Further investigation required as to whether SPARC actually does
require special handling.

--- a/src/hotspot/share/gc/shared/memset_with_concurrent_readers.hpp	   :: 
+++ b/src/hotspot/share/gc/shared/memset_with_concurrent_readers.hpp	   :: 
@@ -32,8 +32,19 @@
 
 // Fill a block of memory with value, like memset, but with the
 // understanding that there may be concurrent readers of that memory.
+void memset_with_concurrent_readers(void* to, int value, size_t size);
+
+#ifdef SPARC
+
+// SPARC requires special handling.  See SPARC-specific definition.
+
+#else
+// All others just use memset.
+
 inline void memset_with_concurrent_readers(void* to, int value, size_t size) {
   ::memset(to, value, size);
 }
 
+#endif // End of target dispatch.
+
 #endif // SHARE_GC_SHARED_MEMSET_WITH_CONCURRENT_READERS_HPP