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 private:
  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 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 #if INCLUDE_JVMCI
  61     _DIR = dir;
  62 #endif
  63     unsigned int hash = 0;
  64     address p = dir->stream()->buffer() + _offset;
  65     for (int i = 0; i < length; i++) {
  66       if (i == 6)  break;
  67       hash *= 127;
  68       hash += p[i];
  69     }
  70     _hash = hash;
  71   }
  72 
  73   DIR_Chunk* find_match(GrowableArray<DIR_Chunk*>* arr,
  74                         int start_index,
  75                         DebugInformationRecorder* dir) {
  76     int end_index = arr->length();
  77     int hash = this->_hash, length = this->_length;
  78     address buf = dir->stream()->buffer();
  79     for (int i = end_index; --i >= start_index; ) {
  80       DIR_Chunk* that = arr->at(i);
  81       if (hash   == that->_hash &&
  82           length == that->_length &&
  83           0 == memcmp(buf + this->_offset, buf + that->_offset, length)) {
  84         return that;
  85       }
  86     }
  87     return NULL;
  88   }
  89 
  90 #if INCLUDE_JVMCI
  91   static int compare(DIR_Chunk* const & a, DIR_Chunk* const & b) {
  92     if (b->_hash > a->_hash) {
  93       return 1;
  94     }
  95     if (b->_hash < a->_hash) {
  96       return -1;
  97     }
  98     if (b->_length > a->_length) {
  99       return 1;
 100     }
 101     if (b->_length < a->_length) {
 102       return -1;
 103     }
 104     address buf = a->_DIR->stream()->buffer();
 105     return memcmp(buf + b->_offset, buf + a->_offset, a->_length);
 106   }
 107 #endif
 108 };
 109 
 110 static inline bool compute_recording_non_safepoints() {
 111   if (JvmtiExport::should_post_compiled_method_load()
 112       && FLAG_IS_DEFAULT(DebugNonSafepoints)) {
 113     // The default value of this flag is taken to be true,
 114     // if JVMTI is looking at nmethod codes.
 115     // We anticipate that JVMTI may wish to participate in profiling.
 116     return true;
 117   }
 118 
 119   // If the flag is set manually, use it, whether true or false.
 120   // Otherwise, if JVMTI is not in the picture, use the default setting.
 121   // (This is true in debug, just for the exercise, false in product mode.)
 122   return DebugNonSafepoints;
 123 }
 124 
 125 DebugInformationRecorder::DebugInformationRecorder(OopRecorder* oop_recorder)
 126   : _recording_non_safepoints(compute_recording_non_safepoints())
 127 {
 128   _pcs_size   = 100;
 129   _pcs        = NEW_RESOURCE_ARRAY(PcDesc, _pcs_size);
 130   _pcs_length = 0;
 131 
 132   _prev_safepoint_pc = PcDesc::lower_offset_limit;
 133 
 134   _stream = new DebugInfoWriteStream(this, 10 * K);
 135   // make sure that there is no stream_decode_offset that is zero
 136   _stream->write_byte((jbyte)0xFF);
 137 
 138   // make sure that we can distinguish the value "serialized_null" from offsets
 139   assert(_stream->position() > serialized_null, "sanity");
 140 
 141   _oop_recorder = oop_recorder;
 142 
 143   _all_chunks    = new GrowableArray<DIR_Chunk*>(300);
 144 #if !INCLUDE_JVMCI
 145   _shared_chunks = new GrowableArray<DIR_Chunk*>(30);
 146 #endif
 147   _next_chunk = _next_chunk_limit = NULL;
 148 
 149   add_new_pc_offset(PcDesc::lower_offset_limit);  // sentinel record
 150 
 151   debug_only(_recording_state = rs_null);
 152 }
 153 
 154 
 155 void DebugInformationRecorder::add_oopmap(int pc_offset, OopMap* map) {
 156   // !!!!! Preserve old style handling of oopmaps for now
 157   _oopmaps->add_gc_map(pc_offset, map);
 158 }
 159 
 160 void DebugInformationRecorder::add_safepoint(int pc_offset, OopMap* map) {
 161   assert(!_oop_recorder->is_complete(), "not frozen yet");
 162   // Store the new safepoint
 163 
 164   // Add the oop map
 165   add_oopmap(pc_offset, map);
 166 
 167   add_new_pc_offset(pc_offset);
 168 
