1 /*
2 * Copyright (c) 1998, 2024, 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 "compiler/oopMap.hpp"
29 #include "prims/jvmtiExport.hpp"
30 #include "runtime/globals_extension.hpp"
31
32 // Private definition.
33 // There is one DIR_Chunk for each scope and values array.
34 // A chunk can potentially be used more than once.
35 // We keep track of these chunks in order to detect
36 // repetition and enable sharing.
37 class DIR_Chunk {
38 private:
39 int _offset; // location in the stream of this scope
40 int _length; // number of bytes in the stream
41 int _hash; // hash of stream bytes (for quicker reuse)
42 DebugInformationRecorder* _DIR;
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 _DIR = dir;
61 unsigned int hash = 0;
62 address p = dir->stream()->buffer() + _offset;
63 for (int i = 0; i < length; i++) {
64 if (i == 6) break;
65 hash *= 127;
66 hash += p[i];
67 }
68 _hash = hash;
69 }
70
71 DIR_Chunk* find_match(GrowableArray<DIR_Chunk*>* arr,
72 int start_index,
73 DebugInformationRecorder* dir) {
74 int end_index = arr->length();
75 int hash = this->_hash, length = this->_length;
76 address buf = dir->stream()->buffer();
77 for (int i = end_index; --i >= start_index; ) {
78 DIR_Chunk* that = arr->at(i);
79 if (hash == that->_hash &&
80 length == that->_length &&
81 0 == memcmp(buf + this->_offset, buf + that->_offset, length)) {
82 return that;
83 }
84 }
85 return nullptr;
86 }
87
88 static int compare(DIR_Chunk* const & a, DIR_Chunk* const & b) {
89 if (b->_hash > a->_hash) {
90 return 1;
91 }
92 if (b->_hash < a->_hash) {
93 return -1;
94 }
95 if (b->_length > a->_length) {
96 return 1;
97 }
98 if (b->_length < a->_length) {
99 return -1;
100 }
101 address buf = a->_DIR->stream()->buffer();
102 return memcmp(buf + b->_offset, buf + a->_offset, a->_length);
103 }
104 };
105
106 static inline bool compute_recording_non_safepoints() {
107 if (JvmtiExport::should_post_compiled_method_load()
108 && FLAG_IS_DEFAULT(DebugNonSafepoints)) {
109 // The default value of this flag is taken to be true,
110 // if JVMTI is looking at nmethod codes.
111 // We anticipate that JVMTI may wish to participate in profiling.
112 return true;
113 }
114
115 // If the flag is set manually, use it, whether true or false.
116 // Otherwise, if JVMTI is not in the picture, use the default setting.
117 // (This is true in debug, just for the exercise, false in product mode.)
118 return DebugNonSafepoints;
119 }
120
121 DebugInformationRecorder::DebugInformationRecorder(OopRecorder* oop_recorder)
122 : _recording_non_safepoints(compute_recording_non_safepoints())
123 {
124 _pcs_size = 100;
125 _pcs = NEW_RESOURCE_ARRAY(PcDesc, _pcs_size);
126 _pcs_length = 0;
127
128 _prev_safepoint_pc = PcDesc::lower_offset_limit;
129
130 _stream = new DebugInfoWriteStream(this, 10 * K);
131 // make sure that there is no stream_decode_offset that is zero
132 _stream->write_byte((jbyte)0xFF);
133
134 // make sure that we can distinguish the value "serialized_null" from offsets
135 assert(_stream->position() > serialized_null, "sanity");
136
137 _oop_recorder = oop_recorder;
138
139 _all_chunks = new GrowableArray<DIR_Chunk*>(300);
140 _next_chunk = _next_chunk_limit = nullptr;
141
142 add_new_pc_offset(PcDesc::lower_offset_limit); // sentinel record
143
144 debug_only(_recording_state = rs_null);
145 }
146
147
148 void DebugInformationRecorder::add_oopmap(int pc_offset, OopMap* map) {
