1 /*
2 * Copyright (c) 2017, 2019, 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.inline.hpp"
28 #include "gc/shenandoah/shenandoahCodeRoots.hpp"
29 #include "gc/shenandoah/shenandoahUtils.hpp"
30 #include "memory/resourceArea.hpp"
31 #include "memory/universe.hpp"
32 #include "runtime/mutex.inline.hpp"
33
34 ShenandoahParallelCodeCacheIterator::ShenandoahParallelCodeCacheIterator(const GrowableArray<CodeHeap*>* heaps) {
35 _length = heaps->length();
36 _iters = NEW_C_HEAP_ARRAY(ShenandoahParallelCodeHeapIterator, _length, mtGC);
37 for (int h = 0; h < _length; h++) {
38 _iters[h] = ShenandoahParallelCodeHeapIterator(heaps->at(h));
39 }
40 }
41
42 ShenandoahParallelCodeCacheIterator::~ShenandoahParallelCodeCacheIterator() {
43 FREE_C_HEAP_ARRAY(ParallelCodeHeapIterator, _iters);
44 }
45
46 void ShenandoahParallelCodeCacheIterator::parallel_blobs_do(CodeBlobClosure* f) {
47 for (int c = 0; c < _length; c++) {
48 _iters[c].parallel_blobs_do(f);
49 }
50 }
51
52 ShenandoahParallelCodeHeapIterator::ShenandoahParallelCodeHeapIterator(CodeHeap* heap) :
53 _heap(heap), _claimed_idx(0), _finished(false) {
54 }
55
56 void ShenandoahParallelCodeHeapIterator::parallel_blobs_do(CodeBlobClosure* f) {
57 assert(SafepointSynchronize::is_at_safepoint(), "Must be at safepoint");
58
59 /*
60 * Parallel code heap walk.
61 *
62 * This code makes all threads scan all code heaps, but only one thread would execute the
63 * closure on given blob. This is achieved by recording the "claimed" blocks: if a thread
64 * had claimed the block, it can process all blobs in it. Others have to fast-forward to
65 * next attempt without processing.
66 *
67 * Late threads would return immediately if iterator is finished.
68 */
69
70 if (_finished) {
71 return;
72 }
73
74 int stride = 256; // educated guess
75 int stride_mask = stride - 1;
76 assert (is_power_of_2(stride), "sanity");
77
78 int count = 0;
79 bool process_block = true;
80
81 for (CodeBlob *cb = CodeCache::first_blob(_heap); cb != NULL; cb = CodeCache::next_blob(_heap, cb)) {
82 int current = count++;
83 if ((current & stride_mask) == 0) {
84 process_block = (current >= _claimed_idx) &&
85 (Atomic::cmpxchg(current + stride, &_claimed_idx, current) == current);
86 }
87 if (process_block) {
88 if (cb->is_alive()) {
89 f->do_code_blob(cb);
90 #ifdef ASSERT
91 if (cb->is_nmethod())
92 Universe::heap()->verify_nmethod((nmethod*)cb);
93 #endif
94 }
95 }
96 }
97
98 _finished = true;
99 }
100
101 class ShenandoahNMethodOopDetector : public OopClosure {
102 private:
