1 /*
 2  * Copyright (c) 2023, Red Hat, Inc. All rights reserved.
 3  * Copyright (c) 2023, Oracle and/or its affiliates. All rights reserved.
 4  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 5  *
 6  * This code is free software; you can redistribute it and/or modify it
 7  * under the terms of the GNU General Public License version 2 only, as
 8  * published by the Free Software Foundation.
 9  *
10  * This code is distributed in the hope that it will be useful, but WITHOUT
11  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
12  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
13  * version 2 for more details (a copy is included in the LICENSE file that
14  * accompanied this code).
15  *
16  * You should have received a copy of the GNU General Public License version
17  * 2 along with this work; if not, write to the Free Software Foundation,
18  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
19  *
20  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
21  * or visit www.oracle.com if you need additional information or have any
22  * questions.
23  *
24  */
25 
26 #include "precompiled.hpp"
27 
28 #ifdef _LP64
29 
30 #include "oops/compressedKlass.hpp"
31 #include "utilities/globalDefinitions.hpp"
32 
33 char* CompressedKlassPointers::reserve_address_space_for_compressed_classes(size_t size, bool aslr, bool optimize_for_zero_base) {
34 
35   char* result = nullptr;
36 
37   // Optimize for unscaled encoding; failing that, for zero-based encoding:
38   if (optimize_for_zero_base) {
39     result = reserve_address_space_for_unscaled_encoding(size, aslr);
40     if (result == nullptr) {
41       result = reserve_address_space_for_zerobased_encoding(size, aslr);
42     }
43   } // end: low-address reservation
44 
45   // Nothing more to optimize for on x64. If base != 0, we will always emit the full 64-bit immediate.
46   return result;
47 }
48 
49 #endif // _LP64