149 // !!!!! Preserve old style handling of oopmaps for now
150 _oopmaps->add_gc_map(pc_offset, map);
151 }
152
153 void DebugInformationRecorder::add_safepoint(int pc_offset, OopMap* map) {
154 assert(!_oop_recorder->is_complete(), "not frozen yet");
155 // Store the new safepoint
156
157 // Add the oop map
158 add_oopmap(pc_offset, map);
159
160 add_new_pc_offset(pc_offset);
161
162 assert(_recording_state == rs_null, "nesting of recording calls");
163 debug_only(_recording_state = rs_safepoint);
164 }
165
166 void DebugInformationRecorder::add_non_safepoint(int pc_offset) {
167 assert(!_oop_recorder->is_complete(), "not frozen yet");
168 assert(_recording_non_safepoints, "must be recording non-safepoints");
169
170 add_new_pc_offset(pc_offset);
171
172 assert(_recording_state == rs_null, "nesting of recording calls");
173 debug_only(_recording_state = rs_non_safepoint);
174 }
175
176 void DebugInformationRecorder::add_new_pc_offset(int pc_offset) {
177 assert(_pcs_length == 0 || last_pc()->pc_offset() < pc_offset,
178 "must specify a new, larger pc offset: %d >= %d", last_pc()->pc_offset(), pc_offset);
179
180 // add the pcdesc
181 if (_pcs_length == _pcs_size) {
182 // Expand
183 int new_pcs_size = _pcs_size * 2;
184 PcDesc* new_pcs = NEW_RESOURCE_ARRAY(PcDesc, new_pcs_size);
185 for (int index = 0; index < _pcs_length; index++) {
186 new_pcs[index] = _pcs[index];
187 }
188 _pcs_size = new_pcs_size;
189 _pcs = new_pcs;
190 }
191 assert(_pcs_size > _pcs_length, "There must be room for after expanding");
192
193 _pcs[_pcs_length++] = PcDesc(pc_offset, DebugInformationRecorder::serialized_null,
194 DebugInformationRecorder::serialized_null);
195 }
196
197
198 int DebugInformationRecorder::serialize_monitor_values(GrowableArray<MonitorValue*>* monitors) {
199 if (monitors == nullptr || monitors->is_empty()) return DebugInformationRecorder::serialized_null;
200 assert(_recording_state == rs_safepoint, "must be recording a safepoint");
201 int result = stream()->position();
202 stream()->write_int(monitors->length());
203 for (int index = 0; index < monitors->length(); index++) {
204 monitors->at(index)->write_on(stream());
205 }
206 assert(result != serialized_null, "sanity");
207
208 // (See comment below on DebugInformationRecorder::describe_scope.)
209 int shared_result = find_sharable_decode_offset(result);
210 if (shared_result != serialized_null) {
211 stream()->set_position(result);
212 result = shared_result;
213 }
214
215 return result;
216 }
217
218
219 int DebugInformationRecorder::serialize_scope_values(GrowableArray<ScopeValue*>* values) {
220 if (values == nullptr || values->is_empty()) return DebugInformationRecorder::serialized_null;
221 assert(_recording_state == rs_safepoint, "must be recording a safepoint");
222 int result = stream()->position();
223 assert(result != serialized_null, "sanity");
224 stream()->write_int(values->length());
225 for (int index = 0; index < values->length(); index++) {
226 values->at(index)->write_on(stream());
227 }
228
229 // (See comment below on DebugInformationRecorder::describe_scope.)
230 int shared_result = find_sharable_decode_offset(result);
231 if (shared_result != serialized_null) {
232 stream()->set_position(result);
233 result = shared_result;
234 }
235
236 return result;
237 }
238
239
240 #ifndef PRODUCT
241 // These variables are put into one block to reduce relocations
242 // and make it simpler to print from the debugger.
