(class basic_string::Rep): Make release member function thread-safe for

ix86 (x>=4) and UltraSPARC.

git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@26820 138bc75d-0d04-0410-961f-82ee72b054a4

diff --git a/libstdc++/std/bastring.h b/libstdc++/std/bastring.h
index f188628..6206713 100644 (file)
--- a/libstdc++/std/bastring.h
+++ b/libstdc++/std/bastring.h
@@ -73,7 +73,34 @@ private:
     charT* data () { return reinterpret_cast<charT *>(this + 1); }
     charT& operator[] (size_t s) { return data () [s]; }
     charT* grab () { if (selfish) return clone (); ++ref; return data (); }
+#if defined __i486__ || defined __i586__ || defined __i686__
+    void release ()
+      {
+       size_t __val;
+       asm ("lock; xaddl %0, %2"
+            : "=r" (__val) : "0" (-1), "m" (ref) : "memory");
+       if (__val == 1)
+         delete this;
+      }
+#elif defined __sparcv9__
+    void release ()
+      {
+       size_t __newval, __oldval = ref;
+       do
+         {
+           __newval = __oldval - 1;
+           __asm__ ("cas       [%4], %2, %0"
+                    : "=r" (__oldval), "=m" (ref)
+                    : "r" (__oldval), "m" (ref), "r"(&(ref)), "0" (__newval));
+         }
+       while (__newval != __oldval);
+
+       if (__oldval == 0)
+         delete this;
+      }
+#else
     void release () { if (--ref == 0) delete this; }
+#endif
 
     inline static void * operator new (size_t, size_t);
     inline static void operator delete (void *);