re PR libstdc++/51811 ([C++0x] Incorrect increment/decrement of atomic pointers)

2012-02-03  Benjamin Kosnik  <bkoz@redhat.com>

	PR libstdc++/51811
	* include/bits/atomic_base.h (atomic<_Tp*>): Fix offsets.
	* testsuite/29_atomics/atomic/operators/51811.cc: New.
	* testsuite/29_atomics/atomic/operators/pointer_partial_void.cc: New.

From-SVN: r183875

libstdc++-v3/ChangeLog

@@ -1,3 +1,10 @@
+2012-02-03  Benjamin Kosnik  <bkoz@redhat.com>
+
+	PR libstdc++/51811
+	* include/bits/atomic_base.h (atomic<_Tp*>): Fix offsets.
+	* testsuite/29_atomics/atomic/operators/51811.cc: New.
+	* testsuite/29_atomics/atomic/operators/pointer_partial_void.cc: New.
+
 2012-02-03  Jakub Jelinek  <jakub@redhat.com>
 
 	* config/abi/post/i386-linux-gnu/baseline_symbols.txt: Update.

libstdc++-v3/include/bits/atomic_base.h

@@ -1,6 +1,6 @@
 // -*- C++ -*- header.
 
-// Copyright (C) 2008, 2009, 2010, 2011 Free Software Foundation, Inc.
+// Copyright (C) 2008, 2009, 2010, 2011, 2012 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
@@ -621,6 +621,13 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
 
       __pointer_type 	_M_p;
 
+      // Factored out to facilitate explicit specialization.
+      constexpr ptrdiff_t
+      _M_type_size(ptrdiff_t __d) { return __d * sizeof(_PTp); }
+
+      constexpr ptrdiff_t
+      _M_type_size(ptrdiff_t __d) volatile { return __d * sizeof(_PTp); }
+
     public:
       __atomic_base() noexcept = default;
       ~__atomic_base() noexcept = default;
@@ -669,43 +676,51 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
 
       __pointer_type
       operator++() noexcept
-      { return __atomic_add_fetch(&_M_p, 1, memory_order_seq_cst); }
+      { return __atomic_add_fetch(&_M_p, _M_type_size(1),
+				  memory_order_seq_cst); }
 
       __pointer_type
       operator++() volatile noexcept
-      { return __atomic_add_fetch(&_M_p, 1, memory_order_seq_cst); }
+      { return __atomic_add_fetch(&_M_p, _M_type_size(1),
+				  memory_order_seq_cst); }
 
       __pointer_type
       operator--() noexcept
-      { return __atomic_sub_fetch(&_M_p, 1, memory_order_seq_cst); }
+      { return __atomic_sub_fetch(&_M_p, _M_type_size(1),
+				  memory_order_seq_cst); }
 
       __pointer_type
       operator--() volatile noexcept
-      { return __atomic_sub_fetch(&_M_p, 1, memory_order_seq_cst); }
+      { return __atomic_sub_fetch(&_M_p, _M_type_size(1),
+				  memory_order_seq_cst); }
 
       __pointer_type
       operator+=(ptrdiff_t __d) noexcept
-      { return __atomic_add_fetch(&_M_p, __d, memory_order_seq_cst); }
+      { return __atomic_add_fetch(&_M_p, _M_type_size(__d),
+				  memory_order_seq_cst); }
 
       __pointer_type
       operator+=(ptrdiff_t __d) volatile noexcept
-      { return __atomic_add_fetch(&_M_p, __d, memory_order_seq_cst); }
+      { return __atomic_add_fetch(&_M_p, _M_type_size(__d),
+				  memory_order_seq_cst); }
 
       __pointer_type
       operator-=(ptrdiff_t __d) noexcept
-      { return __atomic_sub_fetch(&_M_p, __d, memory_order_seq_cst); }
+      { return __atomic_sub_fetch(&_M_p, _M_type_size(__d),
+				  memory_order_seq_cst); }
 
       __pointer_type
       operator-=(ptrdiff_t __d) volatile noexcept
-      { return __atomic_sub_fetch(&_M_p, __d, memory_order_seq_cst); }
+      { return __atomic_sub_fetch(&_M_p, _M_type_size(__d),
+				  memory_order_seq_cst); }
 
       bool
       is_lock_free() const noexcept
-      { return __atomic_is_lock_free (sizeof (_M_p), &_M_p); }
+      { return __atomic_is_lock_free(_M_type_size(1), &_M_p); }
 
       bool
       is_lock_free() const volatile noexcept
-      { return __atomic_is_lock_free (sizeof (_M_p), &_M_p); }
+      { return __atomic_is_lock_free(_M_type_size(1), &_M_p); }
 
       void
       store(__pointer_type __p,
@@ -789,22 +804,22 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
       __pointer_type
       fetch_add(ptrdiff_t __d,
 		memory_order __m = memory_order_seq_cst) noexcept
-      { return __atomic_fetch_add(&_M_p, __d, __m); }
+      { return __atomic_fetch_add(&_M_p, _M_type_size(__d), __m); }
 
