static enum return_value_convention
m68k_return_value (struct gdbarch *gdbarch, struct type *type,
struct regcache *regcache, gdb_byte *readbuf,
const gdb_byte *writebuf)
{
enum type_code code = TYPE_CODE (type);
/* GCC returns a `long double' in memory too. */
if (((code == TYPE_CODE_STRUCT || code == TYPE_CODE_UNION)
&& !m68k_reg_struct_return_p (gdbarch, type))
|| (code == TYPE_CODE_FLT && TYPE_LENGTH (type) == 12))
{
/* The default on m68k is to return structures in static memory.
Consequently a function must return the address where we can
find the return value. */
if (readbuf)
{
ULONGEST addr;
regcache_raw_read_unsigned (regcache, M68K_D0_REGNUM, &addr);
read_memory (addr, readbuf, TYPE_LENGTH (type));
}
return RETURN_VALUE_ABI_RETURNS_ADDRESS;
}
if (readbuf)
m68k_extract_return_value (type, regcache, readbuf);
if (writebuf)
m68k_store_return_value (type, regcache, writebuf);
return RETURN_VALUE_REGISTER_CONVENTION;
}
static enum return_value_convention
m68k_svr4_return_value (struct gdbarch *gdbarch, struct value *function,
struct type *type, struct regcache *regcache,
gdb_byte *readbuf, const gdb_byte *writebuf)
{
enum type_code code = TYPE_CODE (type);
if ((code == TYPE_CODE_STRUCT || code == TYPE_CODE_UNION
|| code == TYPE_CODE_COMPLEX)
&& !m68k_reg_struct_return_p (gdbarch, type))
{
/* The System V ABI says that:
"A function returning a structure or union also sets %a0 to
the value it finds in %a0. Thus when the caller receives
control again, the address of the returned object resides in
register %a0."
So the ABI guarantees that we can always find the return
value just after the function has returned. */
if (readbuf)
{
ULONGEST addr;
regcache_raw_read_unsigned (regcache, M68K_A0_REGNUM, &addr);
read_memory (addr, readbuf, TYPE_LENGTH (type));
}
return RETURN_VALUE_ABI_RETURNS_ADDRESS;
}
/* This special case is for structures consisting of a single
`float' or `double' member. These structures are returned in
%fp0. For these structures, we call ourselves recursively,
changing TYPE into the type of the first member of the structure.
Since that should work for all structures that have only one
member, we don't bother to check the member's type here. */
if (code == TYPE_CODE_STRUCT && TYPE_NFIELDS (type) == 1)
{
type = check_typedef (TYPE_FIELD_TYPE (type, 0));
return m68k_svr4_return_value (gdbarch, function, type, regcache,
readbuf, writebuf);
}
if (readbuf)
m68k_svr4_extract_return_value (type, regcache, readbuf);
if (writebuf)
m68k_svr4_store_return_value (type, regcache, writebuf);
return RETURN_VALUE_REGISTER_CONVENTION;
}
