// Prior to Go1.8, the Writer had a bug where it would output
			// an invalid tar file in certain rare situations because the logic
			// incorrectly believed that the old GNU format had a prefix field.
			// This is wrong and leads to an output file that mangles the
			// atime and ctime fields, which are often left unused.
			//
			// In order to continue reading tar files created by former, buggy

			target = &a[2]
			break
		}
		p.errorf("wrong number of arguments to %s instruction", op)
		return
	case 4:
		if p.arch.Family == sys.S390X || p.arch.Family == sys.PPC64 {
			// 4-operand compare-and-branch.
			prog.From = a[0]
			prog.Reg = p.getRegister(prog, op, &a[1])
			prog.AddRestSource(a[2])
			target = &a[3]
			break
		}
		p.errorf("wrong number of arguments to %s instruction", op)
		return

			} else if err := errors[fileline]; err == "" {
				t.Errorf("%s: missing error, want %s", fileline, all)
			} else if !strings.Contains(err, mm[0][1]) {
				t.Errorf("%s: wrong error for %s:\n%s", fileline, all, err)
			}
		} else {
			if errors[fileline] != "" {
				t.Errorf("unexpected error on %s: %v", fileline, errors[fileline])
			}
		}
		delete(errors, fileline)
	}