Is integer multiplication really done at the same speed as addition on a modern CPU?

Question

I hear this statement quite often, that multiplication on modern hardware is so optimized that it actually is at the same speed as addition. Is that true?

I never ca

Answer 1

This really depends on your machine. Of course, integer multiplication is quite complex compared to addition, but quite a few AMD CPU can execute a multiplication in a single cycle. That is just as fast as addition.

Other CPUs take three or four cycles to do a multiplication, which is a bit slower than addition. But it's nowhere near the performance penalty you had to suffer ten years ago (back then a 32-Bit multiplication could take thirty-something cycles on some CPUs).

So, yes, multiplication is in the same speed class nowadays, but no, it's still not exactly as fast as addition on all CPUs.