1 /*
   2  * Copyright (c) 1998, 2015, 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 #if INCLUDE_JVMCI
  41   DebugInformationRecorder* _DIR;
  42 #endif
  43 
  44   void* operator new(size_t ignore, DebugInformationRecorder* dir) throw() {
  45     assert(ignore == sizeof(DIR_Chunk), "");
  46     if (dir->_next_chunk >= dir->_next_chunk_limit) {
  47       const int CHUNK = 100;
  48       dir->_next_chunk = NEW_RESOURCE_ARRAY(DIR_Chunk, CHUNK);
  49       dir->_next_chunk_limit = dir->_next_chunk + CHUNK;
  50     }
  51     return dir->_next_chunk++;
  52   }
  53 
  54   DIR_Chunk(int offset, int length, DebugInformationRecorder* dir) {
  55     _offset = offset;
  56     _length = length;
  57 #if INCLUDE_JVMCI
  58     _DIR = dir;
  59 #endif
  60     unsigned int hash = 0;
  61     address p = dir->stream()->buffer() + _offset;
  62     for (int i = 0; i < length; i++) {
  63       if (i == 6)  break;
  64       hash *= 127;
  65       hash += p[i];
  66     }
  67     _hash = hash;
  68   }
  69 
  70   DIR_Chunk* find_match(GrowableArray<DIR_Chunk*>* arr,
  71                         int start_index,
  72                         DebugInformationRecorder* dir) {
  73     int end_index = arr->length();
  74     int hash = this->_hash, length = this->_length;
  75     address buf = dir->stream()->buffer();
  76     for (int i = end_index; --i >= start_index; ) {
  77       DIR_Chunk* that = arr->at(i);
  78       if (hash   == that->_hash &&
  79           length == that->_length &&
  80           0 == memcmp(buf + this->_offset, buf + that->_offset, length)) {
  81         return that;
  82       }
  83     }
  84     return NULL;
  85   }
  86 
  87 #if INCLUDE_JVMCI
  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 #endif
 105 };
 106 
 107 static inline bool compute_recording_non_safepoints() {
 108   if (JvmtiExport::should_post_compiled_method_load()
 109       && FLAG_IS_DEFAULT(DebugNonSafepoints)) {
 110     // The default value of this flag is taken to be true,
 111     // if JVMTI is looking at nmethod codes.
 112     // We anticipate that JVMTI may wish to participate in profiling.
 113     return true;
 114   }
 115 
 116   // If the flag is set manually, use it, whether true or false.
 117   // Otherwise, if JVMTI is not in the picture, use the default setting.
 118   // (This is true in debug, just for the exercise, false in product mode.)
 119   return DebugNonSafepoints;
 120 }
 121 
 122 DebugInformationRecorder::DebugInformationRecorder(OopRecorder* oop_recorder)
 123   : _recording_non_safepoints(compute_recording_non_safepoints())
 124 {
 125   _pcs_size   = 100;
 126   _pcs        = NEW_RESOURCE_ARRAY(PcDesc, _pcs_size);
 127   _pcs_length = 0;
 128 
 129   _prev_safepoint_pc = PcDesc::lower_offset_limit;
 130 
 131   _stream = new DebugInfoWriteStream(this, 10 * K);
 132   // make sure that there is no stream_decode_offset that is zero
 133   _stream->write_byte((jbyte)0xFF);
 134 
 135   // make sure that we can distinguish the value "serialized_null" from offsets
 136   assert(_stream->position() > serialized_null, "sanity");
 137 
 138   _oop_recorder = oop_recorder;
 139 
 140   _all_chunks    = new GrowableArray<DIR_Chunk*>(300);
 141 #if !INCLUDE_JVMCI
 142   _shared_chunks = new GrowableArray<DIR_Chunk*>(30);
 143 #endif
 144   _next_chunk = _next_chunk_limit = NULL;
 145 
 146   add_new_pc_offset(PcDesc::lower_offset_limit);  // sentinel record
 147 
 148   debug_only(_recording_state = rs_null);
 149 }
 150 
 151 
 152 void DebugInformationRecorder::add_oopmap(int pc_offset, OopMap* map) {
 153   // !!!!! Preserve old style handling of oopmaps for now
 154   _oopmaps->add_gc_map(pc_offset, map);
 155 }
 156 
 157 void DebugInformationRecorder::add_safepoint(int pc_offset, OopMap* map) {
 158   assert(!_oop_recorder->is_complete(), "not frozen yet");
 159   // Store the new safepoint
 160 
 161   // Add the oop map
 162   add_oopmap(pc_offset, map);
 163 
