1 /* 2 * Copyright (c) 2003, 2009, 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 // An constMethodOop represents portions of a Java method which 26 // do not vary. 27 // 28 // Memory layout (each line represents a word). Note that most 29 // applications load thousands of methods, so keeping the size of this 30 // structure small has a big impact on footprint. 31 // 32 // |------------------------------------------------------| 33 // | header | 34 // | klass | 35 // |------------------------------------------------------| 36 // | fingerprint 1 | 37 // | fingerprint 2 | 38 // | method (oop) | 39 // | stackmap_data (oop) | 40 // | exception_table (oop) | 41 // | constMethod_size | 42 // | interp_kind | flags | code_size | 43 // | name index | signature index | 44 // | method_idnum | generic_signature_index | 45 // |------------------------------------------------------| 46 // | | 47 // | byte codes | 48 // | | 49 // |------------------------------------------------------| 50 // | compressed linenumber table | 51 // | (see class CompressedLineNumberReadStream) | 52 // | (note that length is unknown until decompressed) | 53 // | (access flags bit tells whether table is present) | 54 // | (indexed from start of constMethodOop) | 55 // | (elements not necessarily sorted!) | 56 // |------------------------------------------------------| 57 // | localvariable table elements + length (length last) | 58 // | (length is u2, elements are 6-tuples of u2) | 59 // | (see class LocalVariableTableElement) | 60 // | (access flags bit tells whether table is present) | 61 // | (indexed from end of contMethodOop) | 62 // |------------------------------------------------------| 63 // | checked exceptions elements + length (length last) | 64 // | (length is u2, elements are u2) | 65 // | (see class CheckedExceptionElement) | 66 // | (access flags bit tells whether table is present) | 67 // | (indexed from end of constMethodOop) | 68 // |------------------------------------------------------| 69 70 71 // Utitily class decribing elements in checked exceptions table inlined in methodOop. 72 class CheckedExceptionElement VALUE_OBJ_CLASS_SPEC { 73 public: 74 u2 class_cp_index; 75 }; 76 77 78 // Utitily class decribing elements in local variable table inlined in methodOop. 79 class LocalVariableTableElement VALUE_OBJ_CLASS_SPEC { 80 public: 81 u2 start_bci; 82 u2 length; 83 u2 name_cp_index; 84 u2 descriptor_cp_index; 85 u2 signature_cp_index; 86 u2 slot; 87 }; 88 89 90 class constMethodOopDesc : public oopDesc { 91 friend class constMethodKlass; 92 friend class VMStructs; 93 private: 94 enum { 95 _has_linenumber_table = 1, 96 _has_checked_exceptions = 2, 97 _has_localvariable_table = 4 98 }; 99 100 // Bit vector of signature 101 // Callers interpret 0=not initialized yet and 102 // -1=too many args to fix, must parse the slow way. 103 // The real initial value is special to account for nonatomicity of 64 bit 104 // loads and stores. This value may updated and read without a lock by 105 // multiple threads, so is volatile. 106 volatile uint64_t _fingerprint; 107 volatile bool _is_conc_safe; // if true, safe for concurrent GC processing 108 109 public: 110 oop* oop_block_beg() const { return adr_method(); } 111 oop* oop_block_end() const { return adr_exception_table() + 1; } 112 113 private: 114 // 115 // The oop block. See comment in klass.hpp before making changes. 116 // 117 118 // Backpointer to non-const methodOop (needed for some JVMTI operations) 119 methodOop _method; 120 121 // Raw stackmap data for the method 122 typeArrayOop _stackmap_data; 123 124 // The exception handler table. 4-tuples of ints [start_pc, end_pc, 125 // handler_pc, catch_type index] For methods with no exceptions the 126 // table is pointing to Universe::the_empty_int_array 127 typeArrayOop _exception_table; 128 129 // 130 // End of the oop block. 131 // 132 133 int _constMethod_size; 134 jbyte _interpreter_kind; 135 jbyte _flags; 136 137 // Size of Java bytecodes allocated immediately after methodOop. 138 u2 _code_size; 139 u2 _name_index; // Method name (index in constant pool) 140 u2 _signature_index; // Method signature (index in constant pool) 141 u2 _method_idnum; // unique identification number for the method within the class 142 // initially corresponds to the index into the methods array. 143 // but this may change with redefinition 144 u2 _generic_signature_index; // Generic signature (index in constant pool, 0 if absent) 145 146 public: 147 // Inlined tables 148 void set_inlined_tables_length(int checked_exceptions_len, 149 int compressed_line_number_size, 150 int localvariable_table_len); 151 152 bool has_linenumber_table() const 153 { return (_flags & _has_linenumber_table) != 0; } 154 155 bool has_checked_exceptions() const 156 { return (_flags & _has_checked_exceptions) != 0; } 157 158 bool has_localvariable_table() const 159 { return (_flags & _has_localvariable_table) != 0; } 160 161 void set_interpreter_kind(int kind) { _interpreter_kind = kind; } 162 int interpreter_kind(void) const { return _interpreter_kind; } 163 164 // backpointer to non-const methodOop 165 methodOop method() const { return _method; } 166 void