[Bug target/81821] New: [RX] __atomic_test_and_set overwrites adjacent memory

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81821

            Bug ID: 81821
           Summary: [RX] __atomic_test_and_set overwrites adjacent memory
           Product: gcc
           Version: 7.1.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: target
          Assignee: unassigned at gcc dot gnu.org
          Reporter: olegendo at gcc dot gnu.org
  Target Milestone: ---

__atomic_test_and_set is supposed to change only one byte, but on RX it wrongly
overwrites adjacent memory locations:


int test (volatile char* x)
{
  return __atomic_test_and_set (x, 0);
}

__Z4testPVc:
        mov     #1, r14
        xchg    [r1], r14     // xchg is 32 bit
        movu.B  r14, r1
        rts

It seems a .b or .w specifier can be added to the memory operand of xchg.