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 #include "asm/register.hpp" 31 32 // This class provides the interface between a barrier implementation and 33 // the rest of the system. 34 35 class MacroAssembler; 36 37 class BarrierSet: public CHeapObj<mtGC> { 38 friend class VMStructs; 39 public: 40 enum Name { 41 ModRef, 42 CardTableModRef, 43 CardTableExtension, 44 G1SATBCT, 45 G1SATBCTLogging, 46 ShenandoahBarrierSet, 47 Other, 48 Uninit 49 }; 50 51 enum Flags { 52 None = 0, 53 TargetUninitialized = 1 54 }; 55 protected: 56 int _max_covered_regions; 57 Name _kind; 58 59 public: 60 61 BarrierSet() { _kind = Uninit; } 62 // To get around prohibition on RTTI. 63 BarrierSet::Name kind() { return _kind; } 64 virtual bool is_a(BarrierSet::Name bsn) = 0; 65 66 // These operations indicate what kind of barriers the BarrierSet has. 67 virtual bool has_read_ref_barrier() = 0; 68 virtual bool has_read_prim_barrier() = 0; 69 virtual bool has_write_ref_barrier() = 0; 70 virtual bool has_write_ref_pre_barrier() = 0; 71 virtual bool has_write_prim_barrier() = 0; 72 73 // These functions indicate whether a particular access of the given 74 // kinds requires a barrier. 75 virtual bool read_ref_needs_barrier(void* field) = 0; 76 virtual bool read_prim_needs_barrier(HeapWord* field, size_t bytes) = 0; 77 virtual bool write_prim_needs_barrier(HeapWord* field, size_t bytes, 78 juint val1, juint val2) = 0; 79 80 // The first four operations provide a direct implementation of the 81 // barrier set. An interpreter loop, for example, could call these 82 // directly, as appropriate. 83 84 // Invoke the barrier, if any, necessary when reading the given ref field. 85 virtual void read_ref_field(void* field) = 0; 86 87 // Invoke the barrier, if any, necessary when reading the given primitive 88 // "field" of "bytes" bytes in "obj". 89 virtual void read_prim_field(HeapWord* field, size_t bytes) = 0; 90 91 // Invoke the barrier, if any, necessary when writing "new_val" into the 92 // ref field at "offset" in "obj". 93 // (For efficiency reasons, this operation is specialized for certain 94 // barrier types. Semantically, it should be thought of as a call to the 95 // virtual "_work" function below, which must implement the barrier.) 96 // First the pre-write versions... 97 template <class T> inline void write_ref_field_pre(T* field, oop new_val); 98 private: 99 // Keep this private so as to catch violations at build time. 100 virtual void write_ref_field_pre_work( void* field, oop new_val) { guarantee(false, "Not needed"); }; 101 protected: 102 virtual void write_ref_field_pre_work( oop* field, oop new_val) {}; 103 virtual void write_ref_field_pre_work(narrowOop* field, oop new_val) {}; 104 public: 105 106 // ...then the post-write version. 107 inline void write_ref_field(void* field, oop new_val, bool release = false); 108 protected: 109 virtual void write_ref_field_work(void* field, oop new_val, bool release = false) = 0; 110 public: 111 112 // Invoke the barrier, if any, necessary when writing the "bytes"-byte 113 // value(s) "val1" (and "val2") into the primitive "field". 114 virtual void write_prim_field(HeapWord* field, size_t bytes, 115 juint val1, juint val2) = 0; 116 117 // Operations on arrays, or general regions (e.g., for "clone") may be 118 // optimized by some barriers. 119 120 // The first six operations tell whether such an optimization exists for 121 // the particular barrier. 122 virtual bool has_read_ref_array_opt() = 0; 123 virtual bool has_read_prim_array_opt() = 0; 124 virtual bool has_write_ref_array_pre_opt() { return true; } 125 virtual bool has_write_ref_array_opt() = 0; 126 virtual bool has_write_prim_array_opt() = 0; 127 128 virtual bool has_read_region_opt() = 0; 129 virtual bool has_write_region_opt() = 0; 130 131 // These operations should assert false unless the correponding operation 132 // above returns true. Otherwise, they should perform an appropriate 133 // barrier for an array whose elements are all in the given memory region. 