src/hotspot/cpu/x86/c1_MacroAssembler_x86.cpp

*** 60,69 ****
--- 60,73 ----
  
    // Load object header
    movptr(hdr, Address(obj, hdr_offset));
    // and mark it as unlocked
    orptr(hdr, 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(hdr, ~markOopDesc::biased_lock_bit_in_place);
+   }
    // save unlocked object header into the displaced header location on the stack
    movptr(Address(disp_hdr, 0), hdr);
    // test if object header is still the same (i.e. unlocked), and if so, store the
    // displaced header address in the object header - if it is not the same, get the
    // object header instead
*** 148,158 ****
  }
  
  
  void C1_MacroAssembler::initialize_header(Register obj, Register klass, Register len, Register t1, Register t2) {
    assert_different_registers(obj, klass, len);
!   if (UseBiasedLocking && !len->is_valid()) {
      assert_different_registers(obj, klass, len, t1, t2);
      movptr(t1, Address(klass, Klass::prototype_header_offset()));
      movptr(Address(obj, oopDesc::mark_offset_in_bytes()), t1);
    } else {
      // This assumes that all prototype bits fit in an int32_t
--- 152,163 ----
  }
  
  
  void C1_MacroAssembler::initialize_header(Register obj, Register klass, Register len, Register t1, Register t2) {
    assert_different_registers(obj, klass, len);
!   if ((UseBiasedLocking || EnableValhalla) && !len->is_valid()) {
!     // Need to copy markOopDesc::always_locked_pattern for values.
      assert_different_registers(obj, klass, len, t1, t2);
      movptr(t1, Address(klass, Klass::prototype_header_offset()));
      movptr(Address(obj, oopDesc::mark_offset_in_bytes()), t1);
    } else {
      // This assumes that all prototype bits fit in an int32_t