[Bug target/87598] New: [8/9 Regression] Rejects "%a0" with constant

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=87598

            Bug ID: 87598
           Summary: [8/9 Regression] Rejects "%a0" with constant
           Product: gcc
           Version: 8.2.1
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: target
          Assignee: unassigned at gcc dot gnu.org
          Reporter: rguenth at gcc dot gnu.org
  Target Milestone: ---

void foo()
{
  __asm__ ("\t.long %a0\n" : : "i" (0));
}

is now rejected on aarch64 while it worked in GCC 7.  This affects iPXE
compilation.  Most other targets continue to accept it.

A workaround is to sue %c0.

powerpc64le ICEs on the testcase.