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 #include "utilities/align.hpp" 31 32 // An objArrayOop is an array containing oops. 33 // Evaluating "String arg[10]" will create an objArrayOop. 34 35 class objArrayOopDesc : public arrayOopDesc { 36 friend class ObjArrayKlass; 37 friend class Runtime1; 38 friend class psPromotionManager; 39 friend class CSetMarkOopClosure; 40 friend class G1ParScanPartialArrayClosure; 41 42 template <class T> T* obj_at_addr(int index) const { 43 assert(is_within_bounds(index), "index out of bounds"); 44 return &((T*)base())[index]; 45 } 46 47 private: 48 // Give size of objArrayOop in HeapWords minus the header 49 static int array_size(int length) { 50 const uint OopsPerHeapWord = HeapWordSize/heapOopSize; 51 assert(OopsPerHeapWord >= 1 && (HeapWordSize % heapOopSize == 0), 52 "Else the following (new) computation would be in error"); 53 uint res = ((uint)length + OopsPerHeapWord - 1)/OopsPerHeapWord; 54 #ifdef ASSERT 55 // The old code is left in for sanity-checking; it'll 56 // go away pretty soon. XXX 57 // Without UseCompressedOops, this is simply: 58 // oop->length() * HeapWordsPerOop; 59 // With narrowOops, HeapWordsPerOop is 1/2 or equal 0 as an integer. 60 // The oop elements are aligned up to wordSize 61 const uint HeapWordsPerOop = heapOopSize/HeapWordSize; 62 uint old_res; 63 if (HeapWordsPerOop > 0) { 64 old_res = length * HeapWordsPerOop; 65 } else { 66 old_res = align_up((uint)length, OopsPerHeapWord)/OopsPerHeapWord; 67 } 68 assert(res == old_res, "Inconsistency between old and new."); 69 #endif // ASSERT 70 return res; 71 } 72 73 public: 74 // Returns the offset of the first element. 75 static int base_offset_in_bytes() { 76 return arrayOopDesc::base_offset_in_bytes(T_OBJECT); 77 } 78 79 // base is the address following the header. 80 HeapWord* base() const { return (HeapWord*) arrayOopDesc::base(T_OBJECT); } 81 82 // Accessing 83 oop obj_at(int index) const; 84 85 void inline obj_at_put(int index, oop value); 86 87 oop atomic_compare_exchange_oop(int index, oop exchange_value, oop compare_value); 88 89 // Sizing 90 static int header_size() { return arrayOopDesc::header_size(T_OBJECT); } 91 int object_size() { return object_size(length()); } 92 93 static int object_size(int length) { 94 // This returns the object size in HeapWords. 95 uint asz = array_size(length); 96 uint osz = align_object_size(header_size() + asz); 97 assert(osz >= asz, "no overflow"); 98 assert((int)osz > 0, "no overflow"); 99 return (int)osz; 100 } 101 102 // special iterators for index ranges, returns size of object 103 #define ObjArrayOop_OOP_ITERATE_DECL(OopClosureType, nv_suffix) \ 104 void oop_iterate_range(OopClosureType* blk, int start, int end); 105 106 ALL_OOP_OOP_ITERATE_CLOSURES_1(ObjArrayOop_OOP_ITERATE_DECL) 107 ALL_OOP_OOP_ITERATE_CLOSURES_2(ObjArrayOop_OOP_ITERATE_DECL) 108 }; 109 110 #endif // SHARE_VM_OOPS_OBJARRAYOOP_HPP