[RFC] Implement Undefined Behavior Sanitizer

[Konstantin Serebryany]

On Thu, Jun 6, 2013 at 12:26 PM, Andrew Pinski <pinskia@gmail.com> wrote:
> On Thu, Jun 6, 2013 at 1:21 AM, Jakub Jelinek <jakub@redhat.com> wrote:
>> On Thu, Jun 06, 2013 at 11:46:19AM +0400, Konstantin Serebryany wrote:
>>> If we are going to import the ubsan run-time from LLVM's
>>> projects/compiler-rt/lib/ubsan,
>>> we may also need to update the contents of
>>> libsanitizer/sanitizer_common and keep them in sync afterwards.
>>> (ubsan shares few bits of code with asan/tsan/msan)
>>> The simplest way to do that is to extend libsanitizer/merge.sh
>>
>> Sure.  I've done so far just a partial merge by hand (only 3 changed files
>> for the minimum of changes required to get ubsan to build), and have tested just
>> that it compiles, not that libubsan actually works.
>>
>> P1 patch is the toplevel stuff to add ubsan into GCC libsanitizer, plus
>> ubsan/Makefile* and ubsan/libtool-version (i.e. gcc owned files).
>> P2 is the actual merge of the ubsan files.
>> P3 is something I'd propose for ubsan upstream, without it g++ warns about
>> __int128 in -pedantic mode.
>
> Is there a reason why ubsan runtime in C++?  That seems like a bad
> idea to require linking against libstdc++ when doing development of a
> C only program.

for asan/tsan/msan/lsan the reason is that C++ is a better language
(in the author's humble opinion :).
For ubsan, I think the reason is the same, plus ubsan shares some C++
code with asan/tsan/msan/lsan.

As for libstdc++, I completely agree, we don't want to depend on it,
and we don't.
None of sanitizer run-times uses C++ features  that require libstdc++

--kcc

>
> Also it seems easy enough to write a GCC specific runtime that does
> not depend on the rest of libsanitizer stuff anyways.
>
> Thanks,
> Andrew Pinski