7168280: Eliminate the generic signature index slot from field array for field without generic signature

Only allocate the generic signature index slot in the field array for field with generic signature attribute.

Reviewed-by: coleenp, dlong

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

@@ -81,6 +81,7 @@ public class AccessFlags implements /* imports */ ClassConstants {
   // field flags
   public boolean fieldAccessWatched () { return (flags & JVM_ACC_FIELD_ACCESS_WATCHED) != 0; }
   public boolean fieldModificationWatched() { return (flags & JVM_ACC_FIELD_MODIFICATION_WATCHED) != 0; }
+  public boolean fieldHasGenericSignature() { return (flags & JVM_ACC_FIELD_HAS_GENERIC_SIGNATURE)!= 0; }
 
   public void printOn(PrintStream tty) {
     // prints only .class flags and not the hotspot internal flags

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

@@ -50,7 +50,6 @@ public class InstanceKlass extends Klass {
   private static int INITVAL_INDEX_OFFSET;
   private static int LOW_OFFSET;
   private static int HIGH_OFFSET;
-  private static int GENERIC_SIGNATURE_INDEX_OFFSET;
   private static int FIELD_SLOTS;
 
   // ClassState constants
@@ -99,7 +98,6 @@ public class InstanceKlass extends Klass {
     INITVAL_INDEX_OFFSET           = db.lookupIntConstant("FieldInfo::initval_index_offset").intValue();
     LOW_OFFSET                     = db.lookupIntConstant("FieldInfo::low_offset").intValue();
     HIGH_OFFSET                    = db.lookupIntConstant("FieldInfo::high_offset").intValue();
-    GENERIC_SIGNATURE_INDEX_OFFSET = db.lookupIntConstant("FieldInfo::generic_signature_offset").intValue();
     FIELD_SLOTS                    = db.lookupIntConstant("FieldInfo::field_slots").intValue();
     // read ClassState constants
     CLASS_STATE_UNPARSABLE_BY_GC = db.lookupIntConstant("instanceKlass::unparsable_by_gc").intValue();
@@ -279,7 +277,25 @@ public class InstanceKlass extends Klass {
   }
 
   public short getFieldGenericSignatureIndex(int index) {
-    return getFields().getShortAt(index * FIELD_SLOTS + GENERIC_SIGNATURE_INDEX_OFFSET);
+    int len = (int)getFields().getLength();
+    int allFieldsCount = getAllFieldsCount();
+    int generic_signature_slot = allFieldsCount * FIELD_SLOTS;
+    for (int i = 0; i < allFieldsCount; i++) {
+      short flags = getFieldAccessFlags(i);
+      AccessFlags access = new AccessFlags(flags);
+      if (i == index) {
+        if (access.fieldHasGenericSignature()) {
+          return getFields().getShortAt(generic_signature_slot);
+        } else {
+          return 0;
+        }
+      } else {
+        if (access.fieldHasGenericSignature()) {
+          generic_signature_slot ++;
+        }
+      }
+    }
+    return 0;
   }
 
   public Symbol getFieldGenericSignature(int index) {
@@ -309,7 +325,18 @@ public class InstanceKlass extends Klass {
   public ObjArray  getTransitiveInterfaces() { return (ObjArray)     transitiveInterfaces.getValue(this); }
   public TypeArray getFields()              { return (TypeArray)    fields.getValue(this); }
   public int       getJavaFieldsCount()     { return                (int) javaFieldsCount.getValue(this); }
-  public int       getAllFieldsCount()      { return                (int)getFields().getLength() / FIELD_SLOTS; }
+  public int       getAllFieldsCount()      {
+    int len = (int)getFields().getLength();
+    int allFieldsCount = 0;
+    for (; allFieldsCount*FIELD_SLOTS < len; allFieldsCount++) {
+      short flags = getFieldAccessFlags(allFieldsCount);
+      AccessFlags access = new AccessFlags(flags);
+      if (access.fieldHasGenericSignature()) {
+        len --;
+      }
+    }
+    return allFieldsCount;
+  }
   public ConstantPool getConstants()        { return (ConstantPool) constants.getValue(this); }
   public Oop       getClassLoader()         { return                classLoader.getValue(this); }
   public Oop       getProtectionDomain()    { return                protectionDomain.getValue(this); }

hotspot/agent/src/share/classes/sun/jvm/hotspot/runtime/ClassConstants.java

@@ -153,6 +153,8 @@ public interface ClassConstants
     public static final long JVM_ACC_FIELD_ACCESS_WATCHED         = 0x00002000;
     // field modification is watched by JVMTI
     public static final long JVM_ACC_FIELD_MODIFICATION_WATCHED   = 0x00008000;
+    // field has generic signature
+    public static final long JVM_ACC_FIELD_HAS_GENERIC_SIGNATURE  = 0x00000800;
 
