Re: Patch: scheduler heuristics

[Andreas Jaeger <aj at suse dot de>]

Dale Johannesen <dalej@apple.com> writes:

> Here are a couple of additional scheduler heuristics that do well on
> ppc Darwin:
> almost every Specmark shows a slight improvement, about 2% overall.
> I'd certainly suggest trying this on another target or two before
> accepting.
>
> Index: haifa-sched.c
> ===================================================================
> RCS file: /cvs/gcc/gcc/gcc/haifa-sched.c,v
> retrieving revision 1.213
> diff -u -d -b -w -c -3 -p -r1.213 haifa-sched.c
> cvs server: conflicting specifications of output style
> *** haifa-sched.c       28 Sep 2002 15:29:34 -0000      1.213
> --- haifa-sched.c       1 Nov 2002 20:43:38 -0000
> *************** rank_for_schedule (x, y)
> *** 850,856 ****
> --- 850,874 ----
>      int val, priority_val, weight_val, info_val;
>
>      /* Prefer insn with higher priority.  */
> + #if MAX_MULTIPLICITY > 1
> +   {
> +     /* decrease the priority of single-cycle instructions that can
> go on

Your mailer wraps those lines, can you please resend a correct
version?

Thanks,
Andreas

> +        any of several functional units; these are less likely to
> lead to a
> +        stall if deferred.  */
> +     int pri = INSN_PRIORITY(tmp);
> +     int pri2 = INSN_PRIORITY(tmp2);
> +     if ( insn_unit(tmp) > 0 &&
> function_units[insn_unit(tmp)].multiplicity > 1
> +          && INSN_COST(tmp) == 1 )
> +       pri -= 1;
> +     if ( insn_unit(tmp2) > 0 &&
> function_units[insn_unit(tmp2)].multiplicity > 1
> +          && INSN_COST(tmp2) == 1 )
> +       pri2 -= 1;
> +     priority_val = pri2 - pri;
> +   }
> + #else
>      priority_val = INSN_PRIORITY (tmp2) - INSN_PRIORITY (tmp);
> + #endif
> +
>      if (priority_val)
>        return priority_val;
>
> *************** rank_for_schedule (x, y)
> *** 891,896 ****
> --- 909,932 ----
>          return val;
>        }
>
> +   /* Prefer the insn which makes more later insns available for
> +      execution.  If we have, for example, a large number of
> +      equal-priority loads, it is good to have some non-load
> +      insns available to schedule opposite them.  */
> +   depend_count1 = 0;
> +   for (link = INSN_DEPEND (tmp); link; link = XEXP (link, 1))
> +     if (INSN_DEP_COUNT (XEXP (link, 0)) == 1)
> +       depend_count1++;
> +
> +   depend_count2 = 0;
> +   for (link = INSN_DEPEND (tmp2); link; link = XEXP (link, 1))
> +     if (INSN_DEP_COUNT (XEXP (link, 0)) == 1)
> +       depend_count2++;
> +
> +   val = depend_count2 - depend_count1;
> +   if (val)
> +     return val;
> +
>      /* Prefer the insn which has more later insns that depend on it.
>         This gives the scheduler more freedom when scheduling later
>         instructions at the expense of added register pressure.  */
>

Andreas
-- 
 Andreas Jaeger
  SuSE Labs aj@suse.de
   private aj@arthur.inka.de
    http://www.suse.de/~aj