> I tried a large LTO build with gcc version 4.7.0 20110511 (experimental)
> (GCC)
> on a 18GB machine. It ended with
>
> lto1: out of memory allocating 8589934312 bytes after a total of 6827421696
> bytes
>
> Since a 7+GB single malloc seems somewhat excessive I put a break point
> on xmalloc_failed. It looks like the hash tables are growing
> too aggressively?
I think the problem was introduced by Richi's last commit:
2011-05-12 Richard Guenther <rguent...@suse.de>
* gimple.c (gtc_visit): Compare TREE_ADDRESSABLE, handle
NULLPTR_TYPE similar to VOID_TYPE. Defer type-leader lookup
until after simple checks.
(gimple_types_compatible_p): Likewise.
(iterative_hash_gimple_type): Always hash pointer targets
and function return and argument types.
(iterative_hash_canonical_type): Do not hash TYPE_QUALS,
hash TYPE_ALIGN. Do not hash TYPE_MIN/MAX_VALUE.
(gimple_canonical_types_compatible_p): Compare TREE_ADDRESSABLE,
handle NULLPTR_TYPE similar to VOID_TYPE. Handle non-aggregates
completely in the simple compare section.
(gimple_register_canonical_type): Query the cache again after
registering.
So reverting this patch might get you past the problem. Ysterday I was able
to build your testcase with 3GB of ram, today it got out of memory, too.
The hashtable is not expanding too irrationally, but it saves O(n^2)
information.
I would like to see it die for sure ;)
Honza
