[Bug rtl-optimization/92294] New: alias attribute generates incorrect code

[wilco at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=92294

            Bug ID: 92294
           Summary: alias attribute generates incorrect code
           Product: gcc
           Version: 4.8.4
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: rtl-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: wilco at gcc dot gnu.org
  Target Milestone: ---

The following example (from gcc.c-torture/execute/alias-2.c) always calls abort
on any AArch64 compiler with -O1 or -O2:

static int a[10];
extern int b[10] __attribute__ ((alias("a")));
int off = 0;
void f(void)
{
  b[off]=1;
  a[off]=2;
  if (b[off]!=2)
   __builtin_abort ();
}

Using extern linkage for 'a' avoids the problem, as is doing off = 1 or static
int off = 0. It may only affect targets which use section anchors since
-fno-section-anchors avoids the issue.