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Move with Calculated Address

x86 allows very flexible addressing:

Offset from Register


   movl   %eax,-32(%rbp)  #  %eax -> i

Offset from Two Registers


   movsd %xmm0,-1296(%rbp,%rax) #  ac[]
The offset and contents of the two registers are added to form the effective address.

Offset from Two Registers with Multiplier


   movsd %xmm0,-1296(%rbp,%rax,8) #  x[]
In this case, the second register is multiplied by 2, 4, or 8 before being added. This can allow many aref expressions to be done in a single instruction.