243 static
244 struct dir_stats_struct {
245 int chunks_queried;
246 int chunks_shared;
247 int chunks_elided;
248
249 void print() {
250 tty->print_cr("Debug Data Chunks: %d, shared %d, non-SP's elided %d",
251 chunks_queried, chunks_shared, chunks_elided);
252 }
253 } dir_stats;
254 #endif //PRODUCT
255
256
257 int DebugInformationRecorder::find_sharable_decode_offset(int stream_offset) {
258 NOT_PRODUCT(++dir_stats.chunks_queried);
259 int stream_length = stream()->position() - stream_offset;
260 assert(stream_offset != serialized_null, "should not be null");
261 assert(stream_length != 0, "should not be empty");
262
263 DIR_Chunk* ns = new(this) DIR_Chunk(stream_offset, stream_length, this);
264
265 DIR_Chunk* match = _all_chunks->insert_sorted<DIR_Chunk::compare>(ns);
266 if (match != ns) {
267 // Found an existing chunk
268 NOT_PRODUCT(++dir_stats.chunks_shared);
269 assert(ns+1 == _next_chunk, "");
270 _next_chunk = ns;
271 return match->offset();
272 } else {
273 // Inserted this chunk, so nothing to do
274 return serialized_null;
275 }
276 }
277
278
279 // must call add_safepoint before: it sets PcDesc and this routine uses
280 // the last PcDesc set
281 void DebugInformationRecorder::describe_scope(int pc_offset,
282 const methodHandle& methodH,
283 ciMethod* method,
284 int bci,
285 bool reexecute,
286 bool rethrow_exception,
287 bool is_method_handle_invoke,
288 bool return_oop,
289 bool return_scalarized,
290 bool has_ea_local_in_scope,
291 bool arg_escape,
292 DebugToken* locals,
293 DebugToken* expressions,
294 DebugToken* monitors) {
295 assert(_recording_state != rs_null, "nesting of recording calls");
296 PcDesc* last_pd = last_pc();
297 assert(last_pd->pc_offset() == pc_offset, "must be last pc");
298 int sender_stream_offset = last_pd->scope_decode_offset();
299 // update the stream offset of current pc desc
300 int stream_offset = stream()->position();
301 last_pd->set_scope_decode_offset(stream_offset);
302
303 // Record flags into pcDesc.
304 last_pd->set_should_reexecute(reexecute);
305 last_pd->set_rethrow_exception(rethrow_exception);
306 last_pd->set_is_method_handle_invoke(is_method_handle_invoke);
307 last_pd->set_return_oop(return_oop);
308 last_pd->set_return_scalarized(return_scalarized);
309 last_pd->set_has_ea_local_in_scope(has_ea_local_in_scope);
310 last_pd->set_arg_escape(arg_escape);
311
312 // serialize sender stream offset
313 stream()->write_int(sender_stream_offset);
314
315 // serialize scope
316 Metadata* method_enc;
317 if (method != nullptr) {
318 method_enc = method->constant_encoding();
319 } else if (methodH.not_null()) {
320 method_enc = methodH();
321 } else {
322 method_enc = nullptr;
323 }
324 int method_enc_index = oop_recorder()->find_index(method_enc);
325 stream()->write_int(method_enc_index);
326 stream()->write_bci(bci);
327 assert(method == nullptr ||
328 (method->is_native() && bci == 0) ||
329 (!method->is_native() && 0 <= bci && bci < method->code_size()) ||
330 bci == -1, "illegal bci");
331
332 // serialize the locals/expressions/monitors
333 stream()->write_int((intptr_t) locals);
334 stream()->write_int((intptr_t) expressions);
335 stream()->write_int((intptr_t) monitors);
336
337 // Here's a tricky bit. We just wrote some bytes.
338 // Wouldn't it be nice to find that we had already
339 // written those same bytes somewhere else?
340 // If we get lucky this way, reset the stream
341 // and reuse the old bytes. By the way, this
342 // trick not only shares parent scopes, but also
343 // compresses equivalent non-safepoint PcDescs.
