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From: "manu at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug c/64440] -Wdiv-by-zero false negative on const variables
Date: Tue, 30 Dec 2014 12:31:00 -0000 [thread overview]
Message-ID: <bug-64440-4-uJBkICIw1x@http.gcc.gnu.org/bugzilla/> (raw)
In-Reply-To: <bug-64440-4@http.gcc.gnu.org/bugzilla/>
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64440
Manuel López-Ibáñez <manu at gcc dot gnu.org> changed:
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CC| |manu at gcc dot gnu.org
--- Comment #3 from Manuel López-Ibáñez <manu at gcc dot gnu.org> ---
(In reply to Chengnian Sun from comment #2)
> Thanks for your reply. It seems GCC sometimes does consider "const int" for
> other types of warnings (but not for -Wdiv-by-zero). See the following, with
> -O3, GCC warns that the left shift count is negative.
>
I wonder how this happens? The warning is still given by the FE!
Nonetheless, clang is able to warn without optimization because it has some
constant propagation pass in the FE. GCC does not have such a thing and current
developers are not convinced that it is worth it.
I think there are several PRs open about this, and it doesn't seem useful to
have one PR for each possible warning that could be improved by this.
>From gcc-bugs-return-471924-listarch-gcc-bugs=gcc.gnu.org@gcc.gnu.org Tue Dec 30 12:37:52 2014
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From: "manu at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug bootstrap/50139] in-tree GMP/PPL/CLooG is misconfigured
Date: Tue, 30 Dec 2014 12:37:00 -0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=50139
Manuel López-Ibáñez <manu at gcc dot gnu.org> changed:
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CC| |manu at gcc dot gnu.org
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--- Comment #4 from Manuel López-Ibáñez <manu at gcc dot gnu.org> ---
(In reply to nightstrike from comment #3)
> There's other relevant posts, but you get the idea. Anyway, this should
> eventually be closed.
So be it. Thanks for noticing.
(You can probably get a gcc.gnu.org bugzilla account, if you wish so).
>From gcc-bugs-return-471923-listarch-gcc-bugs=gcc.gnu.org@gcc.gnu.org Tue Dec 30 12:37:23 2014
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From: "mikpelinux at gmail dot com" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug c/64442] -O1 modify output of a simple computation with rounding
Date: Tue, 30 Dec 2014 12:37:00 -0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?idd442
--- Comment #1 from Mikael Pettersson <mikpelinux at gmail dot com> ---
Are you compiling on 32-bit x86? I can reproduce on m68k, but not on x86_64
(even with -m32) or on ARMv5. I suspect you're seeing the effects of excess
precision of the x87 FPU (much like the m68k FPU).
next prev parent reply other threads:[~2014-12-30 12:31 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-12-30 2:27 [Bug c/64440] New: " chengniansun at gmail dot com
2014-12-30 3:01 ` [Bug c/64440] " pinskia at gcc dot gnu.org
2014-12-30 7:53 ` chengniansun at gmail dot com
2014-12-30 12:31 ` manu at gcc dot gnu.org [this message]
2015-01-06 15:23 ` mpolacek at gcc dot gnu.org
2015-01-06 16:07 ` mpolacek at gcc dot gnu.org
2015-01-07 8:22 ` mpolacek at gcc dot gnu.org
2015-01-07 8:22 ` mpolacek at gcc dot gnu.org
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