8040722: G1: Clean up usages of heap_region_containing

Reviewed-by: tschatzl, jmasa

hotspot/src/share/vm/gc_implementation/g1/concurrentMark.cpp

@@ -2655,7 +2655,6 @@ public:
       str = " O";
     } else {
       HeapRegion* hr  = _g1h->heap_region_containing(obj);
-      guarantee(hr != NULL, "invariant");
       bool over_tams = _g1h->allocated_since_marking(obj, hr, _vo);
       bool marked = _g1h->is_marked(obj, _vo);
 
@@ -3413,9 +3412,8 @@ G1CMOopClosure::G1CMOopClosure(G1CollectedHeap* g1h,
 }
 
 void CMTask::setup_for_region(HeapRegion* hr) {
-  // Separated the asserts so that we know which one fires.
   assert(hr != NULL,
-        "claim_region() should have filtered out continues humongous regions");
+        "claim_region() should have filtered out NULL regions");
   assert(!hr->continuesHumongous(),
         "claim_region() should have filtered out continues humongous regions");
 

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

@@ -445,24 +445,18 @@ void G1CollectedHeap::stop_conc_gc_threads() {
 // implementation of is_scavengable() for G1 will indicate that
 // all nmethods must be scanned during a partial collection.
 bool G1CollectedHeap::is_in_partial_collection(const void* p) {
-  HeapRegion* hr = heap_region_containing(p);
-  return hr != NULL && hr->in_collection_set();
+  if (p == NULL) {
+    return false;
+  }
+  return heap_region_containing(p)->in_collection_set();
 }
 #endif
 
 // Returns true if the reference points to an object that
 // can move in an incremental collection.
 bool G1CollectedHeap::is_scavengable(const void* p) {
-  G1CollectedHeap* g1h = G1CollectedHeap::heap();
-  G1CollectorPolicy* g1p = g1h->g1_policy();
   HeapRegion* hr = heap_region_containing(p);
-  if (hr == NULL) {
-     // null
-     assert(p == NULL, err_msg("Not NULL " PTR_FORMAT ,p));
-     return false;
-  } else {
-    return !hr->isHumongous();
-  }
+  return !hr->isHumongous();
 }
 
 void G1CollectedHeap::check_ct_logs_at_safepoint() {
@@ -2952,21 +2946,16 @@ CompactibleSpace* G1CollectedHeap::first_compactible_space() {
 
 
 Space* G1CollectedHeap::space_containing(const void* addr) const {
-  Space* res = heap_region_containing(addr);
-  return res;
+  return heap_region_containing(addr);
 }
 
 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
   Space* sp = space_containing(addr);
-  if (sp != NULL) {
-    return sp->block_start(addr);
-  }
-  return NULL;
+  return sp->block_start(addr);
 }
 
 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
   Space* sp = space_containing(addr);
-  assert(sp != NULL, "block_size of address outside of heap");
   return sp->block_size(addr);
 }
 
@@ -4680,30 +4669,19 @@ G1ParClosureSuper::G1ParClosureSuper(G1CollectedHeap* g1,
   _worker_id(par_scan_state->queue_num()) { }
 
 void G1ParCopyHelper::mark_object(oop obj) {
-#ifdef ASSERT
-  HeapRegion* hr = _g1->heap_region_containing(obj);
-  assert(hr != NULL, "sanity");
-  assert(!hr->in_collection_set(), "should not mark objects in the CSet");
-#endif // ASSERT
+  assert(!_g1->heap_region_containing(obj)->in_collection_set(), "should not mark objects in the CSet");
 
   // We know that the object is not moving so it's safe to read its size.
   _cm->grayRoot(obj, (size_t) obj->size(), _worker_id);
 }
 
 void G1ParCopyHelper::mark_forwarded_object(oop from_obj, oop to_obj) {
-#ifdef ASSERT
   assert(from_obj->is_forwarded(), "from obj should be forwarded");
   assert(from_obj->forwardee() == to_obj, "to obj should be the forwardee");
   assert(from_obj != to_obj, "should not be self-forwarded");
 
-  HeapRegion* from_hr = _g1->heap_region_containing(from_obj);
-  assert(from_hr != NULL, "sanity");
-  assert(from_hr->in_collection_set(), "from obj should be in the CSet");
-
-  HeapRegion* to_hr = _g1->heap_region_containing(to_obj);
-  assert(to_hr != NULL, "sanity");
-  assert(!to_hr->in_collection_set(), "should not mark objects in the CSet");
-#endif // ASSERT
+  assert(_g1->heap_region_containing(from_obj)->in_collection_set(), "from obj should be in the CSet");
+  assert(!_g1->heap_region_containing(to_obj)->in_collection_set(), "should not mark objects in the CSet");
 
