LEA (load effective address) can perform computations of the form BASE + SCALE * INDEX + OFFSET, where scale can be 1, 2, 4 or 8. This allows optimisation of multiplications and additions into a single instruction, and the compiler takes advantage of that.

So if you write:

    a = 4 * b + c + 10;

It will be optimised to a single instruction like:

    lea    0xa(%rsi,%rdi,4),%rax

Rather than the more naive:

    imul   $0x4,%rdi,%rax
    add    %rsi,%rax
    add    $0xa,%rax