     // flags accepted by set_field_flags
     public static final long JVM_ACC_FIELD_FLAGS = 0x00008000 | JVM_ACC_WRITTEN_FLAGS;

hotspot/src/share/vm/classfile/classFileParser.cpp

@@ -1082,12 +1082,36 @@ typeArrayHandle ClassFileParser::parse_fields(Symbol* class_name,
 
   int num_injected = 0;
   InjectedField* injected = JavaClasses::get_injected(class_name, &num_injected);
+  int total_fields = length + num_injected;
 
-  // Tuples of shorts [access, name index, sig index, initial value index, byte offset, generic signature index]
+  // The field array starts with tuples of shorts
-  typeArrayOop new_fields = oopFactory::new_permanent_shortArray((length + num_injected) * FieldInfo::field_slots, CHECK_(nullHandle));
+  // [access, name index, sig index, initial value index, byte offset].
-  typeArrayHandle fields(THREAD, new_fields);
+  // A generic signature slot only exists for field with generic
+  // signature attribute. And the access flag is set with
+  // JVM_ACC_FIELD_HAS_GENERIC_SIGNATURE for that field. The generic
+  // signature slots are at the end of the field array and after all
+  // other fields data.
+  //
+  //   f1: [access, name index, sig index, initial value index, low_offset, high_offset]
+  //   f2: [access, name index, sig index, initial value index, low_offset, high_offset]
+  //       ...
+  //   fn: [access, name index, sig index, initial value index, low_offset, high_offset]
+  //       [generic signature index]
+  //       [generic signature index]
+  //       ...
+  //
+  // Allocate a temporary resource array for field data. For each field,
+  // a slot is reserved in the temporary array for the generic signature
+  // index. After parsing all fields, the data are copied to a permanent
+  // array and any unused slots will be discarded.
+  ResourceMark rm(THREAD);
+  u2* fa = NEW_RESOURCE_ARRAY_IN_THREAD(
+             THREAD, u2, total_fields * (FieldInfo::field_slots + 1));
 
   typeArrayHandle field_annotations;
+  // The generic signature slots start after all other fields' data.
+  int generic_signature_slot = total_fields * FieldInfo::field_slots;
+  int num_generic_signature = 0;
   for (int n = 0; n < length; n++) {
     cfs->guarantee_more(8, CHECK_(nullHandle));  // access_flags, name_index, descriptor_index, attributes_count
 
@@ -1135,14 +1159,19 @@ typeArrayHandle ClassFileParser::parse_fields(Symbol* class_name,
       if (is_synthetic) {
         access_flags.set_is_synthetic();
       }
+      if (generic_signature_index != 0) {
+        access_flags.set_field_has_generic_signature();
+        fa[generic_signature_slot] = generic_signature_index;
+        generic_signature_slot ++;
+        num_generic_signature ++;
+      }
     }
 
-    FieldInfo* field = FieldInfo::from_field_array(fields(), n);
+    FieldInfo* field = FieldInfo::from_field_array(fa, n);
     field->initialize(access_flags.as_short(),
                       name_index,
                       signature_index,
                       constantvalue_index,
-                      generic_signature_index,
                       0);
 
     BasicType type = cp->basic_type_for_signature_at(signature_index);
@@ -1155,8 +1184,8 @@ typeArrayHandle ClassFileParser::parse_fields(Symbol* class_name,
     field->set_offset(atype);
   }
 
