1 /*
2 * Copyright (c) 1998, 2025, 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 "code/debugInfoRec.hpp"
26 #include "code/scopeDesc.hpp"
27 #include "compiler/oopMap.hpp"
28 #include "prims/jvmtiExport.hpp"
29 #include "runtime/globals_extension.hpp"
30
31 // Private definition.
32 // There is one DIR_Chunk for each scope and values array.
33 // A chunk can potentially be used more than once.
34 // We keep track of these chunks in order to detect
35 // repetition and enable sharing.
36 class DIR_Chunk {
37 private:
38 int _offset; // location in the stream of this scope
39 int _length; // number of bytes in the stream
40 int _hash; // hash of stream bytes (for quicker reuse)
41 DebugInformationRecorder* _DIR;
42
43 public:
44 int offset() { return _offset; }
45
46 void* operator new(size_t ignore, DebugInformationRecorder* dir) throw() {
47 assert(ignore == sizeof(DIR_Chunk), "");
48 if (dir->_next_chunk >= dir->_next_chunk_limit) {
49 const int CHUNK = 100;
50 dir->_next_chunk = NEW_RESOURCE_ARRAY(DIR_Chunk, CHUNK);
51 dir->_next_chunk_limit = dir->_next_chunk + CHUNK;
52 }
53 return dir->_next_chunk++;
54 }
55
56 DIR_Chunk(int offset, int length, DebugInformationRecorder* dir) {
57 _offset = offset;
58 _length = length;
59 _DIR = dir;
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 nullptr;
85 }
86
87 static int compare(DIR_Chunk* const & a, DIR_Chunk* const & b) {
88 if (b->_hash > a->_hash) {
89 return 1;
90 }
91 if (b->_hash < a->_hash) {
92 return -1;
93 }
94 if (b->_length > a->_length) {
95 return 1;
96 }
97 if (b->_length < a->_length) {
98 return -1;
99 }
100 address buf = a->_DIR->stream()->buffer();
101 return memcmp(buf + b->_offset, buf + a->_offset, a->_length);
102 }
103 };
104
105 static inline bool compute_recording_non_safepoints() {
106 if (JvmtiExport::should_post_compiled_method_load()
107 && FLAG_IS_DEFAULT(DebugNonSafepoints)) {
108 // The default value of this flag is taken to be true,
109 // if JVMTI is looking at nmethod codes.
110 // We anticipate that JVMTI may wish to participate in profiling.
111 return true;
112 }
113
114 // If the flag is set manually, use it, whether true or false.
115 // Otherwise, if JVMTI is not in the picture, use the default setting.
116 // (This is true in debug, just for the exercise, false in product mode.)
117 return DebugNonSafepoints;
118 }
119
120 DebugInformationRecorder::DebugInformationRecorder(OopRecorder* oop_recorder)
121 : _recording_non_safepoints(compute_recording_non_safepoints())
122 {
123 _pcs_size = 100;
124 _pcs = NEW_RESOURCE_ARRAY(PcDesc, _pcs_size);
125 _pcs_length = 0;
126
127 _prev_safepoint_pc = PcDesc::lower_offset_limit;
128
129 _stream = new DebugInfoWriteStream(this, 10 * K);
130 // make sure that there is no stream_decode_offset that is zero
131 _stream->write_byte((jbyte)0xFF);
132
133 // make sure that we can distinguish the value "serialized_null" from offsets
134 assert(_stream->position() > serialized_null, "sanity");
135
136 _oop_recorder = oop_recorder;
137
138 _all_chunks = new GrowableArray<DIR_Chunk*>(300);
139 _next_chunk = _next_chunk_limit = nullptr;
140
141 add_new_pc_offset(PcDesc::lower_offset_limit); // sentinel record
142
143 debug_only(_recording_state = rs_null);
144 }
145
146
147 void DebugInformationRecorder::add_oopmap(int pc_offset, OopMap* map) {
148 // !!!!! Preserve old style handling of oopmaps for now
149 _oopmaps->add_gc_map(pc_offset, map);
150 }
151
152 void DebugInformationRecorder::add_safepoint(int pc_offset, OopMap* map) {
153 assert(!_oop_recorder->is_complete(), "not frozen yet");
154 // Store the new safepoint
155
156 // Add the oop map
157 add_oopmap(pc_offset, map);
158
159 add_new_pc_offset(pc_offset);
160
161 assert(_recording_state == rs_null, "nesting of recording calls");
162 debug_only(_recording_state = rs_safepoint);
163 }
164
165 void DebugInformationRecorder::add_non_safepoint(int pc_offset) {
166 assert(!_oop_recorder->is_complete(), "not frozen yet");
167 assert(_recording_non_safepoints, "must be recording non-safepoints");
168
169 add_new_pc_offset(pc_offset);
170
171 assert(_recording_state == rs_null, "nesting of recording calls");
172 debug_only(_recording_state = rs_non_safepoint);
173 }
174
175 void DebugInformationRecorder::add_new_pc_offset(int pc_offset) {
176 assert(_pcs_length == 0 || last_pc()->pc_offset() < pc_offset,
177 "must specify a new, larger pc offset: %d >= %d", last_pc()->pc_offset(), pc_offset);
178
179 // add the pcdesc
180 if (_pcs_length == _pcs_size) {
181 // Expand
182 int new_pcs_size = _pcs_size * 2;
