C ++模数乘以2的性能

Question

I was wondering what the typical compiler's assembly reduction would be when performing an integer modulus by 2 operation such as this:

const char* integer_string = "300"; // avoid compiler optimization
int i = atoi(integer_string);
int b = i % 2; // the line in question

I'd imagine the compiler could turn it into a bit-wise operation to just check that last bit (1s place), but does it do this?

Answer 1

The question only makes sense in the context of a particular compiler, platform, optimization options etc.

My compiler ( gcc 4.7.2 on x86_64 ) does do this when -O3 optimizations are turned on:

    andl    $1, %esi