[PATCH] Use __builtin_memmove for trivially copy assignable types

[Glen Fernandes]

Use __builtin_memmove for trivially copy assignable types

2018-06-14  Glen Joseph Fernandes  <glenj...@gmail.com>

        * include/bits/stl_algobase.h
        (__is_simple_copy_move): Defined helper.
        (__copy_move_a): Used helper.
        (__copy_move_backward_a): Likewise.
        * testsuite/25_algorithms/copy/58982.cc: Updated tests.
        * testsuite/25_algorithms/copy_n/58982.cc: Likewise.

Tested x86_64-pc-linux-gnu.

Glen

commit 7ace2ad91fe7d2253b086aef8bfdb99f85d81f31
Author: Glen Fernandes <glenj...@gmail.com>
Date:   Fri Jun 15 07:33:07 2018 -0400

    Use __builtin_memmove for trivially copy assignable types
    
    2018-06-14  Glen Joseph Fernandes  <glenj...@gmail.com>
    
            * include/bits/stl_algobase.h
            (__is_simple_copy_move): Defined helper.
            (__copy_move_a): Used helper.
            (__copy_move_backward_a): Likewise.
            * testsuite/25_algorithms/copy/58982.cc: Updated tests.
            * testsuite/25_algorithms/copy_n/58982.cc: Likewise.

diff --git a/libstdc++-v3/include/bits/stl_algobase.h 
b/libstdc++-v3/include/bits/stl_algobase.h
index 022a3f159..d9e1a7958 100644
--- a/libstdc++-v3/include/bits/stl_algobase.h
+++ b/libstdc++-v3/include/bits/stl_algobase.h
@@ -72,10 +72,20 @@
 
 namespace std _GLIBCXX_VISIBILITY(default)
 {
 _GLIBCXX_BEGIN_NAMESPACE_VERSION
 
+  template<typename _Tp>
+    struct __is_simple_copy_move
+    {
+#if __cplusplus < 201103L
+      enum { __value = __is_trivial(_Tp) };
+#else
+      enum { __value = is_trivially_copy_assignable<_Tp>::value };
+#endif
+    };
+
 #if __cplusplus < 201103L
   // See http://gcc.gnu.org/ml/libstdc++/2004-08/msg00167.html: in a
   // nutshell, we are partially implementing the resolution of DR 187,
   // when it's safe, i.e., the value_types are equal.
   template<bool _BoolType>
@@ -375,11 +385,11 @@ _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_simple_copy_move<_ValueTypeI>::__value
                             && __is_pointer<_II>::__value
                             && __is_pointer<_OI>::__value
                             && __are_same<_ValueTypeI, _ValueTypeO>::__value);
 
       return std::__copy_move<_IsMove, __simple,
@@ -576,11 +586,11 @@ _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_simple_copy_move<_ValueType1>::__value
                             && __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/25_algorithms/copy/58982.cc 
b/libstdc++-v3/testsuite/25_algorithms/copy/58982.cc
index 03d918344..324f0e3b5 100644
--- a/libstdc++-v3/testsuite/25_algorithms/copy/58982.cc
+++ b/libstdc++-v3/testsuite/25_algorithms/copy/58982.cc
@@ -36,6 +36,6 @@ void
 test01(T* result)
 {
   T t[1];
   std::copy(t, t+1, result); // { dg-error "here" }
 }
-// { dg-prune-output "not assignable" }
+// { dg-prune-output "use of deleted function" }
diff --git a/libstdc++-v3/testsuite/25_algorithms/copy_n/58982.cc 
b/libstdc++-v3/testsuite/25_algorithms/copy_n/58982.cc
index dc488cd1f..3eb793218 100644
--- a/libstdc++-v3/testsuite/25_algorithms/copy_n/58982.cc
+++ b/libstdc++-v3/testsuite/25_algorithms/copy_n/58982.cc
@@ -36,6 +36,6 @@ void
 test01(T* result)
 {
   T t[1];
   std::copy_n(t, 1, result); // { dg-error "here" }
 }
-// { dg-prune-output "not assignable" }
+// { dg-prune-output "use of deleted function" }