[libcxx-commits] [PATCH] D124328: [libc++] Forward more often to memmove in copy

[Nikolas Klauser via Phabricator via libcxx-commits]

philnik created this revision.
philnik added reviewers: var-const, Mordante.
Herald added a project: All.
philnik requested review of this revision.
Herald added a project: libc++.
Herald added a subscriber: libcxx-commits.
Herald added a reviewer: libc++.

In D122982 <https://reviews.llvm.org/D122982> I accidentally disabled the memmove optimization. This re-enables it and adds more cases where copy forwards to memmove.
Fixes https://github.com/llvm/llvm-project/issues/33687


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D124328

Files:
  libcxx/include/__algorithm/copy.h


Index: libcxx/include/__algorithm/copy.h
===================================================================
--- libcxx/include/__algorithm/copy.h
+++ libcxx/include/__algorithm/copy.h
@@ -56,33 +56,64 @@
   return std::make_pair(__first + __n, __result + __n);
 }
 
-template <class _InValueT,
-          class _OutValueT,
-          class = __enable_if_t<is_same<typename remove_const<_InValueT>::type, _OutValueT>::value
-                             && is_trivially_copy_assignable<_OutValueT>::value> >
+template <class>
+struct __is_trivially_copy_assignable_unwrapped_impl : false_type {};
+
+template <class _Type>
+struct __is_trivially_copy_assignable_unwrapped_impl<_Type*> : is_trivially_copy_assignable<_Type> {};
+
+template <class _Iter>
+struct __is_trivially_copy_assignable_unwrapped
+    : __is_trivially_copy_assignable_unwrapped_impl<decltype(std::__unwrap_iter<_Iter>(std::declval<_Iter>()))> {};
+
+template <class _InIter,
+          class _OutIter,
+          class = __enable_if_t<is_same<typename remove_const<typename iterator_traits<_InIter>::value_type>::type,
+                                        typename iterator_traits<_OutIter>::value_type>::value
+                             && __is_trivially_copy_assignable_unwrapped<_OutIter>::value
+                             && __is_trivially_copy_assignable_unwrapped<_InIter>::value> >
 inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_AFTER_CXX11
-pair<reverse_iterator<_InValueT*>, reverse_iterator<_OutValueT*> >
-__copy_impl(reverse_iterator<_InValueT*> __first,
-            reverse_iterator<_InValueT*> __last,
-            reverse_iterator<_OutValueT*> __result) {
-  auto __first_base = __first.base();
-  auto __last_base = __last.base();
-  auto __result_base = __result.base();
+pair<reverse_iterator<_InIter>, reverse_iterator<_OutIter> >
+__copy_impl(reverse_iterator<_InIter> __first,
+            reverse_iterator<_InIter> __last,
+            reverse_iterator<_OutIter> __result) {
+  auto __first_base = std::__unwrap_iter(__first.base());
+  auto __last_base = std::__unwrap_iter(__last.base());
+  auto __result_base = std::__unwrap_iter(__result.base());
   auto __result_first = __result_base - (__first_base - __last_base);
   std::__copy_impl(__last_base, __first_base, __result_first);
-  return std::make_pair(__last, reverse_iterator<_OutValueT*>(__result_first));
+  return std::make_pair(__last, reverse_iterator<_OutIter>(std::__rewrap_iter(__result.base(), __result_first)));
 }
 
-template <class _InIter, class _Sent, class _OutIter>
+template <class _InIter, class _Sent, class _OutIter,
+          __enable_if_t<!is_copy_constructible<_InIter>::value
+                     || !is_copy_constructible<_Sent>::value
+                     || !is_copy_constructible<_OutIter>::value>* = nullptr>
 inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_AFTER_CXX11
 pair<_InIter, _OutIter> __copy(_InIter __first, _Sent __last, _OutIter __result) {
   return std::__copy_impl(std::move(__first), std::move(__last), std::move(__result));
 }
 
+template <class _InIter, class _Sent, class _OutIter, __enable_if_t<is_copy_constructible<_InIter>::value
+                     && is_copy_constructible<_Sent>::value
+                     && is_copy_constructible<_OutIter>::value>* = nullptr>
+inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_AFTER_CXX11 pair<_InIter, _OutIter> __copy(_InIter, _Sent, _OutIter);
+
+template <class _InIter, class _Sent, class _OutIter>
+inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_AFTER_CXX11
+pair<reverse_iterator<reverse_iterator<_InIter> >, reverse_iterator<reverse_iterator<_OutIter> > >
+__copy_impl(reverse_iterator<reverse_iterator<_InIter>> __first,
+            reverse_iterator<reverse_iterator<_Sent>> __last,
+            reverse_iterator<reverse_iterator<_OutIter>> __result) {
+  auto __ret = std::__copy(__first.base().base(), __last.base().base(), __result.base().base());
+  return std::make_pair(reverse_iterator<reverse_iterator<_InIter>>(reverse_iterator<_InIter>(__ret.first)),
+                        reverse_iterator<reverse_iterator<_OutIter>>(reverse_iterator<_OutIter>(__ret.second)));
+}
+
 template <class _InIter, class _Sent, class _OutIter,
           __enable_if_t<is_copy_constructible<_InIter>::value
                      && is_copy_constructible<_Sent>::value
-                     && is_copy_constructible<_OutIter>::value> >
+                     && is_copy_constructible<_OutIter>::value>*>
 inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_AFTER_CXX11
 pair<_InIter, _OutIter> __copy(_InIter __first, _Sent __last, _OutIter __result) {
   auto __ret = std::__copy_impl(std::__unwrap_iter(__first), std::__unwrap_iter(__last), std::__unwrap_iter(__result));


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