What is the meaning of MOV (%r11,%r12,1),

Question

What does this instruction do?

mov (%r11,%r12,1), %edx

Answer 1

Look here. It says

In the AT&T Syntax, memory is referenced in the following way,

segment-override:signed-offset(base,index,scale)

Down on the page there are some examples. I find this the best:

GAS memory operand   NASM memory operand
------------------   -------------------
(%ecx,%ebx,2)    [ecx+ebx*2]

mov source, destination in AT&T syntax copies the value from source to destination. Also consider the size of edx. How many bytes (4) do you think mov will copy ?