7109878: The instanceKlass EnclosingMethhod attribute fields can be folded...

7109878: The instanceKlass EnclosingMethhod attribute fields can be folded into the _inner_class field.
Summary: Fold instanceKlass::_enclosing_method_class_index and instanceKlass::_enclosing_method_method_index into the instanceKlass::_inner_classes array.
Reviewed-by: never, coleenp
Contributed-by: NJiangli Zhou <jiangli.zhou@oracle.com>

agent/src/share/classes/sun/jvm/hotspot/oops/InstanceKlass.java

@@ -359,6 +359,12 @@ public class InstanceKlass extends Klass {
     public static final int innerClassNextOffset = 4;
   };
 
+  public static interface EnclosingMethodAttributeOffset {
+    public static final int enclosing_method_class_index_offset = 0;
+    public static final int enclosing_method_method_index_offset = 1;
+    public static final int enclosing_method_attribute_size = 2;
+  };
+
   // refer to compute_modifier_flags in VM code.
   public long computeModifierFlags() {
     long access = getAccessFlags();
@@ -367,9 +373,14 @@ public class InstanceKlass extends Klass {
     int length = ( innerClassList == null)? 0 : (int) innerClassList.getLength();
     if (length > 0) {
        if (Assert.ASSERTS_ENABLED) {
-          Assert.that(length % InnerClassAttributeOffset.innerClassNextOffset == 0, "just checking");
+          Assert.that(length % InnerClassAttributeOffset.innerClassNextOffset == 0 ||
+                      length % InnerClassAttributeOffset.innerClassNextOffset == EnclosingMethodAttributeOffset.enclosing_method_attribute_size,
+                      "just checking");
        }
        for (int i = 0; i < length; i += InnerClassAttributeOffset.innerClassNextOffset) {
+          if (i == length - EnclosingMethodAttributeOffset.enclosing_method_attribute_size) {
+              break;
+          }
           int ioff = innerClassList.getShortAt(i +
                          InnerClassAttributeOffset.innerClassInnerClassInfoOffset);
           // 'ioff' can be zero.
@@ -419,9 +430,14 @@ public class InstanceKlass extends Klass {
     int length = ( innerClassList == null)? 0 : (int) innerClassList.getLength();
     if (length > 0) {
        if (Assert.ASSERTS_ENABLED) {
-         Assert.that(length % InnerClassAttributeOffset.innerClassNextOffset == 0, "just checking");
+         Assert.that(length % InnerClassAttributeOffset.innerClassNextOffset == 0 ||
+                     length % InnerClassAttributeOffset.innerClassNextOffset == EnclosingMethodAttributeOffset.enclosing_method_attribute_size,
+                     "just checking");
        }
        for (int i = 0; i < length; i += InnerClassAttributeOffset.innerClassNextOffset) {
+         if (i == length - EnclosingMethodAttributeOffset.enclosing_method_attribute_size) {
+             break;
+         }
          int ioff = innerClassList.getShortAt(i +
                         InnerClassAttributeOffset.innerClassInnerClassInfoOffset);
          // 'ioff' can be zero.

src/share/vm/classfile/classFileParser.cpp

@@ -2315,13 +2315,32 @@ void ClassFileParser::parse_classfile_source_debug_extension_attribute(constantP
 #define RECOGNIZED_INNER_CLASS_MODIFIERS (JVM_RECOGNIZED_CLASS_MODIFIERS | JVM_ACC_PRIVATE | JVM_ACC_PROTECTED | JVM_ACC_STATIC)
 
 // Return number of classes in the inner classes attribute table
-u2 ClassFileParser::parse_classfile_inner_classes_attribute(constantPoolHandle cp, instanceKlassHandle k, TRAPS) {
+u2 ClassFileParser::parse_classfile_inner_classes_attribute(u1* inner_classes_attribute_start,
+                                                            bool parsed_enclosingmethod_attribute,
+                                                            u2 enclosing_method_class_index,
+                                                            u2 enclosing_method_method_index,
+                                                            constantPoolHandle cp,
+                                                            instanceKlassHandle k, TRAPS) {
   ClassFileStream* cfs = stream();
-  cfs->guarantee_more(2, CHECK_0);  // length
-  u2 length = cfs->get_u2_fast();
+  u1* current_mark = cfs->current();
+  u2 length = 0;
+  if (inner_classes_attribute_start != NULL) {
+    cfs->set_current(inner_classes_attribute_start);
+    cfs->guarantee_more(2, CHECK_0);  // length
+    length = cfs->get_u2_fast();
+  }
 
