[Openmcl-devel] Wow, this is so not what I expected

[Shannon Spires]

What's unexpected about it?

On Apr 12, 2017, at 7:26 PM, Ron Garret wrote:

> Welcome to Clozure Common Lisp Version 1.10-r16479M  (DarwinX8664)!
> 
> ? (defun foo1 (n)
>  (if (<= n 0) 0 (foo1 (1- n))))
> FOO1
> 
> ? (defun foo2 (n)
>  (labels ((foo (n) (if (<= n 0) 0 (foo (1- n)))))
>    (foo n)))
> FOO2
> 
> ? (disassemble 'foo1)
> ;;; (defun foo1 (n) (if (<= n 0) 0 (foo1 (1- n))))
> L0
>    (leaq (@ (:^ L0) (% rip)) (% fn))       ;     [0]
>    (cmpl ($ 8) (% nargs))                  ;     [7]
>    (jne L141)                              ;    [10]
>    (pushq (% rbp))                         ;    [16]
>    (movq (% rsp) (% rbp))                  ;    [17]
>    (pushq (% save0))                       ;    [20]
>    (movq (% arg_z) (% save0))              ;    [22]
> 
> ;;; (<= n 0)
> L25
>    (movq (% save0) (% arg_y))              ;    [25]
>    (testb ($ 7) (% arg_y.b))               ;    [28]
>    (jne L41)                               ;    [32]
>    (testq (% arg_y) (% arg_y))             ;    [34]
>    (jle L66)                               ;    [37]
>    (jmp L72)                               ;    [39]
> L41
>    (xorl (% arg_z.l) (% arg_z.l))          ;    [41]
>    (nop)                                   ;    [43]
>    (callq (@ .SPBUILTIN-LE))               ;    [46]
>    (leaq (@ (:^ L0) (% rip)) (% fn))       ;    [53]
>    (cmpb ($ 11) (% arg_z.b))               ;    [60]
>    (je L72)                                ;    [64]
> 
> ;;; (if (<= n 0) 0 (foo1 (1- n)))
> L66
>    (xorl (% arg_z.l) (% arg_z.l))          ;    [66]
>    (popq (% save0))                        ;    [68]
>    (leaveq)                                ;    [70]
>    (retq)                                  ;    [71]
> 
> ;;; (1- n)
> L72
>    (movq (% save0) (% arg_z))              ;    [72]
>    (testb ($ 7) (% arg_z.b))               ;    [75]
>    (jne L110)                              ;    [79]
>    (addq ($ -8) (% arg_z))                 ;    [81]
>    (jno L132)                              ;    [85]
>    (nop)                                   ;    [87]
>    (nop)                                   ;    [91]
>    (callq (@ .SPFIX-OVERFLOW))             ;    [94]
>    (leaq (@ (:^ L0) (% rip)) (% fn))       ;   [101]
>    (jmp L132)                              ;   [108]
> L110
>    (movq ($ -8) (% arg_y))                 ;   [110]
>    (nop)                                   ;   [117]
>    (callq (@ .SPBUILTIN-PLUS))             ;   [118]
>    (leaq (@ (:^ L0) (% rip)) (% fn))       ;   [125]
> L132
>    (movq (% arg_z) (% save0))              ;   [132]
> 
> ;;; (foo1 (1- n))
>    (jmp L25)                               ;   [135]
> 
> ;;; #<no source text>
> L141
>    (uuo-error-wrong-number-of-args)        ;   [141]
> NIL
> 
> ? (disassemble 'foo2)
> ;;; (defun foo2 (n) (labels ((foo (n) (if (<= n 0) 0 (foo (1- n))))) (foo n)))
> L0
>    (leaq (@ (:^ L0) (% rip)) (% fn))       ;     [0]
>    (cmpl ($ 8) (% nargs))                  ;     [7]
>    (jne L45)                               ;    [10]
>    (pushq (% rbp))                         ;    [12]
>    (movq (% rsp) (% rbp))                  ;    [13]
>    (pushq (% arg_z))                       ;    [16]
> 
> ;;; (foo n)
>    (movl ($ 8) (% nargs))                  ;    [17]
>    (movq (@ '#<Compiled-function (:INTERNAL FOO FOO2) (Non-Global)  #x30200110BE6F> (% fn)) (% temp0)) ;    [22]
>    (leaveq)                                ;    [29]
>    (movq (% fn) (% temp1))                 ;    [30]
>    (movq (% temp0) (% fn))                 ;    [33]
>    (jmpq (% fn))                           ;    [36]
> 
> ;;; #<no source text>
> L45
>    (uuo-error-wrong-number-of-args)        ;    [45]
> NIL
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