This is the mail archive of the
gcc@gcc.gnu.org
mailing list for the GCC project.
Re: Status of SSE support in current gcc mainline
- To: Daniel Berlin <dberlin at redhat dot com>
- Subject: Re: Status of SSE support in current gcc mainline
- From: kumar at chaos dot ph dot utexas dot edu
- Date: Fri, 23 Mar 2001 00:47:37 -0600 (CST)
- cc: Dave Korn <davek-ml at ntlworld dot com>, Jan Hubicka <jh at suse dot cz>, Samuel Figueroa <figueroa at apple dot com>, Bernd Schmidt <bernds at cambridge dot redhat dot com>, gcc at gcc dot gnu dot org
I believe the altivec patches to gcc were done as an example
implementation of the programming model with know problems. It was not
meant to be FSF acceptable code. I believe Samuel's idea to model altivec
support after the SSE implementation is not a bad idea.
> They specify the sizeof of their vector types to always be 16, and the
> sizeof *pointers* to the vector types to be 16 as well.
> Did I mention that the vector types are, in reality, a few different
> sizes, and the pointers certainly aren't 16 bytes?
> I guess 16 just seemed like a nice number.
Vectors are always 16 bytes on altivec. The doc states that 'p' is a
pointer to a vector. I dont understand what is wrong with
sizeof(*p) being 16. Is it not true that de-referencing a pointer to a
double would give a size of 8.
double *d;
printf ("%d\n",sizeof (*d)); /* 8 ? */
I know Motorola is looking into changes to the programming model. Any
pointers to other existing programming models could be useful to that
effort.
- kumar