-  // 4-tuples of shorts [inner_class_info_index, outer_class_info_index, inner_name_index, inner_class_access_flags]
-  typeArrayOop ic = oopFactory::new_permanent_shortArray(length*4, CHECK_0);
+  // 4-tuples of shorts of inner classes data and 2 shorts of enclosing
+  // method data:
+  //   [inner_class_info_index,
+  //    outer_class_info_index,
+  //    inner_name_index,
+  //    inner_class_access_flags,
+  //    ...
+  //    enclosing_method_class_index,
+  //    enclosing_method_method_index]
+  int size = length * 4 + (parsed_enclosingmethod_attribute ? 2 : 0);
+  typeArrayOop ic = oopFactory::new_permanent_shortArray(size, CHECK_0);
   typeArrayHandle inner_classes(THREAD, ic);
   int index = 0;
   int cp_size = cp->length();
@@ -2372,8 +2391,8 @@ u2 ClassFileParser::parse_classfile_inner_classes_attribute(constantPoolHandle c
 
   // 4347400: make sure there's no duplicate entry in the classes array
   if (_need_verify && _major_version >= JAVA_1_5_VERSION) {
-    for(int i = 0; i < inner_classes->length(); i += 4) {
-      for(int j = i + 4; j < inner_classes->length(); j += 4) {
+    for(int i = 0; i < length * 4; i += 4) {
+      for(int j = i + 4; j < length * 4; j += 4) {
         guarantee_property((inner_classes->ushort_at(i)   != inner_classes->ushort_at(j) ||
                             inner_classes->ushort_at(i+1) != inner_classes->ushort_at(j+1) ||
                             inner_classes->ushort_at(i+2) != inner_classes->ushort_at(j+2) ||
@@ -2384,8 +2403,19 @@ u2 ClassFileParser::parse_classfile_inner_classes_attribute(constantPoolHandle c
     }
   }
 
+  // Set EnclosingMethod class and method indexes.
+  if (parsed_enclosingmethod_attribute) {
+    inner_classes->short_at_put(index++, enclosing_method_class_index);
+    inner_classes->short_at_put(index++, enclosing_method_method_index);
+  }
+  assert(index == size, "wrong size");
+
   // Update instanceKlass with inner class info.
   k->set_inner_classes(inner_classes());
+
+  // Restore buffer's current position.
+  cfs->set_current(current_mark);
+
   return length;
 }
 
@@ -2490,6 +2520,10 @@ void ClassFileParser::parse_classfile_attributes(constantPoolHandle cp, instance
   int runtime_visible_annotations_length = 0;
   u1* runtime_invisible_annotations = NULL;
   int runtime_invisible_annotations_length = 0;
+  u1* inner_classes_attribute_start = NULL;
+  u4  inner_classes_attribute_length = 0;
+  u2  enclosing_method_class_index = 0;
+  u2  enclosing_method_method_index = 0;
   // Iterate over attributes
   while (attributes_count--) {
     cfs->guarantee_more(6, CHECK);  // attribute_name_index, attribute_length
@@ -2522,11 +2556,9 @@ void ClassFileParser::parse_classfile_attributes(constantPoolHandle cp, instance
       } else {
         parsed_innerclasses_attribute = true;
       }
-      u2 num_of_classes = parse_classfile_inner_classes_attribute(cp, k, CHECK);
-      if (_need_verify && _major_version >= JAVA_1_5_VERSION) {
-        guarantee_property(attribute_length == sizeof(num_of_classes) + 4 * sizeof(u2) * num_of_classes,
-                          "Wrong InnerClasses attribute length in class file %s", CHECK);
-      }
+      inner_classes_attribute_start = cfs->get_u1_buffer();
+      inner_classes_attribute_length = attribute_length;
+      cfs->skip_u1(inner_classes_attribute_length, CHECK);
     } else if (tag == vmSymbols::tag_synthetic()) {
       // Check for Synthetic tag
       // Shouldn't we check that the synthetic flags wasn't already set? - not required in spec
@@ -2568,22 +2600,21 @@ void ClassFileParser::parse_classfile_attributes(constantPoolHandle cp, instance
           parsed_enclosingmethod_attribute = true;
         }
         cfs->guarantee_more(4, CHECK);  // class_index, method_index
-        u2 class_index  = cfs->get_u2_fast();
-        u2 method_index = cfs->get_u2_fast();
-        if (class_index == 0) {
+        enclosing_method_class_index  = cfs->get_u2_fast();
+        enclosing_method_method_index = cfs->get_u2_fast();
+        if (enclosing_method_class_index == 0) {
           classfile_parse_error("Invalid class index in EnclosingMethod attribute in class file %s", CHECK);
         }
         // Validate the constant pool indices and types
-        if (!cp->is_within_bounds(class_index) ||
-            !is_klass_reference(cp, class_index)) {
+        if (!cp->is_within_bounds(enclosing_method_class_index) ||
+            !is_klass_reference(cp, enclosing_method_class_index)) {
           classfile_parse_error("Invalid or out-of-bounds class index in EnclosingMethod attribute in class file %s", CHECK);
         }
-        if (method_index != 0 &&
-            (!cp->is_within_bounds(method_index) ||
-             !cp->tag_at(method_index).is_name_and_type())) {
+        if (enclosing_method_method_index != 0 &&
+            (!cp->is_within_bounds(enclosing_method_method_index) ||
+             !cp->tag_at(enclosing_method_method_index).is_name_and_type())) {
           classfile_parse_error("Invalid or out-of-bounds method index in EnclosingMethod attribute in class file %s", CHECK);
         }
-        k->set_enclosing_method_indices(class_index, method_index);
       } else if (tag == vmSymbols::tag_bootstrap_methods() &&
                  _major_version >= Verifier::INVOKEDYNAMIC_MAJOR_VERSION) {
         if (parsed_bootstrap_methods_attribute)
@@ -2606,6 +2637,20 @@ void ClassFileParser::parse_classfile_attributes(constantPoolHandle cp, instance
                                                      CHECK);
   k->set_class_annotations(annotations());
 