   // The object might be in the process of being copied by another
   // worker so we cannot trust that its to-space image is
@@ -6461,11 +6439,7 @@ void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) {
 
 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
   HeapRegion* hr = heap_region_containing(p);
-  if (hr == NULL) {
-    return false;
-  } else {
-    return hr->is_in(p);
-  }
+  return hr->is_in(p);
 }
 
 // Methods for the mutator alloc region

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

@@ -1380,17 +1380,15 @@ public:
   // space containing a given address, or else returns NULL.
   virtual Space* space_containing(const void* addr) const;
 
-  // A G1CollectedHeap will contain some number of heap regions.  This
-  // finds the region containing a given address, or else returns NULL.
-  template <class T>
-  inline HeapRegion* heap_region_containing(const T addr) const;
-
-  // Like the above, but requires "addr" to be in the heap (to avoid a
-  // null-check), and unlike the above, may return an continuing humongous
-  // region.
+  // Returns the HeapRegion that contains addr. addr must not be NULL.
   template <class T>
   inline HeapRegion* heap_region_containing_raw(const T addr) const;
 
+  // Returns the HeapRegion that contains addr. addr must not be NULL.
+  // If addr is within a humongous continues region, it returns its humongous start region.
+  template <class T>
+  inline HeapRegion* heap_region_containing(const T addr) const;
+
   // A CollectedHeap is divided into a dense sequence of "blocks"; that is,
   // each address in the (reserved) heap is a member of exactly
   // one block.  The defining characteristic of a block is that it is
@@ -1532,7 +1530,6 @@ public:
   // the region to which the object belongs. An object is dead
   // iff a) it was not allocated since the last mark and b) it
   // is not marked.
-
   bool is_obj_dead(const oop obj, const HeapRegion* hr) const {
     return
       !hr->obj_allocated_since_prev_marking(obj) &&
@@ -1542,7 +1539,6 @@ public:
   // This function returns true when an object has been
   // around since the previous marking and hasn't yet
   // been marked during this marking.
-
   bool is_obj_ill(const oop obj, const HeapRegion* hr) const {
     return
       !hr->obj_allocated_since_next_marking(obj) &&

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

@@ -42,21 +42,22 @@ inline HeapRegion* G1CollectedHeap::region_at(uint index) const { return _hrs.at
 
 template <class T>
 inline HeapRegion*
-G1CollectedHeap::heap_region_containing(const T addr) const {
-  HeapRegion* hr = _hrs.addr_to_region((HeapWord*) addr);
-  // hr can be null if addr in perm_gen
-  if (hr != NULL && hr->continuesHumongous()) {
-    hr = hr->humongous_start_region();
-  }
-  return hr;
+G1CollectedHeap::heap_region_containing_raw(const T addr) const {
+  assert(addr != NULL, "invariant");
+  assert(_g1_reserved.contains((const void*) addr),
+      err_msg("Address "PTR_FORMAT" is outside of the heap ranging from ["PTR_FORMAT" to "PTR_FORMAT")",
+          (void*)addr, _g1_reserved.start(), _g1_reserved.end()));
+  return _hrs.addr_to_region((HeapWord*) addr);
 }
 
 template <class T>
 inline HeapRegion*
-G1CollectedHeap::heap_region_containing_raw(const T addr) const {
-  assert(_g1_reserved.contains((const void*) addr), "invariant");
-  HeapRegion* res = _hrs.addr_to_region_unsafe((HeapWord*) addr);
-  return res;
+G1CollectedHeap::heap_region_containing(const T addr) const {
+  HeapRegion* hr = heap_region_containing_raw(addr);
+  if (hr->continuesHumongous()) {
+    return hr->humongous_start_region();
+  }
+  return hr;
 }
 
