[libcxx-commits] [libcxx] [libc++] Optimize vector growing of trivially relocatable types (PR #76657)

[Louis Dionne via libcxx-commits]

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@@ -0,0 +1,39 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef _LIBCPP___TYPE_TRAITS_IS_TRIVIALLY_RELOCATABLE_H
+#define _LIBCPP___TYPE_TRAITS_IS_TRIVIALLY_RELOCATABLE_H
+
+#include <__config>
+#include <__type_traits/enable_if.h>
+#include <__type_traits/integral_constant.h>
+#include <__type_traits/is_same.h>
+#include <__type_traits/is_trivially_copyable.h>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#  pragma GCC system_header
+#endif
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+#if __has_builtin(__is_trivially_relocatable)
+template <class _Tp, class = void>
+struct __libcpp_is_trivially_relocatable : integral_constant<bool, __is_trivially_relocatable(_Tp)> {};
+#else
+template <class _Tp, class = void>
+struct __libcpp_is_trivially_relocatable : is_trivially_copyable<_Tp> {};
+#endif
+
+template <class _Tp>
+struct __libcpp_is_trivially_relocatable<_Tp,
----------------
ldionne wrote:

Since trivially-relocatable is technically not a term of art in the standard, please document what it means. No need to write an essay, but we shouldn't assume that the reader already knows what this is about.

https://github.com/llvm/llvm-project/pull/76657