From 5979c1d4bdb6219cadd63e79a9d8f40eba942e15 Mon Sep 17 00:00:00 2001
From: Peter Dimov <pdimov@pdimov.com>
Date: Mon, 12 Mar 2012 17:37:51 +0000
Subject: [PATCH] Merge [77315] to release. Closes #5331.

[SVN r77317]
---
 .../smart_ptr/detail/spinlock_gcc_arm.hpp     | 29 +++++++++++++++++--
 1 file changed, 27 insertions(+), 2 deletions(-)

diff --git a/include/boost/smart_ptr/detail/spinlock_gcc_arm.hpp b/include/boost/smart_ptr/detail/spinlock_gcc_arm.hpp
index f58ea44..f1bbaf6 100644
--- a/include/boost/smart_ptr/detail/spinlock_gcc_arm.hpp
+++ b/include/boost/smart_ptr/detail/spinlock_gcc_arm.hpp
@@ -43,13 +43,38 @@ public:
     {
         int r;
 
+#if defined(__ARM_ARCH_6__) \
+    || defined(__ARM_ARCH_6J__) \
+    || defined(__ARM_ARCH_6K__) \
+    || defined(__ARM_ARCH_6Z__) \
+    || defined(__ARM_ARCH_6ZK__) \
+    || defined(__ARM_ARCH_6T2__) \
+    || defined(__ARM_ARCH_7__) \
+    || defined(__ARM_ARCH_7A__) \
+    || defined(__ARM_ARCH_7R__) \
+    || defined(__ARM_ARCH_7M__) \
+    || defined(__ARM_ARCH_7EM__)
+
         __asm__ __volatile__(
-            "swp %0, %1, [%2]\n\t"
-			BOOST_SP_ARM_BARRIER :
+            "ldrex %0, [%2]; \n"
+            "cmp %0, %1; \n"
+            "strexne %0, %1, [%2]; \n"
+            BOOST_SP_ARM_BARRIER :
             "=&r"( r ): // outputs
             "r"( 1 ), "r"( &v_ ): // inputs
             "memory", "cc" );
 
+#else
+
+        __asm__ __volatile__(
+            "swp %0, %1, [%2];\n"
+            BOOST_SP_ARM_BARRIER :
+            "=&r"( r ): // outputs
+            "r"( 1 ), "r"( &v_ ): // inputs
+            "memory", "cc" );
+
+#endif
+
         return r == 0;
     }