On Wed, Dec 18, 2013 at 04:46:40AM +0000, Iyer, Balaji V wrote:
> I have a question regarding the parallel for implementation. I am
> implementing _Cilk_for based on the routines in omp-low.c and I would like to
> create a child function but would like to move the items that
> gimplify_omp_for inserts in for_pre_body in the top-level function. I need to
> do this because in _Cilk_for, we insert the body of the function into a child
> function and then we call a builtin CilkPlus function called
> __cilkrts_cilk_for_64 and pass in the child function's name, data pointer,
> loop-count and grain.
>
> The loop count computation gets to be an issue in C++ when we use
> iterator.
>
> For example, if we have something like this:
> Vector <int> array;
> For (vector<int>::iterator iter = array.begin(); iter != array.end ();
> iter++)
OpenMP also supports C++ iterators, so I don't see why you don't follow
that.
The iterators are lowered already by the C++ FE, what the middle-end sees is
an integral iterator. Just look at one of the several
libgomp/testsuite/libgomp.c++/for-* testcases.
By following what we do for OpenMP here, I'd hope you can get rid of the
loop_count you've added to the gimple structure, what is grain, is that
specific to each of the collapsed trees, or does Cilk+ support only
collapse(1), and if so or if it is global for the _Cilk_for and not for each
iterator, just add a clause for it instead.
Jakub
