On Wed, Jan 06, 2010 at 04:49:29PM +0100, Richard Guenther wrote:
> On Wed, Jan 6, 2010 at 4:45 PM, Richard Guenther
> <richard.guent...@gmail.com> wrote:
> > On Wed, Jan 6, 2010 at 4:25 PM, torbenh <torb...@gmx.de> wrote:
> >>> >
> >>> > Mixer<Ramp,Ramp,Ramp,Ramp> mix __attribute__((restrict))
> >>
> >> void fill_buffer( float * __restrict buf, size_t nframes )
> >> {
> >> for( size_t i=0; i<nframes; i++ )
> >> buf[i] = mix.process();
> >> }
>
> Btw, the same effect can be obtained by instead writing
>
> void fill_buffer( float * __restrict buf, size_t nframes )
> {
> Mixer<Ramp,Ramp,Ramp,Ramp> * restrict mixp = &mix;
> for( size_t i=0; i<nframes; i++ )
> buf[i] = mix->process();
> }
>
> at least in theory (if it doesn't work its worth to try to fix it).
in gcc-4.4 it doesnt work. didnt test with trunk yet.
but the text here suggests, that it should never work.
from gcc/alias.c get_alias_set (tree t):
else if (AGGREGATE_TYPE_P (pointed_to_type))
/* For an aggregate, we must treat the restricted
pointer the same as an ordinary pointer. If we
were to make the type pointed to by the
restricted pointer a subset of the pointed-to
type, then we would believe that other subsets
of the pointed-to type (such as fields of that
type) do not conflict with the type pointed to
by the restricted pointer. */
DECL_POINTER_ALIAS_SET (decl)
= pointed_to_alias_set;
>
> Richard.
--
torben Hohn