 inline void G1CollectedHeap::old_set_remove(HeapRegion* hr) {
@@ -134,8 +135,7 @@ G1CollectedHeap::dirty_young_block(HeapWord* start, size_t word_size) {
   // have to keep calling heap_region_containing_raw() in the
   // asserts below.
   DEBUG_ONLY(HeapRegion* containing_hr = heap_region_containing_raw(start);)
-  assert(containing_hr != NULL && start != NULL && word_size > 0,
-         "pre-condition");
+  assert(word_size > 0, "pre-condition");
   assert(containing_hr->is_in(start), "it should contain start");
   assert(containing_hr->is_young(), "it should be young");
   assert(!containing_hr->isHumongous(), "it should not be humongous");
@@ -246,8 +246,10 @@ inline void G1CollectedHeap::reset_evacuation_should_fail() {
 #endif  // #ifndef PRODUCT
 
 inline bool G1CollectedHeap::is_in_young(const oop obj) {
-  HeapRegion* hr = heap_region_containing(obj);
-  return hr != NULL && hr->is_young();
+  if (obj == NULL) {
+    return false;
+  }
+  return heap_region_containing(obj)->is_young();
 }
 
 // We don't need barriers for initializing stores to objects
@@ -260,21 +262,17 @@ inline bool G1CollectedHeap::can_elide_initializing_store_barrier(oop new_obj) {
 }
 
 inline bool G1CollectedHeap::is_obj_dead(const oop obj) const {
-  const HeapRegion* hr = heap_region_containing(obj);
-  if (hr == NULL) {
-    if (obj == NULL) return false;
-    else return true;
+  if (obj == NULL) {
+    return false;
   }
-  else return is_obj_dead(obj, hr);
+  return is_obj_dead(obj, heap_region_containing(obj));
 }
 
 inline bool G1CollectedHeap::is_obj_ill(const oop obj) const {
-  const HeapRegion* hr = heap_region_containing(obj);
-  if (hr == NULL) {
-    if (obj == NULL) return false;
-    else return true;
+  if (obj == NULL) {
+    return false;
   }
-  else return is_obj_ill(obj, hr);
+  return is_obj_ill(obj, heap_region_containing(obj));
 }
 
 template <class T> inline void G1ParScanThreadState::immediate_rs_update(HeapRegion* from, T* p, int tid) {

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

@@ -125,9 +125,7 @@ inline void G1RootRegionScanClosure::do_oop_nv(T* p) {
   if (!oopDesc::is_null(heap_oop)) {
     oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
     HeapRegion* hr = _g1h->heap_region_containing((HeapWord*) obj);
-    if (hr != NULL) {
-      _cm->grayRoot(obj, obj->size(), _worker_id, hr);
-    }
+    _cm->grayRoot(obj, obj->size(), _worker_id, hr);
   }
 }
 
@@ -154,57 +152,63 @@ inline void G1InvokeIfNotTriggeredClosure::do_oop_nv(T* p) {
 template <class T>
 inline void G1UpdateRSOrPushRefOopClosure::do_oop_nv(T* p) {
   oop obj = oopDesc::load_decode_heap_oop(p);
+  if (obj == NULL) {
+    return;
+  }
+
 #ifdef ASSERT
   // can't do because of races
   // assert(obj == NULL || obj->is_oop(), "expected an oop");
 
   // Do the safe subset of is_oop
-  if (obj != NULL) {
 #ifdef CHECK_UNHANDLED_OOPS
-    oopDesc* o = obj.obj();
+  oopDesc* o = obj.obj();
 #else
-    oopDesc* o = obj;
+  oopDesc* o = obj;
 #endif // CHECK_UNHANDLED_OOPS
-    assert((intptr_t)o % MinObjAlignmentInBytes == 0, "not oop aligned");
-    assert(Universe::heap()->is_in_reserved(obj), "must be in heap");
-  }
+  assert((intptr_t)o % MinObjAlignmentInBytes == 0, "not oop aligned");
+  assert(Universe::heap()->is_in_reserved(obj), "must be in heap");
 #endif // ASSERT
 
   assert(_from != NULL, "from region must be non-NULL");
   assert(_from->is_in_reserved(p), "p is not in from");
 
   HeapRegion* to = _g1->heap_region_containing(obj);
-  if (to != NULL && _from != to) {
-    // The _record_refs_into_cset flag is true during the RSet
-    // updating part of an evacuation pause. It is false at all
-    // other times:
-    //  * rebuilding the remembered sets after a full GC
-    //  * during concurrent refinement.
-    //  * updating the remembered sets of regions in the collection
-    //    set in the event of an evacuation failure (when deferred
-    //    updates are enabled).
+  if (_from == to) {
+    // Normally this closure should only be called with cross-region references.
+    // But since Java threads are manipulating the references concurrently and we
+    // reload the values things may have changed.
+    return;
+  }
 
