On Tue, 17 Nov 2015, Tom de Vries wrote:
> On 17/11/15 16:18, Richard Biener wrote:
> > > > IMHO autopar needs to handle induction itself.
> > > >
> > > >I'm not sure what you mean. Could you elaborate? Autopar handles
> > > induction
> > > >variables, but it doesn't handle exit phis reading the final value of the
> > > >induction variable. Is that what you want fixed? How?
> > Yes. Perform final value replacement.
> >
>
> I see. Calling scev_const_prop in pass_parallelize_loops_oacc_kernels seems to
> work fine.
>
> Doing the same for pass_parallelize_loops like this:
> ...
> diff --git a/gcc/tree-parloops.c b/gcc/tree-parloops.c
> index 17415a8..d944395 100644
> --- a/gcc/tree-parloops.c
> +++ b/gcc/tree-parloops.c
> @@ -2787,6 +2787,9 @@ pass_parallelize_loops::execute (function *fun)
> if (number_of_loops (fun) <= 1)
> return 0;
>
> + unsigned int sccp_todo = scev_const_prop ();
> + gcc_assert (sccp_todo == 0);
> +
> if (parallelize_loops ())
> {
> fun->curr_properties &= ~(PROP_gimple_eomp);
> ...
> seems to fix PR 68373 - "autopar fails on loop exit phi with argument defined
> outside loop".
>
> The new scev_const_prop call in autopar rewrites this phi into an assignment,
> and that allows parloops to succeed:
> ...
> final value replacement:
> n_2 = PHI <n_4(D)(4)>
> with
> n_2 = n_4(D);
> ...
That works for me but please factor out the final value replacement
code from scev_const_prop. I think best would be to have a
helper that does final value replacement for a single loop so you
can call it for loops to paralellize only.
Richard.
> Thanks,
> - Tom
>
>
--
Richard Biener <rguent...@suse.de>
SUSE LINUX GmbH, GF: Felix Imendoerffer, Jane Smithard, Graham Norton, HRB
21284 (AG Nuernberg)
