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 (Convert Long To Quad), which sign-extends %eax to %rax.

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

  
  movsd  %xmm0,-816(%rbp,%rax) # %xmm0->x[%rax]
  

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