8035330: Remove G1ParScanPartialArrayClosure and G1ParScanHeapEvacClosure

Summary: Mentioned closures are actually wrapped methods. This adds confusion to readers, and in this case also increases code size as G1ParScanHeapEvacClosure is part of the oop_oop_iterate() methods. Move them into G1ParScanThreadState as methods.
Reviewed-by: stefank

src/share/vm/gc_implementation/g1/g1CollectedHeap.cpp

@@ -4650,9 +4650,7 @@ bool G1ParScanThreadState::verify_task(StarTask ref) const {
 #endif // ASSERT
 
 void G1ParScanThreadState::trim_queue() {
-  assert(_evac_cl != NULL, "not set");
   assert(_evac_failure_cl != NULL, "not set");
-  assert(_partial_scan_cl != NULL, "not set");
 
   StarTask ref;
   do {
@@ -4854,55 +4852,6 @@ void G1ParCopyClosure<barrier, do_mark_object>::do_oop_work(T* p) {
 template void G1ParCopyClosure<G1BarrierEvac, false>::do_oop_work(oop* p);
 template void G1ParCopyClosure<G1BarrierEvac, false>::do_oop_work(narrowOop* p);
 
-template <class T> void G1ParScanPartialArrayClosure::do_oop_nv(T* p) {
-  assert(has_partial_array_mask(p), "invariant");
-  oop from_obj = clear_partial_array_mask(p);
-
-  assert(Universe::heap()->is_in_reserved(from_obj), "must be in heap.");
-  assert(from_obj->is_objArray(), "must be obj array");
-  objArrayOop from_obj_array = objArrayOop(from_obj);
-  // The from-space object contains the real length.
-  int length                 = from_obj_array->length();
-
-  assert(from_obj->is_forwarded(), "must be forwarded");
-  oop to_obj                 = from_obj->forwardee();
-  assert(from_obj != to_obj, "should not be chunking self-forwarded objects");
-  objArrayOop to_obj_array   = objArrayOop(to_obj);
-  // We keep track of the next start index in the length field of the
-  // to-space object.
-  int next_index             = to_obj_array->length();
-  assert(0 <= next_index && next_index < length,
-         err_msg("invariant, next index: %d, length: %d", next_index, length));
-
-  int start                  = next_index;
-  int end                    = length;
-  int remainder              = end - start;
-  // We'll try not to push a range that's smaller than ParGCArrayScanChunk.
-  if (remainder > 2 * ParGCArrayScanChunk) {
-    end = start + ParGCArrayScanChunk;
-    to_obj_array->set_length(end);
-    // Push the remainder before we process the range in case another
-    // worker has run out of things to do and can steal it.
-    oop* from_obj_p = set_partial_array_mask(from_obj);
-    _par_scan_state->push_on_queue(from_obj_p);
-  } else {
-    assert(length == end, "sanity");
-    // We'll process the final range for this object. Restore the length
-    // so that the heap remains parsable in case of evacuation failure.
-    to_obj_array->set_length(end);
-  }
-  _scanner.set_region(_g1->heap_region_containing_raw(to_obj));
-  // Process indexes [start,end). It will also process the header
-  // along with the first chunk (i.e., the chunk with start == 0).
-  // Note that at this point the length field of to_obj_array is not
-  // correct given that we are using it to keep track of the next
-  // start index. oop_iterate_range() (thankfully!) ignores the length
-  // field and only relies on the start / end parameters.  It does
-  // however return the size of the object which will be incorrect. So
-  // we have to ignore it even if we wanted to use it.
-  to_obj_array->oop_iterate_range(&_scanner, start, end);
-}
-
 class G1ParEvacuateFollowersClosure : public VoidClosure {
 protected:
   G1CollectedHeap*              _g1h;
@@ -5044,13 +4993,9 @@ public:
       ReferenceProcessor*             rp = _g1h->ref_processor_stw();
 
       G1ParScanThreadState            pss(_g1h, worker_id, rp);
-      G1ParScanHeapEvacClosure        scan_evac_cl(_g1h, &pss, rp);
       G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, rp);
-      G1ParScanPartialArrayClosure    partial_scan_cl(_g1h, &pss, rp);
 
-      pss.set_evac_closure(&scan_evac_cl);
       pss.set_evac_failure_closure(&evac_failure_cl);
-      pss.set_partial_scan_closure(&partial_scan_cl);
 
       G1ParScanExtRootClosure        only_scan_root_cl(_g1h, &pss, rp);
       G1ParScanMetadataClosure       only_scan_metadata_cl(_g1h, &pss, rp);
@@ -5510,14 +5455,9 @@ public:
     G1STWIsAliveClosure is_alive(_g1h);
 
