src/hotspot/cpu/x86/assembler_x86.hpp

@@ -1348,11 +1348,10 @@
     LoadLoad   = 1 << 0
   };
 
   // Serializes memory and blows flags
   void membar(Membar_mask_bits order_constraint) {
-    if (os::is_MP()) {
       // We only have to handle StoreLoad
       if (order_constraint & StoreLoad) {
         // All usable chips support "locked" instructions which suffice
         // as barriers, and are much faster than the alternative of
         // using cpuid instruction. We use here a locked add [esp-C],0.

@@ -1383,11 +1382,10 @@
 
         lock();
         addl(Address(rsp, offset), 0);// Assert the lock# signal here
       }
     }
-  }
 
   void mfence();
 
   // Moves