Issue with _Cilk_for

Jakub Jelinek jakub@redhat.com
Fri Jan 31 16:58:00 GMT 2014


On Fri, Jan 31, 2014 at 04:18:28PM +0000, Iyer, Balaji V wrote:
> I tried to do this. The thing is, you had me model like this:
> 
> #pragma omp parallel for 
> _Cilk_for (...)
> {
> 	Body
> }
> 
> Now, the compiler will do something like this:
> 
> #pragma OMP parallel
> {
> 	#pragma Omp for 
> 	{
> 		_Cilk_for (...)
> 			Body
> 	}
> }
> 
> Now, if by the time it starts to look at evaluating/breaking up the
> _Cilk-for's parts, we are already at the scope inside #pragma omp
> parallel.  If I try to pop here, it has some scope issues with #pragma omp
> parallel.  This requires a lot of rewrite of existing OMP code to port it
> for _Cilk_for.  This can be done but will take significant time which I
> don't think I have since we are close to end of stage3.

It really doesn't require lots of rewriting, after all, OpenMP handles
the C++ iterators very similarly.

> We can look into what you want, but in the meantime, can you accept this
> patch with the way I have modelled so that the feature can make it into
> 4.9?

No.  In GCC we do not rush in bad changes just because there is time
pressure.  As Cilk+ is new in GCC 4.9, if you adjust things properly in
say 2-3 weeks frame, we might still make an exception and allow it in
during stage4, otherwise it will have to wait for 5.0.

	Jakub



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