+  if (parsed_innerclasses_attribute || parsed_enclosingmethod_attribute) {
+    u2 num_of_classes = parse_classfile_inner_classes_attribute(
+                            inner_classes_attribute_start,
+                            parsed_innerclasses_attribute,
+                            enclosing_method_class_index,
+                            enclosing_method_method_index,
+                            cp, k, CHECK);
+    if (parsed_innerclasses_attribute &&_need_verify && _major_version >= JAVA_1_5_VERSION) {
+      guarantee_property(
+        inner_classes_attribute_length == sizeof(num_of_classes) + 4 * sizeof(u2) * num_of_classes,
+        "Wrong InnerClasses attribute length in class file %s", CHECK);
+    }
+  }
+
   if (_max_bootstrap_specifier_index >= 0) {
     guarantee_property(parsed_bootstrap_methods_attribute,
                        "Missing BootstrapMethods attribute in class file %s", CHECK);

src/share/vm/classfile/classFileParser.hpp

@@ -130,7 +130,11 @@ class ClassFileParser VALUE_OBJ_CLASS_SPEC {
   void parse_classfile_sourcefile_attribute(constantPoolHandle cp, instanceKlassHandle k, TRAPS);
   void parse_classfile_source_debug_extension_attribute(constantPoolHandle cp,
                                                 instanceKlassHandle k, int length, TRAPS);
-  u2   parse_classfile_inner_classes_attribute(constantPoolHandle cp,
+  u2   parse_classfile_inner_classes_attribute(u1* inner_classes_attribute_start,
+                                               bool parsed_enclosingmethod_attribute,
+                                               u2 enclosing_method_class_index,
+                                               u2 enclosing_method_method_index,
+                                               constantPoolHandle cp,
                                                instanceKlassHandle k, TRAPS);
   void parse_classfile_attributes(constantPoolHandle cp, instanceKlassHandle k, TRAPS);
   void parse_classfile_synthetic_attribute(constantPoolHandle cp, instanceKlassHandle k, TRAPS);

src/share/vm/memory/dump.cpp

@@ -297,16 +297,14 @@ public:
 
