[Bug target/65689] New: [AArch64] S constraint fails for inline asm at -O0

["alalaw01 at gcc dot gnu.org" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65689

            Bug ID: 65689
           Summary: [AArch64] S constraint fails for inline asm at -O0
           Product: gcc
           Version: 5.0
            Status: UNCONFIRMED
          Severity: minor
          Priority: P3
         Component: target
          Assignee: unassigned at gcc dot gnu.org
          Reporter: alalaw01 at gcc dot gnu.org

Starting with r221532
(https://gcc.gnu.org/ml/gcc-patches/2015-03/msg01064.html),

void
test (void)
{
    __asm__ ("@ %c0" : : "S" (&test + 4));
}

fails to compile at -O0 on all aarch64 targets with:

c-output-template-3.c: In function 'test':
c-output-template-3.c:7:5: error: impossible constraint in 'asm'
     __asm__ ("@ %c0" : : "S" (&test + 4));

(This is gcc.target/aarch64/c-output-template-3.c, without the -O added in
r221905, as that leads to successful compilation - however, the testcase should
compile without -O too.)