PR libstdc++/51798 continued

PR libstdc++/51798 continued
	* include/bits/shared_ptr_base.h
	(_Sp_counted_base<_S_atomic>::_M_add_ref_lock): Hoist initial load
	outside compare_exchange loop.
	* include/tr1/shared_ptr.h: Same.
	* include/parallel/compatibility.h (__compare_and_swap_32): Use strong
	version of compare_exchange.
	(__compare_and_swap_64): Same.
	* include/profile/impl/profiler_state.h (__gnu_profile::__turn): Same.
	* libsupc++/guard.cc (__cxa_guard_acquire): Same.

From-SVN: r184171

6 files changed, 29 insertions, 16 deletions

diff --git a/libstdc++-v3/ChangeLog b/libstdc++-v3/ChangeLog
index af3f50a..723007c 100644
--- a/libstdc++-v3/ChangeLog
+++ b/libstdc++-v3/ChangeLog
@@ -1,3 +1,16 @@
+2012-02-13  Richard Henderson  <rth@redhat.com>
+
+	PR libstdc++/51798 continued.
+	* include/bits/shared_ptr_base.h
+	(_Sp_counted_base<_S_atomic>::_M_add_ref_lock): Hoist initial load
+	outside compare_exchange loop.
+	* include/tr1/shared_ptr.h: Same.
+	* include/parallel/compatibility.h (__compare_and_swap_32): Use strong
+	version of compare_exchange.
+	(__compare_and_swap_64): Same.
+	* include/profile/impl/profiler_state.h (__gnu_profile::__turn): Same.
+	* libsupc++/guard.cc (__cxa_guard_acquire): Same.
+
 2012-02-10  Benjamin Kosnik  <bkoz@redhat.com>
             Jonathan Wakely  <jwakely.gcc@gmail.com>
 
diff --git a/libstdc++-v3/include/bits/shared_ptr_base.h b/libstdc++-v3/include/bits/shared_ptr_base.h
index ebdc7ed..c48c18e 100644
--- a/libstdc++-v3/include/bits/shared_ptr_base.h
+++ b/libstdc++-v3/include/bits/shared_ptr_base.h
@@ -236,13 +236,11 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
     _M_add_ref_lock()
     {
       // Perform lock-free add-if-not-zero operation.
-      _Atomic_word __count;
+      _Atomic_word __count = _M_use_count;
       do
 	{
-	  __count = _M_use_count;
 	  if (__count == 0)
 	    __throw_bad_weak_ptr();
-	  
 	  // Replace the current counter value with the old value + 1, as
 	  // long as it's not changed meanwhile. 
 	}
diff --git a/libstdc++-v3/include/parallel/compatibility.h b/libstdc++-v3/include/parallel/compatibility.h
index 460345e..ed75215 100644
--- a/libstdc++-v3/include/parallel/compatibility.h
+++ b/libstdc++-v3/include/parallel/compatibility.h
@@ -252,8 +252,9 @@ namespace __gnu_parallel
                __replacement, __comparand)
              == __comparand;
 #elif defined(__GNUC__)
-    return __atomic_compare_exchange_n(__ptr, &__comparand, __replacement, true,
-				       __ATOMIC_ACQ_REL, __ATOMIC_RELAXED);
+    return __atomic_compare_exchange_n(__ptr, &__comparand, __replacement,
+				       false, __ATOMIC_ACQ_REL,
+				       __ATOMIC_RELAXED);
 #elif defined(__SUNPRO_CC) && defined(__sparc)
     return atomic_cas_32((volatile unsigned int*)__ptr, __comparand,
                          __replacement) == __comparand;
@@ -299,13 +300,15 @@ namespace __gnu_parallel
 #endif
 
 #elif defined(__GNUC__) && defined(__x86_64)
-    return __atomic_compare_exchange_n(__ptr, &__comparand, __replacement, true,
-				       __ATOMIC_ACQ_REL, __ATOMIC_RELAXED);
+    return __atomic_compare_exchange_n(__ptr, &__comparand, __replacement,
+				       false, __ATOMIC_ACQ_REL,
+				       __ATOMIC_RELAXED);
 #elif defined(__GNUC__) && defined(__i386) &&                   \
   (defined(__i686) || defined(__pentium4) || defined(__athlon)  \
    || defined(__k8) || defined(__core2))
-    return __atomic_compare_exchange_n(__ptr, &__comparand, __replacement, true,
-				       __ATOMIC_ACQ_REL, __ATOMIC_RELAXED);
+    return __atomic_compare_exchange_n(__ptr, &__comparand, __replacement,
+				       false, __ATOMIC_ACQ_REL,
+				       __ATOMIC_RELAXED);
 #elif defined(__SUNPRO_CC) && defined(__sparc)
     return atomic_cas_64((volatile unsigned long long*)__ptr,
                          __comparand, __replacement) == __comparand;
diff --git a/libstdc++-v3/include/profile/impl/profiler_state.h b/libstdc++-v3/include/profile/impl/profiler_state.h
index 573aa0e..d48801a 100644
--- a/libstdc++-v3/include/profile/impl/profiler_state.h
+++ b/libstdc++-v3/include/profile/impl/profiler_state.h
@@ -48,7 +48,7 @@ namespace __gnu_profile
   { 
     __state_type inv(__INVALID);
     return __atomic_compare_exchange_n(&_GLIBCXX_PROFILE_DATA(__state),
-				       &inv, __s, true, __ATOMIC_ACQ_REL, 
+				       &inv, __s, false, __ATOMIC_ACQ_REL, 
 				       __ATOMIC_RELAXED);
   }
 
diff --git a/libstdc++-v3/include/tr1/shared_ptr.h b/libstdc++-v3/include/tr1/shared_ptr.h
index 723e317..5a1eb03 100644
--- a/libstdc++-v3/include/tr1/shared_ptr.h
+++ b/libstdc++-v3/include/tr1/shared_ptr.h
@@ -237,13 +237,11 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
     _M_add_ref_lock()
     {
       // Perform lock-free add-if-not-zero operation.
-      _Atomic_word __count;
+      _Atomic_word __count = _M_use_count;
       do
 	{
-	  __count = _M_use_count;
 	  if (__count == 0)
 	    __throw_bad_weak_ptr();
-	  
 	  // Replace the current counter value with the old value + 1, as
 	  // long as it's not changed meanwhile. 
 	}
diff --git a/libstdc++-v3/libsupc++/guard.cc b/libstdc++-v3/libsupc++/guard.cc
index b7b8d3f..adc9608 100644
--- a/libstdc++-v3/libsupc++/guard.cc
+++ b/libstdc++-v3/libsupc++/guard.cc
@@ -251,8 +251,9 @@ namespace __cxxabiv1
 
 	while (1)
 	  {
-	    if (__atomic_compare_exchange_n(gi, &expected, pending_bit, true,
-					    __ATOMIC_ACQ_REL, __ATOMIC_RELAXED))
+	    if (__atomic_compare_exchange_n(gi, &expected, pending_bit, false,
+					    __ATOMIC_ACQ_REL,
+					    __ATOMIC_RELAXED))
 	      {
 		// This thread should do the initialization.
 		return 1;
@@ -266,7 +267,7 @@ namespace __cxxabiv1
 	     if (expected == pending_bit)
 	       {
 		 int newv = expected | waiting_bit;
-		 if (!__atomic_compare_exchange_n(gi, &expected, newv, true,
+		 if (!__atomic_compare_exchange_n(gi, &expected, newv, false,
 						  __ATOMIC_ACQ_REL, 
 						  __ATOMIC_RELAXED))
 		   continue;