https://gcc.gnu.org/bugzilla/show_bug.cgi?id=70940
--- Comment #11 from Jonathan Wakely <redi at gcc dot gnu.org> --- Author: redi Date: Mon Jul 23 19:40:28 2018 New Revision: 262935 URL: https://gcc.gnu.org/viewcvs?rev=262935&root=gcc&view=rev Log: PR libstdc++/70940 optimize pmr::resource_adaptor for allocators using malloc pmr::resource_adaptor can avoid allocating an oversized buffer and doing manual alignment within that buffer when the wrapped allocator is known to always meet the requested alignment. Specifically, if the allocator is known to use malloc or new directly, then we can call the allocator directly for any fundamental alignment. PR libstdc++/70940 * include/experimental/memory_resource (__resource_adaptor_common::_AlignMgr::_M_unadjust): Add assertion. (__resource_adaptor_common::__guaranteed_alignment): New helper to give maximum alignment an allocator guarantees. Specialize for known allocators using new and malloc. (__resource_adaptor_imp::do_allocate): Use __guaranteed_alignment. (__resource_adaptor_imp::do_deallocate): Likewise. * testsuite/experimental/memory_resource/new_delete_resource.cc: Check that new and delete are called with expected sizes. Modified: trunk/libstdc++-v3/ChangeLog trunk/libstdc++-v3/include/experimental/memory_resource trunk/libstdc++-v3/testsuite/experimental/memory_resource/new_delete_resource.cc