       if (obj->blueprint()->oop_is_instanceKlass()) {
         instanceKlass* ik = instanceKlass::cast((klassOop)obj);
-        typeArrayOop inner_classes = ik->inner_classes();
-        if (inner_classes != NULL) {
-          constantPoolOop constants = ik->constants();
-          int n = inner_classes->length();
-          for (int i = 0; i < n; i += instanceKlass::inner_class_next_offset) {
-            int ioff = i + instanceKlass::inner_class_inner_name_offset;
-            int index = inner_classes->ushort_at(ioff);
-            if (index != 0) {
-              _closure->do_symbol(constants->symbol_at_addr(index));
-            }
+        instanceKlassHandle ik_h((klassOop)obj);
+        InnerClassesIterator iter(ik_h);
+        constantPoolOop constants = ik->constants();
+        for (; !iter.done(); iter.next()) {
+          int index = iter.inner_name_index();
+
+          if (index != 0) {
+            _closure->do_symbol(constants->symbol_at_addr(index));
           }
         }
       }

src/share/vm/oops/instanceKlass.cpp

@@ -1132,6 +1132,36 @@ JNIid* instanceKlass::jni_id_for(int offset) {
   return probe;
 }
 
+u2 instanceKlass::enclosing_method_data(int offset) {
+  typeArrayOop inner_class_list = inner_classes();
+  if (inner_class_list == NULL) {
+    return 0;
+  }
+  int length = inner_class_list->length();
+  if (length % inner_class_next_offset == 0) {
+    return 0;
+  } else {
+    int index = length - enclosing_method_attribute_size;
+    typeArrayHandle inner_class_list_h(inner_class_list);
+    assert(offset < enclosing_method_attribute_size, "invalid offset");
+    return inner_class_list_h->ushort_at(index + offset);
+  }
+}
+
+void instanceKlass::set_enclosing_method_indices(u2 class_index,
+                                                 u2 method_index) {
+  typeArrayOop inner_class_list = inner_classes();
+  assert (inner_class_list != NULL, "_inner_classes list is not set up");
+  int length = inner_class_list->length();
+  if (length % inner_class_next_offset == enclosing_method_attribute_size) {
+    int index = length - enclosing_method_attribute_size;
+    typeArrayHandle inner_class_list_h(inner_class_list);
+    inner_class_list_h->ushort_at_put(
+      index + enclosing_method_class_index_offset, class_index);
+    inner_class_list_h->ushort_at_put(
+      index + enclosing_method_method_index_offset, method_index);
+  }
+}
 
 // Lookup or create a jmethodID.
 // This code is called by the VMThread and JavaThreads so the
@@ -2106,28 +2136,21 @@ jint instanceKlass::compute_modifier_flags(TRAPS) const {
   jint access = access_flags().as_int();
 
   // But check if it happens to be member class.
-  typeArrayOop inner_class_list = inner_classes();
-  int length = (inner_class_list == NULL) ? 0 : inner_class_list->length();
-  assert (length % instanceKlass::inner_class_next_offset == 0, "just checking");
-  if (length > 0) {
-    typeArrayHandle inner_class_list_h(THREAD, inner_class_list);
-    instanceKlassHandle ik(THREAD, k);
-    for (int i = 0; i < length; i += instanceKlass::inner_class_next_offset) {
-      int ioff = inner_class_list_h->ushort_at(
-                      i + instanceKlass::inner_class_inner_class_info_offset);
-
-      // Inner class attribute can be zero, skip it.
-      // Strange but true:  JVM spec. allows null inner class refs.
-      if (ioff == 0) continue;
-
-      // only look at classes that are already loaded
-      // since we are looking for the flags for our self.
-      Symbol* inner_name = ik->constants()->klass_name_at(ioff);
-      if ((ik->name() == inner_name)) {
-        // This is really a member class.
-        access = inner_class_list_h->ushort_at(i + instanceKlass::inner_class_access_flags_offset);
-        break;
-      }
+  instanceKlassHandle ik(THREAD, k);
+  InnerClassesIterator iter(ik);
+  for (; !iter.done(); iter.next()) {
+    int ioff = iter.inner_class_info_index();
+    // Inner class attribute can be zero, skip it.
+    // Strange but true:  JVM spec. allows null inner class refs.
+    if (ioff == 0) continue;
+
+    // only look at classes that are already loaded
+    // since we are looking for the flags for our self.
+    Symbol* inner_name = ik->constants()->klass_name_at(ioff);
+    if ((ik->name() == inner_name)) {
+      // This is really a member class.
+      access = iter.inner_access_flags();
+      break;
     }
   }
   // Remember to strip ACC_SUPER bit

