[Thanks for the quick review and sorry for the longish delay]
> +/* Return the index number of the landing pad for STMT, if any. */
> +
> +static int
> +lp_nr_for_store (gimple *stmt)
> +{
> + if (!cfun->can_throw_non_call_exceptions || !cfun->eh)
> + return 0;
> +
> + if (!stmt_could_throw_p (cfun, stmt))
> + return 0;
> +
> + return lookup_stmt_eh_lp (stmt);
> +}
>
> Did you add the wrapper as compile-time optimization? That is,
> I don't see why simply calling lookup_stmt_eh_lp wouldn't work?
Yes, I added it for C & C++, which both trivially fail the first test. More
generally, every additional processing is (directly or indirectly) guarded by
the conjunction cfun->can_throw_non_call_exceptions && cfun->eh throughout.
> + /* If the function can throw and catch non-call exceptions, we'll be
> trying + to merge stores across different basic blocks so we need to
> first unsplit + the EH edges in order to streamline the CFG of the
> function. */ + if (cfun->can_throw_non_call_exceptions && cfun->eh)
> + {
> + free_dominance_info (CDI_DOMINATORS);
> + maybe_remove_unreachable_handlers ();
> + changed = unsplit_all_eh ();
> + if (changed)
> + delete_unreachable_blocks ();
> + }
>
> uh, can unsplitting really result in unreachable blocks or does it
> merely forget to delete forwarders it made unreachable?
The latter.
> Removing unreachable handlers is also to make things match better?
Nope, only because calculate_dominance_info aborts otherwise below.
> Just wondering how much of this work we could delay to the first
> store-merging opportunity with EH we find (but I don't care too much
> about -fnon-call-exceptions).
This block of code is a manual, stripped down ehcleanup pass.
> To isolate the details above maybe move this piece into a helper
> in tree-eh.c so you also can avoid exporting unsplit_all_eh?
The main point is the unsplitting though so this would trade an explicit call
for a less implicit one. But what I could do is to rename unsplit_all_eh into
unsplit_all_eh_1 and hide the technicalities in a new unsplit_all_eh.
--
Eric Botcazou
