do { \
int step = -line_length; \
int align = ~(line_length - 1); \
+ int count; \
end = ((end & align) == end) ? end - line_length : end & align; \
- int count = end - start; \
+ count = end - start; \
WARN_ON(count < 0); \
\
__asm__ __volatile__ (" 1: " #op " %0, %1; \