src/hotspot/cpu/x86/assembler_x86.hpp

*** 1348,1358 ****
      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.
--- 1348,1357 ----
*** 1383,1393 ****
  
          lock();
          addl(Address(rsp, offset), 0);// Assert the lock# signal here
        }
      }
-   }
  
    void mfence();
  
    // Moves
  
--- 1382,1391 ----