1 /* 2 * Copyright (c) 2001, 2008, 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 // Methods of protected closure types 26 27 template <class T> 28 inline void DefNewGeneration::KeepAliveClosure::do_oop_work(T* p) { 29 #ifdef ASSERT 30 { 31 // We never expect to see a null reference being processed 32 // as a weak reference. 33 assert (!oopDesc::is_null(*p), "expected non-null ref"); 34 oop obj = oopDesc::load_decode_heap_oop_not_null(p); 35 assert (obj->is_oop(), "expected an oop while scanning weak refs"); 36 } 37 #endif // ASSERT 38 39 _cl->do_oop_nv(p); 40 41 // Card marking is trickier for weak refs. 42 // This oop is a 'next' field which was filled in while we 43 // were discovering weak references. While we might not need 44 // to take a special action to keep this reference alive, we 45 // will need to dirty a card as the field was modified. 46 // 47 // Alternatively, we could create a method which iterates through 48 // each generation, allowing them in turn to examine the modified 49 // field. 50 // 51 // We could check that p is also in an older generation, but 52 // dirty cards in the youngest gen are never scanned, so the 53 // extra check probably isn't worthwhile. 54 if (Universe::heap()->is_in_reserved(p)) { 55 oop obj = oopDesc::load_decode_heap_oop_not_null(p); 56 _rs->inline_write_ref_field_gc(p, obj); 57 } 58 } 59 60 template <class T> 61 inline void DefNewGeneration::FastKeepAliveClosure::do_oop_work(T* p) { 62 #ifdef ASSERT 63 { 64 // We never expect to see a null reference being processed 65 // as a weak reference. 66 assert (!oopDesc::is_null(*p), "expected non-null ref"); 67 oop obj = oopDesc::load_decode_heap_oop_not_null(p); 68 assert (obj->is_oop(), "expected an oop while scanning weak refs"); 69 } 70 #endif // ASSERT 71 72 _cl->do_oop_nv(p); 73 74 // Optimized for Defnew generation if it's the youngest generation: 75 // we set a younger_gen card if we have an older->youngest 76 // generation pointer. 77 oop obj = oopDesc::load_decode_heap_oop_not_null(p); 78 if (((HeapWord*)obj < _boundary) && Universe::heap()->is_in_reserved(p)) { 79 _rs->inline_write_ref_field_gc(p, obj); 80 } 81 }