[Bug middle-end/49945] [4.7 Regression] gcc.dg/guality/vla-1.c FAILs with -flto

["rguenther at suse dot de" <gcc-bugzilla at gcc dot gnu dot org>]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=49945

--- Comment #4 from rguenther at suse dot de <rguenther at suse dot de> 2011-12-01 10:32:45 UTC ---
On Fri, 25 Nov 2011, jakub at gcc dot gnu.org wrote:

> http://gcc.gnu.org/bugzilla/show_bug.cgi?id=49945
> 
> --- Comment #3 from Jakub Jelinek <jakub at gcc dot gnu.org> 2011-11-25 09:59:31 UTC ---
> This is a bug in lto-streamer-out.c.  TYPE_MAXVAL of the ARRAY_TYPE's
> TYPE_DOMAIN e.g. in f1 is a VAR_DECL (DECL_NAME is NULL, DECL_ARTIFICIAL, but
> !DECL_IGNORED_P).  It is first encountered in a GIMPLE_DEBUG's first operand,
> it hasn't been seen yet, so that VAR_DECL is output.  But, later on
> write_global_stream calls lto_output_tree on the VLA ARRAY_TYPE, with ref_p set
> to false, and this eventually calls lto_output_tree on that VAR_DECL again.
> But this doesn't find it in ob->writer_cache, because the cache has been
> destroyed in between, from output_function -> destroy_output_block ->
> lto_streamer_cache_delete.
> I guess VLA types need to be emitted immediately in the containing function,
> rather than being deferred to be written much later on globally.

Yes, I remember running into this issue as well.  And I have some
patches somewhere that try to do this (but more generally, for all
function-local types IIRC).