1 /* 2 * Copyright (c) 1997, 2020, 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_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 HeapWords minus the header 51 static int array_size(int length) { 52 const uint OopsPerHeapWord = HeapWordSize/heapOopSize; 53 assert(OopsPerHeapWord >= 1 && (HeapWordSize % heapOopSize == 0), 54 "Else the following (new) computation would be in error"); 55 uint res = ((uint)length + OopsPerHeapWord - 1)/OopsPerHeapWord; 56 #ifdef ASSERT 57 // The old code is left in for sanity-checking; it'll 58 // go away pretty soon. XXX 59 // Without UseCompressedOops, this is simply: 60 // oop->length() * HeapWordsPerOop; 61 // With narrowOops, HeapWordsPerOop is 1/2 or equal 0 as an integer. 62 // The oop elements are aligned up to wordSize 63 const uint HeapWordsPerOop = heapOopSize/HeapWordSize; 64 uint old_res; 65 if (HeapWordsPerOop > 0) { 66 old_res = length * HeapWordsPerOop; 67 } else { 68 old_res = align_up((uint)length, OopsPerHeapWord)/OopsPerHeapWord; 69 } 70 assert(res == old_res, "Inconsistency between old and new."); 71 #endif // ASSERT 72 return res; 73 } 74 75 public: 76 // Returns the offset of the first element. 77 static int base_offset_in_bytes() { 78 return arrayOopDesc::base_offset_in_bytes(T_OBJECT); 79 } 80 81 // base is the address following the header. 82 HeapWord* base() const; 83 84 // Accessing 85 oop obj_at(int index) const; 86 87 void obj_at_put(int index, oop value); 88 89 oop atomic_compare_exchange_oop(int index, oop exchange_value, oop compare_value); 90 91 // Sizing 92 static int header_size() { return arrayOopDesc::header_size(T_OBJECT); } 93 int object_size() { return object_size(length()); } 94 95 static int object_size(int length) { 96 // This returns the object size in HeapWords. 97 uint asz = array_size(length); 98 uint osz = align_object_size(header_size() + asz); 99 assert(osz >= asz, "no overflow"); 100 assert((int)osz > 0, "no overflow"); 101 return (int)osz; 102 } 103 104 Klass* element_klass(); 105 106 public: 107 // special iterators for index ranges, returns size of object 108 template <typename OopClosureType> 109 void oop_iterate_range(OopClosureType* blk, int start, int end); 110 }; 111 112 #endif // SHARE_OOPS_OBJARRAYOOP_HPP --- EOF ---