1235 T o = RawAccess<>::oop_load(p);
1236 if (!CompressedOops::is_null(o)) {
1237 oop obj = CompressedOops::decode_not_null(o);
1238 oop fwd = (oop) ShenandoahForwarding::get_forwardee_raw_unchecked(obj);
1239 if (fwd == NULL) {
1240 // There is an odd interaction with VM_HeapWalkOperation, see jvmtiTagMap.cpp.
1241 //
1242 // That operation walks the reachable objects on its own, storing the marking
1243 // wavefront in the object marks. When it is done, it calls the CollectedHeap
1244 // to iterate over all objects to clean up the mess. When it reaches here,
1245 // the Shenandoah fwdptr resolution code encounters the marked objects with
1246 // NULL forwardee. Trying to act on that would crash the VM. Or fail the
1247 // asserts, should we go for resolve_forwarded_pointer(obj).
1248 //
1249 // Therefore, we have to dodge it by doing the raw access to forwardee, and
1250 // assuming the object had no forwardee, if that thing is NULL.
1251 } else {
1252 obj = fwd;
1253 }
1254 assert(oopDesc::is_oop(obj), "must be a valid oop");
1255 if (!_bitmap->is_marked(obj)) {
1256 _bitmap->mark(obj);
1257 _oop_stack->push(obj);
1258 }
1259 }
1260 }
1261 public:
1262 ObjectIterateScanRootClosure(MarkBitMap* bitmap, Stack<oop,mtGC>* oop_stack) :
1263 _bitmap(bitmap), _oop_stack(oop_stack) {}
1264 void do_oop(oop* p) { do_oop_work(p); }
1265 void do_oop(narrowOop* p) { do_oop_work(p); }
1266 };
1267
1268 /*
1269 * This is public API, used in preparation of object_iterate().
1270 * Since we don't do linear scan of heap in object_iterate() (see comment below), we don't
1271 * need to make the heap parsable. For Shenandoah-internal linear heap scans that we can
1272 * control, we call SH::make_tlabs_parsable().
1273 */
1274 void ShenandoahHeap::ensure_parsability(bool retire_tlabs) {
1275 // No-op.
1276 }
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1235 T o = RawAccess<>::oop_load(p);
1236 if (!CompressedOops::is_null(o)) {
1237 oop obj = CompressedOops::decode_not_null(o);
1238 oop fwd = (oop) ShenandoahForwarding::get_forwardee_raw_unchecked(obj);
1239 if (fwd == NULL) {
1240 // There is an odd interaction with VM_HeapWalkOperation, see jvmtiTagMap.cpp.
1241 //
1242 // That operation walks the reachable objects on its own, storing the marking
1243 // wavefront in the object marks. When it is done, it calls the CollectedHeap
1244 // to iterate over all objects to clean up the mess. When it reaches here,
1245 // the Shenandoah fwdptr resolution code encounters the marked objects with
1246 // NULL forwardee. Trying to act on that would crash the VM. Or fail the
1247 // asserts, should we go for resolve_forwarded_pointer(obj).
1248 //
1249 // Therefore, we have to dodge it by doing the raw access to forwardee, and
1250 // assuming the object had no forwardee, if that thing is NULL.
1251 } else {
1252 obj = fwd;
1253 }
1254 assert(oopDesc::is_oop(obj), "must be a valid oop");
1255 if (!_bitmap->is_marked((HeapWord*) obj)) {
1256 _bitmap->mark((HeapWord*) obj);
1257 _oop_stack->push(obj);
1258 }
1259 }
1260 }
1261 public:
1262 ObjectIterateScanRootClosure(MarkBitMap* bitmap, Stack<oop,mtGC>* oop_stack) :
1263 _bitmap(bitmap), _oop_stack(oop_stack) {}
1264 void do_oop(oop* p) { do_oop_work(p); }
1265 void do_oop(narrowOop* p) { do_oop_work(p); }
1266 };
1267
1268 /*
1269 * This is public API, used in preparation of object_iterate().
1270 * Since we don't do linear scan of heap in object_iterate() (see comment below), we don't
1271 * need to make the heap parsable. For Shenandoah-internal linear heap scans that we can
1272 * control, we call SH::make_tlabs_parsable().
1273 */
1274 void ShenandoahHeap::ensure_parsability(bool retire_tlabs) {
1275 // No-op.
1276 }
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