On 27-03-15 15:10, Tom de Vries wrote:
> Hi,
>
> this patch fixes PR65443, a todo in the parloops pass for function
> transform_to_exit_first_loop:
> ...
>     TODO: the common case is that latch of the loop is empty and immediately
>     follows the loop exit.  In this case, it would be better not to copy the
>     body of the loop, but only move the entry of the loop directly before the
>     exit check and increase the number of iterations of the loop by one.
>     This may need some additional preconditioning in case NIT = ~0.
> ...
>
> The current implementation of transform_to_exit_first_loop transforms the loop
> by moving and duplicating the loop body. This patch transforms the loop into the
> same normal form, but without the duplication, if that's possible (determined by
> try_transform_to_exit_first_loop_alt).
>
> The actual transformation, done by transform_to_exit_first_loop_alt transforms
> this loop:
> ...
>       bb preheader:
>       ...
>       goto <bb header>
>
>       <bb header>:
>       ...
>       if (ivtmp < n)
>         goto <bb latch>;
>       else
>         goto <bb exit>;
>
>       <bb latch>:
>       ivtmp = ivtmp + inc;
>       goto <bb header>
> ...
>
> into this one:
> ...
>       bb preheader:
>       ...
>       goto <bb newheader>
>
>       <bb header>:
>       ...
>       goto <bb latch>;
>
>       <bb newheader>:
>       if (ivtmp < n + 1)
>         goto <bb header>;
>       else
>         goto <bb exit>;
>
>       <bb latch>:
>       ivtmp = ivtmp + inc;
>       goto <bb newheader>
> ...
>

Updated patch, now using redirect_edge_var_map and flush_pending_stmts.

Bootstrapped and reg-tested on x86_64.

OK for stage1 trunk?

Thanks,
- Tom