Implement sized deallocation for std::allocator and friends.
Summary:
C++14 sized deallocation is disabled by default due to ABI concerns. However, when a user manually enables it then libc++ should take advantage of it since sized deallocation can provide a significant performance win depending on the underlying malloc implementation. (Note that libc++'s definitions of sized delete don't do anything special yet, but users are free to provide their own).
This patch updates __libcpp_deallocate to selectively call sized operator delete when it's available. `__libcpp_deallocate_unsized` should be used when the size of the allocation is unknown.
On Apple this patch makes no attempt to determine if the sized operator delete is unavailable, only that the language feature is enabled. This could cause a compile error when using `std::allocator`, but the same compile error would occur whenever the user calls `new`, so I don't think it's a problem.
Reviewers: ldionne, mclow.lists
Reviewed By: ldionne
Subscribers: rsmith, ckennelly, libcxx-commits, christof
Differential Revision: https://reviews.llvm.org/D53120
git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@345281 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/include/memory b/include/memory
index 1d28a52..ef35cc2 100644
--- a/include/memory
+++ b/include/memory
@@ -1799,8 +1799,8 @@
" 'n' exceeds maximum supported size");
return static_cast<pointer>(_VSTD::__libcpp_allocate(__n * sizeof(_Tp), __alignof(_Tp)));
}
- _LIBCPP_INLINE_VISIBILITY void deallocate(pointer __p, size_type) _NOEXCEPT
- {_VSTD::__libcpp_deallocate((void*)__p, __alignof(_Tp));}
+ _LIBCPP_INLINE_VISIBILITY void deallocate(pointer __p, size_type __n) _NOEXCEPT
+ {_VSTD::__libcpp_deallocate((void*)__p, __n * sizeof(_Tp), __alignof(_Tp));}
_LIBCPP_INLINE_VISIBILITY size_type max_size() const _NOEXCEPT
{return size_type(~0) / sizeof(_Tp);}
#if !defined(_LIBCPP_HAS_NO_RVALUE_REFERENCES) && !defined(_LIBCPP_HAS_NO_VARIADICS)
@@ -1900,8 +1900,8 @@
" 'n' exceeds maximum supported size");
return static_cast<pointer>(_VSTD::__libcpp_allocate(__n * sizeof(_Tp), __alignof(_Tp)));
}
- _LIBCPP_INLINE_VISIBILITY void deallocate(pointer __p, size_type) _NOEXCEPT
- {_VSTD::__libcpp_deallocate((void*) const_cast<_Tp *>(__p), __alignof(_Tp));}
+ _LIBCPP_INLINE_VISIBILITY void deallocate(pointer __p, size_type __n) _NOEXCEPT
+ {_VSTD::__libcpp_deallocate((void*) const_cast<_Tp *>(__p), __n * sizeof(_Tp), __alignof(_Tp));}
_LIBCPP_INLINE_VISIBILITY size_type max_size() const _NOEXCEPT
{return size_type(~0) / sizeof(_Tp);}
#if !defined(_LIBCPP_HAS_NO_RVALUE_REFERENCES) && !defined(_LIBCPP_HAS_NO_VARIADICS)
@@ -2052,7 +2052,7 @@
inline _LIBCPP_INLINE_VISIBILITY
void return_temporary_buffer(_Tp* __p) _NOEXCEPT
{
- _VSTD::__libcpp_deallocate((void*)__p, __alignof(_Tp));
+ _VSTD::__libcpp_deallocate_unsized((void*)__p, __alignof(_Tp));
}
#if _LIBCPP_STD_VER <= 14 || defined(_LIBCPP_ENABLE_CXX17_REMOVED_AUTO_PTR)