197 if (*byte != dirty_card) {
198 *byte = dirty_card;
199 jt->dirty_card_queue().enqueue(byte);
200 }
201 }
202 } else {
203 MutexLockerEx x(Shared_DirtyCardQ_lock,
204 Mutex::_no_safepoint_check_flag);
205 for (; byte <= last_byte; byte++) {
206 if (*byte == g1_young_gen) {
207 continue;
208 }
209 if (*byte != dirty_card) {
210 *byte = dirty_card;
211 _dcqs.shared_dirty_card_queue()->enqueue(byte);
212 }
213 }
214 }
215 }
216 }
217
218 void G1SATBCardTableModRefBS::write_ref_nmethod_post(oop* dst, nmethod* nm) {
219 oop obj = oopDesc::load_heap_oop(dst);
220 if (obj != NULL) {
221 G1CollectedHeap* g1h = G1CollectedHeap::heap();
222 HeapRegion* hr = g1h->heap_region_containing(obj);
223 hr->add_strong_code_root(nm);
224 }
225 }
226
227 class G1EnsureLastRefToRegion : public OopClosure {
228 G1CollectedHeap* _g1h;
229 HeapRegion* _hr;
230 oop* _dst;
231
232 bool _value;
233 public:
234 G1EnsureLastRefToRegion(G1CollectedHeap* g1h, HeapRegion* hr, oop* dst) :
235 _g1h(g1h), _hr(hr), _dst(dst), _value(true) {}
236
237 void do_oop(oop* p) {
238 if (_value && p != _dst) {
239 oop obj = oopDesc::load_heap_oop(p);
240 if (obj != NULL) {
241 HeapRegion* hr = _g1h->heap_region_containing(obj);
242 if (hr == _hr) {
243 // Another reference to the same region.
244 _value = false;
245 }
246 }
247 }
248 }
249 void do_oop(narrowOop* p) { ShouldNotReachHere(); }
250 bool value() const { return _value; }
251 };
252
253 void G1SATBCardTableModRefBS::write_ref_nmethod_pre(oop* dst, nmethod* nm) {
254 oop obj = oopDesc::load_heap_oop(dst);
255 if (obj != NULL) {
256 G1CollectedHeap* g1h = G1CollectedHeap::heap();
257 HeapRegion* hr = g1h->heap_region_containing(obj);
258 G1EnsureLastRefToRegion ensure_last_ref(g1h, hr, dst);
259 nm->oops_do(&ensure_last_ref);
260 if (ensure_last_ref.value()) {
261 // Last reference to this region, remove the nmethod from the rset.
262 hr->remove_strong_code_root(nm);
263 }
264 }
265 }
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197 if (*byte != dirty_card) {
198 *byte = dirty_card;
199 jt->dirty_card_queue().enqueue(byte);
200 }
201 }
202 } else {
203 MutexLockerEx x(Shared_DirtyCardQ_lock,
204 Mutex::_no_safepoint_check_flag);
205 for (; byte <= last_byte; byte++) {
206 if (*byte == g1_young_gen) {
207 continue;
208 }
209 if (*byte != dirty_card) {
210 *byte = dirty_card;
211 _dcqs.shared_dirty_card_queue()->enqueue(byte);
212 }
213 }
214 }
215 }
216 }
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