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2005-02-08 Andrew Cagney <cagney@gnu.org>

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* value.c (struct value): Move to here ...
	* value.h (struct value): ... from here.  Copy comments to
	corresponding function declarations, re-order.
This commit is contained in:
Andrew Cagney
2005-02-08 05:41:10 +00:00
parent 9bbda50381
commit 91294c8386
3 changed files with 245 additions and 139 deletions
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133
gdb/value.c
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@@ -42,6 +42,139 @@
void _initialize_values (void);
struct value
{
/* Type of value; either not an lval, or one of the various
different possible kinds of lval. */
enum lval_type lval;
/* Is it modifiable? Only relevant if lval != not_lval. */
int modifiable;
/* Location of value (if lval). */
union
{
/* If lval == lval_memory, this is the address in the inferior.
If lval == lval_register, this is the byte offset into the
registers structure. */
CORE_ADDR address;
/* Pointer to internal variable. */
struct internalvar *internalvar;
} location;
/* Describes offset of a value within lval of a structure in bytes.
If lval == lval_memory, this is an offset to the address. If
lval == lval_register, this is a further offset from
location.address within the registers structure. Note also the
member embedded_offset below. */
int offset;
/* Only used for bitfields; number of bits contained in them. */
int bitsize;
/* Only used for bitfields; position of start of field. For
BITS_BIG_ENDIAN=0 targets, it is the position of the LSB. For
BITS_BIG_ENDIAN=1 targets, it is the position of the MSB. */
int bitpos;
/* Frame register value is relative to. This will be described in
the lval enum above as "lval_register". */
struct frame_id frame_id;
/* Type of the value. */
struct type *type;
/* If a value represents a C++ object, then the `type' field gives
the object's compile-time type. If the object actually belongs
to some class derived from `type', perhaps with other base
classes and additional members, then `type' is just a subobject
of the real thing, and the full object is probably larger than
`type' would suggest.
If `type' is a dynamic class (i.e. one with a vtable), then GDB
can actually determine the object's run-time type by looking at
the run-time type information in the vtable. When this
information is available, we may elect to read in the entire
object, for several reasons:
- When printing the value, the user would probably rather see the
full object, not just the limited portion apparent from the
compile-time type.
- If `type' has virtual base classes, then even printing `type'
alone may require reaching outside the `type' portion of the
object to wherever the virtual base class has been stored.
When we store the entire object, `enclosing_type' is the run-time
type -- the complete object -- and `embedded_offset' is the
offset of `type' within that larger type, in bytes. The
value_contents() macro takes `embedded_offset' into account, so
most GDB code continues to see the `type' portion of the value,
just as the inferior would.
If `type' is a pointer to an object, then `enclosing_type' is a
pointer to the object's run-time type, and `pointed_to_offset' is
the offset in bytes from the full object to the pointed-to object
-- that is, the value `embedded_offset' would have if we followed
the pointer and fetched the complete object. (I don't really see
the point. Why not just determine the run-time type when you
indirect, and avoid the special case? The contents don't matter
until you indirect anyway.)
If we're not doing anything fancy, `enclosing_type' is equal to
`type', and `embedded_offset' is zero, so everything works
normally. */
struct type *enclosing_type;
int embedded_offset;
int pointed_to_offset;
/* Values are stored in a chain, so that they can be deleted easily
over calls to the inferior. Values assigned to internal
variables or put into the value history are taken off this
list. */
struct value *next;
/* Register number if the value is from a register. */
short regnum;
/* If zero, contents of this value are in the contents field. If
nonzero, contents are in inferior memory at address in the
location.address field plus the offset field (and the lval field
should be lval_memory).
WARNING: This field is used by the code which handles watchpoints
(see breakpoint.c) to decide whether a particular value can be
watched by hardware watchpoints. If the lazy flag is set for
some member of a value chain, it is assumed that this member of
the chain doesn't need to be watched as part of watching the
value itself. This is how GDB avoids watching the entire struct
or array when the user wants to watch a single struct member or
array element. If you ever change the way lazy flag is set and
reset, be sure to consider this use as well! */
char lazy;
/* If nonzero, this is the value of a variable which does not
actually exist in the program. */
char optimized_out;
/* Actual contents of the value. For use of this value; setting it
uses the stuff above. Not valid if lazy is nonzero. Target
byte-order. We force it to be aligned properly for any possible
value. Note that a value therefore extends beyond what is
declared here. */
union
{
bfd_byte contents[1];
DOUBLEST force_doublest_align;
LONGEST force_longest_align;
CORE_ADDR force_core_addr_align;
void *force_pointer_align;
} aligner;
/* Do not add any new members here -- contents above will trash
them. */
};
/* Prototypes for local functions. */
static void show_values (char *, int);