hfinkel added a comment. In https://reviews.llvm.org/D31885#730853, @hfinkel wrote:
> ... > > >> (And the nonsensicality of the standard very much continues. The code that >> we've all agreed is obviously being miscompiled here is still a strict >> violation of the "improved" union rules in C++, and if we decide to treat it >> as ill-formed we're going to break a massive amount of code (and vector code >> in particular heavily uses unions), because trust me, nobody is reliably >> placement-newing union fields when they're non-trivial. C++'s new rules are >> unworkable in part because they rely on C++-specific features that cannot be >> easily adopted in headers which need to be language-neutral.) > > I think we all agree that the vector types need to have their scalar > (element) types as parents in the current TBAA representation. That's a > separate change that we should just make. That, unfortunately, only fixes a > subset of the union-related miscompiles. Looking at this in more detail, we actually generate builtin-vector types which use char* as their access type (always, even for floating-point vectors). It is only the struct-path info which causes the issue for the test case here. It might be reasonable to make this **less** conservative, but that's another story... Repository: rL LLVM https://reviews.llvm.org/D31885 _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
