--- old/src/hotspot/cpu/x86/macroAssembler_x86.cpp	2019-07-04 11:52:46.000000000 +0200
+++ new/src/hotspot/cpu/x86/macroAssembler_x86.cpp	2019-07-04 11:52:40.000000000 +0200
@@ -1754,6 +1754,10 @@
 
   // 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
--- old/src/hotspot/share/opto/graphKit.cpp	2019-07-04 11:52:51.000000000 +0200
+++ new/src/hotspot/share/opto/graphKit.cpp	2019-07-04 11:52:46.000000000 +0200
@@ -3591,12 +3591,6 @@
   if( !GenerateSynchronizationCode )
     return NULL;                // Not locking things?
 
-  // We cannot lock on a value type
-  const TypeOopPtr* objptr = _gvn.type(obj)->make_oopptr();
-  if (objptr->can_be_value_type()) {
-    gen_value_type_guard(obj, 1);
-  }
-
   if (stopped())                // Dead monitor?
     return NULL;
 
--- old/src/hotspot/share/opto/macro.cpp	2019-07-04 11:52:57.000000000 +0200
+++ new/src/hotspot/share/opto/macro.cpp	2019-07-04 11:52:52.000000000 +0200
@@ -2418,6 +2418,48 @@
     mem_phi->init_req(2, mem);
   }
 
+  const TypeOopPtr* objptr = _igvn.type(obj)->make_oopptr();
+  if (objptr->can_be_value_type()) {
+    // Deoptimize and re-execute if a value
+    assert(EnableValhalla, "should only be used if value types are enabled");
+    Node* mark = make_load(slow_path, mem, obj, oopDesc::mark_offset_in_bytes(), TypeX_X, TypeX_X->basic_type());
+    Node* value_mask = _igvn.MakeConX(markOopDesc::always_locked_pattern);
+    Node* is_value = _igvn.transform(new AndXNode(mark, value_mask));
+    Node* cmp = _igvn.transform(new CmpXNode(is_value, value_mask));
+    Node* bol = _igvn.transform(new BoolNode(cmp, BoolTest::eq));
+    Node* unc_ctrl = generate_slow_guard(&slow_path, bol, NULL);
+
+    int trap_request = Deoptimization::make_trap_request(Deoptimization::Reason_class_check, Deoptimization::Action_none);
+    address call_addr = SharedRuntime::uncommon_trap_blob()->entry_point();
+    const TypePtr* no_memory_effects = NULL;
+    JVMState* jvms = lock->jvms();
+    CallNode* unc = new CallStaticJavaNode(OptoRuntime::uncommon_trap_Type(), call_addr, "uncommon_trap",
+                                           jvms->bci(), no_memory_effects);
+    
+    unc->init_req(TypeFunc::Control, unc_ctrl);
+    unc->init_req(TypeFunc::I_O, lock->i_o());
+    unc->init_req(TypeFunc::Memory, mem); // may gc ptrs
+    unc->init_req(TypeFunc::FramePtr,  lock->in(TypeFunc::FramePtr));
+    unc->init_req(TypeFunc::ReturnAdr, lock->in(TypeFunc::ReturnAdr));
+    unc->init_req(TypeFunc::Parms+0, _igvn.intcon(trap_request));
+    unc->set_cnt(PROB_UNLIKELY_MAG(4));
+    copy_call_debug_info(lock, unc);
+
+    assert(unc->peek_monitor_box() == box, "wrong monitor");
+    assert(unc->peek_monitor_obj() == obj, "wrong monitor");
+
+    // pop monitor and push obj back on stack: we trap before the monitorenter
+    unc->pop_monitor();
+    unc->grow_stack(unc->jvms(), 1);
+    unc->set_stack(unc->jvms(), unc->jvms()->stk_size()-1, obj);
+
+    _igvn.register_new_node_with_optimizer(unc);
+    
+    Node* ctrl = _igvn.transform(new ProjNode(unc, TypeFunc::Control));
+    Node* halt = _igvn.transform(new HaltNode(ctrl, lock->in(TypeFunc::FramePtr)));
+    C->root()->add_req(halt);
+  }
+  
   // Make slow path call
   CallNode *call = make_slow_call((CallNode *) lock, OptoRuntime::complete_monitor_enter_Type(),
                                   OptoRuntime::complete_monitor_locking_Java(), NULL, slow_path,
--- old/src/hotspot/share/opto/macroArrayCopy.cpp	2019-07-04 11:53:03.000000000 +0200
+++ new/src/hotspot/share/opto/macroArrayCopy.cpp	2019-07-04 11:52:57.000000000 +0200
@@ -135,7 +135,7 @@
   return if_slow;
 }
 
-inline Node* PhaseMacroExpand::generate_slow_guard(Node** ctrl, Node* test, RegionNode* region) {
+Node* PhaseMacroExpand::generate_slow_guard(Node** ctrl, Node* test, RegionNode* region) {
   return generate_guard(ctrl, test, region, PROB_UNLIKELY_MAG(3));
 }
 
--- old/src/hotspot/share/runtime/init.cpp	2019-07-04 11:53:09.000000000 +0200
+++ new/src/hotspot/share/runtime/init.cpp	2019-07-04 11:53:03.000000000 +0200
@@ -113,6 +113,7 @@
   codeCache_init();
   VM_Version_init();
   os_init_globals();
+  VMRegImpl::set_regName();  // need this before generate_stubs (for printing oop maps).
   stubRoutines_init1();
   jint status = universe_init();  // dependent on codeCache_init and
                                   // stubRoutines_init1 and metaspace_init.
@@ -125,7 +126,6 @@
   accessFlags_init();
   templateTable_init();
   InterfaceSupport_init();
-  VMRegImpl::set_regName();  // need this before generate_stubs (for printing oop maps).
   SharedRuntime::generate_stubs();
   universe2_init();  // dependent on codeCache_init and stubRoutines_init1
   javaClasses_init();// must happen after vtable initialization, before referenceProcessor_init