     G1ParScanThreadState            pss(_g1h, worker_id, NULL);
-
-    G1ParScanHeapEvacClosure        scan_evac_cl(_g1h, &pss, NULL);
     G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL);
-    G1ParScanPartialArrayClosure    partial_scan_cl(_g1h, &pss, NULL);
 
-    pss.set_evac_closure(&scan_evac_cl);
     pss.set_evac_failure_closure(&evac_failure_cl);
-    pss.set_partial_scan_closure(&partial_scan_cl);
 
     G1ParScanExtRootClosure        only_copy_non_heap_cl(_g1h, &pss, NULL);
     G1ParScanMetadataClosure       only_copy_metadata_cl(_g1h, &pss, NULL);
@@ -5622,13 +5562,9 @@ public:
     HandleMark   hm;
 
     G1ParScanThreadState            pss(_g1h, worker_id, NULL);
-    G1ParScanHeapEvacClosure        scan_evac_cl(_g1h, &pss, NULL);
     G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL);
-    G1ParScanPartialArrayClosure    partial_scan_cl(_g1h, &pss, NULL);
 
-    pss.set_evac_closure(&scan_evac_cl);
     pss.set_evac_failure_closure(&evac_failure_cl);
-    pss.set_partial_scan_closure(&partial_scan_cl);
 
     assert(pss.refs()->is_empty(), "both queue and overflow should be empty");
 
@@ -5752,13 +5688,9 @@ void G1CollectedHeap::process_discovered_references(uint no_of_gc_workers) {
   // We do not embed a reference processor in the copying/scanning
   // closures while we're actually processing the discovered
   // reference objects.
-  G1ParScanHeapEvacClosure        scan_evac_cl(this, &pss, NULL);
   G1ParScanHeapEvacFailureClosure evac_failure_cl(this, &pss, NULL);
-  G1ParScanPartialArrayClosure    partial_scan_cl(this, &pss, NULL);
 
-  pss.set_evac_closure(&scan_evac_cl);
   pss.set_evac_failure_closure(&evac_failure_cl);
-  pss.set_partial_scan_closure(&partial_scan_cl);
 
   assert(pss.refs()->is_empty(), "pre-condition");
 

src/share/vm/gc_implementation/g1/g1CollectedHeap.hpp

@@ -1793,8 +1793,6 @@ protected:
   size_t           _undo_waste;
 
   OopsInHeapRegionClosure*      _evac_failure_cl;
-  G1ParScanHeapEvacClosure*     _evac_cl;
-  G1ParScanPartialArrayClosure* _partial_scan_cl;
 
   int  _hash_seed;
   uint _queue_num;
@@ -1922,14 +1920,6 @@ public:
     return _evac_failure_cl;
   }
 
-  void set_evac_closure(G1ParScanHeapEvacClosure* evac_cl) {
-    _evac_cl = evac_cl;
-  }
-
-  void set_partial_scan_closure(G1ParScanPartialArrayClosure* partial_scan_cl) {
-    _partial_scan_cl = partial_scan_cl;
-  }
-
   int* hash_seed() { return &_hash_seed; }
   uint queue_num() { return _queue_num; }
 