 169   assert(_recording_state == rs_null, "nesting of recording calls");
 170   debug_only(_recording_state = rs_safepoint);
 171 }
 172 
 173 void DebugInformationRecorder::add_non_safepoint(int pc_offset) {
 174   assert(!_oop_recorder->is_complete(), "not frozen yet");
 175   assert(_recording_non_safepoints, "must be recording non-safepoints");
 176 
 177   add_new_pc_offset(pc_offset);
 178 
 179   assert(_recording_state == rs_null, "nesting of recording calls");
 180   debug_only(_recording_state = rs_non_safepoint);
 181 }
 182 
 183 void DebugInformationRecorder::add_new_pc_offset(int pc_offset) {
 184   assert(_pcs_length == 0 || last_pc()->pc_offset() < pc_offset,
 185          "must specify a new, larger pc offset");
 186 
 187   // add the pcdesc
 188   if (_pcs_length == _pcs_size) {
 189     // Expand
 190     int     new_pcs_size = _pcs_size * 2;
 191     PcDesc* new_pcs      = NEW_RESOURCE_ARRAY(PcDesc, new_pcs_size);
 192     for (int index = 0; index < _pcs_length; index++) {
 193       new_pcs[index] = _pcs[index];
 194     }
 195     _pcs_size = new_pcs_size;
 196     _pcs      = new_pcs;
 197   }
 198   assert(_pcs_size > _pcs_length, "There must be room for after expanding");
 199 
 200   _pcs[_pcs_length++] = PcDesc(pc_offset, DebugInformationRecorder::serialized_null,
 201                                DebugInformationRecorder::serialized_null);
 202 }
 203 
 204 
 205 int DebugInformationRecorder::serialize_monitor_values(GrowableArray<MonitorValue*>* monitors) {
 206   if (monitors == NULL || monitors->is_empty()) return DebugInformationRecorder::serialized_null;
 207   assert(_recording_state == rs_safepoint, "must be recording a safepoint");
 208   int result = stream()->position();
 209   stream()->write_int(monitors->length());
 210   for (int index = 0; index < monitors->length(); index++) {
 211     monitors->at(index)->write_on(stream());
 212   }
 213   assert(result != serialized_null, "sanity");
 214 
 215   // (See comment below on DebugInformationRecorder::describe_scope.)
 216   int shared_result = find_sharable_decode_offset(result);
 217   if (shared_result != serialized_null) {
 218     stream()->set_position(result);
 219     result = shared_result;
 220   }
 221 
 222   return result;
 223 }
 224 
 225 
 226 int DebugInformationRecorder::serialize_scope_values(GrowableArray<ScopeValue*>* values) {
 227   if (values == NULL || values->is_empty()) return DebugInformationRecorder::serialized_null;
 228   assert(_recording_state == rs_safepoint, "must be recording a safepoint");
 229   int result = stream()->position();
 230   assert(result != serialized_null, "sanity");
 231   stream()->write_int(values->length());
 232   for (int index = 0; index < values->length(); index++) {
 233     values->at(index)->write_on(stream());
 234   }
 235 
 236   // (See comment below on DebugInformationRecorder::describe_scope.)
 237   int shared_result = find_sharable_decode_offset(result);
 238   if (shared_result != serialized_null) {
 239     stream()->set_position(result);
 240     result = shared_result;
 241   }
 242 
 243   return result;
 244 }
 245 
 246 
 247 #ifndef PRODUCT
 248 // These variables are put into one block to reduce relocations
 249 // and make it simpler to print from the debugger.
 250 static
 251 struct dir_stats_struct {
 252   int chunks_queried;
 253   int chunks_shared;
 254   int chunks_reshared;
 255   int chunks_elided;
 256 
 257   void print() {
 258     tty->print_cr("Debug Data Chunks: %d, shared %d+%d, non-SP's elided %d",
 259                   chunks_queried,
 260                   chunks_shared, chunks_reshared,
 261                   chunks_elided);
 262   }
 263 } dir_stats;
 264 #endif //PRODUCT
 265 
 266 
 267 int DebugInformationRecorder::find_sharable_decode_offset(int stream_offset) {
 268 #if !INCLUDE_JVMCI
 269   // Only pull this trick if non-safepoint recording
 270   // is enabled, for now.
