view src/share/vm/ci/ciKlass.hpp @ 20543:e7d0505c8a30

8059758: Footprint regressions with JDK-8038423 Summary: Changes in JDK-8038423 always initialize (zero out) virtual memory used for auxiliary data structures. This causes a footprint regression for G1 in startup benchmarks. This is because they do not touch that memory at all, so the operating system does not actually commit these pages. The fix is to, if the initialization value of the data structures matches the default value of just committed memory (=0), do not do anything. Reviewed-by: jwilhelm, brutisso
author tschatzl
date Fri, 10 Oct 2014 15:51:58 +0200
parents 2c6ef90f030a
children 7848fc12602b
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/*
 * Copyright (c) 1999, 2013, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 *
 */

#ifndef SHARE_VM_CI_CIKLASS_HPP
#define SHARE_VM_CI_CIKLASS_HPP

#include "ci/ciType.hpp"

// ciKlass
//
// This class and its subclasses represent Klass*s in the
// HotSpot virtual machine.  In the vm, each Klass* contains an
// embedded Klass object.  ciKlass is subclassed to explicitly
// represent the kind of Klass embedded in the Klass*.  For
// example, a Klass* with an embedded ObjArrayKlass object is
// represented in the ciObject hierarchy by the class
// ciObjArrayKlass.
class ciKlass : public ciType {
  CI_PACKAGE_ACCESS
  friend class ciEnv;
  friend class ciField;
  friend class ciMethod;
  friend class ciMethodData;
  friend class ciObjArrayKlass;
  friend class ciReceiverTypeData;

private:
  ciSymbol* _name;
  jint _layout_helper;

protected:
  ciKlass(KlassHandle k_h, ciSymbol* name);
  ciKlass(ciSymbol* name, BasicType bt);

  Klass* get_Klass() const {
    Klass* k = (Klass*)_metadata;
    assert(k != NULL, "illegal use of unloaded klass");
    return k;
  }

  // Certain subklasses have an associated class loader.
  virtual oop loader()             { return NULL; }
  virtual jobject loader_handle()  { return NULL; }

  virtual oop protection_domain()             { return NULL; }
  virtual jobject protection_domain_handle()  { return NULL; }

  const char* type_string() { return "ciKlass"; }

  void print_impl(outputStream* st);

public:
  ciKlass(KlassHandle k_h);

  // What is the name of this klass?
  ciSymbol* name() const { return _name; }

  // What is its layout helper value?
  jint layout_helper() { return _layout_helper; }

  bool is_subtype_of(ciKlass* klass);
  bool is_subclass_of(ciKlass* klass);
  juint super_depth();
  juint super_check_offset();
  ciKlass* super_of_depth(juint i);
  bool can_be_primary_super();
  static juint primary_super_limit() { return Klass::primary_super_limit(); }

  // Is this ciObject the ciInstanceKlass representing java.lang.Object()?
  virtual bool is_java_lang_Object() const  { return false; }

  // Get the shared parent of two klasses.
  ciKlass* least_common_ancestor(ciKlass* k);

  virtual bool is_interface() {
    return false;
  }

  virtual bool is_abstract() {
    return false;
  }

  // Does this type (array, class, interface) have no subtypes?
  virtual bool is_leaf_type() {
    return false;
  }

  // Attempt to get a klass using this ciKlass's loader.
  ciKlass* find_klass(ciSymbol* klass_name);
  // Note:  To find a class from its name string, use ciSymbol::make,
  // but consider adding to vmSymbols.hpp instead.

  // Get the instance of java.lang.Class corresponding to this klass.
  ciInstance*            java_mirror();

  // Fetch Klass::modifier_flags.
  jint                   modifier_flags();

  // Fetch Klass::access_flags.
  jint                   access_flags();

  // What kind of ciObject is this?
  bool is_klass() const { return true; }

  virtual ciKlass* exact_klass() = 0;

  void print_name_on(outputStream* st);
};

#endif // SHARE_VM_CI_CIKLASS_HPP