-  if (num_injected != 0) {
   int index = length;
+  if (num_injected != 0) {
     for (int n = 0; n < num_injected; n++) {
       // Check for duplicates
       if (injected[n].may_be_java) {
@@ -1164,7 +1193,7 @@ typeArrayHandle ClassFileParser::parse_fields(Symbol* class_name,
         Symbol* signature = injected[n].signature();
         bool duplicate = false;
         for (int i = 0; i < length; i++) {
-          FieldInfo* f = FieldInfo::from_field_array(fields(), i);
+          FieldInfo* f = FieldInfo::from_field_array(fa, i);
           if (name      == cp->symbol_at(f->name_index()) &&
               signature == cp->symbol_at(f->signature_index())) {
             // Symbol is desclared in Java so skip this one
@@ -1179,12 +1208,11 @@ typeArrayHandle ClassFileParser::parse_fields(Symbol* class_name,
       }
 
       // Injected field
-      FieldInfo* field = FieldInfo::from_field_array(fields(), index);
+      FieldInfo* field = FieldInfo::from_field_array(fa, index);
       field->initialize(JVM_ACC_FIELD_INTERNAL,
                         injected[n].name_index,
                         injected[n].signature_index,
                         0,
-                        0,
                         0);
 
       BasicType type = FieldType::basic_type(injected[n].signature());
@@ -1197,17 +1225,27 @@ typeArrayHandle ClassFileParser::parse_fields(Symbol* class_name,
       field->set_offset(atype);
       index++;
     }
+  }
 
-    if (index < length + num_injected) {
+  // Now copy the fields' data from the temporary resource array.
-      // sometimes injected fields already exist in the Java source so
+  // Sometimes injected fields already exist in the Java source so
-      // the fields array could be too long.  In that case trim the
+  // the fields array could be too long.  In that case the
-      // fields array.
+  // fields array is trimed. Also unused slots that were reserved
-      new_fields = oopFactory::new_permanent_shortArray(index * FieldInfo::field_slots, CHECK_(nullHandle));
+  // for generic signature indexes are discarded.
-      for (int i = 0; i < index * FieldInfo::field_slots; i++) {
+  typeArrayOop new_fields = oopFactory::new_permanent_shortArray(
-        new_fields->short_at_put(i, fields->short_at(i));
+    index * FieldInfo::field_slots + num_generic_signature,
+    CHECK_(nullHandle));
+  typeArrayHandle fields(THREAD, new_fields);
+  {
+    int i = 0;
+    for (; i < index * FieldInfo::field_slots; i++) {
+      new_fields->short_at_put(i, fa[i]);
     }
-      fields = new_fields;
+    for (int j = total_fields * FieldInfo::field_slots;
+         j < generic_signature_slot; j++) {
+      new_fields->short_at_put(i++, fa[j]);
     }
+    assert(i == new_fields->length(), "");
   }
 
   if (_need_verify && length > 1) {

hotspot/src/share/vm/classfile/systemDictionary.cpp

@@ -2763,7 +2763,7 @@ class ClassStatistics: AllStatic {
       class_size += ik->local_interfaces()->size();
       class_size += ik->transitive_interfaces()->size();
       // We do not have to count implementors, since we only store one!
-      class_size += ik->all_fields_count() * FieldInfo::field_slots;
+      class_size += ik->fields()->length();
     }
   }
 

hotspot/src/share/vm/oops/fieldInfo.hpp

@@ -50,8 +50,7 @@ class FieldInfo VALUE_OBJ_CLASS_SPEC {
     initval_index_offset     = 3,
     low_offset               = 4,
     high_offset              = 5,
-    generic_signature_offset = 6,
+    field_slots              = 6
-    field_slots              = 7
   };
 
  private:
@@ -60,29 +59,28 @@ class FieldInfo VALUE_OBJ_CLASS_SPEC {
   void set_name_index(u2 val)                    { _shorts[name_index_offset] = val;         }
   void set_signature_index(u2 val)               { _shorts[signature_index_offset] = val;    }
   void set_initval_index(u2 val)                 { _shorts[initval_index_offset] = val;      }
-  void set_generic_signature_index(u2 val)       { _shorts[generic_signature_offset] = val;  }
 
   u2 name_index() const                          { return _shorts[name_index_offset];        }
   u2 signature_index() const                     { return _shorts[signature_index_offset];   }
   u2 initval_index() const                       { return _shorts[initval_index_offset];     }
-  u2 generic_signature_index() const             { return _shorts[generic_signature_offset]; }
 
