On Tue, 14 Jan 2020, Richard Biener wrote:
> When an alias-set is an already existing subset there is no need
> to re-record its children as childs of the parent.
>
> I noticed this when doing 1/2 as trivial opportunity to squeeze
> back some performance for the non-caching recursion I added. The
> whole thing is still quadratic in the depth of the structure, of course.
>
> Bootstrapped and tested on x86_64-unknown-linux-gnu.
>
> Since I'm curious I'll test a variant which checks the children
> are actually recorded before pushing this ... (OK, maybe I shouldn't
> do this...)
So I did it. It works but for
FAIL: gnat.dg/interface2.adb 3 blank line(s) in output
FAIL: gnat.dg/interface2.adb (test for excess errors)
UNRESOLVED: gnat.dg/interface2.adb compilation failed to produce
executable
FAIL: gnat.dg/predicate2_main.adb 3 blank line(s) in output
FAIL: gnat.dg/predicate2_main.adb (test for excess errors)
which ICE with the adjusted patch below. Ada calls
record_component_aliases itself and eventually too early when
some types are not yet complete? Which would also mean that
subsets could be failed to recorded properly.
So I'm still inclined to go with the original non-checking patch
unless Eric tells me I'm completely wrong and there isn't a
latent issue in the Ada frontend.
Thanks,
Richard.
diff --git a/gcc/alias.c b/gcc/alias.c
index 336af4e52a7..0eae5386444 100644
--- a/gcc/alias.c
+++ b/gcc/alias.c
@@ -1164,10 +1164,15 @@ record_alias_subset (alias_set_type superset,
alias_set_type subset)
superset_entry->has_zero_child = 1;
else
{
- subset_entry = get_alias_set_entry (subset);
if (!superset_entry->children)
superset_entry->children
= hash_map<alias_set_hash, int>::create_ggc (64);
+
+ /* Enter the SUBSET itself as a child of the SUPERSET. If it was
+ already there we're done. */
+ bool present = superset_entry->children->put (subset, 0);
+
+ subset_entry = get_alias_set_entry (subset);
/* If there is an entry for the subset, enter all of its children
(if they are not already present) as children of the SUPERSET. */
if (subset_entry)
@@ -1182,12 +1187,12 @@ record_alias_subset (alias_set_type superset,
alias_set_type subset)
hash_map<alias_set_hash, int>::iterator iter
= subset_entry->children->begin ();
for (; iter != subset_entry->children->end (); ++iter)
- superset_entry->children->put ((*iter).first, (*iter).second);
+ {
+ bool cpresent = superset_entry->children->put ((*iter).first,
(*iter).second);
+ gcc_assert (!present || cpresent);
+ }
}
}
-
- /* Enter the SUBSET itself as a child of the SUPERSET. */
- superset_entry->children->put (subset, 0);
}
}
