1 /* 2 * Copyright (c) 1998, 2010, 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 #include "precompiled.hpp" 26 #include "code/debugInfoRec.hpp" 27 #include "code/scopeDesc.hpp" 28 #include "prims/jvmtiExport.hpp" 29 30 // Private definition. 31 // There is one DIR_Chunk for each scope and values array. 32 // A chunk can potentially be used more than once. 33 // We keep track of these chunks in order to detect 34 // repetition and enable sharing. 35 class DIR_Chunk { 36 friend class DebugInformationRecorder; 37 int _offset; // location in the stream of this scope 38 int _length; // number of bytes in the stream 39 int _hash; // hash of stream bytes (for quicker reuse) 40 41 void* operator new(size_t ignore, DebugInformationRecorder* dir) { 42 assert(ignore == sizeof(DIR_Chunk), ""); 43 if (dir->_next_chunk >= dir->_next_chunk_limit) { 44 const int CHUNK = 100; 45 dir->_next_chunk = NEW_RESOURCE_ARRAY(DIR_Chunk, CHUNK); 46 dir->_next_chunk_limit = dir->_next_chunk + CHUNK; 47 } 48 return dir->_next_chunk++; 49 } 50 51 DIR_Chunk(int offset, int length, DebugInformationRecorder* dir) { 52 _offset = offset; 53 _length = length; 54 unsigned int hash = 0; 55 address p = dir->stream()->buffer() + _offset; 56 for (int i = 0; i < length; i++) { 57 if (i == 6) break; 58 hash *= 127; 59 hash += p[i]; 60 } 61 _hash = hash; 62 } 63 64 DIR_Chunk* find_match(GrowableArray<DIR_Chunk*>* arr, 65 int start_index, 66 DebugInformationRecorder* dir) { 67 int end_index = arr->length(); 68 int hash = this->_hash, length = this->_length; 69 address buf = dir->stream()->buffer(); 70 for (int i = end_index; --i >= start_index; ) { 71 DIR_Chunk* that = arr->at(i); 72 if (hash == that->_hash && 73 length == that->_length && 74 0 == memcmp(buf + this->_offset, buf + that->_offset, length)) { 75 return that; 76 } 77 } 78 return NULL; 79 } 80 }; 81 82 static inline bool compute_recording_non_safepoints() { 83 if (JvmtiExport::should_post_compiled_method_load() 84 && FLAG_IS_DEFAULT(DebugNonSafepoints)) { 85 // The default value of this flag is taken to be true, 86 // if JVMTI is looking at nmethod codes. 87 // We anticipate that JVMTI may wish to participate in profiling. 88 return true; 89 } 90 91 // If the flag is set manually, use it, whether true or false. 92 // Otherwise, if JVMTI is not in the picture, use the default setting. 93 // (This is true in debug, just for the exercise, false in product mode.) 94 return DebugNonSafepoints; 95 } 96 97 DebugInformationRecorder::DebugInformationRecorder(OopRecorder* oop_recorder) 98 : _recording_non_safepoints(compute_recording_non_safepoints()) 99 { 100 _pcs_size = 100; 101 _pcs = NEW_RESOURCE_ARRAY(PcDesc, _pcs_size); 102 _pcs_length = 0; 103 104 _prev_safepoint_pc = PcDesc::lower_offset_limit; 105 106 _stream = new DebugInfoWriteStream(this, 10 * K); 107 // make sure that there is no stream_decode_offset that is zero 108 _stream->write_byte((jbyte)0xFF); 109 110 // make sure that we can distinguish the value "serialized_null" from offsets 111 assert(_stream->position() > serialized_null, "sanity"); 112 113 _oop_recorder = oop_recorder; 114 115 _all_chunks = new GrowableArray<DIR_Chunk*>(300); 116 _shared_chunks = new GrowableArray<DIR_Chunk*>(30); 117 _next_chunk = _next_chunk_limit = NULL; 118 119 add_new_pc_offset(PcDesc::lower_offset_limit); // sentinel record 120 121 debug_only(_recording_state = rs_null); 122 } 123 124 125 void DebugInformationRecorder::add_oopmap(int pc_offset, OopMap* map) { 126 // !!!!! Preserve old style handling of oopmaps for now 127 _oopmaps->add_gc_map(pc_offset, map); 128 } 129 130 void DebugInformationRecorder::add_safepoint(int pc_offset, OopMap* map) { 131 assert(!