https://gcc.gnu.org/bugzilla/show_bug.cgi?id=87604
Bug ID: 87604
Summary: memmove without std::allocator
Product: gcc
Version: 9.0
Status: UNCONFIRMED
Keywords: missed-optimization
Severity: enhancement
Priority: P3
Component: libstdc++
Assignee: unassigned at gcc dot gnu.org
Reporter: glisse at gcc dot gnu.org
Target Milestone: ---
The current overload of __uninitialized_copy_a that eventually dispatches to a
call to memmove is restricted to std::allocator. However, it should also be
valid for a number of other allocators. Libc++ has a trick where it detects
allocators that do not provide construct() and thus use the one from
allocator_traits. I expect most custom C++11 allocators redefine allocation but
not construction, so this seems like a useful extension of the special case.
(this will become less important at -O3 if PR 86024 gets implemented)
(If the relocation patch is approved, that version may also need to check
destroy())
