Re: prefetch revisited

[Janis Johnson <janis187 at us dot ibm dot com>]

On Tue, Oct 30, 2001 at 06:41:53PM +0100, Jan Hubicka wrote:
> 
> Just to be more specific, the code actually works and is about 2 weeks old.
> I just didn't get around to benchmark it and prepare for review.  Also some
> of my fixes to df.c are still pending as the bitmap issue and few other
> larger patches I would like to see in with higher priority.
> 
> Probably some tweaking of the decision heuristics will be needed and I am
> not quite sure how much benefit it will bring as the paper itself don't mention
> too much.

I'd like to help examine and benchmark various decision heuristics; I've
got access to IA-64 and Pentium III machines and can probably also find
a PowerPC platform to use.
> 
> In case you want to concerntrate on the prefetch instruction representation and
> how to describe those tons of various features various I guess our work don't
> conflict and I would really like to see it in.  In case you want to implement
> the greedy prefetching, we probably should work together.

Yes, I'd like to work together on this.  I'll start by gathering
information about the capabilities of prefetch support on various
kinds of hardware and which ones might be worth exploiting in GCC, and
define the RTL pattern from that, along with the instruction definitions
for ia64 and i386 variants.  This will let me learn a lot about how
these things work in GCC.  I'll also keep track of the suggestions that
come up in this thread, like the one from Joseph Myers about [static
expr] parameter array declarators in C99.

Janis