asm("cas r11, r13, r0"); GC_push_one(TMP_SP); /* through */
asm("cas r11, r14, r0"); GC_push_one(TMP_SP); /* r15 */
asm("cas r11, r15, r0"); GC_push_one(TMP_SP);
asm("cas r11, r13, r0"); GC_push_one(TMP_SP); /* through */
asm("cas r11, r14, r0"); GC_push_one(TMP_SP); /* r15 */
asm("cas r11, r15, r0"); GC_push_one(TMP_SP);