I don't know about Java or Go, but any time I've looked at a C compiler's output it's emitted pretty good assembly for "if (a>b) return 1; else if (a<b) return -1; else return 0;" kinds of input when optimization is on. As long as the type being compared is something the compiler can reason about (and/or has a peephole optimization for I guess).
You could call Long.signum(), but that's not the right solution here: you should not subtract the values, but call Long.compare(a, b) directly, which is clear, efficient and correct.
The reason to avoid subtraction is that you can get integer underflow if one operand is negative and one is positive, and then the result of Long.signum(b - a) is different from Long.compare(a, b).
It could or for integer types less than 4 bytes. For integers, while I don't think Java has this built in, you could use saturating subtraction (so it goes to INT_MIN or something on underflow).
