1 /* 2 * Copyright (c) 1997, 2009, 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 // An objArrayOop is an array containing oops. 26 // Evaluating "String arg[10]" will create an objArrayOop. 27 28 class objArrayOopDesc : public arrayOopDesc { 29 friend class objArrayKlass; 30 friend class Runtime1; 31 friend class psPromotionManager; 32 friend class CSMarkOopClosure; 33 friend class G1ParScanPartialArrayClosure; 34 35 template <class T> T* obj_at_addr(int index) const { 36 assert(is_within_bounds(index), "index out of bounds"); 37 return &((T*)base())[index]; 38 } 39 40 private: 41 // Give size of objArrayOop in HeapWords minus the header 42 static int array_size(int length) { 43 const int OopsPerHeapWord = HeapWordSize/heapOopSize; 44 assert(OopsPerHeapWord >= 1 && (HeapWordSize % heapOopSize == 0), 45 "Else the following (new) computation would be in error"); 46 #ifdef ASSERT 47 // The old code is left in for sanity-checking; it'll 48 // go away pretty soon. XXX 49 // Without UseCompressedOops, this is simply: 50 // oop->length() * HeapWordsPerOop; 51 // With narrowOops, HeapWordsPerOop is 1/2 or equal 0 as an integer. 52 // The oop elements are aligned up to wordSize 53 const int HeapWordsPerOop = heapOopSize/HeapWordSize; 54 int old_res; 55 if (HeapWordsPerOop > 0) { 56 old_res = length * HeapWordsPerOop; 57 } else { 58 old_res = align_size_up(length, OopsPerHeapWord)/OopsPerHeapWord; 59 } 60 #endif // ASSERT 61 int res = ((uint)length + OopsPerHeapWord - 1)/OopsPerHeapWord; 62 assert(res == old_res, "Inconsistency between old and new."); 63 return res; 64 } 65 66 public: 67 // Returns the offset of the first element. 68 static int base_offset_in_bytes() { 69 return arrayOopDesc::base_offset_in_bytes(T_OBJECT); 70 } 71 72 // base is the address following the header. 73 HeapWord* base() const { return (HeapWord*) arrayOopDesc::base(T_OBJECT); } 74 75 // Accessing 76 oop obj_at(int index) const { 77 // With UseCompressedOops decode the narrow oop in the objArray to an 78 // uncompressed oop. Otherwise this is simply a "*" operator. 79 if (UseCompressedOops) { 80 return load_decode_heap_oop(obj_at_addr<narrowOop>(index)); 81 } else { 82 return load_decode_heap_oop(obj_at_addr<oop>(index)); 83 } 84 } 85 86 void obj_at_put(int index, oop value) { 87 if (UseCompressedOops) { 88 oop_store(obj_at_addr<narrowOop>(index), value); 89 } else { 90 oop_store(obj_at_addr<oop>(index), value); 91 } 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 int 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 };