--- old/src/os_cpu/linux_x86/vm/atomic_linux_x86.hpp	2017-08-16 01:47:24.977232759 -0400
+++ new/src/os_cpu/linux_x86/vm/atomic_linux_x86.hpp	2017-08-16 01:47:24.869227210 -0400
@@ -85,6 +85,7 @@
                                                 T volatile* dest,
                                                 T compare_value,
                                                 cmpxchg_memory_order /* order */) const {
+  STATIC_ASSERT(1 == sizeof(T));
   __asm__ volatile ("lock cmpxchgb %1,(%3)"
                     : "=a" (exchange_value)
                     : "q" (exchange_value), "a" (compare_value), "r" (dest)
@@ -98,6 +99,7 @@
                                                 T volatile* dest,
                                                 T compare_value,
                                                 cmpxchg_memory_order /* order */) const {
+  STATIC_ASSERT(4 == sizeof(T));
   __asm__ volatile ("lock cmpxchgl %1,(%3)"
                     : "=a" (exchange_value)
                     : "r" (exchange_value), "a" (compare_value), "r" (dest)
@@ -150,6 +152,7 @@
                                                 T volatile* dest,
                                                 T compare_value,
                                                 cmpxchg_memory_order /* order */) const {
+  STATIC_ASSERT(8 == sizeof(T));
   __asm__ __volatile__ ("lock cmpxchgq %1,(%3)"
                         : "=a" (exchange_value)
                         : "r" (exchange_value), "a" (compare_value), "r" (dest)
@@ -194,7 +197,8 @@
                                                 T volatile* dest,
                                                 T compare_value,
                                                 cmpxchg_memory_order order) const {
-  return cmpxchg_using_stub<jlong>(_Atomic_cmpxchg_long, exchange_value, dest, compare_value);
+  STATIC_ASSERT(8 == sizeof(T));
+  return cmpxchg_using_helper<jlong>(_Atomic_cmpxchg_long, exchange_value, dest, compare_value);
 }
 
 inline jlong Atomic::load(const volatile jlong* src) {