Re: [Qemu-devel] clang -fsanitize=undefined warnings in the string visitors

[Paolo Bonzini <pbonzini@redhat.com>]

On 14/01/2016 12:15, Peter Maydell wrote:
> On 5 November 2015 at 20:05, John Snow <jsnow@redhat.com> wrote:
>>
>>
>> On 10/01/2015 09:38 AM, Paolo Bonzini wrote:
>>>
>>>
>>> On 01/10/2015 12:47, Peter Maydell wrote:
>>>> On 29 May 2015 at 12:12, Paolo Bonzini <pbonzini@redhat.com> wrote:
>>>>>
>>>>>
>>>>> On 29/05/2015 12:56, Peter Maydell wrote:
>>>>>>>>>> Paolo: ping^2, since we're out of release freeze now?
>>>>>>>>
>>>>>>>> I have some patches, but this isn't really the best time for me to post
>>>>>>>> them...
>>>>>> Ping...has the timing improved?
>>>>>
>>>>> Almost. :)  Next week, promised.
>>>>
>>>> Ping again, six months later...
>>>
>>> Uh, I thought they were already in. :)
>>>
>>> Paolo
>>>
>>
>> Did patches ever get posted to list for this?
> 
> Not that I saw -- ping again, Paolo. This is the only warning
> that clang's sanitizer currently produces for me, and arithmetic
> overflows on addition seem genuinely worth investigation...

It happens when the range is 2^64 in size.

Does it still matter if we've decided to use -fwrapv because of left
shifts?  Or are we still considering the possibility to use -std=gnu89
(where left shifts give unspecified behavior rather than undefined)?

Paolo