[PATCH] Add -funknown-commons to work around PR/69368 (and others) in SPEC2006

[Alan Lawrence]

On 22/02/16 12:03, Jakub Jelinek wrote:
>
> (f) A global command-line option, which we check alongside DECL_COMMON and
> further tests (basically, we want only DECL_COMMON decls that either have
> ARRAY_TYPE, or some other aggregate type with flexible array member or some
> other trailing array in the struct), and use the resulting predicate in
> places where we optimize based on DECL_SIZE{,_UNIT} of the decl - if that
> predicate returns true, we assume the DECL_SIZE is
> "variable"/"unlimited"/whatever.
> The two spots known to me that would need to use this new predicate would
> be:
> tree.c (array_at_struct_end_p):
> tree-dfa.c (get_ref_base_and_extent):

Well, with just those two, this fixes 416.gamess, and passes all tests in 
gfortran, with only a few scan-dump/warning tests failing in gcc...

--Alan