1 /* 2 * Copyright (c) 2000, 2015, 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_GC_SHARED_MODREFBARRIERSET_HPP 26 #define SHARE_VM_GC_SHARED_MODREFBARRIERSET_HPP 27 28 #include "gc/shared/barrierSet.hpp" 29 30 // This kind of "BarrierSet" allows a "CollectedHeap" to detect and 31 // enumerate ref fields that have been modified (since the last 32 // enumeration), using a card table. 33 34 class OopClosure; 35 class Generation; 36 37 class ModRefBarrierSet: public BarrierSet { 38 public: 39 40 // Barriers only on ref writes. 41 bool has_read_ref_barrier() { return false; } 42 bool has_read_prim_barrier() { return false; } 43 bool has_write_ref_barrier() { return true; } 44 bool has_write_prim_barrier() { return false; } 45 46 bool read_ref_needs_barrier(void* field) { return false; } 47 bool read_prim_needs_barrier(HeapWord* field, size_t bytes) { return false; } 48 bool write_prim_needs_barrier(HeapWord* field, size_t bytes, 49 juint val1, juint val2) { return false; } 50 51 void write_prim_field(oop obj, size_t offset, size_t bytes, 52 juint val1, juint val2) {} 53 54 void read_ref_field(void* field) {} 55 void read_prim_field(HeapWord* field, size_t bytes) {} 56 57 protected: 58 59 ModRefBarrierSet(const BarrierSet::FakeRtti& fake_rtti) 60 : BarrierSet(fake_rtti.add_tag(BarrierSet::ModRef)) { } 61 ~ModRefBarrierSet() { } 62 63 public: 64 void write_prim_field(HeapWord* field, size_t bytes, 65 juint val1, juint val2) {} 66 67 bool has_read_ref_array_opt() { return false; } 68 bool has_read_prim_array_opt() { return false; } 69 bool has_write_prim_array_opt() { return false; } 70 71 bool has_read_region_opt() { return false; } 72 73 74 // These operations should assert false unless the corresponding operation 75 // above returns true. 76 void read_ref_array(MemRegion mr) { 77 assert(false, "can't call"); 78 } 79 void read_prim_array(MemRegion mr) { 80 assert(false, "can't call"); 81 } 82 void write_prim_array(MemRegion mr) { 83 assert(false, "can't call"); 84 } 85 void read_region(MemRegion mr) { 86 assert(false, "can't call"); 87 } 88 89 // Causes all refs in "mr" to be assumed to be modified. 90 virtual void invalidate(MemRegion mr) = 0; 91 92 // The caller guarantees that "mr" contains no references. (Perhaps it's 93 // objects have been moved elsewhere.) 94 virtual void clear(MemRegion mr) = 0; 95 }; 96 97 template<> 98 struct BarrierSet::GetName<ModRefBarrierSet> { 99 static const BarrierSet::Name value = BarrierSet::ModRef; 100 }; 101 102 #endif // SHARE_VM_GC_SHARED_MODREFBARRIERSET_HPP