What libraries use the We Know Where You Live optimization for std :: make_shared?

Question

More than two years ago, Stefan T. Lavavey described the space-saving savings that he implemented at Microsoft std::make_shared, and I do not know from conversations with him that Microsoft has nothing against other library implementations that use this optimization. If you know for sure whether other libraries were used (for example, for Gnu C ++, Clang, Intel C ++, plus Boost (for boost::make_shared)), please enter your answer. I do not have ready access to these many implementations make_shared, and I am not alone in delving into the depths of those whom I should see if they have implemented WKWYL optimization, but I hope that SO readers are answers for some libraries. I know, looking at the code that with Boost 1.52 WKWYL optimization was not implemented, but Boost is now up to version 1.55.

Note that this optimization is different from the std::make_sharedability to avoid dedicated heap allocation for the reference counter used std::shared_ptr. To discuss the difference between WKWYL and this optimization, refer to this question .

Answer 1

lib ++ implements optimization. See The difference between __shared_ptr_pointerand __shared_ptr_emplaceat http://llvm.org/viewvc/llvm-project/libcxx/trunk/include/memory?revision=210211&view=markup .

libstd++ . . _Sp_counted_ptr _Sp_counted_ptr_inplace https://gcc.gnu.org/viewcvs/gcc/trunk/libstdc%2B%2B-v3/include/bits/shared_ptr_base.h?revision=210015&view=markup.