Re: [RFA] gdbtypes.[ch] rs6000-tdep.c--AltiVec regs types

Andrew Cagney
2002-01-12T01:04:06Z

Your post prompted me to dig. It is just that I kind of regret this
exposure of a GCC internal naming convention (SI, QI, FI, HI, ...) to
the innocent end user. Is the convention really set in stone or can we
reform our ways? :-)

The relevant thread is:
http://sources.redhat.com/ml/gdb-patches/1999-q4/msg00316.html

As an aside, it did take a few years but there are now both more
explicit builtin fp types (see builtin_type_ieee ...); and implemented
the virtual to raw register mapping the thread talks about for MMX. The
i386 MMX registers can finally be implemented as (looks in sandpit, for
wip code):

static void
i386_register_read (struct gdbarch *gdbarch, int regnum, char *buf)
{
if (is_mmx_regnum (regnum))
{
char *mmx_buf = alloca (MAX_REGISTER_RAW_SIZE);
int fpnum = mmnum_to_fpnum (regnum);
regcache_read (fpnum, mmx_buf);
/* Extract (always little endian). */
memcpy (buf, mmx_buf, REGISTER_RAW_SIZE (regnum));
}
else
regcache_read (regnum, buf);
}

(probably time to submit that patch).

Anyway, regarding your patch, perhaps move the construct to
gdbtypes.[hc] to encourage its re-use by other Altivecish targets.

Andrew

PS: Check the man page for [x]calloc() GDB could benefit from its use.

Two questions.

> +static struct type *
> +build_builtin_type_powerpc_altivec (void)
> +{
> + /* Construct a type for the AltiVec registers. The type we're building
> + is this: */
> +#if 0
> + union __gdb_builtin_type_powerpc_altivec
> + {
> + struct __builtin_v16qi v16qi;
> + struct __builtin_v8hi v8hi;
> + struct __builtin_v4si v4si;
> + struct __builtin_v4sf v4sf;
> + uint128_t uint128;
> + };
> +#endif
> +
> + struct type *t;
> + struct field *f;
> +
> + f = (struct field *) xmalloc (sizeof (*f) * 5);
> + memset (f, 0, sizeof (*f) * 5);
> +
> + FIELD_TYPE (f[0]) = builtin_type_int128;
> + FIELD_NAME (f[0]) = "uint128";
> +
> + FIELD_TYPE (f[1]) = builtin_type_v4sf;
> + FIELD_NAME (f[1]) = "v4sf";
> +
> + FIELD_TYPE (f[2]) = builtin_type_v4si;
> + FIELD_NAME (f[2]) = "v4si";
> +
> + FIELD_TYPE (f[3]) = builtin_type_v8hi;
> + FIELD_NAME (f[3]) = "v8hi";
> +
> + FIELD_TYPE (f[4]) = builtin_type_v16qi;
> + FIELD_NAME (f[4]) = "v16qi";
> +
> + /* Build a union type with those fields. */
> + t = init_type (TYPE_CODE_UNION, 16, 0, 0, 0);
> + TYPE_NFIELDS (t) = 5;
> + TYPE_FIELDS (t) = f;
> + TYPE_TAG_NAME (t) = "__gdb_builtin_type_powerpc_altivec";
> +
> + return t;
> +}
> +
>