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_MEMORY_MODREFBARRIERSET_HPP 26 #define SHARE_VM_MEMORY_MODREFBARRIERSET_HPP 27 28 #include "memory/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 bool is_a(BarrierSet::Name bsn) { 41 return bsn == BarrierSet::ModRef; 42 } 43 44 // Barriers only on ref writes. 45 bool has_read_ref_barrier() { return false; } 46 bool has_read_prim_barrier() { return false; } 47 bool has_write_ref_barrier() { return true; } 48 bool has_write_prim_barrier() { return false; } 49 50 bool read_ref_needs_barrier(void* field) { return false; } 51 bool read_prim_needs_barrier(HeapWord* field, size_t bytes) { return false; } 52 bool write_prim_needs_barrier(HeapWord* field, size_t bytes, 53 juint val1, juint val2) { return false; } 54 55 void write_prim_field(oop obj, size_t offset, size_t bytes, 56 juint val1, juint val2) {} 57 58 void read_ref_field(void* field) {} 59 void read_prim_field(HeapWord* field, size_t bytes) {} 60 61 protected: 62 63 ModRefBarrierSet(BarrierSet::Name kind) : BarrierSet(kind) { } 64 ~ModRefBarrierSet() { } 65 66 virtual void write_ref_field_work(void* field, oop new_val, bool release = false) = 0; 67 public: 68 void write_prim_field(HeapWord* field, size_t bytes, 69 juint val1, juint val2) {} 70 71 bool has_read_ref_array_opt() { return false; } 72 bool has_read_prim_array_opt() { return false; } 73 bool has_write_prim_array_opt() { return false; } 74 75 bool has_read_region_opt() { return false; } 76 77 78 // These operations should assert false unless the corresponding operation 79 // above returns true. 80 void read_ref_array(MemRegion mr) { 81 assert(false, "can't call"); 82 } 83 void read_prim_array(MemRegion mr) { 84 assert(false, "can't call"); 85 } 86 void write_prim_array(MemRegion mr) { 87 assert(false, "can't call"); 88 } 89 void read_region(MemRegion mr) { 90 assert(false, "can't call"); 91 } 92 93 // Causes all refs in "mr" to be assumed to be modified. If "whole_heap" 94 // is true, the caller asserts that the entire heap is being invalidated, 95 // which may admit an optimized implementation for some barriers. 96 virtual void invalidate(MemRegion mr, bool whole_heap = false) = 0; 97 98 // The caller guarantees that "mr" contains no references. (Perhaps it's 99 // objects have been moved elsewhere.) 100 virtual void clear(MemRegion mr) = 0; 101 }; 102 103 #endif // SHARE_VM_MEMORY_MODREFBARRIERSET_HPP