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Re: Extending Temporary buffer for rvalues


Christopher Jefferson wrote:
> How's this?
Good, thanks. I'm attaching below what I actually committed to mainline.
> Added a couple of tests. Note that this patch isn't enough to let
> stable_sort sort rvalue references, so that isn't tested. These tests
> just ensure the code works properly if a construction throws (at least
> no memory is leaked).
Great. Looking forward... ;)

Paolo.

////////////////////
2009-08-29  Chris Jefferson  <chris@bubblescope.net>

	* include/bits/move.h (_GLIBCXX_FORWARD): Add.
	* include/bits/stl_uninitialized.h (__uninitialized_construct_range):
	Add.
	* include/bits/stl_tempbuf.h (_Temporary_buffer::
	_Temporary_buffer(_ForwardIterator, _ForwardIterator)): Use the latter.
	* include/bits/stl_construct.h (_Construct(_T1*, _T2&&)): Add in
	C++0x mode.
	* testsuite/util/testsuite_hooks.h (operator<(const copy_tracker&,
    	const copy_tracker&)): Add.
	* testsuite/25_algorithms/stable_partition/mem_check.cc: New.
	* testsuite/25_algorithms/stable_sort/mem_check.cc: Likewise.
Index: include/bits/move.h
===================================================================
--- include/bits/move.h	(revision 151204)
+++ include/bits/move.h	(working copy)
@@ -84,8 +84,10 @@
 _GLIBCXX_END_NAMESPACE
 
 #define _GLIBCXX_MOVE(_Tp) std::move(_Tp)
+#define _GLIBCXX_FORWARD(_Tp, __val) std::forward<_Tp>(__val)
 #else
 #define _GLIBCXX_MOVE(_Tp) (_Tp)
+#define _GLIBCXX_FORWARD(_Tp, __val) (__val)
 #endif
 
 _GLIBCXX_BEGIN_NAMESPACE(std)
Index: include/bits/stl_uninitialized.h
===================================================================
--- include/bits/stl_uninitialized.h	(revision 151204)
+++ include/bits/stl_uninitialized.h	(working copy)
@@ -173,6 +173,68 @@
 
 
   template<bool>
+    struct __uninitialized_construct_range_dispatch
+    {
+      template<typename _ForwardIterator, typename _Tp>
+        static void
+        __ucr(_ForwardIterator __first, _ForwardIterator __last,
+	      _Tp& __value)
+        {
+	  if(__first == __last)
+	    return;
+
+	  _ForwardIterator __cur = __first;
+	  __try
+	    {
+	      std::_Construct(&*__first, _GLIBCXX_MOVE(__value));
+	      _ForwardIterator __prev = __cur;
+	      ++__cur;
+	      for(; __cur != __last; ++__cur, ++__prev)
+		std::_Construct(&*__cur, _GLIBCXX_MOVE(*__prev));
+	      __value = _GLIBCXX_MOVE(*__prev);
+	    }
+	  __catch(...)
+	    {
+	      std::_Destroy(__first, __cur);
+	      __throw_exception_again;
+	    }
+	}
+    };
+
+  template<>
+    struct __uninitialized_construct_range_dispatch<true>
+    {
+      template<typename _ForwardIterator, typename _Tp>
+        static void
+        __ucr(_ForwardIterator, _ForwardIterator, _Tp&) { }
+    };
+
+  // Constructs objects in the range [first, last).
+  // Note that while these new objects will take valid values,
+  // their exact value is not defined. In particular they may
+  // be 'moved from'.
+  //
+  // While __value may altered during this algorithm, it will have
+  // the same value when the algorithm finishes, unless one of the
+  // constructions throws.
+  //
+  // Requirements: _ForwardIterator::value_type(_Tp&&) is valid.
+  template<typename _ForwardIterator, typename _Tp>
+    inline void
+    __uninitialized_construct_range(_ForwardIterator __first,
+				    _ForwardIterator __last,
+				    _Tp& __value)
+    {
+      typedef typename std::iterator_traits<_ForwardIterator>::value_type
+	_ValueType;
+
+      std::__uninitialized_construct_range_dispatch<
+        __has_trivial_constructor(_ValueType)>::
+	  __ucr(__first, __last, __value);
+    }
+
+
+  template<bool>
     struct __uninitialized_fill_n
     {
       template<typename _ForwardIterator, typename _Size, typename _Tp>
Index: include/bits/stl_tempbuf.h
===================================================================
--- include/bits/stl_tempbuf.h	(revision 151204)
+++ include/bits/stl_tempbuf.h	(working copy)
@@ -188,8 +188,9 @@
 					    value_type>(_M_original_len));
 	  _M_buffer = __p.first;
 	  _M_len = __p.second;
-	  if (!__is_pod(_Tp) && _M_len > 0)
-	    std::uninitialized_fill_n(_M_buffer, _M_len, *__first);
+	  if(_M_buffer)
+	    std::__uninitialized_construct_range(_M_buffer, _M_buffer + _M_len,
+						 *__first);
 	}
       __catch(...)
 	{
Index: include/bits/stl_construct.h
===================================================================
--- include/bits/stl_construct.h	(revision 151204)
+++ include/bits/stl_construct.h	(working copy)
@@ -67,11 +67,16 @@
    */
   template<typename _T1, typename _T2>
     inline void
+#ifdef __GXX_EXPERIMENTAL_CXX0X__
+    // Allow perfect forwarding
+    _Construct(_T1* __p, _T2&& __value)
+#else
     _Construct(_T1* __p, const _T2& __value)
+#endif
     {
       // _GLIBCXX_RESOLVE_LIB_DEFECTS
       // 402. wrong new expression in [some_]allocator::construct
-      ::new(static_cast<void*>(__p)) _T1(__value);
+      ::new(static_cast<void*>(__p)) _T1(_GLIBCXX_FORWARD(_T2, __value));
     }
 
