1/*
2 * Copyright (c) 1997, 2019, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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5 * This code is free software; you can redistribute it and/or modify it
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7 * published by the Free Software Foundation.
8 *
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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,
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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
31class Klass;
32
33// An objArrayOop is an array containing oops.
34// Evaluating "String arg[10]" will create an objArrayOop.
35
36class objArrayOopDesc : public arrayOopDesc {
37 friend class ObjArrayKlass;
38 friend class Runtime1;
39 friend class psPromotionManager;
40 friend class CSetMarkOopClosure;
41 friend class G1ParScanPartialArrayClosure;
42
43 template <class T> T* obj_at_addr(int index) const;
44 template <class T> T* obj_at_addr_raw(int index) const;
45
46 template <class T>
47 static ptrdiff_t obj_at_offset(int index) {
48 return base_offset_in_bytes() + sizeof(T) * index;
49 }
50
51private:
52 // Give size of objArrayOop in HeapWords minus the header
53 static int array_size(int length) {
54 const uint OopsPerHeapWord = HeapWordSize/heapOopSize;
55 assert(OopsPerHeapWord >= 1 && (HeapWordSize % heapOopSize == 0),
56 "Else the following (new) computation would be in error");
57 uint res = ((uint)length + OopsPerHeapWord - 1)/OopsPerHeapWord;
58#ifdef ASSERT
59 // The old code is left in for sanity-checking; it'll
60 // go away pretty soon. XXX
61 // Without UseCompressedOops, this is simply:
62 // oop->length() * HeapWordsPerOop;
63 // With narrowOops, HeapWordsPerOop is 1/2 or equal 0 as an integer.
64 // The oop elements are aligned up to wordSize
65 const uint HeapWordsPerOop = heapOopSize/HeapWordSize;
66 uint old_res;
67 if (HeapWordsPerOop > 0) {
68 old_res = length * HeapWordsPerOop;
69 } else {
70 old_res = align_up((uint)length, OopsPerHeapWord)/OopsPerHeapWord;
71 }
72 assert(res == old_res, "Inconsistency between old and new.");
73#endif // ASSERT
74 return res;
75 }
76
77 public:
78 // Returns the offset of the first element.
79 static int base_offset_in_bytes() {
80 return arrayOopDesc::base_offset_in_bytes(T_OBJECT);
81 }
82
83 // base is the address following the header.
84 HeapWord* base() const;
85 HeapWord* base_raw() const;
86
87 // Accessing
88 oop obj_at(int index) const;
89
90 void obj_at_put(int index, oop value);
91
92 oop atomic_compare_exchange_oop(int index, oop exchange_value, oop compare_value);
93
94 // Sizing
95 static int header_size() { return arrayOopDesc::header_size(T_OBJECT); }
96 int object_size() { return object_size(length()); }
97
98 static int object_size(int length) {
99 // This returns the object size in HeapWords.
100 uint asz = array_size(length);
101 uint osz = align_object_size(header_size() + asz);
102 assert(osz >= asz, "no overflow");
103 assert((int)osz > 0, "no overflow");
104 return (int)osz;
105 }
106
107 Klass* element_klass();
108
109public:
110 // special iterators for index ranges, returns size of object
111 template <typename OopClosureType>
112 void oop_iterate_range(OopClosureType* blk, int start, int end);
113};
114
115#endif // SHARE_OOPS_OBJARRAYOOP_HPP
116