[Bug ipa/65270] issues with merging memory accesses from different code paths

["hubicka at gcc dot gnu.org" <gcc-bugzilla at gcc dot gnu dot org>]

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

--- Comment #27 from Jan Hubicka <hubicka at gcc dot gnu.org> ---
here is a variant of orignal testcase for tree-tail-merge

struct a 
{
  int a[100000];
};
typedef struct a misaligned_t __attribute__ ((aligned (8)));
typedef struct a aligned_t __attribute__ ((aligned (32)));

__attribute__ ((used))
__attribute__ ((noinline))
t(void *a, int misaligned, aligned_t *d)
{
  int i,v;
  for (i=0;i<100000;i++)
    {
        if (misaligned)
          v=((misaligned_t *)a)->a[i];
        else
          v=((aligned_t *)a)->a[i];
        d->a[i]+=v;
    }
}
struct b {int v; misaligned_t m;aligned_t aa;} b;
aligned_t d;
main()
{
  t(&b.m, 1, &d);
}

$ ./xgcc -B ./ -O3 t.c -fdump-tree-all-details  
t.c:10:1: warning: return type defaults to ïintï [-Wimplicit-int]
 t(void *a, int misaligned, aligned_t *d)
 ^
t.c:24:1: warning: return type defaults to ïintï [-Wimplicit-int]
 main()
 ^
$ ./a.out
Segmentation fault

It works (by accident) for GCC 4.7, so it is a regression again...