d bits.", bitsize);
1146 /* Truncate it, otherwise adjoining fields may be corrupted. */
1150 oword = extract_unsigned_integer (addr, sizeof oword);
1152 /* Shifting for bit field depends on endianness of the target machine. */
1153 if (BITS_BIG_ENDIAN)
1154 bitpos = sizeof (oword) * 8 - bitpos - bitsize;
1156 oword &= ~(mask << bitpos);
1157 oword |= fieldval << bitpos;
1159 store_unsigned_integer (addr, sizeof oword, oword);
1162 /* Convert C numbers into newly allocated values */
1165 value_from_longest (struct type *type, LONGEST num)
1167 struct value *val = allocate_value (type);
1168 enum type_code code;
1171 code = TYPE_CODE (type);
1172 len = TYPE_LENGTH (type);
1176 case TYPE_CODE_TYPEDEF:
1177 type = check_typedef (type);
1180 case TYPE_CODE_CHAR:
1181 case TYPE_CODE_ENUM:
1182 case TYPE_CODE_BOOL:
1183 case TYPE_CODE_RANGE:
1184 store_signed_integer (value_contents_raw (val), len, num);
1189 store_typed_address (value_contents_raw (val), type, (CORE_ADDR) num);
1193 error ("Unexpected type (%d) encountered for integer constant.", code);
1199 /* Create a value representing a pointer of type TYPE to the address
1202 value_from_pointer (struct type *type, CORE_ADDR addr)
1204 struct value *val = allocate_value (type);
1205 store_typed_address (value_contents_raw (val), type, addr);
1210 /* Create a value for a string constant to be stored locally
1211 (not in the inferior's memory space, but in GDB memory).
1212 This is analogous to value_from_longest, which also does not
1213 use inferior memory. String shall NOT contain embedded nulls. */
1216 value_from_string (char *ptr)
1219 int len = strlen (ptr);
1220 int lowbound = current_language->string_lower_bound;
1221 struct type *string_char_type;
1222 struct type *rangetype;
1223 struct type *stringtype;
1225 rangetype = create_range_type ((struct type *) NULL,
1227 lowbound, len + lowbound - 1);
1228 string_char_type = language_string_char_type (current_language,
1230 stringtype = create_array_type ((struct type *) NULL,
1233 val = allocate_value (stringtype);
1234 memcpy (value_contents_raw (val), ptr, len);
1239 value_from_double (struct type *type, DOUBLEST num)
1241 struct value *val = allocate_value (type);
1242 struct type *base_type = check_typedef (type);
1243 enum type_code code = TYPE_CODE (base_type);
1244 int len = TYPE_LENGTH (base_type);
1246 if (code == TYPE_CODE_FLT)
1248 store_typed_floating (value_contents_raw (val), base_type, num);
1251 error ("Unexpected type encountered for floating constant.");
1257 coerce_ref (struct value *arg)
1259 struct type *value_type_arg_tmp = check_typedef (value_type (arg));
1260 if (TYPE_CODE (value_type_arg_tmp) == TYPE_CODE_REF)
1261 arg = value_at_lazy (TYPE_TARGET_TYPE (value_type_arg_tmp),
1262 unpack_pointer (value_type (arg),
1263 VALUE_CONTENTS (arg)));
1268 coerce_array (struct value *arg)
1270 arg = coerce_ref (arg);
1271 if (current_language->c_style_arrays
1272 && TYPE_CODE (value_type (arg)) == TYPE_CODE_ARRAY)
1273 arg = value_coerce_array (arg);
1274 if (TYPE_CODE (value_type (arg)) == TYPE_CODE_FUNC)
1275 arg = value_coerce_function (arg);
1280 coerce_number (struct value *arg)
1282 arg = coerce_array (arg);
1283 arg = coerce_enum (arg);
1288 coerce_enum (struct value *arg)
1290 if (TYPE_CODE (check_typedef (value_type (arg))) == TYPE_CODE_ENUM)
1291 arg = value_cast (builtin_type_unsigned_int, arg);
1296 /* Should we use DEPRECATED_EXTRACT_STRUCT_VALUE_ADDRESS instead of
1297 EXTRACT_RETURN_VALUE? GCC_P is true if compiled with gcc and TYPE
1298 is the type (which is known to be struct, union or array).
1300 On most machines, the struct convention is used unless we are
1301 using gcc and the type is of a special size. */
1302 /* As of about 31 Mar 93, GCC was changed to be compatible with the
1303 native compiler. GCC 2.3.3 was the last release that did it the
1304 old way. Since gcc2_compiled was not changed, we have no
1305 way to correctly win in all cases, so we just do the right thing
1306 for gcc1 and for gcc2 after this change. Thus it loses for gcc
1307 2.0-2.3.3. This is somewhat unfortunate, but changing gcc2_compiled
1308 would cause more chaos than dealing with some struct returns being
1310 /* NOTE: cagney/2004-06-13: Deleted check for "gcc_p". GCC 1.x is
1314 generic_use_struct_convention (int gcc_p, struct type *value_type)
1316 return !(TYPE_LENGTH (value_type) == 1
1317 || TYPE_LENGTH (value_type) == 2
1318 || TYPE_LENGTH (value_type) == 4
1319 || TYPE_LENGTH (value_type) == 8);
1322 /* Return true if the function returning the specified type is using
1323 the convention of returning structures in memory (passing in the
1324 address as a hidden first parameter). GCC_P is nonzero if compiled
1328 using_struct_return (struct type *value_type, int gcc_p)
1330 enum type_code code = TYPE_CODE (value_type);
1332 if (code == TYPE_CODE_ERROR)
1333 error ("Function return type unknown.");
1335 if (code == TYPE_CODE_VOID)
1336 /* A void return value is never in memory. See also corresponding
1337 code in "print_return_value". */
1340 /* Probe the architecture for the return-value convention. */
1341 return (gdbarch_return_value (current_gdbarch, value_type,
1343 != RETURN_VALUE_REGISTER_CONVENTION);
1347 _initialize_values (void)
1349 add_cmd ("convenience", no_class, show_convenience,
1350 "Debugger convenience (\"$foo\") variables.\n\
1351 These variables are created when you assign them values;\n\
1352 thus, \"print $foo=1\" gives \"$foo\" the value 1. Values may be any type.\n\n\
1353 A few convenience variables are given values automatically:\n\
1354 \"$_\"holds the last address examined with \"x\" or \"info lines\",\n\
1355 \"$__\" holds the contents of the last address examined with \"x\".",
1358 add_cmd ("values", no_class, show_values,
1359 "Elements of value history around item number IDX (or last ten).",