The text mentions that it can also do multiplication but doesn't expand on that.
E.g. for x * 5 gcc issues lea eax, [rdi+rdi*4].
E.g. for x * 5 gcc issues lea eax, [rdi+rdi*4].
So I guess this trick then only works for multiplication by 2, 3, 4, 5, 8 or 9?
x * 6:
lea eax, [rdi+rdi*2]
add eax, eax
x * 7:
lea eax, [0+rdi*8]
sub eax, edi
x * 11:
lea eax, [rdi+rdi*4]
lea eax, [rdi+rax*2]
And on modern CPUs multiplication might not be actually all that slow (but there may be fewer multiply units).