> On May 25, 2017, at 12:54 AM, Elijah DeLee <[email protected]> wrote: > > > > On Wed, May 24, 2017 at 7:15 PM, Roy Stogner <[email protected] > <mailto:[email protected]>> wrote: > > On Wed, 24 May 2017, Boyce Griffith wrote: > > (Elijah, it might be a good idea to have an optional flag that lets > users say which libMesh method to use, and to default to dbg for > debugging builds and to opt for non-debugging builds.) > > Be careful, if you're not just scarfing our CXXFLAGS and CPPFLAGS: > libmesh dbg builds are *not* typically ABI-compatible with opt builds! > > > I suppose we are "scarfing" them, libMesh is built with the same compiler > flags as each build of IBAMR in this system.
Yes, we are scarfing these. I am very familiar with libMesh's debugging flags. :-) > 1. If you build against libstdc++ and you don't configure with > --disable-glibcxx-debugging, then half the standard library container > classes get different ABIs in dbg mode. In theory I think this should > result in a link-time failure, but in practice I've never seen a mixed > build produce a link error and I have seen mixed builds produce plenty > of segfaults. > > > What I am understanding is: > > If using debugging flags: > 1) Use "--with-methods=dbg" > 2) Use "--disable-glibcxx-debugging" > > If doing optimized build: > 1) use "--with-methods=opt" I think this is correct for the cases where we build libMesh for the user. We also should have BuildSystem set up to allow users to specify their own external libMesh build. In this case, I think it is reasonable to require the user to pick one method at configure time. > 2. If you don't configure with --disable-reference-counting, then the > struct layout of ReferenceCounter and subclasses (a.k.a. practically > every heavyweight libMesh object) depends on whether or not the > preprocessor macro DEBUG is defined. > > 3. The error in (2) is just the only one I can name off the top of my > head, because it was the first one that caused a mixed build to > segfault on clang. Since we don't strive for ABI consistency between > build options, I wouldn't be surprised to find other ABI changes that > the failing application just never reached. > > > So, in which case do we need to make sure "--disable-reference-counting" is > used? I think that we do want to use reference counting with debugging. As long as we don't mix-and-match different builds of libMesh, which sounds like a dubious idea to me in any case, then I don't think it is a problem. > Thanks! > Elijah > > 4. Matt, if any of the above makes it into a future version of you > guys' "Firetran" parody, try to strip off embarrassing identifying > details? Thanks. > --- > Roy > ------------------------------------------------------------------------------ Check out the vibrant tech community on one of the world's most engaging tech sites, Slashdot.org! http://sdm.link/slashdot _______________________________________________ Libmesh-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/libmesh-users
