Re: [PING][PR67476] Add param parloops-schedule

[Bernd Schmidt <bschmidt at redhat dot com>]

On 10/04/2015 05:36 PM, Tom de Vries wrote:
> I'll try to give a bit of context:
>
> The omp-expand machinery is used in two contexts:
> 1. when omp annotations are added to the source. In that case,
>     omp-expand is used in non-ssa gimple context.
> 2. when parloops annotates a loop with omp annotations. In that case,
>     omp-expand is used in ssa gimple context.

This much I remembered. The rest is at least useful background information.

> In addition, I've recently (r226427) fixed parloops such that it no
> longer invalidates the loops structure and cancels the loop tree. At the
> parloops side, that involved adding an empty latch block, in order not
> to break the LOOPS_HAVE_SIMPLE_LATCHES property. At the omp-expand side,
> that meant handling the empty latch block, as well as updating the loops
> structure. In r227435, I've applied a similar fix for
> expand_omp_for_static_chunk.

Ok, I see similar pieces in that commit. Probably this means we're 
looking at some changes that are independent from each other and should 
be submitted as such. Is there a way to make these functions share code?

> > For example - this thing is entirely unexplained:
[...]
> This bit is adding missing ssa support. In expand_omp_for_generic, we
> add a loop around the loop we're expanding. Since we're in ssa, that
> means we need to:
> - add phis to the outer loop that connect to the phis in the inner,
>    original loop, and
> - move the loop entry value of the inner phi to the loop entry value of
>    the outer phi.

Explanations like this should go into a comment.

Also, you're using l2_bb in that block, but as far as I can tell it 
could be NULL (if broken_loop). Is there a reason why this can't happen?


Bernd