 271   if (!recording_non_safepoints()) {
 272     return serialized_null;
 273   }
 274 #endif // INCLUDE_JVMCI
 275 
 276   NOT_PRODUCT(++dir_stats.chunks_queried);
 277   int stream_length = stream()->position() - stream_offset;
 278   assert(stream_offset != serialized_null, "should not be null");
 279   assert(stream_length != 0, "should not be empty");
 280 
 281   DIR_Chunk* ns = new(this) DIR_Chunk(stream_offset, stream_length, this);
 282 
 283 #if INCLUDE_JVMCI
 284   DIR_Chunk* match = _all_chunks->insert_sorted<DIR_Chunk::compare>(ns);
 285   if (match != ns) {
 286     // Found an existing chunk
 287     NOT_PRODUCT(++dir_stats.chunks_shared);
 288     assert(ns+1 == _next_chunk, "");
 289     _next_chunk = ns;
 290     return match->offset();
 291   } else {
 292     // Inserted this chunk, so nothing to do
 293     return serialized_null;
 294   }
 295 #else // INCLUDE_JVMCI
 296   // Look in previously shared scopes first:
 297   DIR_Chunk* ms = ns->find_match(_shared_chunks, 0, this);
 298   if (ms != NULL) {
 299     NOT_PRODUCT(++dir_stats.chunks_reshared);
 300     assert(ns+1 == _next_chunk, "");
 301     _next_chunk = ns;
 302     return ms->offset();
 303   }
 304 
 305   // Look in recently encountered scopes next:
 306   const int MAX_RECENT = 50;
 307   int start_index = _all_chunks->length() - MAX_RECENT;
 308   if (start_index < 0)  start_index = 0;
 309   ms = ns->find_match(_all_chunks, start_index, this);
 310   if (ms != NULL) {
 311     NOT_PRODUCT(++dir_stats.chunks_shared);
 312     // Searching in _all_chunks is limited to a window,
 313     // but searching in _shared_chunks is unlimited.
 314     _shared_chunks->append(ms);
 315     assert(ns+1 == _next_chunk, "");
 316     _next_chunk = ns;
 317     return ms->offset();
 318   }
 319 
 320   // No match.  Add this guy to the list, in hopes of future shares.
 321   _all_chunks->append(ns);
 322   return serialized_null;
 323 #endif // INCLUDE_JVMCI
 324 }
 325 
 326 
 327 // must call add_safepoint before: it sets PcDesc and this routine uses
 328 // the last PcDesc set
 329 void DebugInformationRecorder::describe_scope(int         pc_offset,
 330                                               const methodHandle& methodH,
 331                                               ciMethod*   method,
 332                                               int         bci,
 333                                               bool        reexecute,
 334                                               bool        rethrow_exception,
 335                                               bool        is_method_handle_invoke,
 336                                               bool        return_oop,
 337                                               DebugToken* locals,
 338                                               DebugToken* expressions,
 339                                               DebugToken* monitors) {
 340   assert(_recording_state != rs_null, "nesting of recording calls");
 341   PcDesc* last_pd = last_pc();
 342   assert(last_pd->pc_offset() == pc_offset, "must be last pc");
 343   int sender_stream_offset = last_pd->scope_decode_offset();
 344   // update the stream offset of current pc desc
 345   int stream_offset = stream()->position();
 346   last_pd->set_scope_decode_offset(stream_offset);
 347 
 348   // Record flags into pcDesc.
 349   last_pd->set_should_reexecute(reexecute);
 350   last_pd->set_rethrow_exception(rethrow_exception);
 351   last_pd->set_is_method_handle_invoke(is_method_handle_invoke);
 352   last_pd->set_return_oop(return_oop);
 353 
 354   // serialize sender stream offest
 355   stream()->write_int(sender_stream_offset);
 356 
 357   // serialize scope
 358   Metadata* method_enc;
 359   if (method != NULL) {
 360     method_enc = method->constant_encoding();
 361   } else if (methodH.not_null()) {
 362     method_enc = methodH();
 363   } else {
 364     method_enc = NULL;
 365   }
 366   int method_enc_index = oop_recorder()->find_index(method_enc);
 367   stream()->write_int(method_enc_index);
 368   stream()->write_bci(bci);
 369   assert(method == NULL ||
 370          (method->is_native() && bci == 0) ||
 371          (!method->is_native() && 0 <= bci && bci < method->code_size()) ||
 372          (method->is_compiled_lambda_form() && bci == -99) ||  // this might happen in C1
 373          bci == -1, "illegal bci");
 374 
 375   // serialize the locals/expressions/monitors
 376   stream()->write_int((intptr_t) locals);
 377   stream()->write_int((intptr_t) expressions);
 378   stream()->write_int((intptr_t) monitors);
 379 
 380   // Here's a tricky bit.  We just wrote some bytes.
 381   // Wouldn't it be nice to find that we had already
 382   // written those same bytes somewhere else?
 383   // If we get lucky this way, reset the stream
 384   // and reuse the old bytes.  By the way, this
 385   // trick not only shares parent scopes, but also
 386   // compresses equivalent non-safepoint PcDescs.
