1 /*
2 * Copyright (c) 1997, 2012, 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_VM_OOPS_OBJARRAYOOP_HPP
26 #define SHARE_VM_OOPS_OBJARRAYOOP_HPP
27
28 #include "memory/barrierSet.hpp"
29 #include "oops/arrayOop.hpp"
30
31 #if INCLUDE_ALL_GCS
32 #include "gc_implementation/shenandoah/shenandoahBarrierSet.hpp"
33 #endif
34
35 // An objArrayOop is an array containing oops.
36 // Evaluating "String arg[10]" will create an objArrayOop.
37
38 class objArrayOopDesc : public arrayOopDesc {
39 friend class ObjArrayKlass;
40 friend class Runtime1;
41 friend class psPromotionManager;
42 friend class CSetMarkOopClosure;
43 friend class G1ParScanPartialArrayClosure;
44
45 template <class T> T* obj_at_addr(int index) const {
46 assert(is_within_bounds(index), "index out of bounds");
47 return &((T*)base())[index];
48 }
49
50 private:
51 // Give size of objArrayOop in HeapWords minus the header
52 static int array_size(int length) {
53 const uint OopsPerHeapWord = HeapWordSize/heapOopSize;
54 assert(OopsPerHeapWord >= 1 && (HeapWordSize % heapOopSize == 0),
55 "Else the following (new) computation would be in error");
56 uint res = ((uint)length + OopsPerHeapWord - 1)/OopsPerHeapWord;
57 #ifdef ASSERT
58 // The old code is left in for sanity-checking; it'll
59 // go away pretty soon. XXX
60 // Without UseCompressedOops, this is simply:
61 // oop->length() * HeapWordsPerOop;
62 // With narrowOops, HeapWordsPerOop is 1/2 or equal 0 as an integer.
63 // The oop elements are aligned up to wordSize
64 const uint HeapWordsPerOop = heapOopSize/HeapWordSize;
65 uint old_res;
66 if (HeapWordsPerOop > 0) {
67 old_res = length * HeapWordsPerOop;
68 } else {
69 old_res = align_size_up((uint)length, OopsPerHeapWord)/OopsPerHeapWord;
70 }
71 assert(res == old_res, "Inconsistency between old and new.");
72 #endif // ASSERT
73 return res;
74 }
75
76 public:
77 // Returns the offset of the first element.
78 static int base_offset_in_bytes() {
79 return arrayOopDesc::base_offset_in_bytes(T_OBJECT);
80 }
81
82 // base is the address following the header.
83 HeapWord* base() const { return (HeapWord*) arrayOopDesc::base(T_OBJECT); }
84
85 // Accessing
86 oop obj_at(int index) const {
87 oop obj;
88 // With UseCompressedOops decode the narrow oop in the objArray to an
89 // uncompressed oop. Otherwise this is simply a "*" operator.
90 if (UseCompressedOops) {
91 obj = load_decode_heap_oop(obj_at_addr<narrowOop>(index));
92 } else {
93 obj = load_decode_heap_oop(obj_at_addr<oop>(index));
94 }
95 #if INCLUDE_ALL_GCS
96 if (UseShenandoahGC) {
97 obj = ShenandoahBarrierSet::barrier_set()->load_reference_barrier(obj);
98 }
99 #endif
100 return obj;
101 }
102
103 void obj_at_put(int index, oop value) {
104 if (UseCompressedOops) {
105 oop_store(obj_at_addr<narrowOop>(index), value);
106 } else {
107 oop_store(obj_at_addr<oop>(index), value);
108 }
109 }
110 // Sizing
111 static int header_size() { return arrayOopDesc::header_size(T_OBJECT); }
112 int object_size() { return object_size(length()); }
113
114 static int object_size(int length) {
115 // This returns the object size in HeapWords.
116 uint asz = array_size(length);
117 uint osz = align_object_size(header_size() + asz);
118 assert(osz >= asz, "no overflow");
119 assert((int)osz > 0, "no overflow");
120 return (int)osz;
121 }
122
123 // special iterators for index ranges, returns size of object
124 #define ObjArrayOop_OOP_ITERATE_DECL(OopClosureType, nv_suffix) \
125 int oop_iterate_range(OopClosureType* blk, int start, int end);
126
127 ALL_OOP_OOP_ITERATE_CLOSURES_1(ObjArrayOop_OOP_ITERATE_DECL)
128 ALL_OOP_OOP_ITERATE_CLOSURES_2(ObjArrayOop_OOP_ITERATE_DECL)
129 };
130
131 #endif // SHARE_VM_OOPS_OBJARRAYOOP_HPP