230 *byte = dirty_card;
231 jt->dirty_card_queue().enqueue(byte);
232 }
233 }
234 } else {
235 MutexLockerEx x(Shared_DirtyCardQ_lock,
236 Mutex::_no_safepoint_check_flag);
237 for (; byte <= last_byte; byte++) {
238 if (*byte == g1_young_gen) {
239 continue;
240 }
241 if (*byte != dirty_card) {
242 *byte = dirty_card;
243 _dcqs.shared_dirty_card_queue()->enqueue(byte);
244 }
245 }
246 }
247 }
248 }
249 }
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230 *byte = dirty_card;
231 jt->dirty_card_queue().enqueue(byte);
232 }
233 }
234 } else {
235 MutexLockerEx x(Shared_DirtyCardQ_lock,
236 Mutex::_no_safepoint_check_flag);
237 for (; byte <= last_byte; byte++) {
238 if (*byte == g1_young_gen) {
239 continue;
240 }
241 if (*byte != dirty_card) {
242 *byte = dirty_card;
243 _dcqs.shared_dirty_card_queue()->enqueue(byte);
244 }
245 }
246 }
247 }
248 }
249 }
250
251 void G1SATBCardTableModRefBS::write_ref_nmethod_post(oop* dst, nmethod* nm) {
252 oop obj = oopDesc::load_heap_oop(dst);
253 if (obj != NULL) {
254 G1CollectedHeap* g1h = G1CollectedHeap::heap();
255 HeapRegion* hr = g1h->heap_region_containing(obj);
256 hr->add_strong_code_root(nm);
257 }
258 }
259
260 class G1EnsureLastRefToRegion : public OopClosure {
261 G1CollectedHeap* _g1h;
262 HeapRegion* _hr;
263 oop* _dst;
264
265 bool _value;
266 public:
267 G1EnsureLastRefToRegion(G1CollectedHeap* g1h, HeapRegion* hr, oop* dst) :
268 _g1h(g1h), _hr(hr), _dst(dst), _value(true) {}
269
270 void do_oop(oop* p) {
271 if (_value && p != _dst) {
272 oop obj = oopDesc::load_heap_oop(p);
273 if (obj != NULL) {
274 HeapRegion* hr = _g1h->heap_region_containing(obj);
275 if (hr == _hr) {
276 // Another reference to the same region.
277 _value = false;
278 }
279 }
280 }
281 }
282 void do_oop(narrowOop* p) { ShouldNotReachHere(); }
283 bool value() const { return _value; }
284 };
285
286 void G1SATBCardTableModRefBS::write_ref_nmethod_pre(oop* dst, nmethod* nm) {
287 oop obj = oopDesc::load_heap_oop(dst);
288 if (obj != NULL) {
289 G1CollectedHeap* g1h = G1CollectedHeap::heap();
290 HeapRegion* hr = g1h->heap_region_containing(obj);
291 G1EnsureLastRefToRegion ensure_last_ref(g1h, hr, dst);
292 nm->oops_do(&ensure_last_ref);
293 if (ensure_last_ref.value()) {
294 // Last reference to this region, remove the nmethod from the rset.
295 hr->remove_strong_code_root(nm);
296 }
297 }
298 }
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