8349860: Make Class.isArray(), Class.isInterface() and Class.isPrimitive() non-native

src/hotspot/share/classfile/javaClasses.cpp

@@ -1512,7 +1512,7 @@ oop java_lang_Class::primitive_mirror(BasicType t) {
   macro(_signers_offset,             k, "signers",             object_array_signature, false); \
   macro(_modifiers_offset,           k, vmSymbols::modifiers_name(), char_signature,    false); \
   macro(_protection_domain_offset,   k, "protectionDomain",    java_security_ProtectionDomain_signature,  false); \
-  macro(_is_primitive_offset,        k, "isPrimitiveType",     bool_signature,         false);
+  macro(_is_primitive_offset,        k, "primitive",           bool_signature,         false);
 
 void java_lang_Class::compute_offsets() {
   if (_offsets_computed) {

src/java.base/share/classes/java/lang/Class.java

@@ -236,14 +236,14 @@ private static void runtimeSetup() {
      * This constructor is not used and prevents the default constructor being
      * generated.
      */
-    private Class(ClassLoader loader, Class<?> arrayComponentType, char mods, ProtectionDomain pd, boolean primitive) {
+    private Class(ClassLoader loader, Class<?> arrayComponentType, char mods, ProtectionDomain pd, boolean isPrim) {
         // Initialize final field for classLoader.  The initialization value of non-null
         // prevents future JIT optimizations from assuming this final field is null.
         classLoader = loader;
         componentType = arrayComponentType;
         modifiers = mods;
         protectionDomain = pd;
-        isPrimitiveType = primitive;
+        primitive = isPrim;
     }
 
     /**
@@ -847,7 +847,7 @@ public boolean isArray() {
      * @jls 15.8.2 Class Literals
      */
     public boolean isPrimitive() {
-        return isPrimitiveType;
+        return primitive;
     }
 
     /**
@@ -1007,7 +1007,7 @@ public Module getModule() {
     private transient Object classData; // Set by VM
     private transient Object[] signers; // Read by VM, mutable
     private final transient char modifiers;  // Set by the VM
-    private final transient boolean isPrimitiveType;  // Set by the VM
+    private final transient boolean primitive;  // Set by the VM if the Class is a primitive type.
 
     // package-private
     Object getClassData() {
@@ -1292,7 +1292,9 @@ public Class<?> getComponentType() {
         return componentType;
     }
 
-    private final Class<?> componentType;
+    // The componentType field's null value is the sole indication that the class is an array,
+    // see isArray().
+    private transient final Class<?> componentType;
 
     /*
      * Returns the {@code Class} representing the element type of an array class.

src/java.base/share/classes/jdk/internal/reflect/Reflection.java

@@ -56,7 +56,7 @@ public class Reflection {
         fieldFilterMap = Map.of(
             Reflection.class, ALL_MEMBERS,
             AccessibleObject.class, ALL_MEMBERS,
-            Class.class, Set.of("classLoader", "classData", "modifiers", "protectionDomain", "isPrimitiveType"),
+            Class.class, Set.of("classLoader", "classData", "modifiers", "protectionDomain", "primitive"),
             ClassLoader.class, ALL_MEMBERS,
             Constructor.class, ALL_MEMBERS,
             Field.class, ALL_MEMBERS,

test/hotspot/jtreg/compiler/jvmci/jdk.vm.ci.runtime.test/src/jdk/vm/ci/runtime/test/TestResolvedJavaType.java

@@ -934,7 +934,7 @@ private static boolean isHiddenFromReflection(ResolvedJavaField f) {
                    name.equals("classData") ||
                    name.equals("modifiers") ||
                    name.equals("protectionDomain") ||
-                   name.equals("isPrimitiveType");
+                   name.equals("primitive");
         }
         if (f.getDeclaringClass().equals(metaAccess.lookupJavaType(Lookup.class))) {
             return f.getName().equals("allowedModes") || f.getName().equals("lookupClass");

test/jdk/jdk/internal/reflect/Reflection/Filtering.java

@@ -57,7 +57,7 @@ private Object[][] sensitiveFields() {
             { Class.class, "classData" },
             { Class.class, "modifiers" },
             { Class.class, "protectionDomain" },
-            { Class.class, "isPrimitiveType" },
+            { Class.class, "primitive" },
             { ClassLoader.class, "parent" },
             { Field.class, "clazz" },
             { Field.class, "modifiers" },