X86IndexedMemoryOperand is an operand of the form: variable(base, index, size)
variable: an 8, 16, or 32 bit value (from parent variable: either array or complex)
base: (register) or can be null
index: an index into the variable specified by displacement
size: the size of the type of the variable (must be either 2, 4, or 8)
Example:
movl $5, %edx
movl $10, a(,%edx,4)
The above is equivalent to a[5] = 10; //assuming a is an int_array (data type of size 4)