On Mon, 22 Oct 2012, Jan Hubicka wrote:
> Hi,
> with profile feedback we may misupdate the profile and start to believe that
> loops
> iterate more times than they do. This patch makes at least
> nb_iterations_estimate
> no greater than nb_iterations_upper_bound. This makes the
> unrolling/peeling/unswitching
> heuristics to behave more consistently.
> Bootstrapped/regtested x86_64-linux, OK?
Ok with ...
> Honza
>
> * tree-sssa-loop-niter.c (record_niter_bound): Be sure that realistic
> estimate is not bigger than upper bound.
> Index: tree-ssa-loop-niter.c
> ===================================================================
> --- tree-ssa-loop-niter.c (revision 192632)
> +++ tree-ssa-loop-niter.c (working copy)
> @@ -2506,13 +2506,20 @@ record_niter_bound (struct loop *loop, d
> {
> loop->any_upper_bound = true;
> loop->nb_iterations_upper_bound = i_bound;
> + if (loop->any_estimate
> + && i_bound.ult (loop->nb_iterations_estimate))
> + loop->nb_iterations_estimate = i_bound;
> }
> if (realistic
> && (!loop->any_estimate
> || i_bound.ult (loop->nb_iterations_estimate)))
> {
> loop->any_estimate = true;
> - loop->nb_iterations_estimate = i_bound;
> + if (loop->nb_iterations_upper_bound.ult (i_bound)
> + && loop->any_upper_bound)
testing any_upper_bound before accessing loop->nb_iterations_upper_bound
> + loop->nb_iterations_estimate = loop->nb_iterations_upper_bound;
> + else
> + loop->nb_iterations_estimate = i_bound;
> }
>
> /* If an upper bound is smaller than the realistic estimate of the
>
>
--
Richard Biener <[email protected]>
SUSE / SUSE Labs
SUSE LINUX Products GmbH - Nuernberg - AG Nuernberg - HRB 16746
GF: Jeff Hawn, Jennifer Guild, Felix Imend