_oop_recorder->is_complete(), "not frozen yet"); 132 // Store the new safepoint 133 134 // Add the oop map 135 add_oopmap(pc_offset, map); 136 137 add_new_pc_offset(pc_offset); 138 139 assert(_recording_state == rs_null, "nesting of recording calls"); 140 debug_only(_recording_state = rs_safepoint); 141 } 142 143 void DebugInformationRecorder::add_non_safepoint(int pc_offset) { 144 assert(!_oop_recorder->is_complete(), "not frozen yet"); 145 assert(_recording_non_safepoints, "must be recording non-safepoints"); 146 147 add_new_pc_offset(pc_offset); 148 149 assert(_recording_state == rs_null, "nesting of recording calls"); 150 debug_only(_recording_state = rs_non_safepoint); 151 } 152 153 void DebugInformationRecorder::add_new_pc_offset(int pc_offset) { 154 assert(_pcs_length == 0 || last_pc()->pc_offset() < pc_offset, 155 "must specify a new, larger pc offset"); 156 157 // add the pcdesc 158 if (_pcs_length == _pcs_size) { 159 // Expand 160 int new_pcs_size = _pcs_size * 2; 161 PcDesc* new_pcs = NEW_RESOURCE_ARRAY(PcDesc, new_pcs_size); 162 for (int index = 0; index < _pcs_length; index++) { 163 new_pcs[index] = _pcs[index]; 164 } 165 _pcs_size = new_pcs_size; 166 _pcs = new_pcs; 167 } 168 assert(_pcs_size > _pcs_length, "There must be room for after expanding"); 169 170 _pcs[_pcs_length++] = PcDesc(pc_offset, DebugInformationRecorder::serialized_null, 171 DebugInformationRecorder::serialized_null); 172 } 173 174 175 int DebugInformationRecorder::serialize_monitor_values(GrowableArray<MonitorValue*>* monitors) { 176 if (monitors == NULL || monitors->is_empty()) return DebugInformationRecorder::serialized_null; 177 assert(_recording_state == rs_safepoint, "must be recording a safepoint"); 178 int result = stream()->position(); 179 stream()->write_int(monitors->length()); 180 for (int index = 0; index < monitors->length(); index++) { 181 monitors->at(index)->write_on(stream()); 182 } 183 assert(result != serialized_null, "sanity"); 184 185 // (See comment below on DebugInformationRecorder::describe_scope.) 186 int shared_result = find_sharable_decode_offset(result); 187 if (shared_result != serialized_null) { 188 stream()->set_position(result); 189 result = shared_result; 190 } 191 192 return result; 193 } 194 195 196 int DebugInformationRecorder::serialize_scope_values(GrowableArray<ScopeValue*>* values) { 197 if (values == NULL || values->is_empty()) return DebugInformationRecorder::serialized_null; 198 assert(_recording_state == rs_safepoint, "must be recording a safepoint"); 199 int result = stream()->position(); 200 assert(result != serialized_null, "sanity"); 201 stream()->write_int(values->length()); 202 for (int index = 0; index < values->length(); index++) { 203 values->at(index)->write_on(stream()); 204 } 205 206 // (See comment below on DebugInformationRecorder::describe_scope.) 207 int shared_result = find_sharable_decode_offset(result); 208 if (shared_result != serialized_null) { 209 stream()->set_position(result); 210 result = shared_result; 211 } 212 213 return result; 214 } 215 216 217 #ifndef PRODUCT 218 // These variables are put into one block to reduce relocations 219 // and make it simpler to print from the debugger. 