  public:
   static FieldInfo* from_field_array(typeArrayOop fields, int index) {
     return ((FieldInfo*)fields->short_at_addr(index * field_slots));
   }
+  static FieldInfo* from_field_array(u2* fields, int index) {
+    return ((FieldInfo*)(fields + index * field_slots));
+  }
 
   void initialize(u2 access_flags,
                   u2 name_index,
                   u2 signature_index,
                   u2 initval_index,
-                  u2 generic_signature_index,
                   u4 offset) {
     _shorts[access_flags_offset] = access_flags;
     _shorts[name_index_offset] = name_index;
     _shorts[signature_index_offset] = signature_index;
     _shorts[initval_index_offset] = initval_index;
-    _shorts[generic_signature_offset] = generic_signature_index;
     set_offset(offset);
   }
 
@@ -105,14 +103,6 @@ class FieldInfo VALUE_OBJ_CLASS_SPEC {
     return cp->symbol_at(index);
   }
 
-  Symbol* generic_signature(constantPoolHandle cp) const {
-    int index = generic_signature_index();
-    if (index == 0) {
-      return NULL;
-    }
-    return cp->symbol_at(index);
-  }
-
   void set_access_flags(u2 val)                  { _shorts[access_flags_offset] = val;             }
   void set_offset(u4 val)                        {
     _shorts[low_offset] = extract_low_short_from_int(val);

hotspot/src/share/vm/oops/fieldStreams.hpp

@@ -42,21 +42,57 @@ class FieldStreamBase : public StackObj {
   constantPoolHandle  _constants;
   int                 _index;
   int                 _limit;
+  int                 _generic_signature_slot;
 
   FieldInfo* field() const { return FieldInfo::from_field_array(_fields(), _index); }
 
+  int init_generic_signature_start_slot() {
+    int length = _fields->length();
+    int num_fields = 0;
+    int skipped_generic_signature_slots = 0;
+    FieldInfo* fi;
+    AccessFlags flags;
+    /* Scan from 0 to the current _index. Count the number of generic
+       signature slots for field[0] to field[_index - 1]. */
+    for (int i = 0; i < _index; i++) {
+      fi = FieldInfo::from_field_array(_fields(), i);
+      flags.set_flags(fi->access_flags());
+      if (flags.field_has_generic_signature()) {
+        length --;
+        skipped_generic_signature_slots ++;
+      }
+    }
+    /* Scan from the current _index. */
+    for (int i = _index; i*FieldInfo::field_slots < length; i++) {
+      fi = FieldInfo::from_field_array(_fields(), i);
+      flags.set_flags(fi->access_flags());
+      if (flags.field_has_generic_signature()) {
+        length --;
+      }
+      num_fields ++;
+    }
+    _generic_signature_slot = length + skipped_generic_signature_slots;
+    assert(_generic_signature_slot <= _fields->length(), "");
+    return num_fields;
+  }
+
   FieldStreamBase(typeArrayHandle fields, constantPoolHandle constants, int start, int limit) {
     _fields = fields;
     _constants = constants;
     _index = start;
+    int num_fields = init_generic_signature_start_slot();
+    if (limit < start) {
+      _limit = num_fields;
+    } else {
       _limit = limit;
     }
+  }
 
   FieldStreamBase(typeArrayHandle fields, constantPoolHandle constants) {
     _fields = fields;
     _constants = constants;
     _index = 0;
-    _limit = fields->length() / FieldInfo::field_slots;
+    _limit = init_generic_signature_start_slot();
   }
 
  public:
@@ -65,18 +101,26 @@ class FieldStreamBase : public StackObj {
     _constants = klass->constants();
     _index = 0;
     _limit = klass->java_fields_count();
+    init_generic_signature_start_slot();
   }
   FieldStreamBase(instanceKlassHandle klass) {
     _fields = klass->fields();
     _constants = klass->constants();
     _index = 0;
     _limit = klass->java_fields_count();
+    init_generic_signature_start_slot();
   }
 
   // accessors
   int index() const                 { return _index; }
 
-  void next() { _index += 1; }
+  void next() {
+    if (access_flags().field_has_generic_signature()) {
+      _generic_signature_slot ++;
+      assert(_generic_signature_slot <= _fields->length(), "");
+    }
+    _index += 1;
+  }
   bool done() const { return _index >= _limit; }
 