set_method(methodOop m) { oop_store_without_check((oop*)&_method, (oop) m); } 167 168 169 // stackmap table data 170 typeArrayOop stackmap_data() const { return _stackmap_data; } 171 void set_stackmap_data(typeArrayOop sd) { 172 oop_store_without_check((oop*)&_stackmap_data, (oop)sd); 173 } 174 bool has_stackmap_table() const { return _stackmap_data != NULL; } 175 176 // exception handler table 177 typeArrayOop exception_table() const { return _exception_table; } 178 void set_exception_table(typeArrayOop e) { oop_store_without_check((oop*) &_exception_table, (oop) e); } 179 bool has_exception_handler() const { return exception_table() != NULL && exception_table()->length() > 0; } 180 181 void init_fingerprint() { 182 const uint64_t initval = CONST64(0x8000000000000000); 183 _fingerprint = initval; 184 } 185 186 uint64_t fingerprint() const { 187 // Since reads aren't atomic for 64 bits, if any of the high or low order 188 // word is the initial value, return 0. See init_fingerprint for initval. 189 uint high_fp = (uint)(_fingerprint >> 32); 190 if ((int) _fingerprint == 0 || high_fp == 0x80000000) { 191 return 0L; 192 } else { 193 return _fingerprint; 194 } 195 } 196 197 uint64_t set_fingerprint(uint64_t new_fingerprint) { 198 #ifdef ASSERT 199 // Assert only valid if complete/valid 64 bit _fingerprint value is read. 200 uint64_t oldfp = fingerprint(); 201 #endif // ASSERT 202 _fingerprint = new_fingerprint; 203 assert(oldfp == 0L || new_fingerprint == oldfp, 204 "fingerprint cannot change"); 205 assert(((new_fingerprint >> 32) != 0x80000000) && (int)new_fingerprint !=0, 206 "fingerprint should call init to set initial value"); 207 return new_fingerprint; 208 } 209 210 // name 211 int name_index() const { return _name_index; } 212 void set_name_index(int index) { _name_index = index; } 213 214 // signature 215 int signature_index() const { return _signature_index; } 216 void set_signature_index(int index) { _signature_index = index; } 217 218 // generics support 219 int generic_signature_index() const { return _generic_signature_index; } 220 void set_generic_signature_index(int index) { _generic_signature_index = index; } 221 222 // Sizing 223 static int header_size() { 224 return sizeof(constMethodOopDesc)/HeapWordSize; 225 } 226 227 // Object size needed 228 static int object_size(int code_size, int compressed_line_number_size, 229 int local_variable_table_length, 230 int checked_exceptions_length); 231 232 int object_size() const { return _constMethod_size; } 233 void set_constMethod_size(int size) { _constMethod_size = size; } 234 // Is object parsable by gc 235 bool object_is_parsable() { return object_size() > 0; } 236 237 // code size 238 int code_size() const { return _code_size; } 239 void set_code_size(int size) { 240 assert(max_method_code_size < (1 << 16), 241 "u2 is too small to hold method code size in general"); 242 assert(0 <= size && size <= max_method_code_size, "invalid code size"); 243 _code_size = size; 244 } 245 246 // linenumber table - note that length is unknown until decompression, 247 // see class CompressedLineNumberReadStream. 248 u_char* compressed_linenumber_table() const; // not preserved by gc 249 u2* checked_exceptions_length_addr() const; 250 u2* localvariable_table_length_addr() const; 251 252 // checked exceptions 253 int checked_exceptions_length() const; 254 CheckedExceptionElement* checked_exceptions_start() const; 255 256 // localvariable table 257 int localvariable_table_length() const; 258 LocalVariableTableElement* localvariable_table_start() const; 259 260 // byte codes 261 void set_code(address code) { 262 if (code_size() > 0) { 263 memcpy(code_base(), code, code_size()); 264 } 265 } 266 address code_base() const { return (address) (this+1); } 267 address code_end() const { return code_base() + code_size(); } 268 bool contains(address bcp) const { return code_base() <= bcp 269 && bcp < code_end(); } 270 // Offset to bytecodes 271 static ByteSize codes_offset() 272 { return in_ByteSize(sizeof(constMethodOopDesc)); } 273 274 // interpreter support 275 static ByteSize exception_table_offset() 276 { return byte_offset_of(constMethodOopDesc, _exception_table); } 277 278 // Garbage collection support 279 oop* adr_method() const { return (oop*)&_method; } 280 oop* adr_stackmap_data() const { return (oop*)&_stackmap_data; } 281 oop* adr_exception_table() const { return (oop*)&_exception_table; } 282 bool is_conc_safe() { return _is_conc_safe; } 283 void set_is_conc_safe(bool v) { _is_conc_safe = v; } 284 285 // Unique id for the method 286 static const u2 MAX_IDNUM; 287 static const u2 UNSET_IDNUM; 288 u2 method_idnum() const { return _method_idnum; } 289 void set_method_idnum(u2 idnum) { _method_idnum = idnum; } 290 291 private: 292 // Since the size of the compressed line number table is unknown, the 293 // offsets of the other variable sized sections are computed backwards 294 // from the end of the constMethodOop. 295 296 // First byte after constMethodOop 297 address constMethod_end() const 298 { return (address)((oop*)this + _constMethod_size); } 299 300 // Last short in constMethodOop 301 u2* last_u2_element() const 302 { return (u2*)constMethod_end() - 1; } 303 };