[PATCH 0/5] OpenMP/PTX: improve correctness in SIMD regions

[Jakub Jelinek]

On Wed, Jan 18, 2017 at 07:15:34PM +0300, Alexander Monakov wrote:
> On Wed, 18 Jan 2017, Jakub Jelinek wrote:
> > We are talking here about addressable vars, right (so if we turn it into
> > non-addressable, in the SIMT region we just use the normal PTX pseudos),
> > right?  We could emit inner ={v} {CLOBBER}; before SIMT_EXIT() to make it
> > clear it shouldn't be moved afterwards.  For the private vars used directly
> > in SIMD region, for the vars from inlined functions I assume if they are
> > addressable we emit clobbers for them too.  Or perhaps the alias oracle can
> > say that SIMT_EXIT ifn can clobber any addressable var with that
> > flag/attribute.  And yes, SRA would need to propagate it.
> 
> What about motion in the other direction, upwards across SIMT_ENTER()?

I think this is a question for Richard, whether it can be done in the alias
oracle.  If yes, it supposedly can be done for both SIMT_ENTER and
SIMT_EXIT.

> > But I believe it is worth it, because inlining is essential for good
> > performance of the simd regions.
> 
> It is, but I think my approach is compatible with inlining too (and has a more
> localized impact on the compiler).

But your 2/5 patch disables inlining into the SIMT regions.  Or do you mean
the approach with some new IFN for the pointers to privatized vars?
How would that work with the inliner (all copies of addressable vars/params
from functions inlined into the SIMT region would need to gain something
similar)?

	Jakub