Backport r221703 and r221945 from trunk to google/gcc-4_9 branch.

Google refs b/17136920, b/20312340.


git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/branches/google/gcc-4_9@222190 138bc75d-0d04-0410-961f-82ee72b054a4

5 files changed, 134 insertions, 2 deletions

diff --git a/libstdc++-v3/include/bits/atomic_base.h b/libstdc++-v3/include/bits/atomic_base.h
index 1fc0ebb7e40..ceead010ebe 100644
--- a/libstdc++-v3/include/bits/atomic_base.h
+++ b/libstdc++-v3/include/bits/atomic_base.h
@@ -355,7 +355,10 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
     private:
       typedef _ITp 	__int_type;
 
-      __int_type 	_M_i;
+      static constexpr int _S_alignment =
+        sizeof(_ITp) > alignof(_ITp) ? sizeof(_ITp) : alignof(_ITp);
+
+      alignas(_S_alignment) __int_type _M_i;
 
     public:
       __atomic_base() noexcept = default;
diff --git a/libstdc++-v3/include/std/atomic b/libstdc++-v3/include/std/atomic
index ece75a4e4ba..371144628cd 100644
--- a/libstdc++-v3/include/std/atomic
+++ b/libstdc++-v3/include/std/atomic
@@ -161,7 +161,15 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
     struct atomic
     {
     private:
-      _Tp _M_i;
+      // Align 1/2/4/8/16-byte types to at least their size.
+      static constexpr int _S_min_alignment
+	= (sizeof(_Tp) & (sizeof(_Tp) - 1)) || sizeof(_Tp) > 16
+	? 0 : sizeof(_Tp);
+
+      static constexpr int _S_alignment
+        = _S_min_alignment > alignof(_Tp) ? _S_min_alignment : alignof(_Tp);
+
+      alignas(_S_alignment) _Tp _M_i;
 
     public:
       atomic() noexcept = default;
diff --git a/libstdc++-v3/testsuite/29_atomics/atomic/62259.cc b/libstdc++-v3/testsuite/29_atomics/atomic/62259.cc
new file mode 100644
index 00000000000..42b45ec6aa3
--- /dev/null
+++ b/libstdc++-v3/testsuite/29_atomics/atomic/62259.cc
@@ -0,0 +1,59 @@
+// Copyright (C) 2015 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-require-atomic-builtins "" }
+// { dg-require-cstdint "" }
+// { dg-options "-std=gnu++11" }
+// { dg-do compile }
+
+#include <atomic>
+#include <cstdint>
+
+using std::int32_t;
+using std::int64_t;
+
+// libstdc++/62259
+
+struct twoints {
+  int32_t a;
+  int32_t b;
+};
+
+static_assert( alignof(std::atomic<twoints>) == alignof(int64_t),
+               "std::atomic not suitably aligned" );
+
+// libstdc++/65147
+
+struct power_of_two_obj {
+    char c [8];
+};
+
+std::atomic<power_of_two_obj> obj1;
+
+static_assert( alignof(obj1) == alignof(int64_t),
+               "std::atomic not suitably aligned" );
+
+struct container_struct {
+   char c[1];
+   std::atomic<power_of_two_obj> ao;
+};
+
+container_struct obj2;
+
+static_assert( alignof(obj2.ao) == alignof(int64_t),
+               "std::atomic not suitably aligned" );
+
diff --git a/libstdc++-v3/testsuite/29_atomics/atomic/65147.cc b/libstdc++-v3/testsuite/29_atomics/atomic/65147.cc
new file mode 100644
index 00000000000..15c794e2b38
--- /dev/null
+++ b/libstdc++-v3/testsuite/29_atomics/atomic/65147.cc
@@ -0,0 +1,29 @@
+// Copyright (C) 2015 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-options "-std=gnu++11" }
+// { dg-do compile }
+
+#include <atomic>
+
+struct S16 {
+   char c[16];
+};
+
+static_assert( alignof(std::atomic<S16>) >= 16,
+    "atomic<S16> must be aligned to at least its size" );
+
diff --git a/libstdc++-v3/testsuite/29_atomics/atomic_integral/65147.cc b/libstdc++-v3/testsuite/29_atomics/atomic_integral/65147.cc
new file mode 100644
index 00000000000..1cc33e3b8d6
--- /dev/null
+++ b/libstdc++-v3/testsuite/29_atomics/atomic_integral/65147.cc
@@ -0,0 +1,33 @@
+// Copyright (C) 2015 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-options "-std=gnu++11" }
+// { dg-do compile }
+
+#include <atomic>
+
+static_assert( alignof(std::atomic<char>) >= sizeof(char),
+    "atomic<char> must be aligned to at least its size" );
+static_assert( alignof(std::atomic<short>) >= sizeof(short),
+    "atomic<short> must be aligned to at least its size" );
+static_assert( alignof(std::atomic<int>) >= sizeof(int),
+    "atomic<int> must be aligned to at least its size" );
+static_assert( alignof(std::atomic<long>) >= sizeof(long),
+    "atomic<long> must be aligned to at least its size" );
+static_assert( alignof(std::atomic<long long>) >= sizeof(long long),
+    "atomic<long long> must be aligned to at least its size" );
+