1 /*
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 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.
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 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).
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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 #include <type_traits>
31 
32 class Klass;
33 
34 // An objArrayOop is an array containing oops.
35 // Evaluating "String arg[10]" will create an objArrayOop.
36 
37 class objArrayOopDesc : public arrayOopDesc {
38   friend class ObjArrayKlass;
39   friend class Runtime1;
40   friend class psPromotionManager;
41   friend class CSetMarkWordClosure;
42 
43   template <class T> T* obj_at_addr(int index) const;
44 
45   template <class T>
46   static ptrdiff_t obj_at_offset(int index) {
47     return base_offset_in_bytes() + sizeof(T) * index;
48   }
49 
50 private:
51   // Give size of objArrayOop in bytes minus the header
52   static size_t array_size_in_bytes(int length) {
53     return (size_t)length * heapOopSize;
54   }
55 
56  public:
57   // Returns the offset of the first element.
58   static int base_offset_in_bytes() {
59     return arrayOopDesc::base_offset_in_bytes(T_OBJECT);
60   }
61 
62   // base is the address following the header.
63   HeapWord* base() const;
64 
65   // Accessing
66   oop obj_at(int index) const;
67 
68   void obj_at_put(int index, oop value);
69 
70   oop atomic_compare_exchange_oop(int index, oop exchange_value, oop compare_value);
71 
72   // Sizing
73   size_t object_size()        { return object_size(length()); }
74 
75   static size_t object_size(int length) {
76     // This returns the object size in HeapWords.
77     size_t asz = array_size_in_bytes(length);
78     size_t size_words = align_up(base_offset_in_bytes() + asz, HeapWordSize) / HeapWordSize;
79     size_t osz = align_object_size(size_words);
80     assert(osz < max_jint, "no overflow");
81     return osz;
82   }
83 
84   Klass* element_klass();
85 
86 public:
87   // special iterators for index ranges, returns size of object
88   template <typename OopClosureType>
89   void oop_iterate_range(OopClosureType* blk, int start, int end);
90 };
91 
92 // See similar requirement for oopDesc.
93 static_assert(std::is_trivially_default_constructible<objArrayOopDesc>::value, "required");
94 
95 #endif // SHARE_OOPS_OBJARRAYOOP_HPP