On Fri, Feb 07, 2014 at 02:33:41PM +0000, Iyer, Balaji V wrote:
> > So, the issues I see:
> > 1) what is iter.1, why do you have it at all, and, after all, the iterator
> > is a class
> > that needs to be constructed/destructed in the general way, so creating any
> > further copies of something is both costly and undesirable
> >
>
> Well, to get the loop count, I need to calculate it using operator-(array.end
> (), &iter).
>
> Now, if I do that iter is already set. I need to reset iter back to the
> original one (array.begin ()) in the child function. This is why I used a
> temporary variable called iter1.
operator- shouldn't really change iter, if it does, it is purely the user's
fault, isn't it? It isn't operator -=, so it shouldn't really change
array.end () either.
> > 2) the schedule clause doesn't belong on the omp parallel, but on the
> > _Cilk_for
> >
>
> What if grain is a variable say "x"? If I have it in the _Cilk_for, then
> won't it create omp_data_i->x. That is not correct. It should just emit
> "x." But let me look into this to make sure...
You certainly should gimplify the clause operand before the omp parallel, it
must be an integral anyway, right? So just use get_temp_regvar?
Then simply use firstprivate on the #pragma omp parallel. When you actually
omp expand, you'll still be able to find the original variable and look it
up on the parallel. But, if you can't make it work, guess I could live with
the clause on the parallel.
> > 3) iter should be firstprivate, and there should be no explicit private var
> > with
> > assignment during gimplification, just handle it like any other firstprivate
> > during omp lowering
> >
>
> Do you mean to say I should manually insert a firstprivate for iter and
> not the system figure out that it is shared?
Yes. The class iterator is quite special thing, because already the C++ FE
lowers it to an integral iterator instead. And when you make it
firstprivate, omp lowering/expansion should take care of running the copy
constructor/destructor in the parallel for you.
Jakub