-    if (_record_refs_into_cset && to->in_collection_set()) {
-      // We are recording references that point into the collection
-      // set and this particular reference does exactly that...
-      // If the referenced object has already been forwarded
-      // to itself, we are handling an evacuation failure and
-      // we have already visited/tried to copy this object
-      // there is no need to retry.
-      if (!self_forwarded(obj)) {
-        assert(_push_ref_cl != NULL, "should not be null");
-        // Push the reference in the refs queue of the G1ParScanThreadState
-        // instance for this worker thread.
-        _push_ref_cl->do_oop(p);
-      }
+  // The _record_refs_into_cset flag is true during the RSet
+  // updating part of an evacuation pause. It is false at all
+  // other times:
+  //  * rebuilding the remembered sets after a full GC
+  //  * during concurrent refinement.
+  //  * updating the remembered sets of regions in the collection
+  //    set in the event of an evacuation failure (when deferred
+  //    updates are enabled).
 
-      // Deferred updates to the CSet are either discarded (in the normal case),
-      // or processed (if an evacuation failure occurs) at the end
-      // of the collection.
-      // See G1RemSet::cleanup_after_oops_into_collection_set_do().
-      return;
+  if (_record_refs_into_cset && to->in_collection_set()) {
+    // We are recording references that point into the collection
+    // set and this particular reference does exactly that...
+    // If the referenced object has already been forwarded
+    // to itself, we are handling an evacuation failure and
+    // we have already visited/tried to copy this object
+    // there is no need to retry.
+    if (!self_forwarded(obj)) {
+      assert(_push_ref_cl != NULL, "should not be null");
+      // Push the reference in the refs queue of the G1ParScanThreadState
+      // instance for this worker thread.
+      _push_ref_cl->do_oop(p);
     }
 
+    // Deferred updates to the CSet are either discarded (in the normal case),
+    // or processed (if an evacuation failure occurs) at the end
+    // of the collection.
+    // See G1RemSet::cleanup_after_oops_into_collection_set_do().
+  } else {
     // We either don't care about pushing references that point into the
     // collection set (i.e. we're not during an evacuation pause) _or_
     // the reference doesn't point into the collection set. Either way

hotspot/src/share/vm/gc_implementation/g1/g1RemSet.cpp

@@ -210,7 +210,6 @@ public:
 #endif
 
       HeapRegion* card_region = _g1h->heap_region_containing(card_start);
-      assert(card_region != NULL, "Yielding cards not in the heap?");
       _cards++;
 
       if (!card_region->is_on_dirty_cards_region_list()) {
@@ -405,7 +404,6 @@ public:
     HeapWord* start = _ct_bs->addr_for(card_ptr);
     // And find the region containing it.
     HeapRegion* r = _g1->heap_region_containing(start);
-    assert(r != NULL, "unexpected null");
 
     // Scan oops in the card looking for references into the collection set
     // Don't use addr_for(card_ptr + 1) which can ask for
@@ -567,11 +565,6 @@ bool G1RemSet::refine_card(jbyte* card_ptr, uint worker_i,
   HeapWord* start = _ct_bs->addr_for(card_ptr);
   // And find the region containing it.
   HeapRegion* r = _g1->heap_region_containing(start);
-  if (r == NULL) {
-    // Again no need to return that this card contains refs that
-    // point into the collection set.
-    return false;  // Not in the G1 heap (might be in perm, for example.)
-  }
 
   // Why do we have to check here whether a card is on a young region,
   // given that we dirty young regions and, as a result, the
@@ -624,10 +617,6 @@ bool G1RemSet::refine_card(jbyte* card_ptr, uint worker_i,
 
     start = _ct_bs->addr_for(card_ptr);
     r = _g1->heap_region_containing(start);
-    if (r == NULL) {
-      // Not in the G1 heap
-      return false;
-    }
 
     // Checking whether the region we got back from the cache
     // is young here is inappropriate. The region could have been

hotspot/src/share/vm/gc_implementation/g1/g1RemSet.inline.hpp

@@ -45,26 +45,28 @@ inline void G1RemSet::write_ref(HeapRegion* from, T* p) {
 template <class T>
 inline void G1RemSet::par_write_ref(HeapRegion* from, T* p, int tid) {
   oop obj = oopDesc::load_decode_heap_oop(p);
+  if (obj == NULL) {
+    return;
+  }
+
 #ifdef ASSERT
   // can't do because of races
   // assert(obj == NULL || obj->is_oop(), "expected an oop");
 
