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 template <class T> T* obj_at_addr_raw(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 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_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; 84 HeapWord* base_raw() const; 85 86 // Accessing 87 oop obj_at(int index) const; 88 89 void obj_at_put(int index, oop value); 90 91 oop atomic_compare_exchange_oop(int index, oop exchange_value, oop compare_value); 92 93 // Sizing 94 static int header_size() { return arrayOopDesc::header_size(T_OBJECT); } 95 int object_size() { return object_size(length()); } 96 97 static int object_size(int length) { 98 // This returns the object size in HeapWords. 99 uint asz = array_size(length); 100 uint osz = align_object_size(header_size() + asz); 101 assert(osz >= asz, "no overflow"); 102 assert((int)osz > 0, "no overflow"); 103 return (int)osz; 104 } 105 106 Klass* element_klass(); 107 108 public: 109 // special iterators for index ranges, returns size of object 110 template <typename OopClosureType> 111 void oop_iterate_range(OopClosureType* blk, int start, int end); 112 }; 113 114 #endif // SHARE_OOPS_OBJARRAYOOP_HPP