== Check -1 or 0

The most intuitive way would be f, but I came across g in some code base.

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#include <stdio.h>
#include <stdbool.h>
#include <stdlib.h>
#include "./tik.h"

static bool b;

void f(int x)
{
    b = x == -1 || x == 0;
    // cmpl	$-1, %edi
    // sete	%cl
    // testl	%edi, %edi
    // sete	%al
    // orb	%cl, %al

}
void g(int x)
{
    b = (unsigned int)x + 1u <= 1u;
    // incl	%edi
    // cmpl	$2, %edi
    // setb	%al
}

int main(int argc, char **argv)
{
    int count = (int) (1u << 28);

    srand(0);
    printf("fast: ");
    tik();
    for (int i = 0; i < count; ++i) {
        g(rand());
    }
    tik();

    srand(0);
    printf("slow: ");
    tik();
    for (int i = 0; i < count; ++i) {
        f(rand());
    }
    tik();

    srand(0);
    printf("slow: ");
    tik();
    for (int i = 0; i < count; ++i) {
        f(rand());
    }
    tik();

    srand(0);
    printf("fast: ");
    tik();
    for (int i = 0; i < count; ++i) {
        g(rand());
    }
    tik();
    (volatile void) b;
    return 0;
}

The output on my box:

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$ clang -Ofast test.c && ./a.out
fast: 3.361036
slow: 3.479914
slow: 3.548457
fast: 3.360908