On Mon, 14 Jul 2025 at 14:57, Thomas de Bock via Gcc <gcc@gcc.gnu.org> wrote: > > Hello all, I've been looking into a compiler optimization implemented by > clang but not gcc that substitutes a __dynamic_cast call for a simple vtable > ptr comparison in the case that the class being cast to is final. > > However this brings issues with it in some cases (specified in thread). I > believe having the optimization disabled by default, but adding a compiler > flag to enable it would be ideal. Code for the optimization is mostly done so > I'm looking to have this optimization available in gcc somehow now, > interested in hearing any opinions on this :) > > thread link: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63164#add_comment
I agree that we don't want to perform the optimization by default, but it would be useful to have an option to enable it when you know it's safe to do so. Have you done any measurements to show that the optimization is worth it?