 164   add_new_pc_offset(pc_offset);
 165 
 166   assert(_recording_state == rs_null, "nesting of recording calls");
 167   debug_only(_recording_state = rs_safepoint);
 168 }
 169 
 170 void DebugInformationRecorder::add_non_safepoint(int pc_offset) {
 171   assert(!_oop_recorder->is_complete(), "not frozen yet");
 172   assert(_recording_non_safepoints, "must be recording non-safepoints");
 173 
 174   add_new_pc_offset(pc_offset);
 175 
 176   assert(_recording_state == rs_null, "nesting of recording calls");
 177   debug_only(_recording_state = rs_non_safepoint);
 178 }
 179 
 180 void DebugInformationRecorder::add_new_pc_offset(int pc_offset) {
 181   assert(_pcs_length == 0 || last_pc()->pc_offset() < pc_offset,
 182          "must specify a new, larger pc offset");
 183 
 184   // add the pcdesc
 185   if (_pcs_length == _pcs_size) {
 186     // Expand
 187     int     new_pcs_size = _pcs_size * 2;
 188     PcDesc* new_pcs      = NEW_RESOURCE_ARRAY(PcDesc, new_pcs_size);
 189     for (int index = 0; index < _pcs_length; index++) {
 190       new_pcs[index] = _pcs[index];
 191     }
 192     _pcs_size = new_pcs_size;
 193     _pcs      = new_pcs;
 194   }
 195   assert(_pcs_size > _pcs_length, "There must be room for after expanding");
 196 
 197   _pcs[_pcs_length++] = PcDesc(pc_offset, DebugInformationRecorder::serialized_null,
 198                                DebugInformationRecorder::serialized_null);
 199 }
 200 
 201 
 202 int DebugInformationRecorder::serialize_monitor_values(GrowableArray<MonitorValue*>* monitors) {
 203   if (monitors == NULL || monitors->is_empty()) return DebugInformationRecorder::serialized_null;
 204   assert(_recording_state == rs_safepoint, "must be recording a safepoint");
 205   int result = stream()->position();
 206   stream()->write_int(monitors->length());
 207   for (int index = 0; index < monitors->length(); index++) {
 208     monitors->at(index)->write_on(stream());
 209   }
 210   assert(result != serialized_null, "sanity");
 211 
 212   // (See comment below on DebugInformationRecorder::describe_scope.)
 213   int shared_result = find_sharable_decode_offset(result);
 214   if (shared_result != serialized_null) {
 215     stream()->set_position(result);
 216     result = shared_result;
 217   }
 218 
 219   return result;
 220 }
 221 
 222 
 223 int DebugInformationRecorder::serialize_scope_values(GrowableArray<ScopeValue*>* values) {
 224   if (values == NULL || values->is_empty()) return DebugInformationRecorder::serialized_null;
 225   assert(_recording_state == rs_safepoint, "must be recording a safepoint");
 226   int result = stream()->position();
 227   assert(result != serialized_null, "sanity");
 228   stream()->write_int(values->length());
 229   for (int index = 0; index < values->length(); index++) {
 230     values->at(index)->write_on(stream());
 231   }
 232 
 233   // (See comment below on DebugInformationRecorder::describe_scope.)
 234   int shared_result = find_sharable_decode_offset(result);
 235   if (shared_result != serialized_null) {
 236     stream()->set_position(result);
 237     result = shared_result;
 238   }
 239 
 240   return result;
 241 }
 242 
 243 
 244 #ifndef PRODUCT
 245 // These variables are put into one block to reduce relocations
 246 // and make it simpler to print from the debugger.
 247 static
 248 struct dir_stats_struct {
 249   int chunks_queried;
 250   int chunks_shared;
 251   int chunks_reshared;
 252   int chunks_elided;
 253 
 254   void print() {
 255     tty->print_cr("Debug Data Chunks: %d, shared %d+%d, non-SP's elided %d",
 256                   chunks_queried,
 257                   chunks_shared, chunks_reshared,
 258                   chunks_elided);
 259   }
 260 } dir_stats;
 261 #endif //PRODUCT
 262 
 263 
 264 int DebugInformationRecorder::find_sharable_decode_offset(int stream_offset) {
 265 #if !INCLUDE_JVMCI
 266   // Only pull this trick if non-safepoint recording
 267   // is enabled, for now.
