[PATCH] Use __builtin_memmove for trivially copy assignable types

[Glen Fernandes]

On Thu, Jul 19, 2018 at 10:01 AM Glen Fernandes wrote:
>
> I was still unclear about that, but I forwarded you an e-mail from
> Marshall with his answer when I asked whether libc++'s use of
> TriviallyCopyAssignable here was incorrect. Let me know if it applies
> here, and if not (and that interpretation of the standard is
> incorrect), I'll update the patch to do as you suggest and run the
> tests again.
>
> Glen

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.

Glen
-------------- next part --------------
commit 60bf5acca419df37752336c2008123558627ece7
Author: Glen Fernandes <glen.fernandes@gmail.com>
Date:   Thu Jul 19 10:27:54 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.

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,