220 static 221 struct dir_stats_struct { 222 int chunks_queried; 223 int chunks_shared; 224 int chunks_reshared; 225 int chunks_elided; 226 227 void print() { 228 tty->print_cr("Debug Data Chunks: %d, shared %d+%d, non-SP's elided %d", 229 chunks_queried, 230 chunks_shared, chunks_reshared, 231 chunks_elided); 232 } 233 } dir_stats; 234 #endif //PRODUCT 235 236 237 int DebugInformationRecorder::find_sharable_decode_offset(int stream_offset) { 238 // Only pull this trick if non-safepoint recording 239 // is enabled, for now. 240 if (!recording_non_safepoints()) 241 return serialized_null; 242 243 NOT_PRODUCT(++dir_stats.chunks_queried); 244 int stream_length = stream()->position() - stream_offset; 245 assert(stream_offset != serialized_null, "should not be null"); 246 assert(stream_length != 0, "should not be empty"); 247 248 DIR_Chunk* ns = new(this) DIR_Chunk(stream_offset, stream_length, this); 249 250 // Look in previously shared scopes first: 251 DIR_Chunk* ms = ns->find_match(_shared_chunks, 0, this); 252 if (ms != NULL) { 253 NOT_PRODUCT(++dir_stats.chunks_reshared); 254 assert(ns+1 == _next_chunk, ""); 255 _next_chunk = ns; 256 return ms->_offset; 257 } 258 259 // Look in recently encountered scopes next: 260 const int MAX_RECENT = 50; 261 int start_index = _all_chunks->length() - MAX_RECENT; 262 if (start_index < 0) start_index = 0; 263 ms = ns->find_match(_all_chunks, start_index, this); 264 if (ms != NULL) { 265 NOT_PRODUCT(++dir_stats.chunks_shared); 266 // Searching in _all_chunks is limited to a window, 267 // but searching in _shared_chunks is unlimited. 268 _shared_chunks->append(ms); 269 assert(ns+1 == _next_chunk, ""); 270 _next_chunk = ns; 271 return ms->_offset; 272 } 273 274 // No match. Add this guy to the list, in hopes of future shares. 275 _all_chunks->append(ns); 276 return serialized_null; 277 } 278 279 280 // must call add_safepoint before: it sets PcDesc and this routine uses 281 // the last PcDesc set 282 void DebugInformationRecorder::describe_scope(int pc_offset, 283 ciMethod* method, 284 int bci, 285 bool reexecute, 286 bool is_method_handle_invoke, 287 bool return_oop, 288 DebugToken* locals, 289 DebugToken* expressions, 290 DebugToken* monitors) { 291 assert(_recording_state != rs_null, "nesting of recording calls"); 292 PcDesc* last_pd = last_pc(); 293 assert(last_pd->pc_offset() == pc_offset, "must be last pc"); 294 int sender_stream_offset = last_pd->scope_decode_offset(); 295 // update the stream offset of current pc desc 296 int stream_offset = stream()->position(); 297 last_pd->set_scope_decode_offset(stream_offset); 298 299 // Record flags into pcDesc. 300 last_pd->set_should_reexecute(reexecute); 301 last_pd->set_is_method_handle_invoke(is_method_handle_invoke); 302 last_pd->set_return_oop(return_oop); 303 304 // serialize sender stream offest 305 stream()->write_int(sender_stream_offset); 306 307 // serialize scope 308 jobject method_enc = (method == NULL)? NULL: method->constant_encoding(); 309 stream()->write_int(oop_recorder()->find_index(method_enc)); 310 stream()->write_bci(bci); 311 assert(method == NULL || 312 (method->is_native() && bci == 0) || 313 (!method->is_native() && 0 <= bci && bci < method->code_size()) || 314 bci == -1, "illegal bci"); 315 316 // serialize the locals/expressions/monitors 317 stream()->write_int((intptr_t) locals); 318 stream()->write_int((intptr_t) expressions); 319 stream()->write_int((intptr_t) monitors); 320 321 // Here's a tricky bit. We just wrote some bytes. 322 // Wouldn't it be nice to find that we had already 323 // written those same bytes somewhere else? 324 // If we get lucky this way, reset the stream 325 // and reuse the old bytes. By the way, this 326 // trick not only shares parent scopes, but also 327 // compresses equivalent non-safepoint PcDescs. 