6960865: ldc of unloaded class throws an assert in ciTypeFlow

Summary: Support java_mirror for unloaded klasses, arrays as well as instances.  Simplify ciTypeFlow by removing unused path.
Reviewed-by: kvn

src/share/vm/ci/ciInstanceKlass.cpp

@@ -323,12 +323,10 @@ ciInstanceKlass* ciInstanceKlass::super() {
 // ciInstanceKlass::java_mirror
 //
 // Get the instance of java.lang.Class corresponding to this klass.
+// Cache it on this->_java_mirror.
 ciInstance* ciInstanceKlass::java_mirror() {
   if (_java_mirror == NULL) {
-    if (!is_loaded())
-      _java_mirror = ciEnv::current()->get_unloaded_klass_mirror(this);
-    else
-      _java_mirror = ciKlass::java_mirror();
+    _java_mirror = ciKlass::java_mirror();
   }
   return _java_mirror;
 }

src/share/vm/ci/ciKlass.cpp

@@ -192,8 +192,14 @@ ciKlass* ciKlass::find_klass(ciSymbol* klass_name) {
 
 // ------------------------------------------------------------------
 // ciKlass::java_mirror
+//
+// Get the instance of java.lang.Class corresponding to this klass.
+// If it is an unloaded instance or array klass, return an unloaded
+// mirror object of type Class.
 ciInstance* ciKlass::java_mirror() {
   GUARDED_VM_ENTRY(
+    if (!is_loaded())
+      return ciEnv::current()->get_unloaded_klass_mirror(this);
     oop java_mirror = get_Klass()->java_mirror();
     return CURRENT_ENV->get_object(java_mirror)->as_instance();
   )

src/share/vm/ci/ciTypeFlow.cpp

@@ -712,10 +712,8 @@ void ciTypeFlow::StateVector::do_ldc(ciBytecodeStream* str) {
     ciObject* obj = con.as_object();
     if (obj->is_null_object()) {
       push_null();
-    } else if (obj->is_klass()) {
-      // The type of ldc <class> is java.lang.Class
-      push_object(outer()->env()->Class_klass());
     } else {
+      assert(!obj->is_klass(), "must be java_mirror of klass");
       push_object(obj->klass());
     }
   } else {