1 /*
2 * Copyright (c) 2017, 2018, Red Hat, Inc. All rights reserved.
3 *
4 * This code is free software; you can redistribute it and/or modify it
5 * under the terms of the GNU General Public License version 2 only, as
6 * published by the Free Software Foundation.
7 *
8 * This code is distributed in the hope that it will be useful, but WITHOUT
9 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
10 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
11 * version 2 for more details (a copy is included in the LICENSE file that
12 * accompanied this code).
13 *
14 * You should have received a copy of the GNU General Public License version
15 * 2 along with this work; if not, write to the Free Software Foundation,
16 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
17 *
18 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
19 * or visit www.oracle.com if you need additional information or have any
20 * questions.
21 *
22 */
23
24 #include "precompiled.hpp"
25 #include "code/codeCache.hpp"
26 #include "code/nmethod.hpp"
27 #include "gc/shenandoah/shenandoahHeap.hpp"
28 #include "gc/shenandoah/shenandoahHeap.inline.hpp"
29 #include "gc/shenandoah/shenandoahCodeRoots.hpp"
30 #include "memory/resourceArea.hpp"
31
32 ShenandoahParallelCodeCacheIterator::ShenandoahParallelCodeCacheIterator(const GrowableArray<CodeHeap*>* heaps) {
33 _length = heaps->length();
34 _iters = NEW_C_HEAP_ARRAY(ShenandoahParallelCodeHeapIterator, _length, mtGC);
35 for (int h = 0; h < _length; h++) {
36 _iters[h] = ShenandoahParallelCodeHeapIterator(heaps->at(h));
37 }
38 }
39
40 ShenandoahParallelCodeCacheIterator::~ShenandoahParallelCodeCacheIterator() {
41 FREE_C_HEAP_ARRAY(ParallelCodeHeapIterator, _iters);
42 }
43
44 void ShenandoahParallelCodeCacheIterator::parallel_blobs_do(CodeBlobClosure* f) {
45 for (int c = 0; c < _length; c++) {
46 _iters[c].parallel_blobs_do(f);
47 }
48 }
49
50 ShenandoahParallelCodeHeapIterator::ShenandoahParallelCodeHeapIterator(CodeHeap* heap) :
51 _heap(heap), _claimed_idx(0), _finished(false) {
52 }
53
54 void ShenandoahParallelCodeHeapIterator::parallel_blobs_do(CodeBlobClosure* f) {
55 assert(SafepointSynchronize::is_at_safepoint(), "Must be at safepoint");
56
57 /*
58 * Parallel code heap walk.
59 *
60 * This code makes all threads scan all code heaps, but only one thread would execute the
61 * closure on given blob. This is achieved by recording the "claimed" blocks: if a thread
62 * had claimed the block, it can process all blobs in it. Others have to fast-forward to
63 * next attempt without processing.
64 *
65 * Late threads would return immediately if iterator is finished.
66 */
67
68 if (_finished) {
69 return;
70 }
71
72 int stride = 256; // educated guess
73 int stride_mask = stride - 1;
74 assert (is_power_of_2(stride), "sanity");
75
76 int count = 0;
77 bool process_block = true;
78
79 for (CodeBlob *cb = CodeCache::first_blob(_heap); cb != NULL; cb = CodeCache::next_blob(_heap, cb)) {
80 int current = count++;
81 if ((current & stride_mask) == 0) {
82 process_block = (current >= _claimed_idx) &&
83 (Atomic::cmpxchg(current + stride, &_claimed_idx, current) == current);
84 }
85 if (process_block) {
86 if (cb->is_alive()) {
87 f->do_code_blob(cb);
88 #ifdef ASSERT
89 if (cb->is_nmethod())
90 Universe::heap()->verify_nmethod((nmethod*)cb);
91 #endif
92 }
93 }
94 }
95
96 _finished = true;
97 }
98
99 class ShenandoahNMethodOopDetector : public OopClosure {
100 private:
