1/*
2 * Copyright (c) 1997, 2016, 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.
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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
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23 */
24
25#ifndef SHARE_VM_OOPS_OBJARRAYOOP_HPP
26#define SHARE_VM_OOPS_OBJARRAYOOP_HPP
27
28#include "gc/shared/specialized_oop_closures.hpp"
29#include "oops/arrayOop.hpp"
30#include "utilities/align.hpp"
31
32// An objArrayOop is an array containing oops.
33// Evaluating "String arg[10]" will create an objArrayOop.
34
35class objArrayOopDesc : public arrayOopDesc {
36  friend class ObjArrayKlass;
37  friend class Runtime1;
38  friend class psPromotionManager;
39  friend class CSetMarkOopClosure;
40  friend class G1ParScanPartialArrayClosure;
41
42  template <class T> T* obj_at_addr(int index) const {
43    assert(is_within_bounds(index), "index out of bounds");
44    return &((T*)base())[index];
45  }
46
47private:
48  // Give size of objArrayOop in HeapWords minus the header
49  static int array_size(int length) {
50    const uint OopsPerHeapWord = HeapWordSize/heapOopSize;
51    assert(OopsPerHeapWord >= 1 && (HeapWordSize % heapOopSize == 0),
52           "Else the following (new) computation would be in error");
53    uint res = ((uint)length + OopsPerHeapWord - 1)/OopsPerHeapWord;
54#ifdef ASSERT
55    // The old code is left in for sanity-checking; it'll
56    // go away pretty soon. XXX
57    // Without UseCompressedOops, this is simply:
58    // oop->length() * HeapWordsPerOop;
59    // With narrowOops, HeapWordsPerOop is 1/2 or equal 0 as an integer.
60    // The oop elements are aligned up to wordSize
61    const uint HeapWordsPerOop = heapOopSize/HeapWordSize;
62    uint old_res;
63    if (HeapWordsPerOop > 0) {
64      old_res = length * HeapWordsPerOop;
65    } else {
66      old_res = align_up((uint)length, OopsPerHeapWord)/OopsPerHeapWord;
67    }
68    assert(res == old_res, "Inconsistency between old and new.");
69#endif  // ASSERT
70    return res;
71  }
72
73 public:
74  // Returns the offset of the first element.
75  static int base_offset_in_bytes() {
76    return arrayOopDesc::base_offset_in_bytes(T_OBJECT);
77  }
78
79  // base is the address following the header.
80  HeapWord* base() const      { return (HeapWord*) arrayOopDesc::base(T_OBJECT); }
81
82  // Accessing
83  oop obj_at(int index) const;
84
85  void inline obj_at_put(int index, oop value);
86
87  oop atomic_compare_exchange_oop(int index, oop exchange_value, oop compare_value);
88
89  // Sizing
90  static int header_size()    { return arrayOopDesc::header_size(T_OBJECT); }
91  int object_size()           { return object_size(length()); }
92
93  static int object_size(int length) {
94    // This returns the object size in HeapWords.
95    uint asz = array_size(length);
96    uint osz = align_object_size(header_size() + asz);
97    assert(osz >= asz,   "no overflow");
98    assert((int)osz > 0, "no overflow");
99    return (int)osz;
100  }
101
102  // special iterators for index ranges, returns size of object
103#define ObjArrayOop_OOP_ITERATE_DECL(OopClosureType, nv_suffix)     \
104  void oop_iterate_range(OopClosureType* blk, int start, int end);
105
106  ALL_OOP_OOP_ITERATE_CLOSURES_1(ObjArrayOop_OOP_ITERATE_DECL)
107  ALL_OOP_OOP_ITERATE_CLOSURES_2(ObjArrayOop_OOP_ITERATE_DECL)
108};
109
110#endif // SHARE_VM_OOPS_OBJARRAYOOP_HPP
111