103 ResourceMark rm; // For growable array allocation below.
104 GrowableArray<oop*> _oops;
105
106 public:
107 ShenandoahNMethodOopDetector() : _oops(10) {};
108
109 void do_oop(oop* o) {
110 _oops.append(o);
111 }
112 void do_oop(narrowOop* o) {
113 fatal("NMethods should not have compressed oops embedded.");
114 }
115
116 GrowableArray<oop*>* oops() {
117 return &_oops;
118 }
119
120 bool has_oops() {
121 return !_oops.is_empty();
122 }
123 };
124
125 GrowableArray<ShenandoahNMethod*>* ShenandoahCodeRoots::_recorded_nms;
126 ShenandoahLock ShenandoahCodeRoots::_recorded_nms_lock;
127
128 void ShenandoahCodeRoots::initialize() {
129 _recorded_nms = new (ResourceObj::C_HEAP, mtGC) GrowableArray<ShenandoahNMethod*>(100, true, mtGC);
130 }
131
132 void ShenandoahCodeRoots::add_nmethod(nmethod* nm) {
133 switch (ShenandoahCodeRootsStyle) {
134 case 0:
135 case 1:
136 break;
137 case 2: {
138 assert_locked_or_safepoint(CodeCache_lock);
139 ShenandoahLocker locker(CodeCache_lock->owned_by_self() ? NULL : &_recorded_nms_lock);
140
141 ShenandoahNMethodOopDetector detector;
142 nm->oops_do(&detector);
143
144 if (detector.has_oops()) {
145 ShenandoahNMethod* nmr = new ShenandoahNMethod(nm, detector.oops());
146 nmr->assert_alive_and_correct();
147 int idx = _recorded_nms->find(nm, ShenandoahNMethod::find_with_nmethod);
148 if (idx != -1) {
149 ShenandoahNMethod* old = _recorded_nms->at(idx);
150 _recorded_nms->at_put(idx, nmr);
151 delete old;
152 } else {
153 _recorded_nms->append(nmr);
154 }
155 }
156 break;
157 }
158 default:
159 ShouldNotReachHere();
160 }
161 };
162
163 void ShenandoahCodeRoots::remove_nmethod(nmethod* nm) {
164 switch (ShenandoahCodeRootsStyle) {
165 case 0:
166 case 1: {
167 break;
168 }
169 case 2: {
170 assert_locked_or_safepoint(CodeCache_lock);
171 ShenandoahLocker locker(CodeCache_lock->owned_by_self() ? NULL : &_recorded_nms_lock);
172
173 ShenandoahNMethodOopDetector detector;
174 nm->oops_do(&detector, /* allow_dead = */ true);
175
176 if (detector.has_oops()) {
177 int idx = _recorded_nms->find(nm, ShenandoahNMethod::find_with_nmethod);
178 assert(idx != -1, "nmethod " PTR_FORMAT " should be registered", p2i(nm));
179 ShenandoahNMethod* old = _recorded_nms->at(idx);
180 old->assert_same_oops(detector.oops());
181 _recorded_nms->delete_at(idx);
182 delete old;
183 }
184 break;
185 }
186 default:
187 ShouldNotReachHere();
188 }
189 }
190
191 ShenandoahCodeRootsIterator::ShenandoahCodeRootsIterator() :
192 _heap(ShenandoahHeap::heap()),
193 _par_iterator(CodeCache::heaps()),
194 _claimed(0) {
195 assert(SafepointSynchronize::is_at_safepoint(), "Must be at safepoint");
196 assert(!Thread::current()->is_Worker_thread(), "Should not be acquired by workers");
197 switch (ShenandoahCodeRootsStyle) {
198 case 0:
199 case 1: {
200 // No need to do anything here
201 break;
202 }
203 case 2: {
204 CodeCache_lock->lock_without_safepoint_check();
205 break;
206 }
207 default:
208 ShouldNotReachHere();
209 }
210 }
211
212 ShenandoahCodeRootsIterator::~ShenandoahCodeRootsIterator() {
213 switch (ShenandoahCodeRootsStyle) {
214 case 0:
215 case 1: {
216 // No need to do anything here
217 break;
218 }
219 case 2: {
220 CodeCache_lock->unlock();
221 break;
222 }
223 default:
224 ShouldNotReachHere();
225 }
226 }
227
228 template<bool CSET_FILTER>
