1 /* 2 * Copyright (c) 1998, 2023, 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 "compiler/oopMap.hpp" 29 #include "prims/jvmtiExport.hpp" 30 #include "runtime/globals_extension.hpp" 31 32 // Private definition. 33 // There is one DIR_Chunk for each scope and values array. 34 // A chunk can potentially be used more than once. 35 // We keep track of these chunks in order to detect 36 // repetition and enable sharing. 37 class DIR_Chunk { 38 private: 39 int _offset; // location in the stream of this scope 40 int _length; // number of bytes in the stream 41 int _hash; // hash of stream bytes (for quicker reuse) 42 DebugInformationRecorder* _DIR; 43 44 public: 45 int offset() { return _offset; } 46 47 void* operator new(size_t ignore, DebugInformationRecorder* dir) throw() { 48 assert(ignore == sizeof(DIR_Chunk), ""); 49 if (dir->_next_chunk >= dir->_next_chunk_limit) { 50 const int CHUNK = 100; 51 dir->_next_chunk = NEW_RESOURCE_ARRAY(DIR_Chunk, CHUNK); 52 dir->_next_chunk_limit = dir->_next_chunk + CHUNK; 53 } 54 return dir->_next_chunk++; 55 } 56 57 DIR_Chunk(int offset, int length, DebugInformationRecorder* dir) { 58 _offset = offset; 59 _length = length; 60 _DIR = dir; 61 unsigned int hash = 0; 62 address p = dir->stream()->buffer() + _offset; 63 for (int i = 0; i < length; i++) { 64 if (i == 6) break; 65 hash *= 127; 66 hash += p[i]; 67 } 68 _hash = hash; 69 } 70 71 DIR_Chunk* find_match(GrowableArray<DIR_Chunk*>* arr, 72 int start_index, 73 DebugInformationRecorder* dir) { 74 int end_index = arr->length(); 75 int hash = this->_hash, length = this->_length; 76 address buf = dir->stream()->buffer(); 77 for (int i = end_index; --i >= start_index; ) { 78 DIR_Chunk* that = arr->at(i); 79 if (hash == that->_hash && 80 length == that->_length && 81 0 == memcmp(buf + this->_offset, buf + that->_offset, length)) { 82 return that; 83 } 84 } 85 return nullptr; 86 } 87 88 static int compare(DIR_Chunk* const & a, DIR_Chunk* const & b) { 89 if (b->_hash > a->_hash) { 90 return 1; 91 } 92 if (b->_hash < a->_hash) { 93 return -1; 94 } 95 if (b->_length > a->_length) { 96 return 1; 97 } 98 if (b->_length < a->_length) { 99 return -1; 100 } 101 address buf = a->_DIR->stream()->buffer(); 102 return memcmp(buf + b->_offset, buf + a->_offset, a->_length); 103 } 104 }; 105 106 static inline bool compute_recording_non_safepoints() { 107 if (JvmtiExport::should_post_compiled_method_load() 108 && FLAG_IS_DEFAULT(DebugNonSafepoints)) { 109 // The default value of this flag is taken to be true, 110 // if JVMTI is looking at nmethod codes. 111 // We anticipate that JVMTI may wish to participate in profiling. 112 return true; 113 } 114 115 // If the flag is set manually, use it, whether true or false. 116 // Otherwise, if JVMTI is not in the picture, use the default setting. 117 // (This is true in debug, just for the exercise, false in product mode.) 118 return DebugNonSafepoints; 119 } 120 121 DebugInformationRecorder::DebugInformationRecorder(OopRecorder* oop_recorder) 122 : _recording_non_safepoints(compute_recording_non_safepoints()) 123 { 124 _pcs_size = 100; 125 _pcs = NEW_RESOURCE_ARRAY(PcDesc, _pcs_size); 126 _pcs_length = 0; 127 128 _prev_safepoint_pc = PcDesc::lower_offset_limit; 129 130 _stream = new DebugInfoWriteStream(this, 10 * K); 131 // make sure that there is no stream_decode_offset that is zero 132 _stream->write_byte((jbyte)0xFF); 133 134 // make sure that we can distinguish the value "serialized_null" from offsets 135 assert(_stream->position() > serialized_null, "sanity"); 136 137 _oop_recorder = oop_recorder; 138 139 _all_chunks = new GrowableArray<DIR_Chunk*>(300); 140 _next_chunk = _next_chunk_limit = nullptr; 141 142 add_new_pc_offset(PcDesc::lower_offset_limit); // sentinel record 143 144 debug_only(_recording_state = rs_null); 145 } 146 147 148 void DebugInformationRecorder::add_oopmap(int pc_offset, OopMap* map) { 149 // !!!!! Preserve old style handling of oopmaps for now 150 _oopmaps->add_gc_map(pc_offset, map); 151 } 152 153 void DebugInformationRecorder::add_safepoint(int pc_offset, OopMap* map) { 154 assert(!