[Bug libstdc++/80285] `std::make_shared` performs two separate allocations with `-fno-rtti`

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=80285

--- Comment #1 from Jonathan Wakely <redi at gcc dot gnu.org> ---
Author: redi
Date: Thu May 11 13:21:07 2017
New Revision: 247905

URL: https://gcc.gnu.org/viewcvs?rev=247905&root=gcc&view=rev
Log:
PR libstdc++/80285 optimize std::make_shared for -fno-rtti

        PR libstdc++/80285
        * include/bits/shared_ptr_base.h (_Sp_make_shared_tag::_S_ti): Define
        function to get unique fake std::type_info reference.
        (_Sp_counted_ptr_inplace::_M_get_deleter) [!__cpp_rtti]: Compare to
        _S_ti() fake reference.
        (__shared_ptr(_Sp_make_shared_tag, const Alloc&, Args&&...)): Share
        single implementation with or without RTTI enable.
        [!__cpp_rtti]: Pass fake reference to _M_get_deleter.
        * testsuite/20_util/shared_ptr/creation/alloc.cc: Change expected
        allocation and deallocation counts.
        * testsuite/20_util/shared_ptr/creation/single_allocation.cc: New.
        * testsuite/20_util/shared_ptr/creation/single_allocation_no_rtti.cc:
        New.

Added:
   
trunk/libstdc++-v3/testsuite/20_util/shared_ptr/creation/single_allocation.cc
   
trunk/libstdc++-v3/testsuite/20_util/shared_ptr/creation/single_allocation_no_rtti.cc
Modified:
    trunk/libstdc++-v3/ChangeLog
    trunk/libstdc++-v3/include/bits/shared_ptr_base.h
    trunk/libstdc++-v3/testsuite/20_util/shared_ptr/creation/alloc.cc