src/share/vm/oops/instanceKlass.hpp

@@ -188,7 +188,17 @@ class instanceKlass: public Klass {
   klassOop        _host_klass;
   // Class signers.
   objArrayOop     _signers;
-  // inner_classes attribute.
+  // The InnerClasses attribute and EnclosingMethod attribute. The
+  // _inner_classes is an array of shorts. If the class has InnerClasses
+  // attribute, then the _inner_classes array begins with 4-tuples of shorts
+  // [inner_class_info_index, outer_class_info_index,
+  // inner_name_index, inner_class_access_flags] for the InnerClasses
+  // attribute. If the EnclosingMethod attribute exists, it occupies the
+  // last two shorts [class_index, method_index] of the array. If only
+  // the InnerClasses attribute exists, the _inner_classes array length is
+  // number_of_inner_classes * 4. If the class has both InnerClasses
+  // and EnclosingMethod attributes the _inner_classes array length is
+  // number_of_inner_classes * 4 + enclosing_method_attribute_size.
   typeArrayOop    _inner_classes;
   // Implementors of this interface (not valid if it overflows)
   klassOop        _implementors[implementors_limit];
@@ -251,8 +261,6 @@ class instanceKlass: public Klass {
   // Array of interesting part(s) of the previous version(s) of this
   // instanceKlass. See PreviousVersionWalker below.
   GrowableArray<PreviousVersionNode *>* _previous_versions;
-  u2              _enclosing_method_class_index;  // Constant pool index for class of enclosing method, or 0 if none
-  u2              _enclosing_method_method_index; // Constant pool index for name and type of enclosing method, or 0 if none
   // JVMTI fields can be moved to their own structure - see 6315920
   unsigned char * _cached_class_file_bytes;       // JVMTI: cached class file, before retransformable agent modified it in CFLH
   jint            _cached_class_file_len;         // JVMTI: length of above
@@ -351,6 +359,12 @@ class instanceKlass: public Klass {
     inner_class_next_offset = 4
   };
 
+  enum EnclosingMethodAttributeOffset {
+    enclosing_method_class_index_offset = 0,
+    enclosing_method_method_index_offset = 1,
+    enclosing_method_attribute_size = 2
+  };
+
   // method override check
   bool is_override(methodHandle super_method, Handle targetclassloader, Symbol* targetclassname, TRAPS);
 
@@ -533,11 +547,15 @@ class instanceKlass: public Klass {
   Symbol* generic_signature() const                   { return _generic_signature; }
   void set_generic_signature(Symbol* sig)             { _generic_signature = sig; }
 
-  u2 enclosing_method_class_index() const             { return _enclosing_method_class_index; }
-  u2 enclosing_method_method_index() const            { return _enclosing_method_method_index; }
+  u2 enclosing_method_data(int offset);
+  u2 enclosing_method_class_index() {
+    return enclosing_method_data(enclosing_method_class_index_offset);
+  }
+  u2 enclosing_method_method_index() {
+    return enclosing_method_data(enclosing_method_method_index_offset);
+  }
   void set_enclosing_method_indices(u2 class_index,
-                                    u2 method_index)  { _enclosing_method_class_index  = class_index;
-                                                        _enclosing_method_method_index = method_index; }
+                                    u2 method_index);
 
   // jmethodID support
   static jmethodID get_jmethod_id(instanceKlassHandle ik_h,
@@ -1053,4 +1071,83 @@ class nmethodBucket: public CHeapObj {
   nmethod* get_nmethod()                  { return _nmethod; }
 };
 