101 ResourceMark rm; // For growable array allocation below.
102 GrowableArray<oop*> _oops;
103
104 public:
105 ShenandoahNMethodOopDetector() : _oops(10) {};
106
107 void do_oop(oop* o) {
108 _oops.append(o);
109 }
110 void do_oop(narrowOop* o) {
111 fatal("NMethods should not have compressed oops embedded.");
112 }
113
114 GrowableArray<oop*>* oops() {
115 return &_oops;
116 }
117
118 bool has_oops() {
119 return !_oops.is_empty();
120 }
121 };
122
123 class ShenandoahNMethodOopInitializer : public OopClosure {
124 private:
125 ShenandoahHeap* const _heap;
126
127 public:
128 ShenandoahNMethodOopInitializer() : _heap(ShenandoahHeap::heap()) {};
129
130 private:
131 template <class T>
132 inline void do_oop_work(T* p) {
133 T o = RawAccess<>::oop_load(p);
134 if (! CompressedOops::is_null(o)) {
135 oop obj1 = CompressedOops::decode_not_null(o);
136 oop obj2 = ShenandoahBarrierSet::barrier_set()->write_barrier(obj1);
137 if (! oopDesc::equals_raw(obj1, obj2)) {
138 shenandoah_assert_not_in_cset(NULL, obj2);
139 RawAccess<IS_NOT_NULL>::oop_store(p, obj2);
140 if (_heap->is_concurrent_traversal_in_progress()) {
141 ShenandoahBarrierSet::barrier_set()->enqueue(obj2);
142 }
143 }
144 }
145 }
146
147 public:
148 void do_oop(oop* o) {
149 do_oop_work(o);
150 }
151 void do_oop(narrowOop* o) {
152 do_oop_work(o);
153 }
154 };
155
156 ShenandoahCodeRoots::PaddedLock ShenandoahCodeRoots::_recorded_nms_lock;
157 GrowableArray<ShenandoahNMethod*>* ShenandoahCodeRoots::_recorded_nms;
158
159 void ShenandoahCodeRoots::initialize() {
160 _recorded_nms_lock._lock = 0;
161 _recorded_nms = new (ResourceObj::C_HEAP, mtGC) GrowableArray<ShenandoahNMethod*>(100, true, mtGC);
162 }
163
164 void ShenandoahCodeRoots::add_nmethod(nmethod* nm) {
165 switch (ShenandoahCodeRootsStyle) {
166 case 0:
167 case 1: {
168 ShenandoahNMethodOopInitializer init;
169 nm->oops_do(&init);
170 nm->fix_oop_relocations();
171 break;
172 }
173 case 2: {
174 ShenandoahNMethodOopDetector detector;
175 nm->oops_do(&detector);
176
177 if (detector.has_oops()) {
178 ShenandoahNMethodOopInitializer init;
179 nm->oops_do(&init);
180 nm->fix_oop_relocations();
181
182 ShenandoahNMethod* nmr = new ShenandoahNMethod(nm, detector.oops());
183 nmr->assert_alive_and_correct();
184
185 ShenandoahCodeRootsLock lock(true);
186
187 int idx = _recorded_nms->find(nm, ShenandoahNMethod::find_with_nmethod);
188 if (idx != -1) {
189 ShenandoahNMethod* old = _recorded_nms->at(idx);
190 _recorded_nms->at_put(idx, nmr);
191 delete old;
192 } else {
193 _recorded_nms->append(nmr);
194 }
195 }
196 break;
197 }
198 default:
199 ShouldNotReachHere();
200 }
201 };
202
203 void ShenandoahCodeRoots::remove_nmethod(nmethod* nm) {
204 switch (ShenandoahCodeRootsStyle) {
205 case 0:
206 case 1: {
207 break;
208 }
209 case 2: {
210 ShenandoahNMethodOopDetector detector;
211 nm->oops_do(&detector, /* allow_zombie = */ true);
212
213 if (detector.has_oops()) {
214 ShenandoahCodeRootsLock lock(true);
215
216 int idx = _recorded_nms->find(nm, ShenandoahNMethod::find_with_nmethod);
217 assert(idx != -1, "nmethod " PTR_FORMAT " should be registered", p2i(nm));
218 ShenandoahNMethod* old = _recorded_nms->at(idx);
219 old->assert_same_oops(detector.oops());
220 _recorded_nms->delete_at(idx);
221 delete old;
222 }
223 break;
224 }
225 default:
226 ShouldNotReachHere();
227 }
228 }
229
230 ShenandoahCodeRootsIterator::ShenandoahCodeRootsIterator() :
231 _heap(ShenandoahHeap::heap()),
232 _par_iterator(CodeCache::heaps()),
233 _claimed(0) {
234 assert(SafepointSynchronize::is_at_safepoint(), "Must be at safepoint");
235 assert(!Thread::current()->is_Worker_thread(), "Should not be acquired by workers");
236 switch (ShenandoahCodeRootsStyle) {
237 case 0:
238 case 1: {
239 // No need to do anything here
240 break;
241 }
242 case 2: {
243 ShenandoahCodeRoots::acquire_lock(false);
