Re: traced generic functions

[Sam S. <sd...@gn...>]

> * Bruno Haible <oe...@py...t> [2004-10-21 21:05:22 +0200]:
>
>> Alas, it works only for flet/labels that are not really closures.
>> that's because compiled closures access STACK in a pre-computed way
>> which is not correct for the traced closures, so they do not find the
>> right values where they are looking for them.
>
> I don't understand this. The closures are compiled before the outer
> function, therefore they cannot know the STACK offsets of the outer
> function. The only problem I can see with tracing flet/labels is that
> the bytecode operation COPY-CLOSURE needs to be aware of traced closures.

(defun foo (x) (flet ((bar (y) (+ x y))) (bar x)))
(compile 'foo)
(disassemble 'foo)

Disassembly of function FOO
(CONST 0) = #<COMPILED-CLOSURE FOO-BAR>
1 required argument
0 optional arguments
No rest parameter
No keyword parameters
9 byte-code instructions:
0     (NIL)
1     (MAKE-VECTOR1&PUSH 1)
3     (LOAD&STOREC 2 0 0)
7     (LOAD&PUSH 0)
8     (COPY-CLOSURE&PUSH 0 1)             ; #<COMPILED-CLOSURE FOO-BAR>
11    (LOADC&PUSH 1 0)
14    (LOAD 1)
15    (CALLC)
16    (SKIP&RET 4)
NIL

(disassemble (ext:local foo bar))

Disassembly of function FOO-BAR
(CONST 0) = NIL
1 required argument
0 optional arguments
No rest parameter
No keyword parameters
4 byte-code instructions:
0     (LOADV&PUSH 0 1)
3     (LOAD&PUSH 2)
4     (CALLSR 2 53)                       ; +
7     (SKIP&RET 2)
NIL
(trace (ext:local foo bar))

;; Tracing function (EXT:LOCAL FOO BAR).
((EXT:LOCAL FOO BAR))
(foo 10)

1. Trace: ((EXT:LOCAL FOO BAR) '10)
*** - +: #<UNBOUND> is not a NUMBER
The following restarts are available:
USE-VALUE      :R1      You may input a value to be used instead.

(untrace (ext:local foo bar))
((EXT:LOCAL FOO BAR))

(foo 10)
20

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