+// An iterator that's used to access the inner classes indices in the
+// instanceKlass::_inner_classes array.
+class InnerClassesIterator : public StackObj {
+ private:
+  typeArrayHandle _inner_classes;
+  int _length;
+  int _idx;
+ public:
+
+  InnerClassesIterator(instanceKlassHandle k) {
+    _inner_classes = k->inner_classes();
+    if (k->inner_classes() != NULL) {
+      _length = _inner_classes->length();
+      // The inner class array's length should be the multiple of
+      // inner_class_next_offset if it only contains the InnerClasses
+      // attribute data, or it should be
+      // n*inner_class_next_offset+enclosing_method_attribute_size
+      // if it also contains the EnclosingMethod data.
+      assert((_length % instanceKlass::inner_class_next_offset == 0 ||
+              _length % instanceKlass::inner_class_next_offset == instanceKlass::enclosing_method_attribute_size),
+             "just checking");
+      // Remove the enclosing_method portion if exists.
+      if (_length % instanceKlass::inner_class_next_offset == instanceKlass::enclosing_method_attribute_size) {
+        _length -= instanceKlass::enclosing_method_attribute_size;
+      }
+    } else {
+      _length = 0;
+    }
+    _idx = 0;
+  }
+
+  int length() const {
+    return _length;
+  }
+
+  void next() {
+    _idx += instanceKlass::inner_class_next_offset;
+  }
+
+  bool done() const {
+    return (_idx >= _length);
+  }
+
+  u2 inner_class_info_index() const {
+    return _inner_classes->ushort_at(
+               _idx + instanceKlass::inner_class_inner_class_info_offset);
+  }
+
+  void set_inner_class_info_index(u2 index) {
+    _inner_classes->ushort_at_put(
+               _idx + instanceKlass::inner_class_inner_class_info_offset, index);
+  }
+
+  u2 outer_class_info_index() const {
+    return _inner_classes->ushort_at(
+               _idx + instanceKlass::inner_class_outer_class_info_offset);
+  }
+
+  void set_outer_class_info_index(u2 index) {
+    _inner_classes->ushort_at_put(
+               _idx + instanceKlass::inner_class_outer_class_info_offset, index);
+  }
+
+  u2 inner_name_index() const {
+    return _inner_classes->ushort_at(
+               _idx + instanceKlass::inner_class_inner_name_offset);
+  }
+
+  void set_inner_name_index(u2 index) {
+    _inner_classes->ushort_at_put(
+               _idx + instanceKlass::inner_class_inner_name_offset, index);
+  }
+
+  u2 inner_access_flags() const {
+    return _inner_classes->ushort_at(
+               _idx + instanceKlass::inner_class_access_flags_offset);
+  }
+};
+
 #endif // SHARE_VM_OOPS_INSTANCEKLASS_HPP

src/share/vm/oops/instanceKlassKlass.cpp

@@ -416,7 +416,6 @@ instanceKlassKlass::allocate_instance_klass(Symbol* name, int vtable_len, int it
     ik->set_methods_annotations(NULL);
     ik->set_methods_parameter_annotations(NULL);
     ik->set_methods_default_annotations(NULL);
-    ik->set_enclosing_method_indices(0, 0);
     ik->set_jvmti_cached_class_field_map(NULL);
     ik->set_initial_method_idnum(0);
     assert(k()->is_parsable(), "should be parsable here.");

src/share/vm/prims/jvm.cpp

@@ -1301,9 +1301,6 @@ JVM_END
 // Inner class reflection ///////////////////////////////////////////////////////////////////////////////
 
 JVM_ENTRY(jobjectArray, JVM_GetDeclaredClasses(JNIEnv *env, jclass ofClass))
-  const int inner_class_info_index = 0;
-  const int outer_class_info_index = 1;
-
   JvmtiVMObjectAllocEventCollector oam;
   // ofClass is a reference to a java_lang_Class object. The mirror object
   // of an instanceKlass
@@ -1315,26 +1312,26 @@ JVM_ENTRY(jobjectArray, JVM_GetDeclaredClasses(JNIEnv *env, jclass ofClass))
   }
 
   instanceKlassHandle k(thread, java_lang_Class::as_klassOop(JNIHandles::resolve_non_null(ofClass)));
+  InnerClassesIterator iter(k);
 
-  if (k->inner_classes()->length() == 0) {
+  if (iter.length() == 0) {
     // Neither an inner nor outer class
     oop result = oopFactory::new_objArray(SystemDictionary::Class_klass(), 0, CHECK_NULL);
     return (jobjectArray)JNIHandles::make_local(env, result);
   }
 
   // find inner class info
-  typeArrayHandle    icls(thread, k->inner_classes());
   constantPoolHandle cp(thread, k->constants());
-  int length = icls->length();
+  int length = iter.length();
 
   // Allocate temp. result array
   objArrayOop r = oopFactory::new_objArray(SystemDictionary::Class_klass(), length/4, CHECK_NULL);
   objArrayHandle result (THREAD, r);
   int members = 0;
 
-  for(int i = 0; i < length; i += 4) {
-    int ioff = icls->ushort_at(i + inner_class_info_index);
-    int ooff = icls->ushort_at(i + outer_class_info_index);
+  for (; !iter.done(); iter.next()) {
+    int ioff = iter.inner_class_info_index();
+    int ooff = iter.outer_class_info_index();
 
     if (ioff != 0 && ooff != 0) {
       // Check to see if the name matches the class we're looking for
@@ -1392,17 +1389,13 @@ klassOop instanceKlass::compute_enclosing_class_impl(instanceKlassHandle k,
                                                      bool* inner_is_member,
                                                      TRAPS) {
   Thread* thread = THREAD;
-  const int inner_class_info_index = inner_class_inner_class_info_offset;
-  const int outer_class_info_index = inner_class_outer_class_info_offset;
-
-  if (k->inner_classes()->length() == 0) {
+  InnerClassesIterator iter(k);
+  if (iter.length() == 0) {
     // No inner class info => no declaring class
     return NULL;
   }
 