134 virtual void read_ref_array(MemRegion mr) = 0; 135 virtual void read_prim_array(MemRegion mr) = 0; 136 137 // Below length is the # array elements being written 138 virtual void write_ref_array_pre(oop* dst, int length, 139 bool dest_uninitialized = false) {} 140 virtual void write_ref_array_pre(narrowOop* dst, int length, 141 bool dest_uninitialized = false) {} 142 // Below count is the # array elements being written, starting 143 // at the address "start", which may not necessarily be HeapWord-aligned 144 virtual void write_ref_array(HeapWord* start, size_t count); 145 146 // Static versions, suitable for calling from generated code; 147 // count is # array elements being written, starting with "start", 148 // which may not necessarily be HeapWord-aligned. 149 static void static_write_ref_array_pre(HeapWord* start, size_t count); 150 static void static_write_ref_array_post(HeapWord* start, size_t count); 151 152 protected: 153 virtual void write_ref_array_work(MemRegion mr) = 0; 154 public: 155 virtual void write_prim_array(MemRegion mr) = 0; 156 157 virtual void read_region(MemRegion mr) = 0; 158 159 // (For efficiency reasons, this operation is specialized for certain 160 // barrier types. Semantically, it should be thought of as a call to the 161 // virtual "_work" function below, which must implement the barrier.) 162 inline void write_region(MemRegion mr); 163 protected: 164 virtual void write_region_work(MemRegion mr) = 0; 165 public: 166 167 // Some barrier sets create tables whose elements correspond to parts of 168 // the heap; the CardTableModRefBS is an example. Such barrier sets will 169 // normally reserve space for such tables, and commit parts of the table 170 // "covering" parts of the heap that are committed. The constructor is 171 // passed the maximum number of independently committable subregions to 172 // be covered, and the "resize_covoered_region" function allows the 173 // sub-parts of the heap to inform the barrier set of changes of their 174 // sizes. 175 BarrierSet(int max_covered_regions) : 176 _max_covered_regions(max_covered_regions) {} 177 178 // Inform the BarrierSet that the the covered heap region that starts 179 // with "base" has been changed to have the given size (possibly from 0, 180 // for initialization.) 181 virtual void resize_covered_region(MemRegion new_region) = 0; 182 183 // If the barrier set imposes any alignment restrictions on boundaries 184 // within the heap, this function tells whether they are met. 185 virtual bool is_aligned(HeapWord* addr) = 0; 186 187 // Print a description of the memory for the barrier set 188 virtual void print_on(outputStream* st) const = 0; 189 190 virtual oop read_barrier(oop src) { 191 return src; 192 } 193 virtual oop write_barrier(oop src) { 194 return src; 195 } 196 197 virtual bool obj_equals(oop obj1, oop obj2); 198 199 virtual bool obj_equals(narrowOop obj1, narrowOop obj2); 200 201 #ifndef CC_INTERP 202 virtual void interpreter_read_barrier(MacroAssembler* masm, Register dst) { 203 // Default implementation does nothing. 204 } 205 206 virtual void interpreter_read_barrier_not_null(MacroAssembler* masm, Register dst) { 207 // Default implementation does nothing. 208 } 209 210 virtual void interpreter_write_barrier(MacroAssembler* masm, Register dst) { 211 // Default implementation does nothing. 212 } 213 virtual void asm_acmp_barrier(MacroAssembler* masm, Register op1, Register op2) { 214 // Default implementation does nothing. 215 } 216 #endif 217 }; 218 219 #endif // SHARE_VM_MEMORY_BARRIERSET_HPP