 387   int shared_stream_offset = find_sharable_decode_offset(stream_offset);
 388   if (shared_stream_offset != serialized_null) {
 389     stream()->set_position(stream_offset);
 390     last_pd->set_scope_decode_offset(shared_stream_offset);
 391   }
 392 }
 393 
 394 void DebugInformationRecorder::dump_object_pool(GrowableArray<ScopeValue*>* objects) {
 395   guarantee( _pcs_length > 0, "safepoint must exist before describing scopes");
 396   PcDesc* last_pd = &_pcs[_pcs_length-1];
 397   if (objects != NULL) {
 398     for (int i = objects->length() - 1; i >= 0; i--) {
 399       objects->at(i)->as_ObjectValue()->set_visited(false);
 400     }
 401   }
 402   int offset = serialize_scope_values(objects);
 403   last_pd->set_obj_decode_offset(offset);
 404 }
 405 
 406 void DebugInformationRecorder::end_scopes(int pc_offset, bool is_safepoint) {
 407   assert(_recording_state == (is_safepoint? rs_safepoint: rs_non_safepoint),
 408          "nesting of recording calls");
 409   debug_only(_recording_state = rs_null);
 410 
 411   // Try to compress away an equivalent non-safepoint predecessor.
 412   // (This only works because we have previously recognized redundant
 413   // scope trees and made them use a common scope_decode_offset.)
 414   if (_pcs_length >= 2 && recording_non_safepoints()) {
 415     PcDesc* last = last_pc();
 416     PcDesc* prev = prev_pc();
 417     // If prev is (a) not a safepoint and (b) has the same
 418     // stream pointer, then it can be coalesced into the last.
 419     // This is valid because non-safepoints are only sought
 420     // with pc_desc_near, which (when it misses prev) will
 421     // search forward until it finds last.
 422     // In addition, it does not matter if the last PcDesc
 423     // is for a safepoint or not.
 424     if (_prev_safepoint_pc < prev->pc_offset() && prev->is_same_info(last)) {
 425       assert(prev == last-1, "sane");
 426       prev->set_pc_offset(pc_offset);
 427       _pcs_length -= 1;
 428       NOT_PRODUCT(++dir_stats.chunks_elided);
 429     }
 430   }
 431 
 432   // We have just recorded this safepoint.
 433   // Remember it in case the previous paragraph needs to know.
 434   if (is_safepoint) {
 435     _prev_safepoint_pc = pc_offset;
 436   }
 437 }
 438 
 439 #ifdef ASSERT
 440 bool DebugInformationRecorder::recorders_frozen() {
 441   return _oop_recorder->is_complete() || _oop_recorder->is_complete();
 442 }
 443 
 444 void DebugInformationRecorder::mark_recorders_frozen() {
 445   _oop_recorder->freeze();
 446 }
 447 #endif // PRODUCT
 448 
 449 DebugToken* DebugInformationRecorder::create_scope_values(GrowableArray<ScopeValue*>* values) {
 450   assert(!recorders_frozen(), "not frozen yet");
 451   return (DebugToken*) (intptr_t) serialize_scope_values(values);
 452 }
 453 
 454 
 455 DebugToken* DebugInformationRecorder::create_monitor_values(GrowableArray<MonitorValue*>* monitors) {
 456   assert(!recorders_frozen(), "not frozen yet");
 457   return (DebugToken*) (intptr_t) serialize_monitor_values(monitors);
 458 }
 459 
 460 
 461 int DebugInformationRecorder::data_size() {
 462   debug_only(mark_recorders_frozen());  // mark it "frozen" for asserts
 463   return _stream->position();
 464 }
 465 
 466 
 467 int DebugInformationRecorder::pcs_size() {
 468   debug_only(mark_recorders_frozen());  // mark it "frozen" for asserts
 469   if (last_pc()->pc_offset() != PcDesc::upper_offset_limit)
 470     add_new_pc_offset(PcDesc::upper_offset_limit);
 471   return _pcs_length * sizeof(PcDesc);
 472 }
 473 
 474 
 475 void DebugInformationRecorder::copy_to(nmethod* nm) {
 476   nm->copy_scopes_data(stream()->buffer(), stream()->position());
 477   nm->copy_scopes_pcs(_pcs, _pcs_length);
 478 }
 479 
 480 
 481 void DebugInformationRecorder::verify(const nmethod* code) {
 482   Unimplemented();
 483 }
 484 
 485 #ifndef PRODUCT
 486 void DebugInformationRecorder::print_statistics() {
 487   dir_stats.print();
 488 }
 489 #endif //PRODUCT