Hi!
On Tue, Nov 12, 2019 at 04:32:36PM +0100, Ilya Leoshkevich wrote:
> > Am 12.11.2019 um 15:32 schrieb Segher Boessenkool
> > <seg...@kernel.crashing.org>:
> > On Tue, Nov 12, 2019 at 03:11:05PM +0100, Ilya Leoshkevich wrote:
> >> unsigned int
> >> pass_jump_after_combine::execute (function *)
> >> {
> >> + /* Jump threading does not keep dominators up-to-date. */
> >> + free_dominance_info (CDI_DOMINATORS);
> >> + free_dominance_info (CDI_POST_DOMINATORS);
> >> cleanup_cfg (flag_thread_jumps ? CLEANUP_THREADING : 0);
> >> return 0;
> >> }
> >
> > Why do you always free it, if if only gets invalidated if flag_thread_jumps?
> >
> > It may be a good idea to throw away the dom info anyway, but the comment
> > seems off then?
>
> Hmm, come to think of it, it would make sense to make flag_thread_jumps
> a gate for this pass, and then run free_dominance_info (CDI_DOMINATORS)
> and cleanup_cfg (CLEANUP_THREADING) unconditionally. What do you think?
But we want cleanup_cfg (0) if the flag is not set, no? Maybe
something like
unsigned int
pass_jump_after_combine::execute (function *)
{
if (flag_thread_jumps)
{
/* Jump threading does not keep dominators up-to-date. */
free_dominance_info (CDI_DOMINATORS);
cleanup_cfg (CLEANUP_THREADING);
}
else
cleanup_cfg (0);
return 0;
}
But OTOH it may well be the case that other things in cleanup_cfg make
the known dominance info invalid as well, in which case just the comment
is a bit misleading. Sounds likely to me :-)
Segher
