Re: Merge current set of OpenACC changes from gomp-4_0-branch

[Ilya Verbin <iverbin@gmail.com>]

On 03 Feb 13:00, Julian Brown wrote:
> On Tue, 3 Feb 2015 14:28:44 +0300
> Ilya Verbin <iverbin@gmail.com> wrote:
> > On 27 Jan 14:07, Julian Brown wrote:
> > > On Mon, 26 Jan 2015 17:34:26 +0300
> > > Ilya Verbin <iverbin@gmail.com> wrote:
> > > > Here is my current patch, it works for OpenMP->MIC, but obviously
> > > > will not work for PTX, since it requires symmetrical changes in
> > > > the plugin.  Could you please take a look, whether it is possible
> > > > to support this new interface in PTX plugin?
> > > 
> > > I think it can probably be made to work. I'll have a look in more
> > > detail.
> > 
> > Do you have any progress on this?
> 
> I'm still working on a patch to update OpenACC support and the PTX
> backend to use load/unload_image and to unify initialisation/"opening".
> So far I think the answer is basically "yes, the new interface can be
> supported", though I might request a minor tweak -- e.g. that
> load_image takes an extra "void **" argument so that a libgomp backend
> can allocate a block of generic metadata relating to the image, then
> that same block would be passed (void *) to the unload hook so the
> backend can use it there and deallocate it when it's finished with.
> 
> Would that be possible? (It'd mostly be for a "CUmodule" handle: this
> could be stashed away somewhere within the nvptx backend, but it might
> be neater to put it in generic code since it'll probably be useful for
> other backends anyway.)

An extra argument is not a problem, however I don't quite get the idea.
PTX plugin allocates some data while loading, and needs this data while
unloading?  Then why not to create a hash table with image_ptr -> metadata
mapping inside the plugin?  In this case, to the unload hook can deallocate
metadata using the image_ptr key.  Since this metadata is target-specific,
I believe it would be better to keep it inside the plugin.

  -- Ilya