> Hi,
> > gcc/ChangeLog:
> >
> > PR tree-optimization/117790
> > * cfgloopmanip.cc (can_flow_scale_loop_freqs_p): New.
> > (flow_scale_loop_freqs): New.
> > (scale_loop_freqs_with_exit_counts): New.
> > (scale_loop_freqs_hold_exit_counts): New.
> > (scale_loop_profile): Refactor to use the newly-added
> > scale_loop_profile_1, and use scale_loop_freqs_hold_exit_counts to
> > correctly handle reducing the expected niters for loops with multiple
> > exits.
> > (scale_loop_freqs_with_new_exit_count): New.
> > (scale_loop_profile_1): New.
> > (scale_loop_profile_hold_exit_counts): New.
> > * cfgloopmanip.h (scale_loop_profile_hold_exit_counts): New.
> > (scale_loop_freqs_with_new_exit_count): New.
> +template<typename ExitCountFn>
> +static bool
> +can_flow_scale_loop_freqs_p (class loop *loop,
> + ExitCountFn get_exit_count)
> +{
> + basic_block bb = loop->header;
> +
> + const profile_count count_in = loop_count_in (loop);
> + profile_count exit_count = profile_count::zero ();
> +
> + while (bb != loop->latch)
> + {
> + /* Punt if any of the BB counts are uninitialized. */
> + if (!bb->count.initialized_p ())
> + return false;
> +
> + bool found_exit = false;
> + edge internal_edge = nullptr;
> + for (auto e : bb->succs)
> + if (flow_bb_inside_loop_p (loop, e->dest))
> + {
> + if (internal_edge)
> + return false;
> + internal_edge = e;
>
> This assumes that there are at most 2 edges out which is not always the
> case (i.e. for EH and switch). I suppose vectorizer never calls it
> there but probably you want to test that there are precisely two edges
> in can_flow_scale_loop_freqs and if not drop message to dump file, so in
> case we encounter such loops we notice.
Also forgot to write. Ohter interesting case is when loop has inner
loop. In this case there will be 2 edges but both of them internal.
It is also possible that the exit of loop sits inside inner loop.
Honza
