Easy Array References

    (AREF X (+ -8 (* 8 I)))

One way to generate code for the array reference is to:

• use genarith to generate (+ -8 (* 8 I)) in register ( %eax) (move the result to %eax if necessary).

• Issue the instruction CLTQ, which sign-extends %eax to %rax.

• access memory from the offset and sum of the registers.

  
     movsd   %xmm0,-1296(%rbp,%rax)  #  ac[]
  

This is easy from the viewpoint of the compiler writer, but it generates many instructions, including a possibly expensive multiply.