On Thu, Oct 22, 2015 at 09:08:30AM -0400, Nathan Sidwell wrote:
> On 10/22/15 07:10, Julian Brown wrote:
> >On Thu, 22 Oct 2015 10:05:30 +0200
> >Richard Biener <richard.guent...@gmail.com> wrote:
>
> >>So you'd need to be more precise as to what properties you are trying
> >>to preserve by placing a single stmt somewhere.
> >
> >FWIW an earlier, abandoned attempt at solving the same problem was
> >discussed in the following thread, continuing through June:
> >
> > https://gcc.gnu.org/ml/gcc-patches/2015-05/msg02647.html
> >
> >Though the details of lowering of OpenACC constructs have changed with
> >Nathan's current patches, the underlying problem remains the same. PTX
> >requires certain operations (bar.sync) to be executed uniformly by all
> >threads in a CTA. IIUC this affects "JOIN" points across all
> >workers/vectors in a gang, in particular (though this is generic code,
> >other -- particularly GPU -- targets may have similar restrictions).
>
>
> Richard, does this answer your question?
I agree with Richard that it would be better to write more about what kind
of IL changes are acceptable with IFN_UNIQUE in the IL and what are not.
E.g. is inlining ok (I'd hope yes)? Is function splitting ok (bet as long
as all IFN_UNIQUE calls stay in one or the other part, but not both)?
Various loop optimization, ...
Jakub