344 int shared_stream_offset = find_sharable_decode_offset(stream_offset);
345 if (shared_stream_offset != serialized_null) {
346 stream()->set_position(stream_offset);
347 last_pd->set_scope_decode_offset(shared_stream_offset);
348 }
349 }
350
351 void DebugInformationRecorder::dump_object_pool(GrowableArray<ScopeValue*>* objects) {
352 guarantee( _pcs_length > 0, "safepoint must exist before describing scopes");
353 PcDesc* last_pd = &_pcs[_pcs_length-1];
354 if (objects != nullptr) {
355 for (int i = objects->length() - 1; i >= 0; i--) {
356 objects->at(i)->as_ObjectValue()->set_visited(false);
357 }
358 }
359 int offset = serialize_scope_values(objects);
360 last_pd->set_obj_decode_offset(offset);
361 }
362
363 void DebugInformationRecorder::end_scopes(int pc_offset, bool is_safepoint) {
364 assert(_recording_state == (is_safepoint? rs_safepoint: rs_non_safepoint),
365 "nesting of recording calls");
366 debug_only(_recording_state = rs_null);
367
368 // Try to compress away an equivalent non-safepoint predecessor.
369 // (This only works because we have previously recognized redundant
370 // scope trees and made them use a common scope_decode_offset.)
371 if (_pcs_length >= 2 && recording_non_safepoints()) {
372 PcDesc* last = last_pc();
373 PcDesc* prev = prev_pc();
374 // If prev is (a) not a safepoint and (b) has the same
375 // stream pointer, then it can be coalesced into the last.
376 // This is valid because non-safepoints are only sought
377 // with pc_desc_near, which (when it misses prev) will
378 // search forward until it finds last.
379 // In addition, it does not matter if the last PcDesc
380 // is for a safepoint or not.
381 if (_prev_safepoint_pc < prev->pc_offset() && prev->is_same_info(last)) {
382 assert(prev == last-1, "sane");
383 prev->set_pc_offset(pc_offset);
384 _pcs_length -= 1;
385 NOT_PRODUCT(++dir_stats.chunks_elided);
386 }
387 }
388
389 // We have just recorded this safepoint.
390 // Remember it in case the previous paragraph needs to know.
391 if (is_safepoint) {
392 _prev_safepoint_pc = pc_offset;
393 }
394 }
395
396 #ifdef ASSERT
397 bool DebugInformationRecorder::recorders_frozen() {
398 return _oop_recorder->is_complete();
399 }
400
401 void DebugInformationRecorder::mark_recorders_frozen() {
402 _oop_recorder->freeze();
403 }
404 #endif // PRODUCT
405
406 DebugToken* DebugInformationRecorder::create_scope_values(GrowableArray<ScopeValue*>* values) {
407 assert(!recorders_frozen(), "not frozen yet");
408 return (DebugToken*) (intptr_t) serialize_scope_values(values);
409 }
410
411
412 DebugToken* DebugInformationRecorder::create_monitor_values(GrowableArray<MonitorValue*>* monitors) {
413 assert(!recorders_frozen(), "not frozen yet");
414 return (DebugToken*) (intptr_t) serialize_monitor_values(monitors);
415 }
416
417
418 int DebugInformationRecorder::data_size() {
419 debug_only(mark_recorders_frozen()); // mark it "frozen" for asserts
420 return _stream->position();
421 }
422
423
424 int DebugInformationRecorder::pcs_size() {
425 debug_only(mark_recorders_frozen()); // mark it "frozen" for asserts
426 if (last_pc()->pc_offset() != PcDesc::upper_offset_limit)
427 add_new_pc_offset(PcDesc::upper_offset_limit);
428 return _pcs_length * sizeof(PcDesc);
429 }
430
431
432 void DebugInformationRecorder::copy_to(nmethod* nm) {
433 nm->copy_scopes_data(stream()->buffer(), stream()->position());
434 nm->copy_scopes_pcs(_pcs, _pcs_length);
435 }
436
437
438 void DebugInformationRecorder::verify(const nmethod* code) {
439 Unimplemented();
440 }
441
442 #ifndef PRODUCT
443 void DebugInformationRecorder::print_statistics() {
444 dir_stats.print();
445 }
446 #endif //PRODUCT