183 PcDesc* new_pcs = NEW_RESOURCE_ARRAY(PcDesc, new_pcs_size);
184 for (int index = 0; index < _pcs_length; index++) {
185 new_pcs[index] = _pcs[index];
186 }
187 _pcs_size = new_pcs_size;
188 _pcs = new_pcs;
189 }
190 assert(_pcs_size > _pcs_length, "There must be room for after expanding");
191
192 _pcs[_pcs_length++] = PcDesc(pc_offset, DebugInformationRecorder::serialized_null,
193 DebugInformationRecorder::serialized_null);
194 }
195
196
197 int DebugInformationRecorder::serialize_monitor_values(GrowableArray<MonitorValue*>* monitors) {
198 if (monitors == nullptr || monitors->is_empty()) return DebugInformationRecorder::serialized_null;
199 assert(_recording_state == rs_safepoint, "must be recording a safepoint");
200 int result = stream()->position();
201 stream()->write_int(monitors->length());
202 for (int index = 0; index < monitors->length(); index++) {
203 monitors->at(index)->write_on(stream());
204 }
205 assert(result != serialized_null, "sanity");
206
207 // (See comment below on DebugInformationRecorder::describe_scope.)
208 int shared_result = find_sharable_decode_offset(result);
209 if (shared_result != serialized_null) {
210 stream()->set_position(result);
211 result = shared_result;
212 }
213
214 return result;
215 }
216
217
218 int DebugInformationRecorder::serialize_scope_values(GrowableArray<ScopeValue*>* values) {
219 if (values == nullptr || values->is_empty()) return DebugInformationRecorder::serialized_null;
220 assert(_recording_state == rs_safepoint, "must be recording a safepoint");
221 int result = stream()->position();
222 assert(result != serialized_null, "sanity");
223 stream()->write_int(values->length());
224 for (int index = 0; index < values->length(); index++) {
225 values->at(index)->write_on(stream());
226 }
227
228 // (See comment below on DebugInformationRecorder::describe_scope.)
229 int shared_result = find_sharable_decode_offset(result);
230 if (shared_result != serialized_null) {
231 stream()->set_position(result);
232 result = shared_result;
233 }
234
235 return result;
236 }
237
238
239 #ifndef PRODUCT
240 // These variables are put into one block to reduce relocations
241 // and make it simpler to print from the debugger.
242 static
243 struct dir_stats_struct {
244 int chunks_queried;
245 int chunks_shared;
246 int chunks_elided;
247
248 void print() {
249 tty->print_cr("Debug Data Chunks: %d, shared %d, non-SP's elided %d",
250 chunks_queried, chunks_shared, chunks_elided);
251 }
252 } dir_stats;
253 #endif //PRODUCT
254
255
256 int DebugInformationRecorder::find_sharable_decode_offset(int stream_offset) {
257 NOT_PRODUCT(++dir_stats.chunks_queried);
258 int stream_length = stream()->position() - stream_offset;
259 assert(stream_offset != serialized_null, "should not be null");
260 assert(stream_length != 0, "should not be empty");
261
262 DIR_Chunk* ns = new(this) DIR_Chunk(stream_offset, stream_length, this);
263
264 DIR_Chunk* match = _all_chunks->insert_sorted<DIR_Chunk::compare>(ns);
265 if (match != ns) {
266 // Found an existing chunk
267 NOT_PRODUCT(++dir_stats.chunks_shared);
268 assert(ns+1 == _next_chunk, "");
269 _next_chunk = ns;
270 return match->offset();
271 } else {
272 // Inserted this chunk, so nothing to do
273 return serialized_null;
274 }
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 const methodHandle& methodH,
282 ciMethod* method,
283 int bci,
284 bool reexecute,
285 bool rethrow_exception,
286 bool is_method_handle_invoke,
287 bool return_oop,
288 bool has_ea_local_in_scope,
289 bool arg_escape,
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 last_pd->set_has_ea_local_in_scope(has_ea_local_in_scope);
307 last_pd->set_arg_escape(arg_escape);
308
309 // serialize sender stream offset
310 stream()->write_int(sender_stream_offset);
311
312 // serialize scope
313 Metadata* method_enc;
314 if (method != nullptr) {
315 method_enc = method->constant_encoding();
316 } else if (methodH.not_null()) {
317 method_enc = methodH();
318 } else {
319 method_enc = nullptr;
320 }
321 int method_enc_index = oop_recorder()->find_index(method_enc);
322 stream()->write_int(method_enc_index);
323 stream()->write_bci(bci);
324 assert(method == nullptr ||
325 (method->is_native() && bci == 0) ||
326 (!method->is_native() && 0 <= bci && bci < method->code_size()) ||
327 bci == -1, "illegal bci");
328
329 // serialize the locals/expressions/monitors
330 stream()->write_int((intptr_t) locals);
331 stream()->write_int((intptr_t) expressions);
332 stream()->write_int((intptr_t) monitors);
333
334 // Here's a tricky bit. We just wrote some bytes.