       __pointer_type
       fetch_add(ptrdiff_t __d,
 		memory_order __m = memory_order_seq_cst) volatile noexcept
-      { return __atomic_fetch_add(&_M_p, __d, __m); }
+      { return __atomic_fetch_add(&_M_p, _M_type_size(__d), __m); }
 
       __pointer_type
       fetch_sub(ptrdiff_t __d,
 		memory_order __m = memory_order_seq_cst) noexcept
-      { return __atomic_fetch_sub(&_M_p, __d, __m); }
+      { return __atomic_fetch_sub(&_M_p, _M_type_size(__d), __m); }
 
       __pointer_type
       fetch_sub(ptrdiff_t __d,
 		memory_order __m = memory_order_seq_cst) volatile noexcept
-      { return __atomic_fetch_sub(&_M_p, __d, __m); }
+      { return __atomic_fetch_sub(&_M_p, _M_type_size(__d), __m); }
     };
 
   // @} group atomics

libstdc++-v3/testsuite/29_atomics/atomic/operators/51811.cc

@@ -0,0 +1,90 @@
+// { dg-options "-std=gnu++0x" }
+
+// Copyright (C) 2012 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/>.
+
+#include <atomic>
+#include <cstdlib> //std::abs
+#include <testsuite_hooks.h>
+
+// libstdc++/51811
+// pointer arithimetic vs. atomic<_Tp*> specialization
+int main(void)
+{
+  bool test __attribute__((unused)) = true;
+
+  using namespace std;
+
+  typedef int 	value_type;
+  const size_t n = 2;
+  value_type value = 42;
+  atomic<value_type*> p, p2, p3;
+
+  // operator++
+  {
+    p = &value;
+    p2 = p++;
+    VERIFY (p != p2);
+    
+    value_type* vp(p);
+    value_type* vp2(p2);
+    ptrdiff_t dist = reinterpret_cast<char*>(vp) - reinterpret_cast<char*>(vp2);
+    VERIFY ( std::abs(dist) == sizeof(value_type));
+  
+    p = &value;
+    p3 = ++p;
+    VERIFY (p == p3);
+  }
+
+  // operator--
+  {
+    p = &value;
+    p2 = p--;
+    VERIFY (p != p2);
+
+    value_type* vp(p);
+    value_type* vp2(p2);
+    ptrdiff_t dist = reinterpret_cast<char*>(vp) - reinterpret_cast<char*>(vp2);
+    VERIFY ( std::abs(dist) == sizeof(value_type));
+
+    p = &value;
+    p3 = --p;
+    VERIFY (p == p3);
+  }
+
+  // operator+=
+  {
+    p = &value;
+    value_type* vp(p);
+    p+=n;
+    value_type* vp2(p);
+    ptrdiff_t dist = reinterpret_cast<char*>(vp) - reinterpret_cast<char*>(vp2);
+    VERIFY ( std::abs(dist) == sizeof(value_type) * n);
+  }
+
+  // operator-=
+  {
+    p = &value;
+    value_type* vp(p);
+    p-=n;
+    value_type* vp2(p);
+    ptrdiff_t dist = reinterpret_cast<char*>(vp) - reinterpret_cast<char*>(vp2);
+    VERIFY ( std::abs(dist) == sizeof(value_type) * n);
+  }
+
+  return 0;
+}

libstdc++-v3/testsuite/29_atomics/atomic/operators/pointer_partial_void.cc

@@ -0,0 +1,70 @@
+// { dg-options "-std=gnu++0x" }
+
+// Copyright (C) 2012 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/>.
+
+#include <atomic>
+#include <cstdlib> //std::abs
+#include <testsuite_hooks.h>
+
+// pointer arithimetic vs. atomic<void*>.
+// atomic<void*> vs. explicitly specialized w/o operators, like atomic_bool?
+int main(void)
+{
+  // bool test __attribute__((unused)) = true;
+
+  using namespace std;
+
+  typedef int 	value_type;
+  const size_t n = 2;
+  value_type value = 42;
+  value_type* p = &value;
+  void* vp = p;
+  ptrdiff_t dist(0);
+
+  atomic<void*> a(vp);
+
+  // operator++
+  void* vp2(a);
+  a++;
+  void* vp3(a);
+  dist = reinterpret_cast<char*>(vp2) - reinterpret_cast<char*>(vp3);
+  // VERIFY ( std::abs(dist) == sizeof(void*));
+
+  // operator--
+  void* vp4(a);
+  a--;
+  void* vp5(a);
+  dist = reinterpret_cast<char*>(vp4) - reinterpret_cast<char*>(vp5);
+  // VERIFY ( std::abs(dist) == sizeof(void*));
+
+  // operator+=
+  void* vp6(a);
+  a+=n;
+  void* vp7(a);
+  dist = reinterpret_cast<char*>(vp6) - reinterpret_cast<char*>(vp7);
+  // VERIFY ( std::abs(dist) == sizeof(void*) * n);
+
+  // operator-=
+  void* vp8(a);
+  a-=n;
+  void* vp9(a);
+  dist = reinterpret_cast<char*>(vp8) - reinterpret_cast<char*>(vp9);
+  //VERIFY ( std::abs(dist) == sizeof(void*) * n);
+
+  return 0;
+}