Simplest way to check if two integers have same sign?

Question

Which is the simplest way to check if two integers have same sign? Is there any short bitwise trick to do this?

Answer 1

branchless C version:

int sameSign(int a, int b) {
    return ~(a^b) & (1<<(sizeof(int)*8-1));
}

C++ template for integer types:

template  T sameSign(T a, T b) {
    return ~(a^b) & (1<<(sizeof(T)*8-1));
}