1 /*
2 * Copyright (c) 1997, 2020, 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.
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23 */
24
25 #ifndef SHARE_OOPS_OBJARRAYOOP_HPP
26 #define SHARE_OOPS_OBJARRAYOOP_HPP
27
28 #include "oops/arrayOop.hpp"
29 #include "utilities/align.hpp"
30
31 class Klass;
32
33 // An objArrayOop is an array containing oops.
34 // Evaluating "String arg[10]" will create an objArrayOop.
35
36 class objArrayOopDesc : public arrayOopDesc {
37 friend class ObjArrayKlass;
38 friend class Runtime1;
39 friend class psPromotionManager;
40 friend class CSetMarkWordClosure;
41
42 template <class T> T* obj_at_addr(int index) const;
43
44 template <class T>
45 static ptrdiff_t obj_at_offset(int index) {
46 return base_offset_in_bytes() + sizeof(T) * index;
47 }
48
49 private:
50 // Give size of objArrayOop in HeapWords minus the header
51 static int array_size(int length) {
52 const uint OopsPerHeapWord = HeapWordSize/heapOopSize;
53 assert(OopsPerHeapWord >= 1 && (HeapWordSize % heapOopSize == 0),
54 "Else the following (new) computation would be in error");
55 uint res = ((uint)length + OopsPerHeapWord - 1)/OopsPerHeapWord;
56 #ifdef ASSERT
57 // The old code is left in for sanity-checking; it'll
58 // go away pretty soon. XXX
59 // Without UseCompressedOops, this is simply:
60 // oop->length() * HeapWordsPerOop;
61 // With narrowOops, HeapWordsPerOop is 1/2 or equal 0 as an integer.
62 // The oop elements are aligned up to wordSize
63 const uint HeapWordsPerOop = heapOopSize/HeapWordSize;
64 uint old_res;
65 if (HeapWordsPerOop > 0) {
66 old_res = length * HeapWordsPerOop;
67 } else {
68 old_res = align_up((uint)length, OopsPerHeapWord)/OopsPerHeapWord;
69 }
70 assert(res == old_res, "Inconsistency between old and new.");
71 #endif // ASSERT
72 return res;
73 }
74
75 public:
76 // Returns the offset of the first element.
77 static int base_offset_in_bytes() {
78 return arrayOopDesc::base_offset_in_bytes(T_OBJECT);
79 }
80
81 // base is the address following the header.
82 HeapWord* base() const;
83
84 // Accessing
85 oop obj_at(int index) const;
86
87 void obj_at_put(int index, oop value);
88
89 oop atomic_compare_exchange_oop(int index, oop exchange_value, oop compare_value);
90
91 // Sizing
92 static int header_size() { return arrayOopDesc::header_size(T_OBJECT); }
93 int object_size() { return object_size(length()); }
94
95 static int object_size(int length) {
96 // This returns the object size in HeapWords.
97 uint asz = array_size(length);
98 uint osz = align_object_size(header_size() + asz);
99 assert(osz >= asz, "no overflow");
100 assert((int)osz > 0, "no overflow");
101 return (int)osz;
102 }
103
104 Klass* element_klass();
105
106 public:
107 // special iterators for index ranges, returns size of object
108 template <typename OopClosureType>
109 void oop_iterate_range(OopClosureType* blk, int start, int end);
110 };
111
112 #endif // SHARE_OOPS_OBJARRAYOOP_HPP