#include <string.h>
#include <stdint.h>

#define aliases __attribute__((__may_alias__))

int memcmp(const void *_l, const void *_r, size_t n)
{
	const unsigned char *l = _l, *r = _r;
	const size_t aliases *wl, aliases *wr;

	if (n < sizeof(size_t) * 3 || ((uintptr_t)l | (uintptr_t)r)
	    & sizeof(size_t) - 1) goto bytewise;

	for (; (uintptr_t)l & sizeof(size_t) - 1 && *l == *r; l++, r++, n--);
	if ((uintptr_t)l & sizeof(size_t) -1) return *l - *r;

	wl = (const void *)l;
	wr = (const void *)r;
	for (; n >= sizeof(size_t) && *wl == *wr
	     ; wl++, wr++, n -= sizeof(size_t));
	l = (const void *)wl;
	r = (const void *)wr;

bytewise:
	for (; n && *l == *r; l++, r++, n--);

	return n ? *l - *r : 0;
}