1 /* 2 * Copyright (c) 1997, 2018, 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 #include "precompiled.hpp" 26 #include "classfile/javaClasses.hpp" 27 #include "classfile/systemDictionary.hpp" 28 #include "oops/instanceRefKlass.inline.hpp" 29 #include "oops/oop.inline.hpp" 30 31 void InstanceRefKlass::update_nonstatic_oop_maps(Klass* k) { 32 // Clear the nonstatic oop-map entries corresponding to referent 33 // and discovered fields. They are treated specially by the 34 // garbage collector. 35 InstanceKlass* ik = InstanceKlass::cast(k); 36 37 // Check that we have the right class 38 debug_only(static bool first_time = true); 39 assert(k == SystemDictionary::Reference_klass() && first_time, 40 "Invalid update of maps"); 41 debug_only(first_time = false); 42 assert(ik->nonstatic_oop_map_count() == 1, "just checking"); 43 44 OopMapBlock* map = ik->start_of_nonstatic_oop_maps(); 45 46 #ifdef ASSERT 47 // Verify fields are in the expected places. 48 int referent_offset = java_lang_ref_Reference::referent_offset; 49 int queue_offset = java_lang_ref_Reference::queue_offset; 50 int next_offset = java_lang_ref_Reference::next_offset; 51 int discovered_offset = java_lang_ref_Reference::discovered_offset; 52 assert(referent_offset < queue_offset, "just checking"); 53 assert(queue_offset < next_offset, "just checking"); 54 assert(next_offset < discovered_offset, "just checking"); 55 const unsigned int count = 56 1 + ((discovered_offset - referent_offset) / heapOopSize); 57 assert(count == 4, "just checking"); 58 #endif // ASSERT 59 60 // Updated map starts at "queue", covers "queue" and "next". 61 const int new_offset = java_lang_ref_Reference::queue_offset; 62 const unsigned int new_count = 2; // queue and next 63 64 // Verify existing map is as expected, and update if needed. 65 if (UseSharedSpaces) { 66 assert(map->offset() == new_offset, "just checking"); 67 assert(map->count() == new_count, "just checking"); 68 } else { 69 assert(map->offset() == referent_offset, "just checking"); 70 assert(map->count() == count, "just checking"); 71 map->set_offset(new_offset); 72 map->set_count(new_count); 73 } 74 } 75 76 77 // Verification 78 79 void InstanceRefKlass::oop_verify_on(oop obj, outputStream* st) { 80 InstanceKlass::oop_verify_on(obj, st); 81 // Verify referent field 82 oop referent = java_lang_ref_Reference::referent(obj); 83 if (referent != NULL) { 84 guarantee(oopDesc::is_oop(referent), "referent field heap failed"); 85 } 86 // Additional verification for next field, which must be a Reference or null 87 oop next = java_lang_ref_Reference::next(obj); 88 if (next != NULL) { 89 guarantee(oopDesc::is_oop(next), "next field should be an oop"); 90 guarantee(next->is_instance(), "next field should be an instance"); 91 guarantee(InstanceKlass::cast(next->klass())->is_reference_instance_klass(), "next field verify failed"); 92 } 93 }