--- a/hotspot/src/share/vm/runtime/atomic.cpp	Fri Jun 21 10:55:26 2013 -0700
+++ b/hotspot/src/share/vm/runtime/atomic.cpp	Sun Jun 23 22:08:28 2013 -0700
@@ -80,3 +80,32 @@
   }
   return old;
 }
+
+void Atomic::inc(volatile short* dest) {
+  // Most platforms do not support atomic increment on a 2-byte value. However,
+  // if the value occupies the most significant 16 bits of an aligned 32-bit
+  // word, then we can do this with an atomic add of 0x10000 to the 32-bit word.
+  //
+  // The least significant parts of this 32-bit word will never be affected, even
+  // in case of overflow/underflow.
+  //
+  // Use the ATOMIC_SHORT_PAIR macro to get the desired alignment.
+#ifdef VM_LITTLE_ENDIAN
+  assert((intx(dest) & 0x03) == 0x02, "wrong alignment");
+  (void)Atomic::add(0x10000, (volatile int*)(dest-1));
+#else
+  assert((intx(dest) & 0x03) == 0x00, "wrong alignment");
+  (void)Atomic::add(0x10000, (volatile int*)(dest));
+#endif
+}
+
+void Atomic::dec(volatile short* dest) {
+#ifdef VM_LITTLE_ENDIAN
+  assert((intx(dest) & 0x03) == 0x02, "wrong alignment");
+  (void)Atomic::add(-0x10000, (volatile int*)(dest-1));
+#else
+  assert((intx(dest) & 0x03) == 0x00, "wrong alignment");
+  (void)Atomic::add(-0x10000, (volatile int*)(dest));
+#endif
+}
+