GNU bug report logs - #31474
logxor+ash trigger compilation bug?

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From: help-debbugs <at> gnu.org (GNU bug Tracking System)
To: Mark H Weaver <mhw <at> netris.org>
Cc: tracker <at> debbugs.gnu.org
Subject: bug#31474: closed (logxor+ash trigger compilation bug?)
Date: Mon, 11 Jun 2018 14:30:02 +0000

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Your message dated Mon, 11 Jun 2018 10:28:28 -0400
with message-id <87po0x75yr.fsf <at> netris.org>
and subject line Re: bug#31474: logxor+ash trigger compilation bug?
has caused the debbugs.gnu.org bug report #31474,
regarding logxor+ash trigger compilation bug?
to be marked as done.

(If you believe you have received this mail in error, please contact
help-debbugs <at> gnu.org.)


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From: Jan Nieuwenhuizen <janneke <at> gnu.org>
To: bug-guile <at> gnu.org
Subject: logxor+ash trigger compilation bug?
Date: Wed, 16 May 2018 20:16:31 +0200

Hi!

Trying to implement bit-fields for MesCC, I stumble upon this.  I was
looking for a bitwise left shift that introduces 1's instead of zeros.

This code

--8<---------------cut here---------------start------------->8---
;; foo.scm
(let* ((set-mask (pk 'set-mask (ash 3 3)))
       (clear-mask (pk 'clear-mask (logxor set-mask -1))))
  (pk 'expected (logxor 24 -1))
  (display clear-mask)
  (newline)
  clear-mask)
--8<---------------cut here---------------end--------------->8---

behaves as I expect when compilation is turned off (compile or
auto-compile behave alike for me)

--8<---------------cut here---------------start------------->8---
19:50:43 janneke <at> dundal:~/src/mes 
$ guile --no-auto-compile foo.scm

;;; (set-mask 24)

;;; (clear-mask -25)

;;; (expected -25)
-25
--8<---------------cut here---------------end--------------->8---

but when (auto)compiled, look:

--8<---------------cut here---------------start------------->8---
19:50:47 janneke <at> dundal:~/src/mes 
$ guile foo.scm
;;; note: auto-compilation is enabled, set GUILE_AUTO_COMPILE=0
;;;       or pass the --no-auto-compile argument to disable.
;;; compiling /home/janneke/src/mes/foo.scm
;;; compiled /home/janneke/.cache/guile/ccache/2.2-LE-8-3.A/home/janneke/src/mes/foo.scm.go

;;; (set-mask 24)

;;; (clear-mask -1)

;;; (expected -25)
-1
--8<---------------cut here---------------end--------------->8---

I'm using guile-2.2.3 from Guix master.

Is this a bug, can you suggest a workaround?

Greetings,
janneke

-- 
Jan Nieuwenhuizen <janneke <at> gnu.org> | GNU LilyPond http://lilypond.org
Freelance IT http://JoyofSource.com | Avatar® http://AvatarAcademy.com

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From: Mark H Weaver <mhw <at> netris.org>
To: Jan Nieuwenhuizen <janneke <at> gnu.org>
Cc: Andy Wingo <wingo <at> pobox.com>, 31474-done <at> debbugs.gnu.org
Subject: Re: bug#31474: logxor+ash trigger compilation bug?
Date: Mon, 11 Jun 2018 10:28:28 -0400

Jan Nieuwenhuizen <janneke <at> gnu.org> writes:

> Mark H Weaver writes:
>
>> Here's an improved version of my patch.  It's functionally equivalent
>> but with more comprehensible code and more comments.  I think this is
>> ready to push to the stable-2.2 branch.  Comments and suggestions
>> welcome.
>
> I tried it and it works for me.  Thanks a lot!
>
> Also, thanks for the workarounds you suggested, they indeed work without
> this patch.

I pushed the patch as commit 2733e97395db30c6233f79f341959e722b4bd4ff to
the stable-2.2 branch.  I'm closing this bug now, but feel free to
reopen if needed.

     Thanks,
       Mark

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