   // Do the safe subset of is_oop
-  if (obj != NULL) {
 #ifdef CHECK_UNHANDLED_OOPS
-    oopDesc* o = obj.obj();
+  oopDesc* o = obj.obj();
 #else
-    oopDesc* o = obj;
+  oopDesc* o = obj;
 #endif // CHECK_UNHANDLED_OOPS
-    assert((intptr_t)o % MinObjAlignmentInBytes == 0, "not oop aligned");
-    assert(Universe::heap()->is_in_reserved(obj), "must be in heap");
-  }
+  assert((intptr_t)o % MinObjAlignmentInBytes == 0, "not oop aligned");
+  assert(Universe::heap()->is_in_reserved(obj), "must be in heap");
 #endif // ASSERT
 
   assert(from == NULL || from->is_in_reserved(p), "p is not in from");
 
   HeapRegion* to = _g1->heap_region_containing(obj);
-  if (to != NULL && from != to) {
+  if (from != to) {
     assert(to->rem_set() != NULL, "Need per-region 'into' remsets.");
     to->rem_set()->add_reference(p, tid);
   }

hotspot/src/share/vm/gc_implementation/g1/heapRegionRemSet.cpp

@@ -797,7 +797,6 @@ bool OtherRegionsTable::contains_reference(OopOrNarrowOopStar from) const {
 
 bool OtherRegionsTable::contains_reference_locked(OopOrNarrowOopStar from) const {
   HeapRegion* hr = _g1h->heap_region_containing_raw(from);
-  if (hr == NULL) return false;
   RegionIdx_t hr_ind = (RegionIdx_t) hr->hrs_index();
   // Is this region in the coarse map?
   if (_coarse_map.at(hr_ind)) return true;

hotspot/src/share/vm/gc_implementation/g1/heapRegionSeq.cpp

@@ -240,7 +240,6 @@ void HeapRegionSeq::verify_optional() {
       // Asserts will fire if i is >= _length
       HeapWord* addr = hr->bottom();
       guarantee(addr_to_region(addr) == hr, "sanity");
-      guarantee(addr_to_region_unsafe(addr) == hr, "sanity");
     } else {
       guarantee(hr->is_empty(), "sanity");
       guarantee(!hr->isHumongous(), "sanity");

hotspot/src/share/vm/gc_implementation/g1/heapRegionSeq.hpp

@@ -110,10 +110,6 @@ class HeapRegionSeq: public CHeapObj<mtGC> {
   // HeapRegion, otherwise return NULL.
   inline HeapRegion* addr_to_region(HeapWord* addr) const;
 
-  // Return the HeapRegion that corresponds to the given
-  // address. Assume the address is valid.
-  inline HeapRegion* addr_to_region_unsafe(HeapWord* addr) const;
-
   // Return the number of regions that have been committed in the heap.
   uint length() const { return _committed_length; }
 

hotspot/src/share/vm/gc_implementation/g1/heapRegionSeq.inline.hpp

@@ -28,21 +28,17 @@
 #include "gc_implementation/g1/heapRegion.hpp"
 #include "gc_implementation/g1/heapRegionSeq.hpp"
 
-inline HeapRegion* HeapRegionSeq::addr_to_region_unsafe(HeapWord* addr) const {
+inline HeapRegion* HeapRegionSeq::addr_to_region(HeapWord* addr) const {
+  assert(addr < heap_end(),
+        err_msg("addr: "PTR_FORMAT" end: "PTR_FORMAT, addr, heap_end()));
+  assert(addr >= heap_bottom(),
+        err_msg("addr: "PTR_FORMAT" bottom: "PTR_FORMAT, addr, heap_bottom()));
+
   HeapRegion* hr = _regions.get_by_address(addr);
   assert(hr != NULL, "invariant");
   return hr;
 }
 
-inline HeapRegion* HeapRegionSeq::addr_to_region(HeapWord* addr) const {
-  if (addr != NULL && addr < heap_end()) {
-    assert(addr >= heap_bottom(),
-          err_msg("addr: "PTR_FORMAT" bottom: "PTR_FORMAT, addr, heap_bottom()));
-    return addr_to_region_unsafe(addr);
-  }
-  return NULL;
-}
-
 inline HeapRegion* HeapRegionSeq::at(uint index) const {
   assert(index < length(), "pre-condition");
   HeapRegion* hr = _regions.get_by_index(index);