Handle alignment in __atomic_is_lock_free

gcc:

2015-09-17  Richard Henderson  <rth@redhat.com>

	PR libstdc++/65913
	* builtins.c (fold_builtin_atomic_always_lock_free): Handle fake
	pointers that encode the alignment of the object.

libstdc++-v3:

2015-09-17  Jonathan Wakely  <jwakely@redhat.com>

	PR libstdc++/65913
	* include/bits/atomic_base.h (__atomic_base<_TTp>::is_lock_free(),
	__atomic_base<_PTp*>::is_lock_free()): Call the built-in with the
	immediate pointer value, not a variable.
	* include/std/atomic (atomic<T>::is_lock_free()): Likewise.
	* testsuite/29_atomics/atomic/65913.cc: New.

git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@227878 138bc75d-0d04-0410-961f-82ee72b054a4

4 files changed, 60 insertions, 14 deletions

diff --git a/libstdc++-v3/ChangeLog b/libstdc++-v3/ChangeLog
index fd1ed22cb93..a1b0c3545f8 100644
--- a/libstdc++-v3/ChangeLog
+++ b/libstdc++-v3/ChangeLog
@@ -1,5 +1,12 @@
 2015-09-17  Jonathan Wakely  <jwakely@redhat.com>
 
+	PR libstdc++/65913
+	* include/bits/atomic_base.h (__atomic_base<_TTp>::is_lock_free(),
+	__atomic_base<_PTp*>::is_lock_free()): Call the built-in with the
+	immediate pointer value, not a variable.
+	* include/std/atomic (atomic<T>::is_lock_free()): Likewise.
+	* testsuite/29_atomics/atomic/65913.cc: New.
+
 	* testsuite/experimental/filesystem/operations/canonical.cc: Remove
 	non-deterministic part of the test.
 
diff --git a/libstdc++-v3/include/bits/atomic_base.h b/libstdc++-v3/include/bits/atomic_base.h
index 79769cf46d8..75a7ca7731a 100644
--- a/libstdc++-v3/include/bits/atomic_base.h
+++ b/libstdc++-v3/include/bits/atomic_base.h
@@ -350,17 +350,17 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
       bool
       is_lock_free() const noexcept
       {
-	// Produce a fake, minimally aligned pointer.
-	void *__a = reinterpret_cast<void *>(-__alignof(_M_i));
-	return __atomic_is_lock_free(sizeof(_M_i), __a);
+	// Use a fake, minimally aligned pointer.
+	return __atomic_is_lock_free(sizeof(_M_i),
+	    reinterpret_cast<void *>(-__alignof(_M_i)));
       }
 
       bool
       is_lock_free() const volatile noexcept
       {
-	// Produce a fake, minimally aligned pointer.
-	void *__a = reinterpret_cast<void *>(-__alignof(_M_i));
-	return __atomic_is_lock_free(sizeof(_M_i), __a);
+	// Use a fake, minimally aligned pointer.
+	return __atomic_is_lock_free(sizeof(_M_i),
+	    reinterpret_cast<void *>(-__alignof(_M_i)));
       }
 
       _GLIBCXX_ALWAYS_INLINE void
@@ -666,16 +666,16 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
       is_lock_free() const noexcept
       {
 	// Produce a fake, minimally aligned pointer.
-	void *__a = reinterpret_cast<void *>(-__alignof(_M_p));
-	return __atomic_is_lock_free(sizeof(_M_p), __a);
+	return __atomic_is_lock_free(sizeof(_M_p),
+	    reinterpret_cast<void *>(-__alignof(_M_p)));
       }
 
       bool
       is_lock_free() const volatile noexcept
       {
 	// Produce a fake, minimally aligned pointer.
-	void *__a = reinterpret_cast<void *>(-__alignof(_M_p));
-	return __atomic_is_lock_free(sizeof(_M_p), __a);
+	return __atomic_is_lock_free(sizeof(_M_p),
+	    reinterpret_cast<void *>(-__alignof(_M_p)));
       }
 
       _GLIBCXX_ALWAYS_INLINE void
diff --git a/libstdc++-v3/include/std/atomic b/libstdc++-v3/include/std/atomic
index 125e37a2838..cdd1f0b992d 100644
--- a/libstdc++-v3/include/std/atomic
+++ b/libstdc++-v3/include/std/atomic
@@ -208,16 +208,16 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
       is_lock_free() const noexcept
       {
 	// Produce a fake, minimally aligned pointer.
-	void *__a = reinterpret_cast<void *>(-__alignof(_M_i));
-	return __atomic_is_lock_free(sizeof(_M_i), __a);
+	return __atomic_is_lock_free(sizeof(_M_i),
+	    reinterpret_cast<void *>(-__alignof(_M_i)));
       }
 
       bool
       is_lock_free() const volatile noexcept
       {
 	// Produce a fake, minimally aligned pointer.
-	void *__a = reinterpret_cast<void *>(-__alignof(_M_i));
-	return __atomic_is_lock_free(sizeof(_M_i), __a);
+	return __atomic_is_lock_free(sizeof(_M_i),
+	    reinterpret_cast<void *>(-__alignof(_M_i)));
       }
 
       void
diff --git a/libstdc++-v3/testsuite/29_atomics/atomic/65913.cc b/libstdc++-v3/testsuite/29_atomics/atomic/65913.cc
new file mode 100644
index 00000000000..dbdd9cf7db6
--- /dev/null
+++ b/libstdc++-v3/testsuite/29_atomics/atomic/65913.cc
@@ -0,0 +1,39 @@
+// 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-do run { target x86_64-*-linux* powerpc*-*-linux* } }
+// { dg-options "-std=gnu++11 -O0" }
+
+#include <atomic>
+#include <testsuite_hooks.h>
+
+// PR libstdc++/65913
+
+void
+test01()
+{
+  struct Int { int i; };
+  VERIFY( std::atomic<Int>{}.is_lock_free() );
+  VERIFY( std::atomic<int>{}.is_lock_free() );
+  VERIFY( std::atomic<int*>{}.is_lock_free() );
+}
+
+int
+main()
+{
+  test01();
+}