| Message ID | 20121022152625.GA18262@kam.mff.cuni.cz |
|---|---|
| State | New |
| Headers | show |
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 > >
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) + 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