[PATCH] Use __builtin_memmove for trivially copy assignable types

Glen Fernandes glen.fernandes@gmail.com
Thu Jul 19 15:04:00 GMT 2018


On Thu, Jul 19, 2018 at 10:40 AM Jonathan Wakely <jwakely@redhat.com> wrote:
> On 19/07/18 10:32 -0400, Glen Fernandes wrote:
> >Attached: patch.txt
> >Use __builtin_memmove for trivially copyable types
> >2018-07-19  Glen Joseph Fernandes  <glenjofe@gmail.com>
> >    * include/bits/stl_algobase.h
> >    (__copy_move_a): Used __is_trivially_copyable.
> >    (__copy_move_backward_a): Likewise.
> >Tested x86_64-pc-linux-gnu.
>
> Ah, that was quick :-)
>
> Can we keep the new test you added in the previous patch? It seems
> useful to add anyway.

Affirmative. Attached: patch.txt

Use __builtin_memmove for trivially copyable types

2018-07-19  Glen Joseph Fernandes  <glenjofe@gmail.com>

    * include/bits/stl_algobase.h
    (__copy_move_a): Used __is_trivially_copyable.
    (__copy_move_backward_a): Likewise.
    * testsuite/20_util/specialized_algorithms/uninitialized_copy/1.cc:
    New test.

Glen
-------------- next part --------------
commit f08d827c2e7e525f94b31d9ad5c22dab5a84e451
Author: Glen Fernandes <glen.fernandes@gmail.com>
Date:   Thu Jul 19 10:54:50 2018 -0400

    Use __builtin_memmove for trivially copyable types
    
    2018-07-19  Glen Joseph Fernandes  <glenjofe@gmail.com>
    
        * include/bits/stl_algobase.h
        (__copy_move_a): Used __is_trivially_copyable.
        (__copy_move_backward_a): Likewise.
        * testsuite/20_util/specialized_algorithms/uninitialized_copy/1.cc:
        New test.

diff --git a/libstdc++-v3/include/bits/stl_algobase.h b/libstdc++-v3/include/bits/stl_algobase.h
index 16a3f83b6..f0130bc41 100644
--- a/libstdc++-v3/include/bits/stl_algobase.h
+++ b/libstdc++-v3/include/bits/stl_algobase.h
@@ -389,11 +389,11 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
     __copy_move_a(_II __first, _II __last, _OI __result)
     {
       typedef typename iterator_traits<_II>::value_type _ValueTypeI;
       typedef typename iterator_traits<_OI>::value_type _ValueTypeO;
       typedef typename iterator_traits<_II>::iterator_category _Category;
-      const bool __simple = (__is_trivial(_ValueTypeI)
+      const bool __simple = (__is_trivially_copyable(_ValueTypeI)
 			     && __is_pointer<_II>::__value
 			     && __is_pointer<_OI>::__value
 			     && __are_same<_ValueTypeI, _ValueTypeO>::__value);
 
       return std::__copy_move<_IsMove, __simple,
@@ -591,11 +591,11 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
     __copy_move_backward_a(_BI1 __first, _BI1 __last, _BI2 __result)
     {
       typedef typename iterator_traits<_BI1>::value_type _ValueType1;
       typedef typename iterator_traits<_BI2>::value_type _ValueType2;
       typedef typename iterator_traits<_BI1>::iterator_category _Category;
-      const bool __simple = (__is_trivial(_ValueType1)
+      const bool __simple = (__is_trivially_copyable(_ValueType1)
 			     && __is_pointer<_BI1>::__value
 			     && __is_pointer<_BI2>::__value
 			     && __are_same<_ValueType1, _ValueType2>::__value);
 
       return std::__copy_move_backward<_IsMove, __simple,
diff --git a/libstdc++-v3/testsuite/20_util/specialized_algorithms/uninitialized_copy/1.cc b/libstdc++-v3/testsuite/20_util/specialized_algorithms/uninitialized_copy/1.cc
new file mode 100644
index 000000000..461d1f242
--- /dev/null
+++ b/libstdc++-v3/testsuite/20_util/specialized_algorithms/uninitialized_copy/1.cc
@@ -0,0 +1,37 @@
+// Copyright (C) 2018 Free Software Foundation, Inc.
+//
+// This file is part of the GNU ISO C++ Library.  This library is free
+// software; you can redistribute it and/or modify it under the
+// terms of the GNU General Public License as published by the
+// Free Software Foundation; either version 3, or (at your option)
+// any later version.
+
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License along
+// with this library; see the file COPYING3.  If not see
+// <http://www.gnu.org/licenses/>.
+
+// { dg-do compile { target c++11 } }
+
+#include <memory>
+
+struct T
+{
+  T() { }
+  T(const T&) = delete;
+};
+
+static_assert(__is_trivially_assignable(T&, const T&) &&
+  !__is_trivial(T), "T is only trivially copy assignable");
+
+void
+test01(T* result)
+{
+  T t[1];
+  std::uninitialized_copy(t, t+1, result); // { dg-error "here" }
+}
+// { dg-prune-output "use of deleted function" }


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