 268   if (!recording_non_safepoints()) {
 269     return serialized_null;
 270   }
 271 #endif // INCLUDE_JVMCI
 272 
 273   NOT_PRODUCT(++dir_stats.chunks_queried);
 274   int stream_length = stream()->position() - stream_offset;
 275   assert(stream_offset != serialized_null, "should not be null");
 276   assert(stream_length != 0, "should not be empty");
 277 
 278   DIR_Chunk* ns = new(this) DIR_Chunk(stream_offset, stream_length, this);
 279 
 280 #if INCLUDE_JVMCI
 281   DIR_Chunk* match = _all_chunks->insert_sorted<DIR_Chunk::compare>(ns);
 282   if (match != ns) {
 283     // Found an existing chunk
 284     NOT_PRODUCT(++dir_stats.chunks_shared);
 285     assert(ns+1 == _next_chunk, "");
 286     _next_chunk = ns;
 287     return match->_offset;
 288   } else {
 289     // Inserted this chunk, so nothing to do
 290     return serialized_null;
 291   }
 292 #else // INCLUDE_JVMCI
 293   // Look in previously shared scopes first:
 294   DIR_Chunk* ms = ns->find_match(_shared_chunks, 0, this);
 295   if (ms != NULL) {
 296     NOT_PRODUCT(++dir_stats.chunks_reshared);
 297     assert(ns+1 == _next_chunk, "");
 298     _next_chunk = ns;
 299     return ms->_offset;
 300   }
 301 
 302   // Look in recently encountered scopes next:
 303   const int MAX_RECENT = 50;
 304   int start_index = _all_chunks->length() - MAX_RECENT;
 305   if (start_index < 0)  start_index = 0;
 306   ms = ns->find_match(_all_chunks, start_index, this);
 307   if (ms != NULL) {
 308     NOT_PRODUCT(++dir_stats.chunks_shared);
 309     // Searching in _all_chunks is limited to a window,
 310     // but searching in _shared_chunks is unlimited.
 311     _shared_chunks->append(ms);
 312     assert(ns+1 == _next_chunk, "");
 313     _next_chunk = ns;
 314     return ms->_offset;
 315   }
 316 
 317   // No match.  Add this guy to the list, in hopes of future shares.
 318   _all_chunks->append(ns);
 319   return serialized_null;
 320 #endif // INCLUDE_JVMCI
 321 }
 322 
 323 
 324 // must call add_safepoint before: it sets PcDesc and this routine uses
 325 // the last PcDesc set
 326 void DebugInformationRecorder::describe_scope(int         pc_offset,
 327                                               const methodHandle& methodH,
 328                                               ciMethod*   method,
 329                                               int         bci,
 330                                               bool        reexecute,
 331                                               bool        rethrow_exception,
 332                                               bool        is_method_handle_invoke,
 333                                               bool        return_oop,
 334                                               DebugToken* locals,
 335                                               DebugToken* expressions,
 336                                               DebugToken* monitors) {
 337   assert(_recording_state != rs_null, "nesting of recording calls");
 338   PcDesc* last_pd = last_pc();
 339   assert(last_pd->pc_offset() == pc_offset, "must be last pc");
 340   int sender_stream_offset = last_pd->scope_decode_offset();
 341   // update the stream offset of current pc desc
 342   int stream_offset = stream()->position();
 343   last_pd->set_scope_decode_offset(stream_offset);
 344 
 345   // Record flags into pcDesc.
 346   last_pd->set_should_reexecute(reexecute);
 347   last_pd->set_rethrow_exception(rethrow_exception);
 348   last_pd->set_is_method_handle_invoke(is_method_handle_invoke);
 349   last_pd->set_return_oop(return_oop);
 350 
 351   // serialize sender stream offest
 352   stream()->write_int(sender_stream_offset);
 353 
 354   // serialize scope
 355   Metadata* method_enc;
 356   if (method != NULL) {
 357     method_enc = method->constant_encoding();
 358   } else if (methodH.not_null()) {
 359     method_enc = methodH();
 360   } else {
 361     method_enc = NULL;
 362   }
 363   int method_enc_index = oop_recorder()->find_index(method_enc);
 364   stream()->write_int(method_enc_index);
 365   stream()->write_bci(bci);
 366   assert(method == NULL ||
 367          (method->is_native() && bci == 0) ||
 368          (!method->is_native() && 0 <= bci && bci < method->code_size()) ||
 369          (method->is_compiled_lambda_form() && bci == -99) ||  // this might happen in C1
 370          bci == -1, "illegal bci");
 371 
 372   // serialize the locals/expressions/monitors
 373   stream()->write_int((intptr_t) locals);
 374   stream()->write_int((intptr_t) expressions);
 375   stream()->write_int((intptr_t) monitors);
 376 
 377   // Here's a tricky bit.  We just wrote some bytes.
 378   // Wouldn't it be nice to find that we had already
 379   // written those same bytes somewhere else?
 380   // If we get lucky this way, reset the stream
 381   // and reuse the old bytes.  By the way, this
 382   // trick not only shares parent scopes, but also
 383   // compresses equivalent non-safepoint PcDescs.
