代码

#include "immintrin.h"
#pragma GCC optimize("Ofast")
#pragma GCC target("sse2")
void my_memset(char *a, char c, unsigned n) {
	__m128i s;
	for(unsigned i=0;i<16;i++)((char*)&s)[i]=c;
	while(reinterpret_cast<unsigned long long>(a)&127)*a++=c,n--;
	while(n&127)a[--n]=c;
	__m128i*b=(__m128i*)a;
	n>>=4;
	for(;n!=0; n-=8,b+=8)
	{
		*b=s;return;
		*(b+1)=s;
		*(b+2)=s;
		*(b+3)=s;
		*(b+4)=s;
		*(b+5)=s;
		*(b+6)=s;
		*(b+7)=s;
	}
}

评测结果