-  typeArrayHandle i_icls(thread, k->inner_classes());
   constantPoolHandle i_cp(thread, k->constants());
-  int i_length = i_icls->length();
 
   bool found = false;
   klassOop ok;
@@ -1410,10 +1403,10 @@ klassOop instanceKlass::compute_enclosing_class_impl(instanceKlassHandle k,
   *inner_is_member = false;
 
   // Find inner_klass attribute
-  for (int i = 0; i < i_length && !found; i += inner_class_next_offset) {
-    int ioff = i_icls->ushort_at(i + inner_class_info_index);
-    int ooff = i_icls->ushort_at(i + outer_class_info_index);
-    int noff = i_icls->ushort_at(i + inner_class_inner_name_offset);
+  for (; !iter.done() && !found; iter.next()) {
+    int ioff = iter.inner_class_info_index();
+    int ooff = iter.outer_class_info_index();
+    int noff = iter.inner_name_index();
     if (ioff != 0) {
       // Check to see if the name matches the class we're looking for
       // before attempting to find the class.

src/share/vm/prims/jvmtiClassFileReconstituter.cpp

@@ -292,8 +292,8 @@ void JvmtiClassFileReconstituter::write_signature_attribute(u2 generic_signature
 
 // Compute the number of entries in the InnerClasses attribute
 u2 JvmtiClassFileReconstituter::inner_classes_attribute_length() {
-  typeArrayOop inner_class_list = ikh()->inner_classes();
-  return (inner_class_list == NULL) ? 0 : inner_class_list->length();
+  InnerClassesIterator iter(ikh());
+  return iter.length();
 }
 
 // Write an annotation attribute.  The VM stores them in raw form, so all we need
@@ -324,26 +324,20 @@ void JvmtiClassFileReconstituter::write_annotations_attribute(const char* attr_n
 // JVMSpec|     } classes[number_of_classes];
 // JVMSpec|   }
 void JvmtiClassFileReconstituter::write_inner_classes_attribute(int length) {
-  typeArrayOop inner_class_list = ikh()->inner_classes();
-  guarantee(inner_class_list != NULL && inner_class_list->length() == length,
+  InnerClassesIterator iter(ikh());
+  guarantee(iter.length() != 0 && iter.length() == length,
             "caller must check");
-  typeArrayHandle inner_class_list_h(thread(), inner_class_list);
-  assert (length % instanceKlass::inner_class_next_offset == 0, "just checking");
   u2 entry_count = length / instanceKlass::inner_class_next_offset;
   u4 size = 2 + entry_count * (2+2+2+2);
 
   write_attribute_name_index("InnerClasses");
   write_u4(size);
   write_u2(entry_count);
-  for (int i = 0; i < length; i += instanceKlass::inner_class_next_offset) {
-    write_u2(inner_class_list_h->ushort_at(
-                      i + instanceKlass::inner_class_inner_class_info_offset));
-    write_u2(inner_class_list_h->ushort_at(
-                      i + instanceKlass::inner_class_outer_class_info_offset));
-    write_u2(inner_class_list_h->ushort_at(
-                      i + instanceKlass::inner_class_inner_name_offset));
-    write_u2(inner_class_list_h->ushort_at(
-                      i + instanceKlass::inner_class_access_flags_offset));
+  for (; !iter.done(); iter.next()) {
+    write_u2(iter.inner_class_info_index());
+    write_u2(iter.outer_class_info_index());
+    write_u2(iter.inner_name_index());
+    write_u2(iter.inner_access_flags());
   }
 }
 

