263     NOT_PRODUCT(++dir_stats.chunks_shared);
 264     // Searching in _all_chunks is limited to a window,
 265     // but searching in _shared_chunks is unlimited.
 266     _shared_chunks->append(ms);
 267     assert(ns+1 == _next_chunk, "");
 268     _next_chunk = ns;
 269     return ms->_offset;
 270   }
 271 
 272   // No match.  Add this guy to the list, in hopes of future shares.
 273   _all_chunks->append(ns);
 274   return serialized_null;
 275 }
 276 
 277 
 278 // must call add_safepoint before: it sets PcDesc and this routine uses
 279 // the last PcDesc set
 280 void DebugInformationRecorder::describe_scope(int         pc_offset,
 281                                               ciMethod*   method,
 282                                               int         bci,

 283                                               DebugToken* locals,
 284                                               DebugToken* expressions,
 285                                               DebugToken* monitors) {
 286   assert(_recording_state != rs_null, "nesting of recording calls");
 287   PcDesc* last_pd = last_pc();
 288   assert(last_pd->pc_offset() == pc_offset, "must be last pc");
 289   int sender_stream_offset = last_pd->scope_decode_offset();
 290   // update the stream offset of current pc desc
 291   int stream_offset = stream()->position();
 292   last_pd->set_scope_decode_offset(stream_offset);
 293 
 294   // serialize sender stream offest
 295   stream()->write_int(sender_stream_offset);
 296 
 297   // serialize scope
 298   jobject method_enc = (method == NULL)? NULL: method->encoding();
 299   stream()->write_int(oop_recorder()->find_index(method_enc));
 300   stream()->write_bci(bci);
 301   assert(method == NULL ||
 302          (method->is_native() && bci == 0) ||
 303          (!method->is_native() && 0 <= bci && bci < method->code_size()) ||
 304          bci == -1, "illegal bci");
 305 
 306   // serialize the locals/expressions/monitors
 307   stream()->write_int((intptr_t) locals);
 308   stream()->write_int((intptr_t) expressions);
 309   stream()->write_int((intptr_t) monitors);
 310 
 311   // Here's a tricky bit.  We just wrote some bytes.
 312   // Wouldn't it be nice to find that we had already
 313   // written those same bytes somewhere else?
 314   // If we get lucky this way, reset the stream
 315   // and reuse the old bytes.  By the way, this
 316   // trick not only shares parent scopes, but also
 317   // compresses equivalent non-safepoint PcDescs.
 318   int shared_stream_offset = find_sharable_decode_offset(stream_offset);
 319   if (shared_stream_offset != serialized_null) {
 320     stream()->set_position(stream_offset);

 263     NOT_PRODUCT(++dir_stats.chunks_shared);
 264     // Searching in _all_chunks is limited to a window,
 265     // but searching in _shared_chunks is unlimited.
 266     _shared_chunks->append(ms);
 267     assert(ns+1 == _next_chunk, "");
 268     _next_chunk = ns;
 269     return ms->_offset;
 270   }
 271 
 272   // No match.  Add this guy to the list, in hopes of future shares.
 273   _all_chunks->append(ns);
 274   return serialized_null;
 275 }
 276 
 277 
 278 // must call add_safepoint before: it sets PcDesc and this routine uses
 279 // the last PcDesc set
 280 void DebugInformationRecorder::describe_scope(int         pc_offset,
 281                                               ciMethod*   method,
 282                                               int         bci,
 283                                               bool        reexecute,
 284                                               DebugToken* locals,
 285                                               DebugToken* expressions,
 286                                               DebugToken* monitors) {
 287   assert(_recording_state != rs_null, "nesting of recording calls");
 288   PcDesc* last_pd = last_pc();
 289   assert(last_pd->pc_offset() == pc_offset, "must be last pc");
 290   int sender_stream_offset = last_pd->scope_decode_offset();
 291   // update the stream offset of current pc desc
 292   int stream_offset = stream()->position();
 293   last_pd->set_scope_decode_offset(stream_offset);
 294 
 295   // serialize sender stream offest
 296   stream()->write_int(sender_stream_offset);
 297 
 298   // serialize scope
 299   jobject method_enc = (method == NULL)? NULL: method->encoding();
 300   stream()->write_int(oop_recorder()->find_index(method_enc));
 301   stream()->write_bci_and_reexecute(bci, reexecute);
 302   assert(method == NULL ||
 303          (method->is_native() && bci == 0) ||
 304          (!method->is_native() && 0 <= bci && bci < method->code_size()) ||
 305          bci == -1, "illegal bci");
 306 
 307   // serialize the locals/expressions/monitors
 308   stream()->write_int((intptr_t) locals);
 309   stream()->write_int((intptr_t) expressions);
 310   stream()->write_int((intptr_t) monitors);
 311 
 312   // Here's a tricky bit.  We just wrote some bytes.
 313   // Wouldn't it be nice to find that we had already
 314   // written those same bytes somewhere else?
 315   // If we get lucky this way, reset the stream
 316   // and reuse the old bytes.  By the way, this
 317   // trick not only shares parent scopes, but also
 318   // compresses equivalent non-safepoint PcDescs.
 319   int shared_stream_offset = find_sharable_decode_offset(stream_offset);
 320   if (shared_stream_offset != serialized_null) {
 321     stream()->set_position(stream_offset);