distinguishing gcc compilation valgrind false positives

[Jeff Law]

On 11/24/2021 12:15 PM, Paul Floyd via Gcc wrote:
>
> On 24/11/2021 20:05, Zdenek Sojka via Gcc wrote:
>> Hello,
>>
>> from time to time, I come upon a testcase that failed during the 
>> automated
>> runs, but passes during reduction; there are valgrind warnings present,
>> however. How do I distinguish what warnings are valid and which are 
>> false
>> positives? Is there any way gcc could prevent generating the false
>> positives?
>
>
> What makes you think that any are false positives?
>
> Memcheck generally has a low false positive rate (though I am little 
> biased).
>
> You need to read the source and decide based on that.
Agreed.  Work from the assumption it's a real GCC issue until proven 
otherwise.

I believe GCC has annotations to help valgrind that are turned on by a 
magic configuration option as well.

Finally, there is an issue with sparsesets that will trigger a warning 
from valgrind.  Those are the only ones I would consistently ignore from 
GCC.

Jeff