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