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Re: [PATCH] more loop.c fixes for -fprofile-loop-arrays
- From: Janis Johnson <janis187 at us dot ibm dot com>
- To: Richard Henderson <rth at redhat dot com>, Janis Johnson <janis187 at us dot ibm dot com>, gcc-patches at gcc dot gnu dot org
- Date: Thu, 16 May 2002 08:31:32 -0700
- Subject: Re: [PATCH] more loop.c fixes for -fprofile-loop-arrays
- References: <20020515144637.A27879@us.ibm.com> <20020515172750.F25336@redhat.com>
On Wed, May 15, 2002 at 05:27:50PM -0700, Richard Henderson wrote:
> On Wed, May 15, 2002 at 02:46:38PM -0700, Janis Johnson wrote:
> > - For conditional code, skip the prefetch if PREFETCH_CONDITIONAL
> > is zero (this was originally intended), but preserve the current
> > behavior by defining PREFETCH_CONDITIONAL to one if it has not
> > already been defined.
>
> Is there some benefit to preserving the old behaviour?
On large benchmarks (SPEC int) it doesn't make much difference on ia64.
On small artificial benchmarks written just to check out this behavior,
prefetching even for accesses that are seldom executed helps on ia64.
For this and the other symbols controlling which heuristics are used
I'd like to do more experimenting so that the defines in loop.c are good
for the common case, and they can be overridden for each target (and
documented, of course).
>
> > - index += size;
> > + /* index += size; */
>
> Remove code; do not commit it out.
Oops, that wasn't supposed to be there.
>
> Otherwise ok.
>
>
> r~