229 void ShenandoahCodeRootsIterator::dispatch_parallel_blobs_do(CodeBlobClosure *f) {
230 switch (ShenandoahCodeRootsStyle) {
231 case 0: {
232 if (_seq_claimed.try_set()) {
233 CodeCache::blobs_do(f);
234 }
235 break;
236 }
237 case 1: {
238 _par_iterator.parallel_blobs_do(f);
239 break;
240 }
241 case 2: {
242 ShenandoahCodeRootsIterator::fast_parallel_blobs_do<CSET_FILTER>(f);
243 break;
244 }
245 default:
246 ShouldNotReachHere();
247 }
248 }
249
250 void ShenandoahAllCodeRootsIterator::possibly_parallel_blobs_do(CodeBlobClosure *f) {
251 ShenandoahCodeRootsIterator::dispatch_parallel_blobs_do<false>(f);
252 }
253
254 void ShenandoahCsetCodeRootsIterator::possibly_parallel_blobs_do(CodeBlobClosure *f) {
255 ShenandoahCodeRootsIterator::dispatch_parallel_blobs_do<true>(f);
256 }
257
258 template <bool CSET_FILTER>
259 void ShenandoahCodeRootsIterator::fast_parallel_blobs_do(CodeBlobClosure *f) {
260 assert(SafepointSynchronize::is_at_safepoint(), "Must be at safepoint");
261
262 size_t stride = 256; // educated guess
263
264 GrowableArray<ShenandoahNMethod*>* list = ShenandoahCodeRoots::_recorded_nms;
265
266 size_t max = (size_t)list->length();
267 while (_claimed < max) {
268 size_t cur = Atomic::add(stride, &_claimed) - stride;
269 size_t start = cur;
270 size_t end = MIN2(cur + stride, max);
271 if (start >= max) break;
272
273 for (size_t idx = start; idx < end; idx++) {
274 ShenandoahNMethod* nmr = list->at((int) idx);
275 nmr->assert_alive_and_correct();
276
277 if (CSET_FILTER && !nmr->has_cset_oops(_heap)) {
278 continue;
279 }
280
281 f->do_code_blob(nmr->nm());
282 }
283 }
284 }
285
286 ShenandoahNMethod::ShenandoahNMethod(nmethod* nm, GrowableArray<oop*>* oops) {
287 _nm = nm;
288 _oops = NEW_C_HEAP_ARRAY(oop*, oops->length(), mtGC);
289 _oops_count = oops->length();
290 for (int c = 0; c < _oops_count; c++) {
291 _oops[c] = oops->at(c);
292 }
293 }
294
295 ShenandoahNMethod::~ShenandoahNMethod() {
296 if (_oops != NULL) {
297 FREE_C_HEAP_ARRAY(oop*, _oops);
298 }
299 }
300
301 bool ShenandoahNMethod::has_cset_oops(ShenandoahHeap *heap) {
302 for (int c = 0; c < _oops_count; c++) {
303 oop o = RawAccess<>::oop_load(_oops[c]);
304 if (heap->in_collection_set(o)) {
305 return true;
306 }
307 }
308 return false;
309 }
310
311 #ifdef ASSERT
312 void ShenandoahNMethod::assert_alive_and_correct() {
313 assert(_nm->is_alive(), "only alive nmethods here");
314 assert(_oops_count > 0, "should have filtered nmethods without oops before");
315 ShenandoahHeap* heap = ShenandoahHeap::heap();
316 for (int c = 0; c < _oops_count; c++) {
317 oop *loc = _oops[c];
318 assert(_nm->code_contains((address) loc) || _nm->oops_contains(loc), "nmethod should contain the oop*");
319 oop o = RawAccess<>::oop_load(loc);
320 shenandoah_assert_correct_except(loc, o,
321 o == NULL ||
322 heap->is_full_gc_move_in_progress() ||
323 (VMThread::vm_operation() != NULL) && (VMThread::vm_operation()->type() == VM_Operation::VMOp_HeapWalkOperation)
324 );
325 }
326 }
327
328 void ShenandoahNMethod::assert_same_oops(GrowableArray<oop*>* oops) {
329 assert(_oops_count == oops->length(), "should have the same number of oop*");
330 for (int c = 0; c < _oops_count; c++) {
331 assert(_oops[c] == oops->at(c), "should be the same oop*");
332 }
333 }
334 #endif