   // Accessors for current field
@@ -103,7 +147,13 @@ class FieldStreamBase : public StackObj {
   }
 
   Symbol* generic_signature() const {
-    return field()->generic_signature(_constants);
+    if (access_flags().field_has_generic_signature()) {
+      assert(_generic_signature_slot < _fields->length(), "out of bounds");
+      int index = _fields->short_at(_generic_signature_slot);
+      return _constants->symbol_at(index);
+    } else {
+      return NULL;
+    }
   }
 
   int offset() const {
@@ -139,11 +189,19 @@ class JavaFieldStream : public FieldStreamBase {
   }
   int generic_signature_index() const {
     assert(!field()->is_internal(), "regular only");
-    return field()->generic_signature_index();
+    if (access_flags().field_has_generic_signature()) {
+      assert(_generic_signature_slot < _fields->length(), "out of bounds");
+      return _fields->short_at(_generic_signature_slot);
+    } else {
+      return 0;
+    }
   }
   void set_generic_signature_index(int index) {
     assert(!field()->is_internal(), "regular only");
-    field()->set_generic_signature_index(index);
+    if (access_flags().field_has_generic_signature()) {
+      assert(_generic_signature_slot < _fields->length(), "out of bounds");
+      _fields->short_at_put(_generic_signature_slot, index);
+    }
   }
   int initval_index() const {
     assert(!field()->is_internal(), "regular only");
@@ -159,8 +217,8 @@ class JavaFieldStream : public FieldStreamBase {
 // Iterate over only the internal fields
 class InternalFieldStream : public FieldStreamBase {
  public:
-  InternalFieldStream(instanceKlass* k):      FieldStreamBase(k->fields(), k->constants(), k->java_fields_count(), k->all_fields_count()) {}
+  InternalFieldStream(instanceKlass* k):      FieldStreamBase(k->fields(), k->constants(), k->java_fields_count(), 0) {}
-  InternalFieldStream(instanceKlassHandle k): FieldStreamBase(k->fields(), k->constants(), k->java_fields_count(), k->all_fields_count()) {}
+  InternalFieldStream(instanceKlassHandle k): FieldStreamBase(k->fields(), k->constants(), k->java_fields_count(), 0) {}
 };
 
 

hotspot/src/share/vm/oops/instanceKlass.hpp

@@ -168,8 +168,19 @@ class instanceKlass: public Klass {
   objArrayOop     _local_interfaces;
   // Interface (klassOops) this class implements transitively.
   objArrayOop     _transitive_interfaces;
-  // Instance and static variable information, 5-tuples of shorts [access, name
+  // Instance and static variable information, starts with 6-tuples of shorts
-  // index, sig index, initval index, offset].
+  // [access, name index, sig index, initval index, low_offset, high_offset]
+  // for all fields, followed by the generic signature data at the end of
+  // the array. Only fields with generic signature attributes have the generic
+  // signature data set in the array. The fields array looks like following:
+  //
+  // f1: [access, name index, sig index, initial value index, low_offset, high_offset]
+  // f2: [access, name index, sig index, initial value index, low_offset, high_offset]
+  //      ...
+  // fn: [access, name index, sig index, initial value index, low_offset, high_offset]
+  //     [generic signature index]
+  //     [generic signature index]
+  //     ...
   typeArrayOop    _fields;
   // Constant pool for this class.
   constantPoolOop _constants;
@@ -351,9 +362,6 @@ class instanceKlass: public Klass {
   // Number of Java declared fields
   int java_fields_count() const           { return (int)_java_fields_count; }
 
-  // Number of fields including any injected fields
-  int all_fields_count() const            { return _fields->length() / FieldInfo::field_slots; }
-
   typeArrayOop fields() const              { return _fields; }
 
   void set_fields(typeArrayOop f, u2 java_fields_count) {

hotspot/src/share/vm/runtime/fieldDescriptor.cpp

@@ -28,6 +28,7 @@
 #include "memory/resourceArea.hpp"
 #include "memory/universe.inline.hpp"
 #include "oops/instanceKlass.hpp"
+#include "oops/fieldStreams.hpp"
 #include "runtime/fieldDescriptor.hpp"
 #include "runtime/handles.inline.hpp"
 #include "runtime/signature.hpp"
@@ -37,6 +38,20 @@ oop fieldDescriptor::loader() const {
   return instanceKlass::cast(_cp->pool_holder())->class_loader();
 }
 
