rjmccall added a comment. In D136919#3906133 <https://reviews.llvm.org/D136919#3906133>, @rjmccall wrote:
> We talked about this on the Itanium list, and as currently specified, it is > absolutely not correct for `__bf16` to have the same mangling as > `std::bfloat16_t`, because `__bf16` does not have the correct semantics for > `std::bfloat16_t` and must be a distinct type. If GCC changed `__bf16` to > use the new mangling without also updating the semantics, it is a bug. > > That discussion was here: https://github.com/itanium-cxx-abi/cxx-abi/pull/147 > > If we want to implement `std::bfloat16_t` in Clang, we need to make it a > normal arithmetic type, and in practice it needs to guarantee > excess-precision arithmetic, as I discussed on that thread. Coincidentally, > we did recently implement excess-precision arithmetic in Clang for `_Float16`. Jakub Jelinek has clarified that GCC did indeed change the semantics of `__bf16` on i386 and x86_64 to be a proper extended floating point type. We could change the mangling to match GCC, but I think it would be inappropriate to do that without also matching the semantics change. Since the mangling change is trivial to land, I think the semantics change should happen first. Repository: rG LLVM Github Monorepo CHANGES SINCE LAST ACTION https://reviews.llvm.org/D136919/new/ https://reviews.llvm.org/D136919 _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
