1 /*
   2  * Copyright (c) 1998, 2013, 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) throw() {
  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   Metadata* 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          (method->is_compiled_lambda_form() && bci == -99) ||  // this might happen in C1
 315          bci == -1, "illegal bci");
 316 
 317   // serialize the locals/expressions/monitors
 318   stream()->write_int((intptr_t) locals);
 319   stream()->write_int((intptr_t) expressions);
 320   stream()->write_int((intptr_t) monitors);
 321 
 322   // Here's a tricky bit.  We just wrote some bytes.
 323   // Wouldn't it be nice to find that we had already
 324   // written those same bytes somewhere else?
 325   // If we get lucky this way, reset the stream
 326   // and reuse the old bytes.  By the way, this
 327   // trick not only shares parent scopes, but also
 328   // compresses equivalent non-safepoint PcDescs.
 329   int shared_stream_offset = find_sharable_decode_offset(stream_offset);
 330   if (shared_stream_offset != serialized_null) {
 331     stream()->set_position(stream_offset);
 332     last_pd->set_scope_decode_offset(shared_stream_offset);
 333   }
 334 }
 335 
 336 void DebugInformationRecorder::dump_object_pool(GrowableArray<ScopeValue*>* objects) {
 337   guarantee( _pcs_length > 0, "safepoint must exist before describing scopes");
 338   PcDesc* last_pd = &_pcs[_pcs_length-1];
 339   if (objects != NULL) {
 340     for (int i = objects->length() - 1; i >= 0; i--) {
 341       ((ObjectValue*) objects->at(i))->set_visited(false);
 342     }
 343   }
 344   int offset = serialize_scope_values(objects);
 345   last_pd->set_obj_decode_offset(offset);
 346 }
 347 
 348 void DebugInformationRecorder::end_scopes(int pc_offset, bool is_safepoint) {
 349   assert(_recording_state == (is_safepoint? rs_safepoint: rs_non_safepoint),
 350          "nesting of recording calls");
 351   debug_only(_recording_state = rs_null);
 352 
 353   // Try to compress away an equivalent non-safepoint predecessor.
 354   // (This only works because we have previously recognized redundant
 355   // scope trees and made them use a common scope_decode_offset.)
 356   if (_pcs_length >= 2 && recording_non_safepoints()) {
 357     PcDesc* last = last_pc();
 358     PcDesc* prev = prev_pc();
 359     // If prev is (a) not a safepoint and (b) has the same
 360     // stream pointer, then it can be coalesced into the last.
 361     // This is valid because non-safepoints are only sought
 362     // with pc_desc_near, which (when it misses prev) will
 363     // search forward until it finds last.
 364     // In addition, it does not matter if the last PcDesc
 365     // is for a safepoint or not.
 366     if (_prev_safepoint_pc < prev->pc_offset() && prev->is_same_info(last)) {
 367       assert(prev == last-1, "sane");
 368       prev->set_pc_offset(pc_offset);
 369       _pcs_length -= 1;
 370       NOT_PRODUCT(++dir_stats.chunks_elided);
 371     }
 372   }
 373 
 374   // We have just recorded this safepoint.
 375   // Remember it in case the previous paragraph needs to know.
 376   if (is_safepoint) {
 377     _prev_safepoint_pc = pc_offset;
 378   }
 379 }
 380 
 381 #ifdef ASSERT
 382 bool DebugInformationRecorder::recorders_frozen() {
 383   return _oop_recorder->is_complete() || _oop_recorder->is_complete();
 384 }
 385 
 386 void DebugInformationRecorder::mark_recorders_frozen() {
 387   _oop_recorder->freeze();
 388 }
 389 #endif // PRODUCT
 390 
 391 DebugToken* DebugInformationRecorder::create_scope_values(GrowableArray<ScopeValue*>* values) {
 392   assert(!recorders_frozen(), "not frozen yet");
 393   return (DebugToken*) (intptr_t) serialize_scope_values(values);
 394 }
 395 
 396 
 397 DebugToken* DebugInformationRecorder::create_monitor_values(GrowableArray<MonitorValue*>* monitors) {
 398   assert(!recorders_frozen(), "not frozen yet");
 399   return (DebugToken*) (intptr_t) serialize_monitor_values(monitors);
 400 }
 401 
 402 
 403 int DebugInformationRecorder::data_size() {
 404   debug_only(mark_recorders_frozen());  // mark it "frozen" for asserts
 405   return _stream->position();
 406 }
 407 
 408 
 409 int DebugInformationRecorder::pcs_size() {
 410   debug_only(mark_recorders_frozen());  // mark it "frozen" for asserts
 411   if (last_pc()->pc_offset() != PcDesc::upper_offset_limit)
 412     add_new_pc_offset(PcDesc::upper_offset_limit);
 413   return _pcs_length * sizeof(PcDesc);
 414 }
 415 
 416 
 417 void DebugInformationRecorder::copy_to(nmethod* nm) {
 418   nm->copy_scopes_data(stream()->buffer(), stream()->position());
 419   nm->copy_scopes_pcs(_pcs, _pcs_length);
 420 }
 421 
 422 
 423 void DebugInformationRecorder::verify(const nmethod* code) {
 424   Unimplemented();
 425 }
 426 
 427 #ifndef PRODUCT
 428 void DebugInformationRecorder::print_statistics() {
 429   dir_stats.print();
 430 }
 431 #endif //PRODUCT