Chasing a potential wrong-code bug on trunk

[Martin Reinecke]

Hi Markus,

I feel deeply embarrassed now ... the sanitizer indeed found a spot
where I relied on (undefined) semantics of signed integer overflow.
Changing the offending "int" to "unsigned" fixed the problem.

Thanks a lot for the tip - I will definitely use the sanitizers more
often in the future!

Sorry for the noise,
  Martin


On 11/17/16 10:53, Markus Trippelsdorf wrote:
> On 2016.11.17 at 10:49 +0100, Martin Reinecke wrote:
>> Hi,
>>
>> At some point in May 2016 there was a patch to the gcc trunk which
>> caused one of my numerical codes to give incorrect results when compiled
>> with this gcc version. This may of course be caused by some undefined
>> behavior I'm unknowingly invoking in the code, or it may be a code
>> generation bug in gcc. I tried to isolate the exact gcc commit that
>> caused the change, but I got stuck...
> 
> You should check this first by compiling with -fsanitize=undefined and
> fixing all issues that may pop up.
>