On Mon, Mar 24, 2014 at 1:46 PM, Yangfei (Felix) <felix.y...@huawei.com> wrote:
> Hello everyone,
>
> I'm thinking of the right way of adding some loop related pragmas to GCC.
> An example:
>
> #pragma loop unroll = 2
> for (i = 0; i < n; i ++)
> {
> Whatever...
> }
>
> Here I want the unroll factor of the loop to be 2 when doing RTL loop
> unrolling.
> But I find that it's kind of difficult to achieve this in GCC.
> The reason is that the loop structures are initialized and finalized at
> run time. Also the RTL expand phase is kind of complex and it does not care
> about loops.
> So how to deliver the pragma information to RTL loop unrolling pass? What
> the the elegant way of doing this?
> Can anyone give some suggestions on this please?
Look at how we implement #pragma ivdep (see replace_loop_annotate ()
and fortran/trans-stmt.c where it builds ANNOTATE_EXPR).
Richard.
> Many thanks.
>
