1 /* 2 * Copyright (c) 1997, 2016, 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_VM_OOPS_OBJARRAYOOP_HPP 26 #define SHARE_VM_OOPS_OBJARRAYOOP_HPP 27 28 #include "gc/shared/specialized_oop_closures.hpp" 29 #include "oops/arrayOop.hpp" 30 31 // An objArrayOop is an array containing oops. 32 // Evaluating "String arg[10]" will create an objArrayOop. 33 34 class objArrayOopDesc : public arrayOopDesc { 35 friend class ObjArrayKlass; 36 friend class Runtime1; 37 friend class psPromotionManager; 38 friend class CSetMarkOopClosure; 39 friend class G1ParScanPartialArrayClosure; 40 41 template <class T> T* obj_at_addr(int index) const { 42 assert(is_within_bounds(index), "index out of bounds"); 43 return &((T*)base())[index]; 44 } 45 46 template <class T> 47 static jlong obj_at_offset(int index) { 48 return base_offset_in_bytes() + sizeof(T) * index; 49 } 50 51 private: 52 // Give size of objArrayOop in HeapWords minus the header 53 static int array_size(int length) { 54 const uint OopsPerHeapWord = HeapWordSize/heapOopSize; 55 assert(OopsPerHeapWord >= 1 && (HeapWordSize % heapOopSize == 0), 56 "Else the following (new) computation would be in error"); 57 uint res = ((uint)length + OopsPerHeapWord - 1)/OopsPerHeapWord; 58 #ifdef ASSERT 59 // The old code is left in for sanity-checking; it'll 60 // go away pretty soon. XXX 61 // Without UseCompressedOops, this is simply: 62 // oop->length() * HeapWordsPerOop; 63 // With narrowOops, HeapWordsPerOop is 1/2 or equal 0 as an integer. 64 // The oop elements are aligned up to wordSize 65 const uint HeapWordsPerOop = heapOopSize/HeapWordSize; 66 uint old_res; 67 if (HeapWordsPerOop > 0) { 68 old_res = length * HeapWordsPerOop; 69 } else { 70 old_res = align_size_up((uint)length, OopsPerHeapWord)/OopsPerHeapWord; 71 } 72 assert(res == old_res, "Inconsistency between old and new."); 73 #endif // ASSERT 74 return res; 75 } 76 77 public: 78 // Returns the offset of the first element. 79 static int base_offset_in_bytes() { 80 return arrayOopDesc::base_offset_in_bytes(T_OBJECT); 81 } 82 83 // base is the address following the header. 84 HeapWord* base() const { return (HeapWord*) arrayOopDesc::base(T_OBJECT); } 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 // special iterators for index ranges, returns size of object 107 #define ObjArrayOop_OOP_ITERATE_DECL(OopClosureType, nv_suffix) \ 108 void oop_iterate_range(OopClosureType* blk, int start, int end); 109 110 ALL_OOP_OOP_ITERATE_CLOSURES_1(ObjArrayOop_OOP_ITERATE_DECL) 111 ALL_OOP_OOP_ITERATE_CLOSURES_2(ObjArrayOop_OOP_ITERATE_DECL) 112 }; 113 114 #endif // SHARE_VM_OOPS_OBJARRAYOOP_HPP