8334772: Change Class::signers to an explicit field

Reviewed-by: dholmes, alanb, rriggs, coleenp

src/hotspot/share/classfile/javaClasses.cpp

@@ -1220,10 +1220,6 @@ objArrayOop java_lang_Class::signers(oop java_class) {
   assert(_signers_offset != 0, "must be set");
   return (objArrayOop)java_class->obj_field(_signers_offset);
 }
-void java_lang_Class::set_signers(oop java_class, objArrayOop signers) {
-  assert(_signers_offset != 0, "must be set");
-  java_class->obj_field_put(_signers_offset, signers);
-}
 
 oop java_lang_Class::class_data(oop java_class) {
   assert(_classData_offset != 0, "must be set");
@@ -1418,12 +1414,13 @@ oop java_lang_Class::primitive_mirror(BasicType t) {
 }
 
 #define CLASS_FIELDS_DO(macro) \
-  macro(_classRedefinedCount_offset, k, "classRedefinedCount", int_signature,         false); \
+  macro(_classRedefinedCount_offset, k, "classRedefinedCount", int_signature,          false); \
-  macro(_class_loader_offset,        k, "classLoader",         classloader_signature, false); \
+  macro(_class_loader_offset,        k, "classLoader",         classloader_signature,  false); \
-  macro(_component_mirror_offset,    k, "componentType",       class_signature,       false); \
+  macro(_component_mirror_offset,    k, "componentType",       class_signature,        false); \
-  macro(_module_offset,              k, "module",              module_signature,      false); \
+  macro(_module_offset,              k, "module",              module_signature,       false); \
-  macro(_name_offset,                k, "name",                string_signature,      false); \
+  macro(_name_offset,                k, "name",                string_signature,       false); \
-  macro(_classData_offset,           k, "classData",           object_signature,      false);
+  macro(_classData_offset,           k, "classData",           object_signature,       false); \
+  macro(_signers_offset,             k, "signers",             object_array_signature, false);
 
 void java_lang_Class::compute_offsets() {
   if (_offsets_computed) {

src/hotspot/share/classfile/javaClasses.hpp

@@ -208,7 +208,6 @@ class java_lang_String : AllStatic {
   macro(java_lang_Class, oop_size,               int_signature,     false) \
   macro(java_lang_Class, static_oop_field_count, int_signature,     false) \
   macro(java_lang_Class, protection_domain,      object_signature,  false) \
-  macro(java_lang_Class, signers,                object_signature,  false) \
   macro(java_lang_Class, source_file,            object_signature,  false) \
 
 class java_lang_Class : AllStatic {
@@ -299,8 +298,7 @@ class java_lang_Class : AllStatic {
     set_init_lock(java_class, nullptr);
   }
   static oop  component_mirror(oop java_class);
-  static objArrayOop  signers(oop java_class);
+  static objArrayOop signers(oop java_class);
-  static void set_signers(oop java_class, objArrayOop signers);
   static oop  class_data(oop java_class);
   static void set_class_data(oop java_class, oop classData);
 

src/hotspot/share/include/jvm.h

@@ -552,12 +552,6 @@ JVM_GetClassInterfaces(JNIEnv *env, jclass cls);
 JNIEXPORT jboolean JNICALL
 JVM_IsInterface(JNIEnv *env, jclass cls);
 
-JNIEXPORT jobjectArray JNICALL
-JVM_GetClassSigners(JNIEnv *env, jclass cls);
-
-JNIEXPORT void JNICALL
-JVM_SetClassSigners(JNIEnv *env, jclass cls, jobjectArray signers);
-
 JNIEXPORT jobject JNICALL
 JVM_GetProtectionDomain(JNIEnv *env, jclass cls);
 

src/hotspot/share/prims/jvm.cpp

@@ -1252,45 +1252,6 @@ JVM_ENTRY(jboolean, JVM_IsHiddenClass(JNIEnv *env, jclass cls))
   return k->is_hidden();
 JVM_END
 