335 // Wouldn't it be nice to find that we had already
336 // written those same bytes somewhere else?
337 // If we get lucky this way, reset the stream
338 // and reuse the old bytes. By the way, this
339 // trick not only shares parent scopes, but also
340 // compresses equivalent non-safepoint PcDescs.
341 int shared_stream_offset = find_sharable_decode_offset(stream_offset);
342 if (shared_stream_offset != serialized_null) {
343 stream()->set_position(stream_offset);
344 last_pd->set_scope_decode_offset(shared_stream_offset);
345 }
346 }
347
348 void DebugInformationRecorder::dump_object_pool(GrowableArray<ScopeValue*>* objects) {
349 guarantee( _pcs_length > 0, "safepoint must exist before describing scopes");
350 PcDesc* last_pd = &_pcs[_pcs_length-1];
351 if (objects != nullptr) {
352 for (int i = objects->length() - 1; i >= 0; i--) {
353 objects->at(i)->as_ObjectValue()->set_visited(false);
354 }
355 }
356 int offset = serialize_scope_values(objects);
357 last_pd->set_obj_decode_offset(offset);
358 }
359
360 void DebugInformationRecorder::end_scopes(int pc_offset, bool is_safepoint) {
361 assert(_recording_state == (is_safepoint? rs_safepoint: rs_non_safepoint),
362 "nesting of recording calls");
363 debug_only(_recording_state = rs_null);
364
365 // Try to compress away an equivalent non-safepoint predecessor.
366 // (This only works because we have previously recognized redundant
367 // scope trees and made them use a common scope_decode_offset.)
368 if (_pcs_length >= 2 && recording_non_safepoints()) {
369 PcDesc* last = last_pc();
370 PcDesc* prev = prev_pc();
371 // If prev is (a) not a safepoint and (b) has the same
372 // stream pointer, then it can be coalesced into the last.
373 // This is valid because non-safepoints are only sought
374 // with pc_desc_near, which (when it misses prev) will
375 // search forward until it finds last.
376 // In addition, it does not matter if the last PcDesc
377 // is for a safepoint or not.
378 if (_prev_safepoint_pc < prev->pc_offset() && prev->is_same_info(last)) {
379 assert(prev == last-1, "sane");
380 prev->set_pc_offset(pc_offset);
381 _pcs_length -= 1;
382 NOT_PRODUCT(++dir_stats.chunks_elided);
383 }
384 }
385
386 // We have just recorded this safepoint.
387 // Remember it in case the previous paragraph needs to know.
388 if (is_safepoint) {
389 _prev_safepoint_pc = pc_offset;
390 }
391 }
392
393 #ifdef ASSERT
394 bool DebugInformationRecorder::recorders_frozen() {
395 return _oop_recorder->is_complete();
396 }
397
398 void DebugInformationRecorder::mark_recorders_frozen() {
399 _oop_recorder->freeze();
400 }
401 #endif // PRODUCT
402
403 DebugToken* DebugInformationRecorder::create_scope_values(GrowableArray<ScopeValue*>* values) {
404 assert(!recorders_frozen(), "not frozen yet");
405 return (DebugToken*) (intptr_t) serialize_scope_values(values);
406 }
407
408
409 DebugToken* DebugInformationRecorder::create_monitor_values(GrowableArray<MonitorValue*>* monitors) {
410 assert(!recorders_frozen(), "not frozen yet");
411 return (DebugToken*) (intptr_t) serialize_monitor_values(monitors);
412 }
413
414
415 int DebugInformationRecorder::data_size() {
416 debug_only(mark_recorders_frozen()); // mark it "frozen" for asserts
417 return _stream->position();
418 }
419
420
421 int DebugInformationRecorder::pcs_size() {
422 debug_only(mark_recorders_frozen()); // mark it "frozen" for asserts
423 if (last_pc()->pc_offset() != PcDesc::upper_offset_limit)
424 add_new_pc_offset(PcDesc::upper_offset_limit);
425 return _pcs_length * sizeof(PcDesc);
426 }
427
428
429 void DebugInformationRecorder::copy_to(nmethod* nm) {
430 nm->copy_scopes_data(stream()->buffer(), stream()->position());
431 nm->copy_scopes_pcs(_pcs, _pcs_length);
432 }
433
434
435 void DebugInformationRecorder::verify(const nmethod* code) {
436 Unimplemented();
437 }
438
439 #ifndef PRODUCT
440 void DebugInformationRecorder::print_statistics() {
441 dir_stats.print();
442 }
443 #endif //PRODUCT