Implement car, cdr, cddr and cddar as primitives

scm/inc/compiler.scm

@@ -167,6 +167,21 @@
     (emit "movq %rsi, %rax") ; rax = rsi | 1  (cons cell/pair tag)
     (emit "orq  $~a, %rax" #b001)
     (emit "addq $8,  %rsi")) ; bump rsi
    ((car)
     (emit-expr (primcall-operand1 x) si env)
     (emit "movl -1(%rax), %eax"))
    ((cdr)
     (emit-expr (primcall-operand1 x) si env)
     (emit "movl 3(%rax), %eax"))
    ((cddr)
     (emit-expr (primcall-operand1 x) si env)
     (emit "movl 3(%rax), %eax")
     (emit "movl 3(%rax), %eax"))
    ((cddar)
     (emit-expr (primcall-operand1 x) si env)
     (emit "movl 3(%rax), %eax")
     (emit "movl 3(%rax), %eax")
     (emit "movl -1(%rax), %eax"))
    ))
(define (compile-program x)