-JVM_ENTRY(jobjectArray, JVM_GetClassSigners(JNIEnv *env, jclass cls))
-  JvmtiVMObjectAllocEventCollector oam;
-  oop mirror = JNIHandles::resolve_non_null(cls);
-  if (java_lang_Class::is_primitive(mirror)) {
-    // There are no signers for primitive types
-    return nullptr;
-  }
-
-  objArrayHandle signers(THREAD, java_lang_Class::signers(mirror));
-
-  // If there are no signers set in the class, or if the class
-  // is an array, return null.
-  if (signers == nullptr) return nullptr;
-
-  // copy of the signers array
-  Klass* element = ObjArrayKlass::cast(signers->klass())->element_klass();
-  objArrayOop signers_copy = oopFactory::new_objArray(element, signers->length(), CHECK_NULL);
-  for (int index = 0; index < signers->length(); index++) {
-    signers_copy->obj_at_put(index, signers->obj_at(index));
-  }
-
-  // return the copy
-  return (jobjectArray) JNIHandles::make_local(THREAD, signers_copy);
-JVM_END
-
-
-JVM_ENTRY(void, JVM_SetClassSigners(JNIEnv *env, jclass cls, jobjectArray signers))
-  oop mirror = JNIHandles::resolve_non_null(cls);
-  if (!java_lang_Class::is_primitive(mirror)) {
-    // This call is ignored for primitive types and arrays.
-    // Signers are only set once, ClassLoader.java, and thus shouldn't
-    // be called with an array.  Only the bootstrap loader creates arrays.
-    Klass* k = java_lang_Class::as_Klass(mirror);
-    if (k->is_instance_klass()) {
-      java_lang_Class::set_signers(k->java_mirror(), objArrayOop(JNIHandles::resolve(signers)));
-    }
-  }
-JVM_END
-
 
 JVM_ENTRY(jobject, JVM_GetProtectionDomain(JNIEnv *env, jclass cls))
   oop mirror = JNIHandles::resolve_non_null(cls);

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

@@ -1110,8 +1110,8 @@ public final class Class<T> implements java.io.Serializable,
     // will throw NoSuchFieldException
     private final ClassLoader classLoader;
 
-    // Set by VM
+    private transient Object classData; // Set by VM
-    private transient Object classData;
+    private transient Object[] signers; // Read by VM, mutable
 
     // package-private
     Object getClassData() {
@@ -1510,14 +1510,19 @@ public final class Class<T> implements java.io.Serializable,
      *          a primitive type or void.
      * @since   1.1
      */
-    public native Object[] getSigners();
+    public Object[] getSigners() {
-
+        var signers = this.signers;
+        return signers == null ? null : signers.clone();
+    }
 
     /**
      * Set the signers of this class.
      */
-    native void setSigners(Object[] signers);
+    void setSigners(Object[] signers) {
-
+        if (!isPrimitive() && !isArray()) {
+            this.signers = signers;
+        }
+    }
 
     /**
      * If this {@code Class} object represents a local or anonymous

src/java.base/share/native/libjava/Class.c

@@ -58,8 +58,6 @@ static JNINativeMethod methods[] = {
     {"getSuperclass",    "()" CLS,          NULL},
     {"getInterfaces0",   "()[" CLS,         (void *)&JVM_GetClassInterfaces},
     {"isInterface",      "()Z",             (void *)&JVM_IsInterface},
-    {"getSigners",       "()[" OBJ,         (void *)&JVM_GetClassSigners},
-    {"setSigners",       "([" OBJ ")V",     (void *)&JVM_SetClassSigners},
     {"isArray",          "()Z",             (void *)&JVM_IsArrayClass},
     {"isHidden",         "()Z",             (void *)&JVM_IsHiddenClass},
     {"isPrimitive",      "()Z",             (void *)&JVM_IsPrimitiveClass},