--- old/src/hotspot/share/c1/c1_GraphBuilder.cpp	2019-03-07 19:52:20.033912950 -0800
+++ new/src/hotspot/share/c1/c1_GraphBuilder.cpp	2019-03-07 19:52:19.781904090 -0800
@@ -1716,7 +1716,7 @@
         }
         LoadField* load_field = new LoadField(append(obj), offset, field, true,
                                         state_before, needs_patching);
-        if (field->is_never_null()) {
+        if (field->is_q_type()) {
           load_field->set_never_null(true);
         }
         push(type, append(load_field));
--- old/src/hotspot/share/c1/c1_LIRGenerator.cpp	2019-03-07 19:52:20.693936157 -0800
+++ new/src/hotspot/share/c1/c1_LIRGenerator.cpp	2019-03-07 19:52:20.449927578 -0800
@@ -1543,9 +1543,12 @@
   if (x->needs_null_check() &&
       (needs_patching ||
        MacroAssembler::needs_explicit_null_check(x->offset()))) {
-    if (needs_patching && x->field()->is_never_null()) {
-      // We are storing a field of type "QT;", but T is not yet loaded, so we don't
-      // know whether this field is flattened or not. Let's deoptimize and recompile.
+    if (needs_patching && x->field()->is_q_type()) {
+      // We are storing a field of type "QT;" into holder class H, but H is not yet
+      // loaded. (If H had been loaded, then T must also have already been loaded
+      // due to the "Q" signature, and needs_patching would be false).
+      assert(!x->field()->holder()->is_loaded(), "must be");
+      // We don't know the offset of this field. Let's deopt and recompile.
       CodeStub* stub = new DeoptimizeStub(new CodeEmitInfo(info),
                                           Deoptimization::Reason_unloaded,
                                           Deoptimization::Action_make_not_entrant);
@@ -1868,7 +1871,7 @@
   return _barrier_set->resolve(this, decorators, obj);
 }
 
-Value LIRGenerator::non_nullable_load_field_prolog(LoadField* x, CodeEmitInfo* info) {
+Value LIRGenerator::q_type_load_field_prolog(LoadField* x, CodeEmitInfo* info) {
   ciField* field = x->field();
   ciInstanceKlass* holder = field->holder();
   Value default_value = NULL;
@@ -1971,8 +1974,8 @@
 #endif
 
   Value default_value = NULL;
-  if (x->field()->is_never_null()) {
-    default_value = non_nullable_load_field_prolog(x, info);
+  if (x->field()->is_q_type()) {
+    default_value = q_type_load_field_prolog(x, info);
   }
 
   bool stress_deopt = StressLoopInvariantCodeMotion && info && info->deoptimize_on_exception();
--- old/src/hotspot/share/c1/c1_LIRGenerator.hpp	2019-03-07 19:52:21.357959505 -0800
+++ new/src/hotspot/share/c1/c1_LIRGenerator.hpp	2019-03-07 19:52:21.117951066 -0800
@@ -266,7 +266,7 @@
   void do_update_CRC32C(Intrinsic* x);
   void do_vectorizedMismatch(Intrinsic* x);
 
-  Value non_nullable_load_field_prolog(LoadField* x, CodeEmitInfo* info);
+  Value q_type_load_field_prolog(LoadField* x, CodeEmitInfo* info);
   void access_flattened_array(bool is_load, LIRItem& array, LIRItem& index, LIRItem& obj_item);
   bool needs_flattened_array_store_check(StoreIndexed* x);
   void check_flattened_array(LIRItem& array, CodeStub* slow_path);
--- old/src/hotspot/share/ci/ciField.hpp	2019-03-07 19:52:21.981981446 -0800
+++ new/src/hotspot/share/ci/ciField.hpp	2019-03-07 19:52:21.737972867 -0800
@@ -202,7 +202,7 @@
              klass_name == ciSymbol::java_lang_Long_LongCache()));
   }
 
-  bool is_never_null() const {
+  bool is_q_type() const {
     // Cannot use (type()->basic_type() == T_VALUETYPE) -- if the class is not loaded,
     // type() is an unloaded ciInstanceKlass!
     return signature()->char_at(0) == 'Q';