src/share/vm/prims/jvmtiRedefineClasses.cpp

@@ -2400,44 +2400,33 @@ void VM_RedefineClasses::set_new_constant_pool(
   // new constant indices as needed. The inner classes info is a
   // quadruple:
   // (inner_class_info, outer_class_info, inner_name, inner_access_flags)
-  typeArrayOop inner_class_list = scratch_class->inner_classes();
-  int icl_length = (inner_class_list == NULL) ? 0 : inner_class_list->length();
-  if (icl_length > 0) {
-    typeArrayHandle inner_class_list_h(THREAD, inner_class_list);
-    for (int i = 0; i < icl_length;
-         i += instanceKlass::inner_class_next_offset) {
-      int cur_index = inner_class_list_h->ushort_at(i
-                        + instanceKlass::inner_class_inner_class_info_offset);
-      if (cur_index == 0) {
-        continue;  // JVM spec. allows null inner class refs so skip it
-      }
-      int new_index = find_new_index(cur_index);
-      if (new_index != 0) {
-        RC_TRACE_WITH_THREAD(0x00080000, THREAD,
-          ("inner_class_info change: %d to %d", cur_index, new_index));
-        inner_class_list_h->ushort_at_put(i
-          + instanceKlass::inner_class_inner_class_info_offset, new_index);
-      }
-      cur_index = inner_class_list_h->ushort_at(i
-                    + instanceKlass::inner_class_outer_class_info_offset);
-      new_index = find_new_index(cur_index);
-      if (new_index != 0) {
-        RC_TRACE_WITH_THREAD(0x00080000, THREAD,
-          ("outer_class_info change: %d to %d", cur_index, new_index));
-        inner_class_list_h->ushort_at_put(i
-          + instanceKlass::inner_class_outer_class_info_offset, new_index);
-      }
-      cur_index = inner_class_list_h->ushort_at(i
-                    + instanceKlass::inner_class_inner_name_offset);
-      new_index = find_new_index(cur_index);
-      if (new_index != 0) {
-        RC_TRACE_WITH_THREAD(0x00080000, THREAD,
-          ("inner_name change: %d to %d", cur_index, new_index));
-        inner_class_list_h->ushort_at_put(i
-          + instanceKlass::inner_class_inner_name_offset, new_index);
-      }
-    } // end for each inner class
-  } // end if we have inner classes
+  InnerClassesIterator iter(scratch_class);
+  for (; !iter.done(); iter.next()) {
+    int cur_index = iter.inner_class_info_index();
+    if (cur_index == 0) {
+      continue;  // JVM spec. allows null inner class refs so skip it
+    }
+    int new_index = find_new_index(cur_index);
+    if (new_index != 0) {
+      RC_TRACE_WITH_THREAD(0x00080000, THREAD,
+        ("inner_class_info change: %d to %d", cur_index, new_index));
+      iter.set_inner_class_info_index(new_index);
+    }
+    cur_index = iter.outer_class_info_index();
+    new_index = find_new_index(cur_index);
+    if (new_index != 0) {
+      RC_TRACE_WITH_THREAD(0x00080000, THREAD,
+        ("outer_class_info change: %d to %d", cur_index, new_index));
+      iter.set_outer_class_info_index(new_index);
+    }
+    cur_index = iter.inner_name_index();
+    new_index = find_new_index(cur_index);
+    if (new_index != 0) {
+      RC_TRACE_WITH_THREAD(0x00080000, THREAD,
+        ("inner_name change: %d to %d", cur_index, new_index));
+      iter.set_inner_name_index(new_index);
+    }
+  } // end for each inner class
 
   // Attach each method in klass to the new constant pool and update
   // to use new constant pool indices as needed:

src/share/vm/runtime/reflection.cpp

@@ -591,14 +591,11 @@ bool Reflection::is_same_package_member(klassOop class1, klassOop class2, TRAPS)
 // Caller is responsible for figuring out in advance which case must be true.
 void Reflection::check_for_inner_class(instanceKlassHandle outer, instanceKlassHandle inner,
                                        bool inner_is_member, TRAPS) {
-  const int inner_class_info_index = 0;
-  const int outer_class_info_index = 1;
-
-  typeArrayHandle    icls (THREAD, outer->inner_classes());
+  InnerClassesIterator iter(outer);
   constantPoolHandle cp   (THREAD, outer->constants());
-  for(int i = 0; i < icls->length(); i += 4) {
-     int ioff = icls->ushort_at(i + inner_class_info_index);
-     int ooff = icls->ushort_at(i + outer_class_info_index);
+  for (; !iter.done(); iter.next()) {
+     int ioff = iter.inner_class_info_index();
+     int ooff = iter.outer_class_info_index();
 
      if (inner_is_member && ioff != 0 && ooff != 0) {
         klassOop o = cp->klass_at(ooff, CHECK);