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

Reviewed-by: dlong, rriggs, vlivanov, yzheng, liach

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

@@ -236,13 +236,15 @@ public final class Class<T> implements java.io.Serializable,
      * This constructor is not used and prevents the default constructor being
      * generated.
      */
-    private Class(ClassLoader loader, Class<?> arrayComponentType, int mods, ProtectionDomain pd) {
+    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.
+        // The following assignments are done directly by the VM without calling this constructor.
         classLoader = loader;
         componentType = arrayComponentType;
         modifiers = mods;
         protectionDomain = pd;
+        primitive = isPrim;
     }
 
     /**
@@ -790,8 +792,9 @@ public final class Class<T> implements java.io.Serializable,
      * @return  {@code true} if this {@code Class} object represents an interface;
      *          {@code false} otherwise.
      */
-    @IntrinsicCandidate
-    public native boolean isInterface();
+    public boolean isInterface() {
+        return Modifier.isInterface(modifiers);
+    }
 
 
     /**
@@ -801,8 +804,9 @@ public final class Class<T> implements java.io.Serializable,
      *          {@code false} otherwise.
      * @since   1.1
      */
-    @IntrinsicCandidate
-    public native boolean isArray();
+    public boolean isArray() {
+        return componentType != null;
+    }
 
 
     /**
@@ -843,8 +847,9 @@ public final class Class<T> implements java.io.Serializable,
      * @since 1.1
      * @jls 15.8.2 Class Literals
      */
-    @IntrinsicCandidate
-    public native boolean isPrimitive();
+    public boolean isPrimitive() {
+        return primitive;
+    }
 
     /**
      * Returns true if this {@code Class} object represents an annotation
@@ -1002,7 +1007,8 @@ public final class Class<T> implements java.io.Serializable,
 
     private transient Object classData; // Set by VM
     private transient Object[] signers; // Read by VM, mutable
-    private final transient int modifiers;  // Set by the VM
+    private final transient char modifiers;  // Set by the VM
+    private final transient boolean primitive;  // Set by the VM if the Class is a primitive type.
 
     // package-private
     Object getClassData() {
@@ -1284,15 +1290,12 @@ public final class Class<T> implements java.io.Serializable,
      * @since 1.1
      */
     public Class<?> getComponentType() {
-        // Only return for array types. Storage may be reused for Class for instance types.
-        if (isArray()) {
-            return componentType;
-        } else {
-            return null;
-        }
+        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"),
+            Class.class, Set.of("classLoader", "classData", "modifiers", "protectionDomain", "primitive"),
             ClassLoader.class, ALL_MEMBERS,
             Constructor.class, ALL_MEMBERS,
             Field.class, ALL_MEMBERS,