 384   int shared_stream_offset = find_sharable_decode_offset(stream_offset);
 385   if (shared_stream_offset != serialized_null) {
 386     stream()->set_position(stream_offset);
 387     last_pd->set_scope_decode_offset(shared_stream_offset);
 388   }
 389 }
 390 
 391 void DebugInformationRecorder::dump_object_pool(GrowableArray<ScopeValue*>* objects) {
 392   guarantee( _pcs_length > 0, "safepoint must exist before describing scopes");
 393   PcDesc* last_pd = &_pcs[_pcs_length-1];
 394   if (objects != NULL) {
 395     for (int i = objects->length() - 1; i >= 0; i--) {
 396       objects->at(i)->as_ObjectValue()->set_visited(false);
 397     }
 398   }
 399   int offset = serialize_scope_values(objects);
 400   last_pd->set_obj_decode_offset(offset);
 401 }
 402 
 403 void DebugInformationRecorder::end_scopes(int pc_offset, bool is_safepoint) {
 404   assert(_recording_state == (is_safepoint? rs_safepoint: rs_non_safepoint),
 405          "nesting of recording calls");
 406   debug_only(_recording_state = rs_null);
 407 
 408   // Try to compress away an equivalent non-safepoint predecessor.
 409   // (This only works because we have previously recognized redundant
 410   // scope trees and made them use a common scope_decode_offset.)
 411   if (_pcs_length >= 2 && recording_non_safepoints()) {
 412     PcDesc* last = last_pc();
 413     PcDesc* prev = prev_pc();
 414     // If prev is (a) not a safepoint and (b) has the same
 415     // stream pointer, then it can be coalesced into the last.
 416     // This is valid because non-safepoints are only sought
 417     // with pc_desc_near, which (when it misses prev) will
 418     // search forward until it finds last.
 419     // In addition, it does not matter if the last PcDesc
 420     // is for a safepoint or not.
 421     if (_prev_safepoint_pc < prev->pc_offset() && prev->is_same_info(last)) {
 422       assert(prev == last-1, "sane");
 423       prev->set_pc_offset(pc_offset);
 424       _pcs_length -= 1;
 425       NOT_PRODUCT(++dir_stats.chunks_elided);
 426     }
 427   }
 428 
 429   // We have just recorded this safepoint.
 430   // Remember it in case the previous paragraph needs to know.
 431   if (is_safepoint) {
 432     _prev_safepoint_pc = pc_offset;
 433   }
 434 }
 435 
 436 #ifdef ASSERT
 437 bool DebugInformationRecorder::recorders_frozen() {
 438   return _oop_recorder->is_complete() || _oop_recorder->is_complete();
 439 }
 440 
 441 void DebugInformationRecorder::mark_recorders_frozen() {
 442   _oop_recorder->freeze();
 443 }
 444 #endif // PRODUCT
 445 
 446 DebugToken* DebugInformationRecorder::create_scope_values(GrowableArray<ScopeValue*>* values) {
 447   assert(!recorders_frozen(), "not frozen yet");
 448   return (DebugToken*) (intptr_t) serialize_scope_values(values);
 449 }
 450 
 451 
 452 DebugToken* DebugInformationRecorder::create_monitor_values(GrowableArray<MonitorValue*>* monitors) {
 453   assert(!recorders_frozen(), "not frozen yet");
 454   return (DebugToken*) (intptr_t) serialize_monitor_values(monitors);
 455 }
 456 
 457 
 458 int DebugInformationRecorder::data_size() {
 459   debug_only(mark_recorders_frozen());  // mark it "frozen" for asserts
 460   return _stream->position();
 461 }
 462 
 463 
 464 int DebugInformationRecorder::pcs_size() {
 465   debug_only(mark_recorders_frozen());  // mark it "frozen" for asserts
 466   if (last_pc()->pc_offset() != PcDesc::upper_offset_limit)
 467     add_new_pc_offset(PcDesc::upper_offset_limit);
 468   return _pcs_length * sizeof(PcDesc);
 469 }
 470 
 471 
 472 void DebugInformationRecorder::copy_to(nmethod* nm) {
 473   nm->copy_scopes_data(stream()->buffer(), stream()->position());
 474   nm->copy_scopes_pcs(_pcs, _pcs_length);
 475 }
 476 
 477 
 478 void DebugInformationRecorder::verify(const nmethod* code) {
 479   Unimplemented();
 480 }
 481 
 482 #ifndef PRODUCT
 483 void DebugInformationRecorder::print_statistics() {
 484   dir_stats.print();
 485 }
 486 #endif //PRODUCT