From: Jonathan Wakely <jwakely.gcc@gmail.com>
To: wempwer@gmail.com
Cc: gcc-help <gcc-help@gcc.gnu.org>
Subject: Re: how to make gcc warn about arithmetic signed overflow
Date: Sun, 22 Sep 2013 15:52:00 -0000 [thread overview]
Message-ID: <CAH6eHdQs4_MYPAvb6sB=MW1e6XzUihCgay6uTFXTLpFTVpXBvg@mail.gmail.com> (raw)
In-Reply-To: <20130921193306.GH3086@a.lan>
On 21 September 2013 20:33, <wempwer@gmail.com> wrote:
>
> But compiler also knows the operand values even if they are not
> constant? These values must be known to produce the multiplication
> result.
No, in general the processor produces the result of multiplying two
variables, not the compiler.
> Is this warning produced only when two operands are constant
> and optimization is turned on because this is just the way gcc does it
> and the warnings could also be produced for non-const operands if a
> compiler worked in a different way?
Yes, Marc and I have both said that, please read our replies more carefully.
next prev parent reply other threads:[~2013-09-22 15:52 UTC|newest]
Thread overview: 40+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-09-21 16:45 wempwer
2013-09-21 17:24 ` Jonathan Wakely
2013-09-21 17:41 ` wempwer
2013-09-21 18:30 ` Jonathan Wakely
2013-09-21 18:50 ` wempwer
2013-09-21 19:55 ` Jędrzej Dudkiewicz
2013-09-21 20:16 ` wempwer
2013-09-21 20:52 ` Jędrzej Dudkiewicz
2013-09-21 21:07 ` wempwer
2013-09-23 4:04 ` James K. Lowden
2013-09-23 7:55 ` Jonathan Wakely
2013-09-23 15:47 ` James K. Lowden
2013-09-23 21:50 ` Jonathan Wakely
2013-09-23 22:44 ` James K. Lowden
2013-09-23 23:20 ` Jonathan Wakely
2013-09-23 19:38 ` Dave Allured - NOAA Affiliate
2013-09-23 19:43 ` Oleg Endo
2013-09-23 20:37 ` Dave Allured - NOAA Affiliate
2013-09-23 19:48 ` Andrew Haley
2013-09-23 22:00 ` James K. Lowden
2013-09-24 17:48 ` Andrew Haley
2013-09-26 2:30 ` James K. Lowden
2013-09-26 8:29 ` Vincent Lefevre
2013-09-26 14:49 ` Andrew Haley
2013-09-26 17:03 ` Vincent Lefevre
2013-09-26 18:19 ` Andrew Haley
2013-09-27 7:58 ` Vincent Lefevre
2013-09-27 8:23 ` Andrew Haley
2013-09-27 9:28 ` Vincent Lefevre
2013-09-27 9:43 ` Andrew Haley
2013-09-26 17:41 ` Andrew Haley
2013-09-24 7:42 ` Brian Drummond
2013-09-21 17:53 ` Marc Glisse
2013-09-21 18:09 ` wempwer
2013-09-21 18:27 ` Jonathan Wakely
2013-09-21 19:32 ` wempwer
2013-09-22 15:52 ` Jonathan Wakely [this message]
2013-09-23 13:04 ` David Brown
2013-09-21 17:36 ` Brian Drummond
2013-09-21 17:45 ` wempwer
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