src/hotspot/cpu/ppc/compressedKlass_ppc.cpp - master - githubmirror/jdk22

src/hotspot/cpu/ppc/compressedKlass_ppc.cpp

48 строк2 KB

Thomas Stuefe

8320368: Per-CPU optimization of Klass range reservation

29 ноя 2023, 16:16

29 ноя 2023, 16:16033cced

/*
 * Copyright (c) 2023, Red Hat, Inc. All rights reserved.
 * Copyright (c) 2023, 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.
 *
 */

#include "precompiled.hpp"
#include "oops/compressedKlass.hpp"
#include "utilities/globalDefinitions.hpp"

char* CompressedKlassPointers::reserve_address_space_for_compressed_classes(size_t size, bool aslr, bool optimize_for_zero_base) {

  char* result = nullptr;

  // Optimize for base=0 shift=0; failing that, for base=0 shift>0
  if (optimize_for_zero_base) {
    result = reserve_address_space_for_unscaled_encoding(size, aslr);
    if (result == nullptr) {
      result = reserve_address_space_for_zerobased_encoding(size, aslr);
    }
  }

  // Optimize for a single 16-bit move: a base that has only bits set in its third quadrant [32..48).
  if (result == nullptr) {
    result = reserve_address_space_for_16bit_move(size, aslr);
  }

  return result;
}