| /* | |
| * Copyright (c) 2023, Red Hat, Inc. All rights reserved. | |
| * Copyright (c) 2023, 2025, 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 "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; | |
| } |