On Tue, Jan 7, 2020 at 3:13 PM John McCall <rjmcc...@gmail.com> wrote: > > On Tue, Jan 7, 2020 at 3:02 PM Aaron Ballman <aa...@aaronballman.com> wrote: > > On Tue, Jan 7, 2020 at 2:57 PM John McCall via cfe-commits > > <cfe-commits@lists.llvm.org> wrote: > > > On Tue, Jan 7, 2020 at 1:44 PM Aaron Ballman via Phabricator > > > <revi...@reviews.llvm.org> wrote: > > > > Sorry to dredge up an old review, but I recently ran into a bug in this > > > > area and am not certain of how to fix it. What should happen if the asm > > > > label is a literal which is empty? > > > > > > The problems here are unique to empty labels, right? > > > > To the best of my knowledge, yes. > > > > > Can we just > > > diagnose this as an error? > > > > I don't think so -- GCC's function attribute documentation seems to > > suggest you should do this with noinline functions (see the docs for > > noinline here > > https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#Common-Function-Attributes) > > That's an assembly statement, not a label.
Oh! Good catch! It seems like GCC doesn't do good things when trying to link two functions with empty asm labels but Clang does seem to do something reasonable. I can't quite tell whether this is a case for a diagnostic or not. Note the generated assembly in: https://godbolt.org/z/HFfPs6 > > > Is this bug occurring with real code, or > > > is LLDB constructing something bizarre? > > > > It was a c-reduced test case that we found when doing AST dumping to > > JSON, so I think the code was probably real at one point. > > Unless your reducer is smart enough to try to minimize string > literals, which it might be. Also possible. Regardless, a failed assertion isn't a good outcome. If we think it's fine to diagnose empty labels, I'm fine with the change. I don't know enough about how asm labels are used to have a feeling for the correct way to resolve the issue. ~Aaron > > John. _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
