1 /*
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 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
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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 bytes minus the header
51   static size_t array_size_in_bytes(int length) {
52     return (size_t)length * heapOopSize;
53   }
54 
55  public:
56   // Returns the offset of the first element.
57   static int base_offset_in_bytes() {
58     return arrayOopDesc::base_offset_in_bytes(T_OBJECT);
59   }
60 
61   // base is the address following the header.
62   HeapWord* base() const;
63 
64   // Accessing
65   oop obj_at(int index) const;
66 
67   void obj_at_put(int index, oop value);
68 
69   oop atomic_compare_exchange_oop(int index, oop exchange_value, oop compare_value);
70 
71   // Sizing
72   int object_size()           { return object_size(length()); }
73 
74   static int object_size(int length) {
75     // This returns the object size in HeapWords.
76     size_t asz = array_size_in_bytes(length);
77     size_t size_words = align_up(base_offset_in_bytes() + asz, HeapWordSize) / HeapWordSize;
78     size_t osz = align_object_size(size_words);
79     assert(osz < max_jint, "no overflow");
80     return checked_cast<int>(osz);
81   }
82 
83   Klass* element_klass();
84 
85 public:
86   // special iterators for index ranges, returns size of object
87   template <typename OopClosureType>
88   void oop_iterate_range(OopClosureType* blk, int start, int end);
89 };
90 
91 #endif // SHARE_OOPS_OBJARRAYOOP_HPP