_oop_recorder->is_complete(), "not frozen yet"); 155 // Store the new safepoint 156 157 // Add the oop map 158 add_oopmap(pc_offset, map); 159 160 add_new_pc_offset(pc_offset); 161 162 assert(_recording_state == rs_null, "nesting of recording calls"); 163 debug_only(_recording_state = rs_safepoint); 164 } 165 166 void DebugInformationRecorder::add_non_safepoint(int pc_offset) { 167 assert(!_oop_recorder->is_complete(), "not frozen yet"); 168 assert(_recording_non_safepoints, "must be recording non-safepoints"); 169 170 add_new_pc_offset(pc_offset); 171 172 assert(_recording_state == rs_null, "nesting of recording calls"); 173 debug_only(_recording_state = rs_non_safepoint); 174 } 175 176 void DebugInformationRecorder::add_new_pc_offset(int pc_offset) { 177 assert(_pcs_length == 0 || last_pc()->pc_offset() < pc_offset, 178 "must specify a new, larger pc offset"); 179 180 // add the pcdesc 181 if (_pcs_length == _pcs_size) { 182 // Expand 183 int new_pcs_size = _pcs_size * 2; 184 PcDesc* new_pcs = NEW_RESOURCE_ARRAY(PcDesc, new_pcs_size); 185 for (int index = 0; index < _pcs_length; index++) { 186 new_pcs[index] = _pcs[index]; 187 } 188 _pcs_size = new_pcs_size; 189 _pcs = new_pcs; 190 } 191 assert(_pcs_size > _pcs_length, "There must be room for after expanding"); 192 193 _pcs[_pcs_length++] = PcDesc(pc_offset, DebugInformationRecorder::serialized_null, 194 DebugInformationRecorder::serialized_null); 195 } 196 197 198 int DebugInformationRecorder::serialize_monitor_values(GrowableArray<MonitorValue*>* monitors) { 199 if (monitors == nullptr || monitors->is_empty()) return DebugInformationRecorder::serialized_null; 200 assert(_recording_state == rs_safepoint, "must be recording a safepoint"); 201 int result = stream()->position(); 202 stream()->write_int(monitors->length()); 203 for (int index = 0; index < monitors->length(); index++) { 204 monitors->at(index)->write_on(stream()); 205 } 206 assert(result != serialized_null, "sanity"); 207 208 // (See comment below on DebugInformationRecorder::describe_scope.) 209 int shared_result = find_sharable_decode_offset(result); 210 if (shared_result != serialized_null) { 211 stream()->set_position(result); 212 result = shared_result; 213 } 214 215 return result; 216 } 217 218 219 int DebugInformationRecorder::serialize_scope_values(GrowableArray<ScopeValue*>* values) { 220 if (values == nullptr || values->is_empty()) return DebugInformationRecorder::serialized_null; 221 assert(_recording_state == rs_safepoint, "must be recording a safepoint"); 222 int result = stream()->position(); 223 assert(result != serialized_null, "sanity"); 224 stream()->write_int(values->length()); 225 for (int index = 0; index < values->length(); index++) { 226 values->at(index)->write_on(stream()); 227 } 228 229 // (See comment below on DebugInformationRecorder::describe_scope.) 230 int shared_result = find_sharable_decode_offset(result); 231 if (shared_result != serialized_null) { 232 stream()->set_position(result); 233 result = shared_result; 234 } 235 236 return result; 237 } 238 239 240 #ifndef PRODUCT 241 // These variables are put into one block to reduce relocations 242 // and make it simpler to print from the debugger. 