As Chandler said, disabling extern templates may help with some simple tests, but the only reliable way to get rid of MSan false positives is linking with instrumented libc++.
We should concentrate on making is easier to build and use instrumented libc++ instead. On Mon, Aug 18, 2014 at 6:30 AM, Eric Fiselier <[email protected]> wrote: >> FWIW, I don't think that MSan was *ever* intended to not have false >> positives with an uninstrumented standard library. So I really don't >> understand why this is an interesting thing to dig into. > > That is new information to me so I'll have to take that into consideration. > What I was trying to avoid was breaking MSAN usability for end users of > libc++. > Since its unlikely that they have a instrumented standard library it would > be nice if their system libc++ didn't always cause the first MSAN failure. > > Since __attribute__((__always_inline__)) seems to cause a lot of these > failures I imagine it is possible to reduce the FP's without removing the > extern template declarations. > In that case it might still be work putting time into. > > /Eric > > > On Sun, Aug 17, 2014 at 8:24 PM, Howard Hinnant <[email protected]> > wrote: >> >> On Aug 17, 2014, at 9:26 PM, Justin Bogner <[email protected]> wrote: >> >> > Howard Hinnant <[email protected]> writes: >> >> On Aug 17, 2014, at 9:06 PM, Justin Bogner <[email protected]> >> >> wrote: >> >> >> >>> I really don't think it's worth the cost of insantiating these very >> >>> fundamental templates in *every single user* to work around a >> >>> limitation >> >>> in the memory sanitizer. This is an unreasonable amount of overhead >> >>> for >> >>> standard library types. >> >> >> >> Always measure. I’m not saying you’re wrong. I’m saying you’re >> >> stating a performance conclusion without measurements (which should >> >> never be acceptable). >> > >> > I did measure :) Though, I sent it to llvm-dev and it probably should've >> > been cfe-dev. Sorry about that. >> > >> > http://lists.cs.uiuc.edu/pipermail/llvmdev/2014-August/075793.html >> >> Ah, I have not been monitoring llvm-dev. Thank you for the link. >> >> Howard >> > > > _______________________________________________ > cfe-commits mailing list > [email protected] > http://lists.cs.uiuc.edu/mailman/listinfo/cfe-commits > _______________________________________________ cfe-commits mailing list [email protected] http://lists.cs.uiuc.edu/mailman/listinfo/cfe-commits
