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
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 GrowableArray<ShenandoahNMethod*>* ShenandoahCodeRoots::_recorded_nms;
124 ShenandoahLock ShenandoahCodeRoots::_recorded_nms_lock;
125
126 void ShenandoahCodeRoots::initialize() {
127 _recorded_nms = new (ResourceObj::C_HEAP, mtGC) GrowableArray<ShenandoahNMethod*>(100, true, mtGC);
128 }
129
130 void ShenandoahCodeRoots::add_nmethod(nmethod* nm) {
131 switch (ShenandoahCodeRootsStyle) {
132 case 0:
133 case 1:
134 break;
135 case 2: {
136 assert_locked_or_safepoint(CodeCache_lock);
137 ShenandoahLocker locker(CodeCache_lock->owned_by_self() ? NULL : &_recorded_nms_lock);
138
139 ShenandoahNMethodOopDetector detector;
140 nm->oops_do(&detector);
141
142 if (detector.has_oops()) {
143 ShenandoahNMethod* nmr = new ShenandoahNMethod(nm, detector.oops());
144 nmr->assert_alive_and_correct();
145 int idx = _recorded_nms->find(nm, ShenandoahNMethod::find_with_nmethod);
146 if (idx != -1) {
147 ShenandoahNMethod* old = _recorded_nms->at(idx);
148 _recorded_nms->at_put(idx, nmr);
149 delete old;
150 } else {
151 _recorded_nms->append(nmr);
152 }
153 }
154 break;
155 }
156 default:
157 ShouldNotReachHere();
158 }
159 };
160
161 void ShenandoahCodeRoots::remove_nmethod(nmethod* nm) {
162 switch (ShenandoahCodeRootsStyle) {
163 case 0:
164 case 1: {
165 break;
166 }
167 case 2: {
168 assert_locked_or_safepoint(CodeCache_lock);
169 ShenandoahLocker locker(CodeCache_lock->owned_by_self() ? NULL : &_recorded_nms_lock);
170
171 ShenandoahNMethodOopDetector detector;
172 nm->oops_do(&detector, /* allow_zombie = */ true);
173
174 if (detector.has_oops()) {
175 int idx = _recorded_nms->find(nm, ShenandoahNMethod::find_with_nmethod);
176 assert(idx != -1, "nmethod " PTR_FORMAT " should be registered", p2i(nm));
177 ShenandoahNMethod* old = _recorded_nms->at(idx);
178 old->assert_same_oops(detector.oops());
179 _recorded_nms->delete_at(idx);
180 delete old;
181 }
182 break;
183 }
184 default:
185 ShouldNotReachHere();
186 }
187 }
188
189 ShenandoahCodeRootsIterator::ShenandoahCodeRootsIterator() :
190 _heap(ShenandoahHeap::heap()),
191 _par_iterator(CodeCache::heaps()),
192 _claimed(0) {
193 assert(SafepointSynchronize::is_at_safepoint(), "Must be at safepoint");
194 assert(!Thread::current()->is_Worker_thread(), "Should not be acquired by workers");
195 switch (ShenandoahCodeRootsStyle) {
196 case 0:
197 case 1: {
198 // No need to do anything here
199 break;
200 }
201 case 2: {
202 CodeCache_lock->lock_without_safepoint_check();
203 break;
204 }
205 default:
206 ShouldNotReachHere();
207 }
208 }
209
210 ShenandoahCodeRootsIterator::~ShenandoahCodeRootsIterator() {
211 switch (ShenandoahCodeRootsStyle) {
212 case 0:
213 case 1: {
214 // No need to do anything here
215 break;
216 }
217 case 2: {
218 CodeCache_lock->unlock();
219 break;
220 }
221 default:
222 ShouldNotReachHere();
223 }
224 }
225
226 template<bool CSET_FILTER>
227 void ShenandoahCodeRootsIterator::dispatch_parallel_blobs_do(CodeBlobClosure *f) {
228 switch (ShenandoahCodeRootsStyle) {
229 case 0: {
230 if (_seq_claimed.try_set()) {
