--- old/src/hotspot/cpu/x86/stubGenerator_x86_64.cpp	2018-09-26 10:02:21.993171704 -0400
+++ new/src/hotspot/cpu/x86/stubGenerator_x86_64.cpp	2018-09-26 10:02:20.421080243 -0400
@@ -610,7 +610,7 @@
     address start = __ pc();
 
     __ movl(rax, c_rarg2);
-   if ( os::is_MP() ) __ lock();
+    __ lock();
     __ cmpxchgl(c_rarg0, Address(c_rarg1, 0));
     __ ret(0);
 
@@ -636,7 +636,7 @@
     address start = __ pc();
 
     __ movsbq(rax, c_rarg2);
-   if ( os::is_MP() ) __ lock();
+    __ lock();
     __ cmpxchgb(c_rarg0, Address(c_rarg1, 0));
     __ ret(0);
 
@@ -662,7 +662,7 @@
     address start = __ pc();
 
     __ movq(rax, c_rarg2);
-   if ( os::is_MP() ) __ lock();
+    __ lock();
     __ cmpxchgq(c_rarg0, Address(c_rarg1, 0));
     __ ret(0);
 
@@ -683,7 +683,7 @@
     address start = __ pc();
 
     __ movl(rax, c_rarg0);
-   if ( os::is_MP() ) __ lock();
+    __ lock();
     __ xaddl(Address(c_rarg1, 0), c_rarg0);
     __ addl(rax, c_rarg0);
     __ ret(0);
@@ -705,7 +705,7 @@
     address start = __ pc();
 
     __ movptr(rax, c_rarg0); // Copy to eax we need a return value anyhow
-   if ( os::is_MP() ) __ lock();
+    __ lock();
     __ xaddptr(Address(c_rarg1, 0), c_rarg0);
     __ addptr(rax, c_rarg0);
     __ ret(0);