The IA32 assembler operand for x[i] used the scaled index form where x is an int array.

      (%eax, %edx, 4)

      %eax contains the beginning address of arrray x
      %edx contains the value of i
      4 multiplier

      address: contentsOf(%eax) + 4 * contentsOf(%edx)
   

The index i can't just be added to the address of x to get the address of x[i] since the size of each int is 4 bytes.

For example, the address of x[1] is not 0x8001, but is 0x8004:

Element	i	Address
x[0]	0	0x8000
x[1]	1	0x8004
x[2]	2	0x8008
x[3]	3	0x800C

So i must be multiplied by this size 4 and then added.

Using scaled index operand does the multiplication without needing a separate imull instruction.