231 CodeCache::blobs_do(f);
232 }
233 break;
234 }
235 case 1: {
236 _par_iterator.parallel_blobs_do(f);
237 break;
238 }
239 case 2: {
240 ShenandoahCodeRootsIterator::fast_parallel_blobs_do<CSET_FILTER>(f);
241 break;
242 }
243 default:
244 ShouldNotReachHere();
245 }
246 }
247
248 void ShenandoahAllCodeRootsIterator::possibly_parallel_blobs_do(CodeBlobClosure *f) {
249 ShenandoahCodeRootsIterator::dispatch_parallel_blobs_do<false>(f);
250 }
251
252 void ShenandoahCsetCodeRootsIterator::possibly_parallel_blobs_do(CodeBlobClosure *f) {
253 ShenandoahCodeRootsIterator::dispatch_parallel_blobs_do<true>(f);
254 }
255
256 template <bool CSET_FILTER>
257 void ShenandoahCodeRootsIterator::fast_parallel_blobs_do(CodeBlobClosure *f) {
258 assert(SafepointSynchronize::is_at_safepoint(), "Must be at safepoint");
259
260 size_t stride = 256; // educated guess
261
262 GrowableArray<ShenandoahNMethod*>* list = ShenandoahCodeRoots::_recorded_nms;
263
264 size_t max = (size_t)list->length();
265 while (_claimed < max) {
266 size_t cur = Atomic::add(stride, &_claimed) - stride;
267 size_t start = cur;
268 size_t end = MIN2(cur + stride, max);
269 if (start >= max) break;
270
271 for (size_t idx = start; idx < end; idx++) {
272 ShenandoahNMethod* nmr = list->at((int) idx);
273 nmr->assert_alive_and_correct();
274
275 if (CSET_FILTER && !nmr->has_cset_oops(_heap)) {
276 continue;
277 }
278
279 f->do_code_blob(nmr->nm());
280 }
281 }
282 }
283
284 ShenandoahNMethod::ShenandoahNMethod(nmethod* nm, GrowableArray<oop*>* oops) {
285 _nm = nm;
286 _oops = NEW_C_HEAP_ARRAY(oop*, oops->length(), mtGC);
287 _oops_count = oops->length();
288 for (int c = 0; c < _oops_count; c++) {
289 _oops[c] = oops->at(c);
290 }
291 }
292
293 ShenandoahNMethod::~ShenandoahNMethod() {
294 if (_oops != NULL) {
295 FREE_C_HEAP_ARRAY(oop*, _oops);
296 }
297 }
298
299 bool ShenandoahNMethod::has_cset_oops(ShenandoahHeap *heap) {
300 for (int c = 0; c < _oops_count; c++) {
301 oop o = RawAccess<>::oop_load(_oops[c]);
302 if (heap->in_collection_set(o)) {
303 return true;
304 }
305 }
306 return false;
307 }
308
309 #ifdef ASSERT
310 void ShenandoahNMethod::assert_alive_and_correct() {
311 assert(_nm->is_alive(), "only alive nmethods here");
312 assert(_oops_count > 0, "should have filtered nmethods without oops before");
313 ShenandoahHeap* heap = ShenandoahHeap::heap();
314 for (int c = 0; c < _oops_count; c++) {
315 oop *loc = _oops[c];
316 assert(_nm->code_contains((address) loc) || _nm->oops_contains(loc), "nmethod should contain the oop*");
317 oop o = RawAccess<>::oop_load(loc);
318 shenandoah_assert_correct_except(loc, o,
319 o == NULL ||
320 heap->is_full_gc_move_in_progress() ||
321 (VMThread::vm_operation() != NULL) && (VMThread::vm_operation()->type() == VM_Operation::VMOp_HeapWalkOperation)
322 );
323 }
324 }
325
326 void ShenandoahNMethod::assert_same_oops(GrowableArray<oop*>* oops) {
327 assert(_oops_count == oops->length(), "should have the same number of oop*");
328 for (int c = 0; c < _oops_count; c++) {
329 assert(_oops[c] == oops->at(c), "should be the same oop*");
330 }
331 }
332 #endif