244 break;
245 }
246 default:
247 ShouldNotReachHere();
248 }
249 }
250
251 ShenandoahCodeRootsIterator::~ShenandoahCodeRootsIterator() {
252 switch (ShenandoahCodeRootsStyle) {
253 case 0:
254 case 1: {
255 // No need to do anything here
256 break;
257 }
258 case 2: {
259 ShenandoahCodeRoots::release_lock(false);
260 break;
261 }
262 default:
263 ShouldNotReachHere();
264 }
265 }
266
267 template<bool CSET_FILTER>
268 void ShenandoahCodeRootsIterator::dispatch_parallel_blobs_do(CodeBlobClosure *f) {
269 switch (ShenandoahCodeRootsStyle) {
270 case 0: {
271 if (_seq_claimed.try_set()) {
272 CodeCache::blobs_do(f);
273 }
274 break;
275 }
276 case 1: {
277 _par_iterator.parallel_blobs_do(f);
278 break;
279 }
280 case 2: {
281 ShenandoahCodeRootsIterator::fast_parallel_blobs_do<CSET_FILTER>(f);
282 break;
283 }
284 default:
285 ShouldNotReachHere();
286 }
287 }
288
289 ShenandoahAllCodeRootsIterator ShenandoahCodeRoots::iterator() {
290 return ShenandoahAllCodeRootsIterator();
291 }
292
293 ShenandoahCsetCodeRootsIterator ShenandoahCodeRoots::cset_iterator() {
294 return ShenandoahCsetCodeRootsIterator();
295 }
296
297 void ShenandoahAllCodeRootsIterator::possibly_parallel_blobs_do(CodeBlobClosure *f) {
298 ShenandoahCodeRootsIterator::dispatch_parallel_blobs_do<false>(f);
299 }
300
301 void ShenandoahCsetCodeRootsIterator::possibly_parallel_blobs_do(CodeBlobClosure *f) {
302 ShenandoahCodeRootsIterator::dispatch_parallel_blobs_do<true>(f);
303 }
304
305 template <bool CSET_FILTER>
306 void ShenandoahCodeRootsIterator::fast_parallel_blobs_do(CodeBlobClosure *f) {
307 assert(SafepointSynchronize::is_at_safepoint(), "Must be at safepoint");
308
309 size_t stride = 256; // educated guess
310
311 GrowableArray<ShenandoahNMethod*>* list = ShenandoahCodeRoots::_recorded_nms;
312
313 size_t max = (size_t)list->length();
314 while (_claimed < max) {
315 size_t cur = Atomic::add(stride, &_claimed) - stride;
316 size_t start = cur;
317 size_t end = MIN2(cur + stride, max);
318 if (start >= max) break;
319
320 for (size_t idx = start; idx < end; idx++) {
321 ShenandoahNMethod* nmr = list->at((int) idx);
322 nmr->assert_alive_and_correct();
323
324 if (CSET_FILTER && !nmr->has_cset_oops(_heap)) {
325 continue;
326 }
327
328 f->do_code_blob(nmr->nm());
329 }
330 }
331 }
332
333 ShenandoahNMethod::ShenandoahNMethod(nmethod* nm, GrowableArray<oop*>* oops) {
334 _nm = nm;
335 _oops = NEW_C_HEAP_ARRAY(oop*, oops->length(), mtGC);
336 _oops_count = oops->length();
337 for (int c = 0; c < _oops_count; c++) {
338 _oops[c] = oops->at(c);
339 }
340 }
341
342 ShenandoahNMethod::~ShenandoahNMethod() {
343 if (_oops != NULL) {
344 FREE_C_HEAP_ARRAY(oop*, _oops);
345 }
346 }
347
348 bool ShenandoahNMethod::has_cset_oops(ShenandoahHeap *heap) {
349 for (int c = 0; c < _oops_count; c++) {
350 oop o = RawAccess<>::oop_load(_oops[c]);
351 if (heap->in_collection_set(o)) {
352 return true;
353 }
354 }
355 return false;
356 }
357
358 #ifdef ASSERT
359 void ShenandoahNMethod::assert_alive_and_correct() {
360 assert(_nm->is_alive(), "only alive nmethods here");
361 assert(_oops_count > 0, "should have filtered nmethods without oops before");
362 ShenandoahHeap* heap = ShenandoahHeap::heap();
363 for (int c = 0; c < _oops_count; c++) {
364 oop *loc = _oops[c];
365 assert(_nm->code_contains((address) loc) || _nm->oops_contains(loc), "nmethod should contain the oop*");
366 oop o = RawAccess<>::oop_load(loc);
367 shenandoah_assert_correct_except(loc, o, o == NULL || heap->is_full_gc_move_in_progress());
368 }
369 }
370
371 void ShenandoahNMethod::assert_same_oops(GrowableArray<oop*>* oops) {
372 assert(_oops_count == oops->length(), "should have the same number of oop*");
373 for (int c = 0; c < _oops_count; c++) {
374 assert(_oops[c] == oops->at(c), "should be the same oop*");
375 }
376 }
377 #endif