GNU bug report logs - #15533
optimizing away noticeable effects

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Message #11 received at 15533 <at> debbugs.gnu.org (full text, mbox):

From: Mark H Weaver <mhw <at> netris.org>
To: Ian Price <ianprice90 <at> googlemail.com>
Cc: 15533 <at> debbugs.gnu.org
Subject: Re: bug#15533: optimizing away noticeable effects
Date: Sat, 05 Oct 2013 16:45:59 -0400

Mark H Weaver <mhw <at> netris.org> writes:

> Ian Price <ianprice90 <at> googlemail.com> writes:
>
>> scheme@(guile-user)> ,optimize (define (foo f arg)
>>   (let* ((l '())
>>          (m (if (pair? arg)
>>                 (begin
>>                   (set! l (cdr arg))
>>                   (car arg))
>>                 arg)))
>>     (lambda () (apply f m l))))
>> $14 = (define (foo f arg)
>>   (let ((m (if (pair? arg)
>>              (begin (begin (cdr arg) (if #f #f)) (car arg))
>>              arg)))
>>     (lambda () (f m))))
>
> I can confirm that the same thing happens on the stable-2.0 branch.

Further investigation has revealed that 'peval' incorrectly removes the
'l' from the call to 'apply'.

     Mark

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