1 /* 2 * Copyright (c) 2000, 2011, 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_BARRIERSET_HPP 26 #define SHARE_VM_MEMORY_BARRIERSET_HPP 27 28 #include "memory/memRegion.hpp" 29 #include "oops/oopsHierarchy.hpp" 30 31 // This class provides the interface between a barrier implementation and 32 // the rest of the system. 33 34 class BarrierSet: public CHeapObj { 35 friend class VMStructs; 36 public: 37 enum Name { 38 ModRef, 39 CardTableModRef, 40 CardTableExtension, 41 G1SATBCT, 42 G1SATBCTLogging, 43 Other, 44 Uninit 45 }; 46 47 enum Flags { 48 None = 0, 49 TargetUninitialized = 1 50 }; 51 protected: 52 int _max_covered_regions; 53 Name _kind; 54 55 public: 56 57 BarrierSet() { _kind = Uninit; } 58 // To get around prohibition on RTTI. 59 BarrierSet::Name kind() { return _kind; } 60 virtual bool is_a(BarrierSet::Name bsn) = 0; 61 62 // These operations indicate what kind of barriers the BarrierSet has. 63 virtual bool has_read_ref_barrier() = 0; 64 virtual bool has_read_prim_barrier() = 0; 65 virtual bool has_write_ref_barrier() = 0; 66 virtual bool has_write_ref_pre_barrier() = 0; 67 virtual bool has_write_prim_barrier() = 0; 68 69 // These functions indicate whether a particular access of the given 70 // kinds requires a barrier. 71 virtual bool read_ref_needs_barrier(void* field) = 0; 72 virtual bool read_prim_needs_barrier(HeapWord* field, size_t bytes) = 0; 73 virtual bool write_ref_needs_barrier(void* field, oop new_val) = 0; 74 virtual bool write_prim_needs_barrier(HeapWord* field, size_t bytes, 75 juint val1, juint val2) = 0; 76 77 // The first four operations provide a direct implementation of the 78 // barrier set. An interpreter loop, for example, could call these 79 // directly, as appropriate. 80 81 // Invoke the barrier, if any, necessary when reading the given ref field. 82 virtual void read_ref_field(void* field) = 0; 83 84 // Invoke the barrier, if any, necessary when reading the given primitive 85 // "field" of "bytes" bytes in "obj". 86 virtual void read_prim_field(HeapWord* field, size_t bytes) = 0; 87 88 // Invoke the barrier, if any, necessary when writing "new_val" into the 89 // ref field at "offset" in "obj". 90 // (For efficiency reasons, this operation is specialized for certain 91 // barrier types. Semantically, it should be thought of as a call to the 92 // virtual "_work" function below, which must implement the barrier.) 93 // First the pre-write versions... 94 template <class T> inline void write_ref_field_pre(T* field, oop new_val); 95 private: 96 // Keep this private so as to catch violations at build time. 97 virtual void write_ref_field_pre_work( void* field, oop new_val) { guarantee(false, "Not needed"); }; 98 protected: 99 virtual void write_ref_field_pre_work( oop* field, oop new_val) {}; 100 virtual void write_ref_field_pre_work(narrowOop* field, oop new_val) {}; 101 public: 102 103 // ...then the post-write version. 104 inline void write_ref_field(void* field, oop new_val); 105 protected: 106 virtual void write_ref_field_work(void* field, oop new_val) = 0; 107 public: 108 109 // Invoke the barrier, if any, necessary when writing the "bytes"-byte 110 // value(s) "val1" (and "val2") into the primitive "field". 111 virtual void write_prim_field(HeapWord* field, size_t bytes, 112 juint val1, juint val2) = 0; 113 114 // Operations on arrays, or general regions (e.g., for "clone") may be 115 // optimized by some barriers. 116 117 // The first six operations tell whether such an optimization exists for 118 // the particular barrier. 119 virtual bool has_read_ref_array_opt() = 0; 120 virtual bool has_read_prim_array_opt() = 0; 121 virtual bool has_write_ref_array_pre_opt() { return true; } 122 virtual bool has_write_ref_array_opt() = 0; 123 virtual bool has_write_prim_array_opt() = 0; 124 125 virtual bool has_read_region_opt() = 0; 126 virtual bool has_write_region_opt() = 0; 127 128 // These operations should assert false unless the correponding operation 129 // above returns true. Otherwise, they should perform an appropriate 130 // barrier for an array whose elements are all in the given memory region. 131 virtual void read_ref_array(MemRegion mr) = 0; 132 virtual void read_prim_array(MemRegion mr) = 0; 133 134 // Below length is the # array elements being written 135 virtual void write_ref_array_pre(oop* dst, int length, 136 bool dest_uninitialized = false) {} 137 virtual void write_ref_array_pre(narrowOop* dst, int length, 138 bool dest_uninitialized = false) {} 139 // Below count is the # array elements being written, starting 140 // at the address "start", which may not necessarily be HeapWord-aligned 141 inline void write_ref_array(HeapWord* start, size_t count); 142 143 // Static versions, suitable for calling from generated code; 144 // count is # array elements being written, starting with "start", 145 // which may not necessarily be HeapWord-aligned. 146 static void static_write_ref_array_pre(HeapWord* start, size_t count); 147 static void static_write_ref_array_post(HeapWord* start, size_t count); 148 149 protected: 150 virtual void write_ref_array_work(MemRegion mr) = 0; 151 public: 152 virtual void write_prim_array(MemRegion mr) = 0; 153 154 virtual void read_region(MemRegion mr) = 0; 155 156 // (For efficiency reasons, this operation is specialized for certain 157 // barrier types. Semantically, it should be thought of as a call to the 158 // virtual "_work" function below, which must implement the barrier.) 159 inline void write_region(MemRegion mr); 160 protected: 161 virtual void write_region_work(MemRegion mr) = 0; 162 public: 163 164 // Some barrier sets create tables whose elements correspond to parts of 165 // the heap; the CardTableModRefBS is an example. Such barrier sets will 166 // normally reserve space for such tables, and commit parts of the table 167 // "covering" parts of the heap that are committed. The constructor is 168 // passed the maximum number of independently committable subregions to 169 // be covered, and the "resize_covoered_region" function allows the 170 // sub-parts of the heap to inform the barrier set of changes of their 171 // sizes. 172 BarrierSet(int max_covered_regions) : 173 _max_covered_regions(max_covered_regions) {} 174 175 // Inform the BarrierSet that the the covered heap region that starts 176 // with "base" has been changed to have the given size (possibly from 0, 177 // for initialization.) 178 virtual void resize_covered_region(MemRegion new_region) = 0; 179 180 // If the barrier set imposes any alignment restrictions on boundaries 181 // within the heap, this function tells whether they are met. 182 virtual bool is_aligned(HeapWord* addr) = 0; 183 184 }; 185 186 #endif // SHARE_VM_MEMORY_BARRIERSET_HPP