[Bug ipa/65270] [5 regression] ICF needs to match TYPE attributes on memory accesses

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65270

--- Comment #12 from rguenther at suse dot de <rguenther at suse dot de> ---
On Tue, 3 Mar 2015, hubicka at gcc dot gnu.org wrote:

> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65270
> 
> --- Comment #10 from Jan Hubicka <hubicka at gcc dot gnu.org> ---
> Hi,
> while looking for a testcase that would trigger with tree-tail-merge (because
> gimple-fold seems to also miss MEM_REF merging) I noticed following oddity:
> 
> struct a 
> {
>   int a[100000];
> };
> typedef struct a b __attribute__ ((aligned (32)));
> typedef struct a c __attribute__ ((aligned (8)));
> typedef struct a d __attribute__ ((aligned (32)));
> 
> __attribute__ ((used))
> t(b *a, int aligned, b *d)
> {
>   int i,v;
>         c *ptr = a;
>   for (i=0;i<100000;i++)
>     {
>         ptr->a[i]++;
>     }
> }
> main()
> {
> }
> 
> here the loop gets vectorized with assumed alignmen 32.
> Changing declaretion to:
> t(c *a, int aligned, b *d)
> produces correct 8 byte alignment loop.
> Alignment of the type of variable A shall not be used.

Hmm.  And it's correctly handled by get_object_alignment.  It's
the vectorizer code that does odd things here.  I'll fix it.