https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63164
--- Comment #8 from Florian Weimer <fw at gcc dot gnu.org> --- There's this big comment in typeinfo: // Determine whether typeinfo names for the same type are merged (in which // case comparison can just compare pointers) or not (in which case strings // must be compared), and whether comparison is to be implemented inline or // not. We used to do inline pointer comparison by default if weak symbols // are available, but even with weak symbols sometimes names are not merged // when objects are loaded with RTLD_LOCAL, so now we always use strcmp by // default. For ABI compatibility, we do the strcmp inline if weak symbols // are available, and out-of-line if not. Out-of-line pointer comparison // is used where the object files are to be portable to multiple systems, // some of which may not be able to use pointer comparison, but the // particular system for which libstdc++ is being built can use pointer // comparison; in particular for most ARM EABI systems, where the ABI // specifies out-of-line comparison. The compiler's target configuration // can override the defaults by defining __GXX_TYPEINFO_EQUALITY_INLINE to // 1 or 0 to indicate whether or not comparison is inline, and // __GXX_MERGED_TYPEINFO_NAMES to 1 or 0 to indicate whether or not pointer // comparison can be used. So I'm not sure how much we can optimize the final case for GNU systems.