328 int shared_stream_offset = find_sharable_decode_offset(stream_offset); 329 if (shared_stream_offset != serialized_null) { 330 stream()->set_position(stream_offset); 331 last_pd->set_scope_decode_offset(shared_stream_offset); 332 } 333 } 334 335 void DebugInformationRecorder::dump_object_pool(GrowableArray<ScopeValue*>* objects) { 336 guarantee( _pcs_length > 0, "safepoint must exist before describing scopes"); 337 PcDesc* last_pd = &_pcs[_pcs_length-1]; 338 if (objects != NULL) { 339 for (int i = objects->length() - 1; i >= 0; i--) { 340 ((ObjectValue*) objects->at(i))->set_visited(false); 341 } 342 } 343 int offset = serialize_scope_values(objects); 344 last_pd->set_obj_decode_offset(offset); 345 } 346 347 void DebugInformationRecorder::end_scopes(int pc_offset, bool is_safepoint) { 348 assert(_recording_state == (is_safepoint? rs_safepoint: rs_non_safepoint), 349 "nesting of recording calls"); 350 debug_only(_recording_state = rs_null); 351 352 // Try to compress away an equivalent non-safepoint predecessor. 353 // (This only works because we have previously recognized redundant 354 // scope trees and made them use a common scope_decode_offset.) 355 if (_pcs_length >= 2 && recording_non_safepoints()) { 356 PcDesc* last = last_pc(); 357 PcDesc* prev = prev_pc(); 358 // If prev is (a) not a safepoint and (b) has the same 359 // stream pointer, then it can be coalesced into the last. 360 // This is valid because non-safepoints are only sought 361 // with pc_desc_near, which (when it misses prev) will 362 // search forward until it finds last. 363 // In addition, it does not matter if the last PcDesc 364 // is for a safepoint or not. 365 if (_prev_safepoint_pc < prev->pc_offset() && prev->is_same_info(last)) { 366 assert(prev == last-1, "sane"); 367 prev->set_pc_offset(pc_offset); 368 _pcs_length -= 1; 369 NOT_PRODUCT(++dir_stats.chunks_elided); 370 } 371 } 372 373 // We have just recorded this safepoint. 374 // Remember it in case the previous paragraph needs to know. 375 if (is_safepoint) { 376 _prev_safepoint_pc = pc_offset; 377 } 378 } 379 380 DebugToken* DebugInformationRecorder::create_scope_values(GrowableArray<ScopeValue*>* values) { 381 assert(!_oop_recorder->is_complete(), "not frozen yet"); 382 return (DebugToken*) (intptr_t) serialize_scope_values(values); 383 } 384 385 386 DebugToken* DebugInformationRecorder::create_monitor_values(GrowableArray<MonitorValue*>* monitors) { 387 assert(!_oop_recorder->is_complete(), "not frozen yet"); 388 return (DebugToken*) (intptr_t) serialize_monitor_values(monitors); 389 } 390 391 392 int DebugInformationRecorder::data_size() { 393 debug_only(_oop_recorder->oop_size()); // mark it "frozen" for asserts 394 return _stream->position(); 395 } 396 397 398 int DebugInformationRecorder::pcs_size() { 399 debug_only(_oop_recorder->oop_size()); // mark it "frozen" for asserts 400 if (last_pc()->pc_offset() != PcDesc::upper_offset_limit) 401 add_new_pc_offset(PcDesc::upper_offset_limit); 402 return _pcs_length * sizeof(PcDesc); 403 } 404 405 406 void DebugInformationRecorder::copy_to(nmethod* nm) { 407 nm->copy_scopes_data(stream()->buffer(), stream()->position()); 408 nm->copy_scopes_pcs(_pcs, _pcs_length); 409 } 410 411 412 void DebugInformationRecorder::verify(const nmethod* code) { 413 Unimplemented(); 414 } 415 416 #ifndef PRODUCT 417 void DebugInformationRecorder::print_statistics() { 418 dir_stats.print(); 419 } 420 #endif //PRODUCT