From: Stefan Monnier <monnier@iro.umontreal.ca>
Cc: rms@gnu.org, emacs-devel@gnu.org
Subject: Re: Preventing warnings in FIXNUM_OVERFLOW_P
Date: Thu, 18 Jan 2007 14:39:05 -0500 [thread overview]
Message-ID: <jwvps9cktwf.fsf-monnier+emacs@gnu.org> (raw)
In-Reply-To: <85lkk0npzj.fsf@lola.goethe.zz> (David Kastrup's message of "Thu\, 18 Jan 2007 19\:34\:24 +0100")
>> You can avoid it by using unsigned types. I think that something like
>> this will do the trick:
>>
>> #define FIXNUM_OVERFLOW_P(i) \
>> ((unsigned long long)(i) > MOST_POSITIVE_FIXNUM \
>> && (unsigned long long)(i) < MOST_NEGATIVE_FIXNUM)
>>
>> Would someone please give that approach a try and see if it works? I
>> am having too much trouble with concentration right now to see whether
>> that code is correct -- it might need somewhat more change than that
>> in order to get the comparisons right in an unsigned type.
> unsigned long long is neither guaranteed to exist on all supported
> architectures, nor guaranteed to be longer than long.
> It seems to me like something along the lines of
> #define FIXNUM_OVERFLOW_P(i) \
> (((unsigned long)(i)-(unsigned long)MOST_NEGATIVE_FIXNUM) > \
> (unsigned long)MOST_POSITIVE_FIXNUM)
That might be OK if we're trying to obfuscate the code.
Eli's current workaround is still the least bad I've seen.
Stefan
next prev parent reply other threads:[~2007-01-18 19:39 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-01-18 17:27 Preventing warnings in FIXNUM_OVERFLOW_P Richard Stallman
2007-01-18 18:34 ` David Kastrup
2007-01-18 19:39 ` Stefan Monnier [this message]
2007-01-19 10:42 ` Richard Stallman
2007-01-19 11:50 ` Eli Zaretskii
2007-01-19 19:19 ` Stefan Monnier
2007-01-20 2:10 ` Richard Stallman
2007-01-20 13:45 ` Eli Zaretskii
2007-01-21 6:49 ` Richard Stallman
2007-01-19 10:42 ` Richard Stallman
2007-01-18 21:49 ` Eli Zaretskii
2007-01-19 10:43 ` Richard Stallman
2007-01-19 10:57 ` Eli Zaretskii
2007-01-20 2:10 ` Richard Stallman
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