[libcxx-commits] [libcxx] [libc++] Optimize vector growth for nothrow move constructible types (PR #214690)

[Louis Dionne via libcxx-commits]

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@@ -402,32 +404,46 @@ template <class _Alloc, class _ContiguousIterator>
 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 void __uninitialized_allocator_relocate(
     _Alloc& __alloc, _ContiguousIterator __first, _ContiguousIterator __last, _ContiguousIterator __result) {
   static_assert(__libcpp_is_contiguous_iterator<_ContiguousIterator>::value, "");
-  using _ValueType = typename iterator_traits<_ContiguousIterator>::value_type;
   static_assert(
       __is_cpp17_move_insertable_v<_Alloc>, "The specified type does not meet the requirements of Cpp17MoveInsertable");
-  if (__libcpp_is_constant_evaluated() || !__is_trivially_relocatable_v<_ValueType> ||
-      !__allocator_has_trivial_move_construct_v<_Alloc, _ValueType> ||
-      !__allocator_has_trivial_destroy_v<_Alloc, _ValueType>) {
+
+  using __value_type = typename iterator_traits<_ContiguousIterator>::value_type;
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ldionne wrote:

I'm not super happy with making this function more complex, instead I'd rather reimplement public API operations in terms of simpler building blocks like `__uninitialized_relocate` without a strong exception safety guarantee (and use different building blocks when the types are potentially throwing), but I think this is correct and it should be an optimization, so I'm fine with the patch.

https://github.com/llvm/llvm-project/pull/214690