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

[Andrew Cagney <ac131313@cygnus.com>]

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;
> +}
> +
>