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