1 /*
2 * Copyright (c) 2017, 2025, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #ifndef SHARE_OOPS_COMPRESSEDKLASS_INLINE_HPP
26 #define SHARE_OOPS_COMPRESSEDKLASS_INLINE_HPP
27
28 #include "oops/compressedKlass.hpp"
29
30 #include "memory/universe.hpp"
31 #include "oops/oop.hpp"
32 #include "utilities/align.hpp"
33 #include "utilities/globalDefinitions.hpp"
34
35 inline Klass* CompressedKlassPointers::decode_not_null_without_asserts(narrowKlass v, address narrow_base_base, int shift) {
36 return (Klass*)((uintptr_t)narrow_base_base +((uintptr_t)v << shift));
37 }
38
39 inline narrowKlass CompressedKlassPointers::encode_not_null_without_asserts(Klass* k, address narrow_base, int shift) {
40 return (narrowKlass)(pointer_delta(k, narrow_base, 1) >> shift);
41 }
42
43 inline Klass* CompressedKlassPointers::decode_not_null_without_asserts(narrowKlass v) {
44 return decode_not_null_without_asserts(v, base(), shift());
45 }
46
47 inline Klass* CompressedKlassPointers::decode_without_asserts(narrowKlass v) {
48 return is_null(v) ? nullptr : decode_not_null_without_asserts(v, base(), shift());
49 }
50
51 inline Klass* CompressedKlassPointers::decode_not_null(narrowKlass v) {
52 assert(!is_null(v), "narrow klass value can never be zero");
53 DEBUG_ONLY(check_valid_narrow_klass_id(v);)
54 Klass* const k = decode_not_null_without_asserts(v, base(), shift());
55 DEBUG_ONLY(check_encodable(k));
56 return k;
57 }
58
59 inline Klass* CompressedKlassPointers::decode(narrowKlass v) {
60 return is_null(v) ? nullptr : decode_not_null(v);
61 }
62
63 inline narrowKlass CompressedKlassPointers::encode_not_null(Klass* v) {
64 assert(!is_null(v), "klass value can never be zero");
65 DEBUG_ONLY(check_encodable(v);)
66 const narrowKlass nk = encode_not_null_without_asserts(v, base(), shift());
67 assert(decode_not_null_without_asserts(nk, base(), shift()) == v, "reversibility");
68 DEBUG_ONLY(check_valid_narrow_klass_id(nk);)
69 return nk;
70 }
71
72 inline narrowKlass CompressedKlassPointers::encode(Klass* v) {
73 return is_null(v) ? (narrowKlass)0 : encode_not_null(v);
74 }
75
76 #ifdef ASSERT
77 inline void CompressedKlassPointers::check_encodable(const void* addr) {
78 assert(UseCompressedClassPointers, "Only call for +UseCCP");
79 assert(addr != nullptr, "Null Klass?");
80 assert(is_encodable(addr),
81 "Address " PTR_FORMAT " is not encodable (Klass range: " RANGEFMT ", klass alignment: %d)",
82 p2i(addr), RANGE2FMTARGS(_klass_range_start, _klass_range_end), klass_alignment_in_bytes());
83 }
84
85 inline void CompressedKlassPointers::check_valid_narrow_klass_id(narrowKlass nk) {
86 check_init(_base);
87 assert(UseCompressedClassPointers, "Only call for +UseCCP");
88 assert(nk > 0, "narrow Klass ID is 0");
89 const uint64_t nk_mask = ~right_n_bits(narrow_klass_pointer_bits());
90 assert(((uint64_t)nk & nk_mask) == 0, "narrow klass id bit spillover (%u)", nk);
91 assert(nk >= _lowest_valid_narrow_klass_id &&
92 nk <= _highest_valid_narrow_klass_id, "narrowKlass ID out of range (%u)", nk);
93 }
94 #endif // ASSERT
95
96 // Given a narrow Klass ID, returns true if it appears to be valid
97 inline bool CompressedKlassPointers::is_valid_narrow_klass_id(narrowKlass nk) {
98 return nk >= _lowest_valid_narrow_klass_id && nk < _highest_valid_narrow_klass_id;
99 }
100
101 inline address CompressedKlassPointers::encoding_range_end() {
102 const int max_bits = narrow_klass_pointer_bits() + _shift;
103 return (address)((uintptr_t)_base + nth_bit(max_bits));
104 }
105
106 #endif // SHARE_OOPS_COMPRESSEDKLASS_INLINE_HPP