@@ -1977,19 +1967,121 @@ public:
                                                  false /* retain */);
     }
   }
+private:
+  #define G1_PARTIAL_ARRAY_MASK 0x2
+
+  inline bool has_partial_array_mask(oop* ref) const {
+    return ((uintptr_t)ref & G1_PARTIAL_ARRAY_MASK) == G1_PARTIAL_ARRAY_MASK;
+  }
+
+  // We never encode partial array oops as narrowOop*, so return false immediately.
+  // This allows the compiler to create optimized code when popping references from
+  // the work queue.
+  inline bool has_partial_array_mask(narrowOop* ref) const {
+    assert(((uintptr_t)ref & G1_PARTIAL_ARRAY_MASK) != G1_PARTIAL_ARRAY_MASK, "Partial array oop reference encoded as narrowOop*");
+    return false;
+  }
+
+  // Only implement set_partial_array_mask() for regular oops, not for narrowOops.
+  // We always encode partial arrays as regular oop, to allow the
+  // specialization for has_partial_array_mask() for narrowOops above.
+  // This means that unintentional use of this method with narrowOops are caught
+  // by the compiler.
+  inline oop* set_partial_array_mask(oop obj) const {
+    assert(((uintptr_t)(void *)obj & G1_PARTIAL_ARRAY_MASK) == 0, "Information loss!");
+    return (oop*) ((uintptr_t)(void *)obj | G1_PARTIAL_ARRAY_MASK);
+  }
+
+  inline oop clear_partial_array_mask(oop* ref) const {
+    return cast_to_oop((intptr_t)ref & ~G1_PARTIAL_ARRAY_MASK);
+  }
+
+  void do_oop_partial_array(oop* p) {
+    assert(has_partial_array_mask(p), "invariant");
+    oop from_obj = clear_partial_array_mask(p);
+
+    assert(Universe::heap()->is_in_reserved(from_obj), "must be in heap.");
+    assert(from_obj->is_objArray(), "must be obj array");
+    objArrayOop from_obj_array = objArrayOop(from_obj);
+    // The from-space object contains the real length.
+    int length                 = from_obj_array->length();
+
+    assert(from_obj->is_forwarded(), "must be forwarded");
+    oop to_obj                 = from_obj->forwardee();
+    assert(from_obj != to_obj, "should not be chunking self-forwarded objects");
+    objArrayOop to_obj_array   = objArrayOop(to_obj);
+    // We keep track of the next start index in the length field of the
+    // to-space object.
+    int next_index             = to_obj_array->length();
+    assert(0 <= next_index && next_index < length,
+           err_msg("invariant, next index: %d, length: %d", next_index, length));
+
+    int start                  = next_index;
+    int end                    = length;
+    int remainder              = end - start;
+    // We'll try not to push a range that's smaller than ParGCArrayScanChunk.
+    if (remainder > 2 * ParGCArrayScanChunk) {
+      end = start + ParGCArrayScanChunk;
+      to_obj_array->set_length(end);
+      // Push the remainder before we process the range in case another
+      // worker has run out of things to do and can steal it.
+      oop* from_obj_p = set_partial_array_mask(from_obj);
+      push_on_queue(from_obj_p);
+    } else {
+      assert(length == end, "sanity");
+      // We'll process the final range for this object. Restore the length
+      // so that the heap remains parsable in case of evacuation failure.
+      to_obj_array->set_length(end);
+    }
+    _scanner.set_region(_g1h->heap_region_containing_raw(to_obj));
+    // Process indexes [start,end). It will also process the header
+    // along with the first chunk (i.e., the chunk with start == 0).
+    // Note that at this point the length field of to_obj_array is not
+    // correct given that we are using it to keep track of the next
+    // start index. oop_iterate_range() (thankfully!) ignores the length
+    // field and only relies on the start / end parameters.  It does
+    // however return the size of the object which will be incorrect. So
+    // we have to ignore it even if we wanted to use it.
+    to_obj_array->oop_iterate_range(&_scanner, start, end);
+  }
+
+  // This method is applied to the fields of the objects that have just been copied.
+  template <class T> void do_oop_evac(T* p, HeapRegion* from) {
+    assert(!oopDesc::is_null(oopDesc::load_decode_heap_oop(p)),
+           "Reference should not be NULL here as such are never pushed to the task queue.");
+    oop obj = oopDesc::load_decode_heap_oop_not_null(p);
+
+    // Although we never intentionally push references outside of the collection
+    // set, due to (benign) races in the claim mechanism during RSet scanning more
+    // than one thread might claim the same card. So the same card may be
+    // processed multiple times. So redo this check.
+    if (_g1h->in_cset_fast_test(obj)) {
+      oop forwardee;
+      if (obj->is_forwarded()) {
+        forwardee = obj->forwardee();
+      } else {
+        forwardee = copy_to_survivor_space(obj);
+      }
+      assert(forwardee != NULL, "forwardee should not be NULL");
+      oopDesc::encode_store_heap_oop(p, forwardee);
+    }
+
+    assert(obj != NULL, "Must be");
+    update_rs(from, p, queue_num());
+  }
+public:
 
   oop copy_to_survivor_space(oop const obj);
 
   template <class T> void deal_with_reference(T* ref_to_scan) {
-    if (has_partial_array_mask(ref_to_scan)) {
-      _partial_scan_cl->do_oop_nv(ref_to_scan);
-    } else {
+    if (!has_partial_array_mask(ref_to_scan)) {
       // Note: we can use "raw" versions of "region_containing" because
       // "obj_to_scan" is definitely in the heap, and is not in a
       // humongous region.
       HeapRegion* r = _g1h->heap_region_containing_raw(ref_to_scan);
-      _evac_cl->set_region(r);
-      _evac_cl->do_oop_nv(ref_to_scan);
+      do_oop_evac(ref_to_scan, r);
+    } else {
+      do_oop_partial_array((oop*)ref_to_scan);
     }
   }
 

src/share/vm/gc_implementation/g1/g1OopClosures.hpp

@@ -80,53 +80,6 @@ public:
   virtual void do_oop(narrowOop* p)    { do_oop_nv(p); }
 };
 
