On 5 April 2013 11:13, Jonathan Wakely wrote: > This should fix the handlers for platforms without __atomic_exchange > for pointers by using a mutex. I used the old __mutex type not > std::mutex because it's available on more platforms and works for the > 'single' thread model too. I didn't try to optimise away the atomic > ops for accessing the handlers because throwing exceptions and > getting/setting these handlers should not be on the fast path of > performance sensitive code. > > PR libstdc++/56841 > * libsupc++/eh_ptr.cc (rethrow_exception): Use get_unexpected() and > get_terminate() accessors. > * libsupc++/eh_throw.cc (__cxa_throw): Likewise. > * libsupc++/eh_terminate.cc: Use mutex when atomic builtins not > available. > * libsupc++/new_handler.cc: Likewise. > > Tested x86_64-linux and hppa2.0-linux, committed to trunk.
I did think about adding a new accessor for internal use: std::pair<unexpected_handler, terminate_handler> __get_handlers(); which could be used in eh_throw.cc and eh_ptr.cc to avoid doing two separate PIC calls to get_unexpected() and get_terminate(), and so that platforms using a mutex would only lock it once. We can reconsider doing that later, it's only an optimisation not needed for correctness. I think we could also remove the extern declarations of __unexpected_handler and __terminate_handler and make them internal to eh_terminate.cc, as I already did for __new_handler. Although those names were visible to users they should not be used, are not part of the IA-64 ABI, and are not exported from the shared lib.