   /**
Index: testsuite/25_algorithms/stable_partition/mem_check.cc
===================================================================
--- testsuite/25_algorithms/stable_partition/mem_check.cc	(revision 0)
+++ testsuite/25_algorithms/stable_partition/mem_check.cc	(revision 0)
@@ -0,0 +1,71 @@
+// Copyright (C) 2009 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/>.
+
+// 25.2.12 [lib.alg.partitions] Partitions.
+
+#include <algorithm>
+#include <testsuite_hooks.h>
+#include <testsuite_iterators.h>
+
+using __gnu_test::test_container;
+using __gnu_test::random_access_iterator_wrapper;
+using __gnu_test::copy_tracker;
+using __gnu_test::copy_constructor;
+using __gnu_test::assignment_operator;
+using __gnu_test::destructor;
+
+typedef test_container<copy_tracker, random_access_iterator_wrapper> Container;
+
+const int A[] = {10, 20, 1, 11, 2, 21, 28, 29, 12, 35, 15, 27, 6, 16, 7, 
+                 25, 17, 8, 23, 18, 9, 19, 24, 30, 13, 4, 14, 22, 26};
+
+bool even(const copy_tracker& ct)
+{ return ct.id() < 19; }
+
+void
+test1(int throw_count)
+{
+  bool test __attribute__((unused)) = true;
+
+  copy_tracker vals[30];
+  for(int i = 0; i < 30; ++i)
+    vals[i] = A[i];
+
+  Container con(vals, vals + 30);
+  copy_tracker::reset();
+  copy_constructor::throw_on(throw_count);
+  int throw_occurred = 0;
+  try
+    {
+      std::stable_partition(con.begin(), con.end(), even);
+    }
+  catch(...) 
+    {
+      throw_occurred = 1;
+    }
+
+  // If a throw occurred in copy_constructor, we will end up with one more
+  // copy_construct than destructor.
+  VERIFY( destructor::count() == copy_constructor::count() - throw_occurred );
+}
+
+int main()
+{
+  for(int i = 0; i < 32; ++i)
+    test1(i);
+  return 0;
+}
Index: testsuite/25_algorithms/stable_sort/mem_check.cc
===================================================================
--- testsuite/25_algorithms/stable_sort/mem_check.cc	(revision 0)
+++ testsuite/25_algorithms/stable_sort/mem_check.cc	(revision 0)
@@ -0,0 +1,103 @@
+// Copyright (C) 2009 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/>.
+
+// 25.3.1.2 [lib.stable.sort]
+
+#include <algorithm>
+#include <testsuite_hooks.h>
+#include <testsuite_iterators.h>
+
+using __gnu_test::test_container;
+using __gnu_test::random_access_iterator_wrapper;
+using __gnu_test::copy_tracker;
+using __gnu_test::copy_constructor;
+using __gnu_test::assignment_operator;
+using __gnu_test::destructor;
+
+typedef test_container<copy_tracker, random_access_iterator_wrapper> Container;
+
+const int A[] = {10, 20, 1, 11, 2, 21, 28, 29, 12, 35, 15, 27, 6, 16, 7, 
+                 25, 17, 8, 23, 18, 9, 19, 24, 30, 13, 4, 14, 22, 26};
+
+void
+test_mem1(int throw_count)
+{
+  bool test __attribute__((unused)) = true;
+
+  copy_tracker vals[30];
+  for(int i = 0; i < 30; ++i)
+    vals[i] = A[i];
+
+  Container con(vals, vals + 30);
+  copy_tracker::reset();
+  copy_constructor::throw_on(throw_count);
+  int throw_occurred = 0;
+  try
+    {
+      std::stable_sort(con.begin(), con.end());
+    }
+  catch(...) 
+    {
+      throw_occurred = 1;
+    }
+
+  // If a throw occurred in copy_constructor, we will end up with one more
+  // copy_construct than destructor.
+  VERIFY( destructor::count() == copy_constructor::count() - throw_occurred );
+}
+
+bool
+is_ordered(const copy_tracker& lhs, const copy_tracker& rhs)
+{ return lhs < rhs; }
+
+void
+test_mem2(int throw_count)
+{
+  bool test __attribute__((unused)) = true;
+
+  copy_tracker vals[30];
+  for(int i = 0; i < 30; ++i)
+    vals[i] = A[i];
+
+  Container con(vals, vals + 30);
+  copy_tracker::reset();
+  copy_constructor::throw_on(throw_count);
+  int throw_occurred = 0;
+  try
+    {
+      std::stable_sort(con.begin(), con.end(), is_ordered);
+    }
+  catch(...) 
+    {
+      throw_occurred = 1;
+    }
+
+  // If a throw occurred in copy_constructor, we will end up with one more
+  // copy_construct than destructor.
+  VERIFY( destructor::count() == copy_constructor::count() - throw_occurred );
+}
+
+int main()
+{
+  for(int i = 0; i < 60; ++i)
+  {
+    test_mem1(i);
+    test_mem2(i);
+  }
+
+  return 0;
+}
Index: testsuite/util/testsuite_hooks.h
===================================================================
--- testsuite/util/testsuite_hooks.h	(revision 151204)
+++ testsuite/util/testsuite_hooks.h	(working copy)
@@ -301,6 +301,10 @@
   operator==(const copy_tracker& lhs, const copy_tracker& rhs)
   { return lhs.id() == rhs.id(); }
 
+  inline bool
+  operator<(const copy_tracker& lhs, const copy_tracker& rhs)
+  { return lhs.id() < rhs.id(); }
+
   // Class for checking required type conversions, implicit and
   // explicit for given library data structures. 
   template<typename _Container>

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