This is the mail archive of the
gcc@gcc.gnu.org
mailing list for the GCC project.
Re: modulo scheduling for IA64
- From: Jim Wilson <wilson at redhat dot com>
- To: David Edelsohn <dje at watson dot ibm dot com>
- Cc: "Deepak B. Nayak" <deepakbn at csa dot iisc dot ernet dot in>, gcc at gcc dot gnu dot org
- Date: 30 Sep 2002 15:38:58 -0400
- Subject: Re: modulo scheduling for IA64
- References: <200209301748.NAA30690@makai.watson.ibm.com>
> The GCC DFA scheduler already has a software-pipelining feature
>which has not been merged into the FSF sources, but which should provide
>modulo scheduling. Why not complete that work?
Actually it is RCSP, Resource Constrained Software Pipelining. It is a good
algorithm, but unfortunately not the right one for IA-64 as I understand it.
This is because RCSP doesn't support register rotation, and modulo scheduling
does. You need to use register rotation on IA-64 if you want the best
performance, and thus modulo scheduling is better for IA-64. RCSP may be
better for all other targets though, since IA-64 is the only target with
register rotation.
Jim