sse-isspecial.cpp

#include <stdio.h>
#include <string.h>
#include <emmintrin.h>    // SSE2
#include <time.h>

static inline
bool is_foo(char c) {
    return c == '"' || c == '\\' || c < ' ';
}

int main(void)
{
    #define X 16000000
    volatile char* str = (char*)malloc(X);
    memset((void*) str, 'a',  X);
    str[300017] = ' ';

    // asm("int $3");

    clock_t t = clock();

    __m128i a = _mm_set1_epi8('"');
    __m128i b = _mm_set1_epi8('\\');
    __m128i c = _mm_set1_epi8(' ');

    for (int i = 0; i < X; i += 16) {
        __m128i s = _mm_loadu_si128((__m128i const *)str);
        __m128i hasA = _mm_cmpeq_epi8(s, a);
        __m128i hasB = _mm_cmpeq_epi8(s, b);
        __m128i hasAorB = _mm_or_si128(hasA, hasB);
        __m128i hasC = _mm_cmplt_epi8(s, c);
        __m128i hasAny = _mm_or_si128(hasAorB, hasC);
        int x = _mm_movemask_epi8(hasAny);
        if (x) {
            printf("has at index: %d\n", i + __builtin_ctz(x & 0xffff));
        }
        str += 16;
    }

    // for (int i = 0; i < X; i++) {
    //     if (is_foo(str[i])) {
    //         printf("has at index: %d\n", i);
    //     }
    // }

    printf("time: %ld\n", clock() - t);

    return 0;
}