+Symbol* fieldDescriptor::generic_signature() const {
+  int idx = 0;
+  instanceKlass* ik = instanceKlass::cast(field_holder());
+  for (AllFieldStream fs(ik); !fs.done(); fs.next()) {
+    if (idx == _index) {
+      return fs.generic_signature();
+    } else {
+      idx ++;
+    }
+  }
+  assert(false, "should never happen");
+  return NULL;
+}
+
 typeArrayOop fieldDescriptor::annotations() const {
   instanceKlass* ik = instanceKlass::cast(field_holder());
   objArrayOop md = ik->fields_annotations();

hotspot/src/share/vm/runtime/fieldDescriptor.hpp

@@ -67,7 +67,7 @@ class fieldDescriptor VALUE_OBJ_CLASS_SPEC {
   oop loader() const;
   // Offset (in words) of field from start of instanceOop / klassOop
   int offset() const                   { return field()->offset(); }
-  Symbol* generic_signature() const    { return field()->generic_signature(_cp); }
+  Symbol* generic_signature() const;
   int index() const                    { return _index; }
   typeArrayOop annotations() const;
 

hotspot/src/share/vm/runtime/vmStructs.cpp

@@ -2352,7 +2352,6 @@ static inline uint64_t cast_uint64_t(size_t x)
   declare_constant(FieldInfo::initval_index_offset)                       \
   declare_constant(FieldInfo::low_offset)                                 \
   declare_constant(FieldInfo::high_offset)                                \
-  declare_constant(FieldInfo::generic_signature_offset)                   \
   declare_constant(FieldInfo::field_slots)                                \
                                                                           \
   /************************************************/                      \

hotspot/src/share/vm/utilities/accessFlags.hpp

@@ -80,10 +80,12 @@ enum {
   JVM_ACC_FIELD_ACCESS_WATCHED       = 0x00002000,  // field access is watched by JVMTI
   JVM_ACC_FIELD_MODIFICATION_WATCHED = 0x00008000,  // field modification is watched by JVMTI
   JVM_ACC_FIELD_INTERNAL             = 0x00000400,  // internal field, same as JVM_ACC_ABSTRACT
+  JVM_ACC_FIELD_HAS_GENERIC_SIGNATURE = 0x00000800, // field has generic signature
 
   JVM_ACC_FIELD_INTERNAL_FLAGS       = JVM_ACC_FIELD_ACCESS_WATCHED |
                                        JVM_ACC_FIELD_MODIFICATION_WATCHED |
-                                       JVM_ACC_FIELD_INTERNAL,
+                                       JVM_ACC_FIELD_INTERNAL |
+                                       JVM_ACC_FIELD_HAS_GENERIC_SIGNATURE,
 
                                                     // flags accepted by set_field_flags()
   JVM_ACC_FIELD_FLAGS                = JVM_RECOGNIZED_FIELD_MODIFIERS | JVM_ACC_FIELD_INTERNAL_FLAGS
@@ -156,6 +158,8 @@ class AccessFlags VALUE_OBJ_CLASS_SPEC {
   bool is_field_modification_watched() const
                                         { return (_flags & JVM_ACC_FIELD_MODIFICATION_WATCHED) != 0; }
   bool is_internal() const              { return (_flags & JVM_ACC_FIELD_INTERNAL) != 0; }
+  bool field_has_generic_signature() const
+                                        { return (_flags & JVM_ACC_FIELD_HAS_GENERIC_SIGNATURE) != 0; }
 
   // get .class file flags
   jint get_flags               () const { return (_flags & JVM_ACC_WRITTEN_FLAGS); }
@@ -225,6 +229,10 @@ class AccessFlags VALUE_OBJ_CLASS_SPEC {
                                            atomic_clear_bits(JVM_ACC_FIELD_MODIFICATION_WATCHED);
                                          }
                                        }
+  void set_field_has_generic_signature()
+                                       {
+                                         atomic_set_bits(JVM_ACC_FIELD_HAS_GENERIC_SIGNATURE);
+                                       }
 
   // Conversion
   jshort as_short() const              { return (jshort)_flags; }