243 static 244 struct dir_stats_struct { 245 int chunks_queried; 246 int chunks_shared; 247 int chunks_reshared; 248 int chunks_elided; 249 250 void print() { 251 tty->print_cr("Debug Data Chunks: %d, shared %d+%d, non-SP's elided %d", 252 chunks_queried, 253 chunks_shared, chunks_reshared, 254 chunks_elided); 255 } 256 } dir_stats; 257 #endif //PRODUCT 258 259 260 int DebugInformationRecorder::find_sharable_decode_offset(int stream_offset) { 261 NOT_PRODUCT(++dir_stats.chunks_queried); 262 int stream_length = stream()->position() - stream_offset; 263 assert(stream_offset != serialized_null, "should not be null"); 264 assert(stream_length != 0, "should not be empty"); 265 266 DIR_Chunk* ns = new(this) DIR_Chunk(stream_offset, stream_length, this); 267 268 DIR_Chunk* match = _all_chunks->insert_sorted<DIR_Chunk::compare>(ns); 269 if (match != ns) { 270 // Found an existing chunk 271 NOT_PRODUCT(++dir_stats.chunks_shared); 272 assert(ns+1 == _next_chunk, ""); 273 _next_chunk = ns; 274 return match->offset(); 275 } else { 276 // Inserted this chunk, so nothing to do 277 return serialized_null; 278 } 279 } 280 281 282 // must call add_safepoint before: it sets PcDesc and this routine uses 283 // the last PcDesc set 284 void DebugInformationRecorder::describe_scope(int pc_offset, 285 const methodHandle& methodH, 286 ciMethod* method, 287 int bci, 288 bool reexecute, 289 bool rethrow_exception, 290 bool is_method_handle_invoke, 291 bool return_oop, 292 bool has_ea_local_in_scope, 293 bool arg_escape, 294 DebugToken* locals, 295 DebugToken* expressions, 296 DebugToken* monitors) { 297 assert(_recording_state != rs_null, "nesting of recording calls"); 298 PcDesc* last_pd = last_pc(); 299 assert(last_pd->pc_offset() == pc_offset, "must be last pc"); 300 int sender_stream_offset = last_pd->scope_decode_offset(); 301 // update the stream offset of current pc desc 302 int stream_offset = stream()->position(); 303 last_pd->set_scope_decode_offset(stream_offset); 304 305 // Record flags into pcDesc. 306 last_pd->set_should_reexecute(reexecute); 307 last_pd->set_rethrow_exception(rethrow_exception); 308 last_pd->set_is_method_handle_invoke(is_method_handle_invoke); 309 last_pd->set_return_oop(return_oop); 310 last_pd->set_has_ea_local_in_scope(has_ea_local_in_scope); 311 last_pd->set_arg_escape(arg_escape); 312 313 // serialize sender stream offset 314 stream()->write_int(sender_stream_offset); 315 316 // serialize scope 317 Metadata* method_enc; 318 if (method != nullptr) { 319 method_enc = method->constant_encoding(); 320 } else if (methodH.not_null()) { 321 method_enc = methodH(); 322 } else { 323 method_enc = nullptr; 324 } 325 int method_enc_index = oop_recorder()->find_index(method_enc); 326 stream()->write_int(method_enc_index); 327 stream()->write_bci(bci); 328 assert(method == nullptr || 329 (method->is_native() && bci == 0) || 330 (!method->is_native() && 0 <= bci && bci < method->code_size()) || 331 bci == -1, "illegal bci"); 332 333 // serialize the locals/expressions/monitors 334 stream()->write_int((intptr_t) locals); 335 stream()->write_int((intptr_t) expressions); 336 stream()->write_int((intptr_t) monitors); 337 338 // Here's a tricky bit. We just wrote some bytes. 339 // Wouldn't it be nice to find that we had already 340 // written those same bytes somewhere else? 341 // If we get lucky this way, reset the stream 342 // and reuse the old bytes. By the way, this 343 // trick not only shares parent scopes, but also 344 // compresses equivalent non-safepoint PcDescs. 