1 /* 2 * Copyright (c) 2000, 2012, 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<mtGC> { 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 // Some barrier sets create tables whose elements correspond to parts of 53 // the heap; the CardTableModRefBS is an example. Such barrier sets will 54 // normally reserve space for such tables, and commit parts of the table 55 // "covering" parts of the heap that are committed. At most one covered 56 // region per generation is needed. 57 static const int _max_covered_regions = 2; 58 Name _kind; 59 60 public: 61 62 BarrierSet() { _kind = Uninit; } 63 // To get around prohibition on RTTI. 64 BarrierSet::Name kind() { return _kind; } 65 virtual bool is_a(BarrierSet::Name bsn) = 0; 66 67 // These operations indicate what kind of barriers the BarrierSet has. 68 virtual bool has_read_ref_barrier() = 0; 69 virtual bool has_read_prim_barrier() = 0; 70 virtual bool has_write_ref_barrier() = 0; 71 virtual bool has_write_ref_pre_barrier() = 0; 72 virtual bool has_write_prim_barrier() = 0; 73 74 // These functions indicate whether a particular access of the given 75 // kinds requires a barrier. 76 virtual bool read_ref_needs_barrier(void* field) = 0; 77 virtual bool read_prim_needs_barrier(HeapWord* field, size_t bytes) = 0; 78 virtual bool write_prim_needs_barrier(HeapWord* field, size_t bytes, 79 juint val1, juint val2) = 0; 80 81 // The first four operations provide a direct implementation of the 82 // barrier set. An interpreter loop, for example, could call these 83 // directly, as appropriate. 84 85 // Invoke the barrier, if any, necessary when reading the given ref field. 86 virtual void read_ref_field(void* field) = 0; 87 88 // Invoke the barrier, if any, necessary when reading the given primitive 89 // "field" of "bytes" bytes in "obj". 90 virtual void read_prim_field(HeapWord* field, size_t bytes) = 0; 91 92 // Invoke the barrier, if any, necessary when writing "new_val" into the 93 // ref field at "offset" in "obj". 94 // (For efficiency reasons, this operation is specialized for certain 95 // barrier types. Semantically, it should be thought of as a call to the 96 // virtual "_work" function below, which must implement the barrier.) 97 // First the pre-write versions... 98 template <class T> inline void write_ref_field_pre(T* field, oop new_val); 99 private: 100 // Keep this private so as to catch violations at build time. 101 virtual void write_ref_field_pre_work( void* field, oop new_val) { guarantee(false, "Not needed"); }; 102 protected: 103 virtual void write_ref_field_pre_work( oop* field, oop new_val) {}; 104 virtual void write_ref_field_pre_work(narrowOop* field, oop new_val) {}; 105 public: 106 107 // ...then the post-write version. 108 inline void write_ref_field(void* field, oop new_val, bool release = false); 109 protected: 110 virtual void write_ref_field_work(void* field, oop new_val, bool release = false) = 0; 111 public: 112 113 // Invoke the barrier, if any, necessary when writing the "bytes"-byte 114 // value(s) "val1" (and "val2") into the primitive "field". 115 virtual void write_prim_field(HeapWord* field, size_t bytes, 116 juint val1, juint val2) = 0; 117 118 // Operations on arrays, or general regions (e.g., for "clone") may be 119 // optimized by some barriers. 120 121 // The first six operations tell whether such an optimization exists for 122 // the particular barrier. 123 virtual bool has_read_ref_array_opt() = 0; 124 virtual bool has_read_prim_array_opt() = 0; 125 virtual bool has_write_ref_array_pre_opt() { return true; } 126 virtual bool has_write_ref_array_opt() = 0; 127 virtual bool has_write_prim_array_opt() = 0; 128 129 virtual bool has_read_region_opt() = 0; 130 virtual bool has_write_region_opt() = 0; 131 132 // These operations should assert false unless the corresponding operation 133 // above returns true. Otherwise, they should perform an appropriate 134 // barrier for an array whose elements are all in the given memory region. 135 virtual void read_ref_array(MemRegion mr) = 0; 136 virtual void read_prim_array(MemRegion mr) = 0; 137 138 // Below length is the # array elements being written 139 virtual void write_ref_array_pre(oop* dst, int length, 140 bool dest_uninitialized = false) {} 141 virtual void write_ref_array_pre(narrowOop* dst, int length, 142 bool dest_uninitialized = false) {} 143 // Below count is the # array elements being written, starting 144 // at the address "start", which may not necessarily be HeapWord-aligned 145 inline void write_ref_array(HeapWord* start, size_t count); 146 147 // Static versions, suitable for calling from generated code; 148 // count is # array elements being written, starting with "start", 149 // which may not necessarily be HeapWord-aligned. 150 static void static_write_ref_array_pre(HeapWord* start, size_t count); 151 static void static_write_ref_array_post(HeapWord* start, size_t count); 152 153 protected: 154 virtual void write_ref_array_work(MemRegion mr) = 0; 155 public: 156 virtual void write_prim_array(MemRegion mr) = 0; 157 158 virtual void read_region(MemRegion mr) = 0; 159 160 // (For efficiency reasons, this operation is specialized for certain 161 // barrier types. Semantically, it should be thought of as a call to the 162 // virtual "_work" function below, which must implement the barrier.) 163 inline void write_region(MemRegion mr); 164 protected: 165 virtual void write_region_work(MemRegion mr) = 0; 166 public: 167 // Inform the BarrierSet that the the covered heap region that starts 168 // with "base" has been changed to have the given size (possibly from 0, 169 // for initialization.) 170 virtual void resize_covered_region(MemRegion new_region) = 0; 171 172 // If the barrier set imposes any alignment restrictions on boundaries 173 // within the heap, this function tells whether they are met. 174 virtual bool is_aligned(HeapWord* addr) = 0; 175 176 // Print a description of the memory for the barrier set 177 virtual void print_on(outputStream* st) const = 0; 178 }; 179 180 #endif // SHARE_VM_MEMORY_BARRIERSET_HPP