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Re: [PATCH] fix generic std::atomic<T>::compare_exchange_{weak,strong}


----- Original Message -----
> On 07/26/2013 08:42 PM, Nathan Froyd wrote:
> > Sure, I can do that.  For maximum effectiveness, it'd be good to have it
> > check the specializations for atomic<>, too.  Is there something in the
> > libstdc++ testsuite for iterating template instantiations over a list of
> > types, or do I have to roll the list myself?
> testsuite/29_atomics already uses testsuite_common_types.h

New patch, this time with tests.  Let me know if test placement, etc. need
adjusting.

Tested on x86_64-unknown-linux-gnu.  OK for commit to trunk and active branches?

-Nathan

	* include/std/atomic (compare_exchange_weak, compare_exchange_strong):
	Add call to __cmpexch_failure_order.
	* testsuite/util/testsuite_common_types.h
	(compare_exchange_order_lowering): New generator.
	* testsuite/29_atomics/atomic/requirements/compare_exchange_lowering.cc:
	New test.

diff --git a/libstdc++-v3/ChangeLog b/libstdc++-v3/ChangeLog
index ac2cb45..3b79d91 100644
diff --git a/libstdc++-v3/include/std/atomic b/libstdc++-v3/include/std/atomic
index 813f574..2d66729 100644
--- a/libstdc++-v3/include/std/atomic
+++ b/libstdc++-v3/include/std/atomic
@@ -252,12 +252,14 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
       bool
       compare_exchange_weak(_Tp& __e, _Tp __i,
 			    memory_order __m = memory_order_seq_cst) noexcept
-      { return compare_exchange_weak(__e, __i, __m, __m); }
+      { return compare_exchange_weak(__e, __i, __m,
+                                     __cmpexch_failure_order(__m)); }
 
       bool
       compare_exchange_weak(_Tp& __e, _Tp __i,
 		     memory_order __m = memory_order_seq_cst) volatile noexcept
-      { return compare_exchange_weak(__e, __i, __m, __m); }
+      { return compare_exchange_weak(__e, __i, __m,
+                                     __cmpexch_failure_order(__m)); }
 
       bool
       compare_exchange_strong(_Tp& __e, _Tp __i, memory_order __s, 
@@ -276,12 +278,14 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
       bool
       compare_exchange_strong(_Tp& __e, _Tp __i,
 			       memory_order __m = memory_order_seq_cst) noexcept
-      { return compare_exchange_strong(__e, __i, __m, __m); }
+      { return compare_exchange_strong(__e, __i, __m,
+                                       __cmpexch_failure_order(__m)); }
 
       bool
       compare_exchange_strong(_Tp& __e, _Tp __i,
 		     memory_order __m = memory_order_seq_cst) volatile noexcept
-      { return compare_exchange_strong(__e, __i, __m, __m); }
+      { return compare_exchange_strong(__e, __i, __m,
+                                       __cmpexch_failure_order(__m)); }
     };
 
 
diff --git a/libstdc++-v3/testsuite/29_atomics/atomic/requirements/compare_exchange_lowering.cc b/libstdc++-v3/testsuite/29_atomics/atomic/requirements/compare_exchange_lowering.cc
new file mode 100644
index 0000000..75e7406
--- /dev/null
+++ b/libstdc++-v3/testsuite/29_atomics/atomic/requirements/compare_exchange_lowering.cc
@@ -0,0 +1,65 @@
+// { dg-options "-std=gnu++0x" }
+// { dg-do compile }
+
+// Copyright (C) 2008-2013 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 <testsuite_common_types.h>
+
+#define TEST_ALL_ORDERS()                       \
+  do {                                          \
+    ORDER_TEST(std::memory_order_relaxed);      \
+    ORDER_TEST(std::memory_order_consume);      \
+    ORDER_TEST(std::memory_order_acquire);      \
+    ORDER_TEST(std::memory_order_release);      \
+    ORDER_TEST(std::memory_order_acq_rel);      \
+    ORDER_TEST(std::memory_order_seq_cst);      \
+  } while(0)
+  
+void test01()
+{
+#define ORDER_TEST(ORDER)                                               \
+  do {                                                                  \
+    __gnu_test::compare_exchange_order_lowering<ORDER> test;            \
+    __gnu_cxx::typelist::apply_generator(test,                          \
+                                         __gnu_test::integral_types::type()); \
+  } while (0);
+  TEST_ALL_ORDERS();
+#undef ORDER_TEST
+
+  enum e { a, b, c };
+#define ORDER_TEST(ORDER)                               \
+  do {                                                  \
+    std::atomic<e> x(a);                                \
+    e expected = a;                                     \
+    x.compare_exchange_strong(expected, b, ORDER);      \
+    x.compare_exchange_weak(expected, c, ORDER);        \
+  } while (0);
+  TEST_ALL_ORDERS();
+#undef ORDER_TEST
+
+#define ORDER_TEST(ORDER)                       \
+  do {                                          \
+    std::atomic<void*> x(nullptr);              \
+    void* expected = nullptr;                   \
+    x.compare_exchange_strong(expected, nullptr, ORDER);        \
+    x.compare_exchange_weak(expected, nullptr, ORDER);          \
+  } while (0);
+  TEST_ALL_ORDERS();
+#undef ORDER_TEST
+}
diff --git a/libstdc++-v3/testsuite/util/testsuite_common_types.h b/libstdc++-v3/testsuite/util/testsuite_common_types.h
index 54d6a75..e7f081b 100644
--- a/libstdc++-v3/testsuite/util/testsuite_common_types.h
+++ b/libstdc++-v3/testsuite/util/testsuite_common_types.h
@@ -872,5 +872,22 @@ namespace __gnu_test
 	  = &_Concept::__constraint;
       }
   };
+
+#if __cplusplus >= 201103L
+  // Generator to test lowering requirements for compare-and-exchange.
+  template<std::memory_order order>
+  struct compare_exchange_order_lowering
+  {
+    template<typename _Tp>
+      void
+      operator()()
+      {
+        std::atomic<_Tp> x;
+        _Tp __expected = 0;
+        x.compare_exchange_strong(__expected, 1, order);
+        x.compare_exchange_weak(__expected, 1, order);
+      }
+  };
+#endif
 } // namespace __gnu_test
 #endif


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