-#define G1_PARTIAL_ARRAY_MASK 0x2
-
-inline bool has_partial_array_mask(oop* ref) {
-  return ((uintptr_t)ref & G1_PARTIAL_ARRAY_MASK) == G1_PARTIAL_ARRAY_MASK;
-}
-
-// We never encode partial array oops as narrowOop*, so return false immediately.
-// This allows the compiler to create optimized code when popping references from
-// the work queue.
-inline bool has_partial_array_mask(narrowOop* ref) {
-  assert(((uintptr_t)ref & G1_PARTIAL_ARRAY_MASK) != G1_PARTIAL_ARRAY_MASK, "Partial array oop reference encoded as narrowOop*");
-  return false;
-}
-
-// Only implement set_partial_array_mask() for regular oops, not for narrowOops.
-// We always encode partial arrays as regular oop, to allow the
-// specialization for has_partial_array_mask() for narrowOops above.
-// This means that unintentional use of this method with narrowOops are caught
-// by the compiler.
-inline oop* set_partial_array_mask(oop obj) {
-  assert(((uintptr_t)(void *)obj & G1_PARTIAL_ARRAY_MASK) == 0, "Information loss!");
-  return (oop*) ((uintptr_t)(void *)obj | G1_PARTIAL_ARRAY_MASK);
-}
-
-template <class T> inline oop clear_partial_array_mask(T* ref) {
-  return cast_to_oop((intptr_t)ref & ~G1_PARTIAL_ARRAY_MASK);
-}
-
-class G1ParScanPartialArrayClosure : public G1ParClosureSuper {
-  G1ParScanClosure _scanner;
-
-public:
-  G1ParScanPartialArrayClosure(G1CollectedHeap* g1, G1ParScanThreadState* par_scan_state, ReferenceProcessor* rp) :
-    G1ParClosureSuper(g1, par_scan_state), _scanner(g1, par_scan_state, rp)
-  {
-    assert(_ref_processor == NULL, "sanity");
-  }
-
-  G1ParScanClosure* scanner() {
-    return &_scanner;
-  }
-
-  template <class T> void do_oop_nv(T* p);
-  virtual void do_oop(oop* p)       { do_oop_nv(p); }
-  virtual void do_oop(narrowOop* p) { do_oop_nv(p); }
-};
-
 // Add back base class for metadata
 class G1ParCopyHelper : public G1ParClosureSuper {
 protected:
@@ -173,15 +126,8 @@ typedef G1ParCopyClosure<G1BarrierKlass, false> G1ParScanMetadataClosure;
 typedef G1ParCopyClosure<G1BarrierNone, true> G1ParScanAndMarkExtRootClosure;
 typedef G1ParCopyClosure<G1BarrierKlass, true> G1ParScanAndMarkMetadataClosure;
 
-// The following closure type is defined in g1_specialized_oop_closures.hpp:
-//
-// typedef G1ParCopyClosure<G1BarrierEvac, false> G1ParScanHeapEvacClosure;
-
 // We use a separate closure to handle references during evacuation
 // failure processing.
-// We could have used another instance of G1ParScanHeapEvacClosure
-// (since that closure no longer assumes that the references it
-// handles point into the collection set).
 
 typedef G1ParCopyClosure<G1BarrierEvac, false> G1ParScanHeapEvacFailureClosure;
 

src/share/vm/gc_implementation/g1/g1_specialized_oop_closures.hpp

@@ -43,8 +43,6 @@ class G1ParCopyClosure;
 class G1ParScanClosure;
 class G1ParPushHeapRSClosure;
 
-typedef G1ParCopyClosure<G1BarrierEvac, false> G1ParScanHeapEvacClosure;
-
 class FilterIntoCSClosure;
 class FilterOutOfRegionClosure;
 class G1CMOopClosure;
@@ -61,7 +59,6 @@ class G1UpdateRSOrPushRefOopClosure;
 #endif
 
 #define FURTHER_SPECIALIZED_OOP_OOP_ITERATE_CLOSURES(f) \
-      f(G1ParScanHeapEvacClosure,_nv)                   \
       f(G1ParScanClosure,_nv)                           \
       f(G1ParPushHeapRSClosure,_nv)                     \
       f(FilterIntoCSClosure,_nv)                        \