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.
 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 #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   friend class Continuation;
43   template <typename T>
44   friend class RawOopWriter;
45 
46   template <class T> T* obj_at_addr(int index) const;
47 
48   template <class T>
49   static ptrdiff_t obj_at_offset(int index) {
50     return base_offset_in_bytes() + sizeof(T) * index;
51   }
52 
53 private:
54   // Give size of objArrayOop in bytes minus the header
55   static size_t array_size_in_bytes(int length) {
56     return (size_t)length * heapOopSize;
57   }
58 
59  public:
60   // Returns the offset of the first element.
61   static int base_offset_in_bytes() {
62     return arrayOopDesc::base_offset_in_bytes(T_OBJECT);
63   }
64 
65   // base is the address following the header.
66   HeapWord* base() const;
67 
68   // Accessing
69   oop obj_at(int index) const;
70 
71   void obj_at_put(int index, oop value);
72 
73   oop atomic_compare_exchange_oop(int index, oop exchange_value, oop compare_value);
74 
75   // Sizing
76   size_t object_size()        { return object_size(length()); }
77 
78   static size_t object_size(int length) {
79     // This returns the object size in HeapWords.
80     size_t asz = array_size_in_bytes(length);
81     size_t size_words = align_up(base_offset_in_bytes() + asz, HeapWordSize) / HeapWordSize;
82     size_t osz = align_object_size(size_words);
83     assert(osz < max_jint, "no overflow");
84     return osz;
85   }
86 
87   Klass* element_klass();
88 
89 public:
90   // special iterators for index ranges, returns size of object
91   template <typename OopClosureType>
92   void oop_iterate_range(OopClosureType* blk, int start, int end);
93 };
94 
95 // See similar requirement for oopDesc.
96 static_assert(std::is_trivially_default_constructible<objArrayOopDesc>::value, "required");
97 
98 #endif // SHARE_OOPS_OBJARRAYOOP_HPP