src/hotspot/cpu/x86/macroAssembler_x86.cpp

@@ -1752,10 +1752,14 @@
   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,