345 int shared_stream_offset = find_sharable_decode_offset(stream_offset); 346 if (shared_stream_offset != serialized_null) { 347 stream()->set_position(stream_offset); 348 last_pd->set_scope_decode_offset(shared_stream_offset); 349 } 350 } 351 352 void DebugInformationRecorder::dump_object_pool(GrowableArray<ScopeValue*>* objects) { 353 guarantee( _pcs_length > 0, "safepoint must exist before describing scopes"); 354 PcDesc* last_pd = &_pcs[_pcs_length-1]; 355 if (objects != nullptr) { 356 for (int i = objects->length() - 1; i >= 0; i--) { 357 objects->at(i)->as_ObjectValue()->set_visited(false); 358 } 359 } 360 int offset = serialize_scope_values(objects); 361 last_pd->set_obj_decode_offset(offset); 362 } 363 364 void DebugInformationRecorder::end_scopes(int pc_offset, bool is_safepoint) { 365 assert(_recording_state == (is_safepoint? rs_safepoint: rs_non_safepoint), 366 "nesting of recording calls"); 367 debug_only(_recording_state = rs_null); 368 369 // Try to compress away an equivalent non-safepoint predecessor. 370 // (This only works because we have previously recognized redundant 371 // scope trees and made them use a common scope_decode_offset.) 372 if (_pcs_length >= 2 && recording_non_safepoints()) { 373 PcDesc* last = last_pc(); 374 PcDesc* prev = prev_pc(); 375 // If prev is (a) not a safepoint and (b) has the same 376 // stream pointer, then it can be coalesced into the last. 377 // This is valid because non-safepoints are only sought 378 // with pc_desc_near, which (when it misses prev) will 379 // search forward until it finds last. 380 // In addition, it does not matter if the last PcDesc 381 // is for a safepoint or not. 382 if (_prev_safepoint_pc < prev->pc_offset() && prev->is_same_info(last)) { 383 assert(prev == last-1, "sane"); 384 prev->set_pc_offset(pc_offset); 385 _pcs_length -= 1; 386 NOT_PRODUCT(++dir_stats.chunks_elided); 387 } 388 } 389 390 // We have just recorded this safepoint. 391 // Remember it in case the previous paragraph needs to know. 392 if (is_safepoint) { 393 _prev_safepoint_pc = pc_offset; 394 } 395 } 396 397 #ifdef ASSERT 398 bool DebugInformationRecorder::recorders_frozen() { 399 return _oop_recorder->is_complete(); 400 } 401 402 void DebugInformationRecorder::mark_recorders_frozen() { 403 _oop_recorder->freeze(); 404 } 405 #endif // PRODUCT 406 407 DebugToken* DebugInformationRecorder::create_scope_values(GrowableArray<ScopeValue*>* values) { 408 assert(!recorders_frozen(), "not frozen yet"); 409 return (DebugToken*) (intptr_t) serialize_scope_values(values); 410 } 411 412 413 DebugToken* DebugInformationRecorder::create_monitor_values(GrowableArray<MonitorValue*>* monitors) { 414 assert(!recorders_frozen(), "not frozen yet"); 415 return (DebugToken*) (intptr_t) serialize_monitor_values(monitors); 416 } 417 418 419 int DebugInformationRecorder::data_size() { 420 debug_only(mark_recorders_frozen()); // mark it "frozen" for asserts 421 return _stream->position(); 422 } 423 424 425 int DebugInformationRecorder::pcs_size() { 426 debug_only(mark_recorders_frozen()); // mark it "frozen" for asserts 427 if (last_pc()->pc_offset() != PcDesc::upper_offset_limit) 428 add_new_pc_offset(PcDesc::upper_offset_limit); 429 return _pcs_length * sizeof(PcDesc); 430 } 431 432 433 void DebugInformationRecorder::copy_to(nmethod* nm) { 434 nm->copy_scopes_data(stream()->buffer(), stream()->position()); 435 nm->copy_scopes_pcs(_pcs, _pcs_length); 436 } 437 438 439 void DebugInformationRecorder::verify(const nmethod* code) { 440 Unimplemented(); 441 } 442 443 #ifndef PRODUCT 444 void DebugInformationRecorder::print_statistics() { 445 dir_stats.print(); 446 } 447 #endif //PRODUCT