src/hotspot/cpu/x86/macroAssembler_x86.cpp

*** 1752,1761 ****
--- 1752,1765 ----
    testptr(tmpReg, markOopDesc::monitor_value); // inflated vs stack-locked|neutral|biased
    jccb(Assembler::notZero, IsInflated);
  
    // Attempt stack-locking ...
    orptr (tmpReg, markOopDesc::unlocked_value);
+   if (EnableValhalla && !UseBiasedLocking) {
+     // Mask always_locked bit such that we go to the slow path if object is a value type
+     andptr(tmpReg, ~markOopDesc::biased_lock_bit_in_place);
+   }
    movptr(Address(boxReg, 0), tmpReg);          // Anticipate successful CAS
    lock();
    cmpxchgptr(boxReg, Address(objReg, oopDesc::mark_offset_in_bytes()));      // Updates tmpReg
    if (counters != NULL) {
      cond_inc32(Assembler::equal,