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src/share/vm/gc/g1/heapRegion.hpp
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@@ -41,10 +41,19 @@
// The problem is that the existence of this method breaks
// the independence of barrier sets from remembered sets.
// The solution is to remove this method from the definition
// of a Space.
+// Each heap region is self contained. top() and end() can never
+// be set beyond the end of the region. For humongous objects,
+// the first region is a StartsHumongous region. If the humongous
+// object is larger than a heap region, the following regions will
+// be of type ContinuesHumongous. In this case the top() and end()
+// of the StartHumongous region will point to the end of that region.
+// The same will be true for all ContinuesHumongous regions except
+// the last, which will have its' top() at the objects' top.
+
class G1CollectedHeap;
class HeapRegionRemSet;
class HeapRegionRemSetIterator;
class HeapRegion;
class HeapRegionSetBase;
@@ -387,12 +396,10 @@
// A lower bound on the amount of garbage bytes in the region.
size_t garbage_bytes() {
size_t used_at_mark_start_bytes =
(prev_top_at_mark_start() - bottom()) * HeapWordSize;
- assert(used_at_mark_start_bytes >= marked_bytes(),
- "Can't mark more than we have.");
return used_at_mark_start_bytes - marked_bytes();
}
// Return the amount of bytes we'll reclaim if we collect this
// region. This includes not only the known garbage bytes in the
@@ -407,11 +414,10 @@
// An upper bound on the number of live bytes in the region.
size_t max_live_bytes() { return used() - garbage_bytes(); }
void add_to_marked_bytes(size_t incr_bytes) {
_next_marked_bytes = _next_marked_bytes + incr_bytes;
- assert(_next_marked_bytes <= used(), "invariant" );
}
void zero_marked_bytes() {
_prev_marked_bytes = _next_marked_bytes = 0;
}
@@ -443,61 +449,17 @@
// For a humongous region, region in which it starts.
HeapRegion* humongous_start_region() const {
return _humongous_start_region;
}
- // Return the number of distinct regions that are covered by this region:
- // 1 if the region is not humongous, >= 1 if the region is humongous.
- uint region_num() const {
- if (!is_humongous()) {
- return 1U;
- } else {
- assert(is_starts_humongous(), "doesn't make sense on HC regions");
- assert(capacity() % HeapRegion::GrainBytes == 0, "sanity");
- return (uint) (capacity() >> HeapRegion::LogOfHRGrainBytes);
- }
- }
-
- // Return the index + 1 of the last HC regions that's associated
- // with this HS region.
- uint last_hc_index() const {
- assert(is_starts_humongous(), "don't call this otherwise");
- return hrm_index() + region_num();
- }
-
- // Same as Space::is_in_reserved, but will use the original size of the region.
- // The original size is different only for start humongous regions. They get
- // their _end set up to be the end of the last continues region of the
- // corresponding humongous object.
- bool is_in_reserved_raw(const void* p) const {
- return _bottom <= p && p < orig_end();
- }
-
// Makes the current region be a "starts humongous" region, i.e.,
// the first region in a series of one or more contiguous regions
- // that will contain a single "humongous" object. The two parameters
- // are as follows:
- //
- // new_top : The new value of the top field of this region which
- // points to the end of the humongous object that's being
- // allocated. If there is more than one region in the series, top
- // will lie beyond this region's original end field and on the last
- // region in the series.
+ // that will contain a single "humongous" object.
//
- // new_end : The new value of the end field of this region which
- // points to the end of the last region in the series. If there is
- // one region in the series (namely: this one) end will be the same
- // as the original end of this region.
- //
- // Updating top and end as described above makes this region look as
- // if it spans the entire space taken up by all the regions in the
- // series and an single allocation moved its top to new_top. This
- // ensures that the space (capacity / allocated) taken up by all
- // humongous regions can be calculated by just looking at the
- // "starts humongous" regions and by ignoring the "continues
- // humongous" regions.
- void set_starts_humongous(HeapWord* new_top, HeapWord* new_end);
+ // obj_top : points to the end of the humongous object that's being
+ // allocated.
+ void set_starts_humongous(HeapWord* obj_top);
// Makes the current region be a "continues humongous'
// region. first_hr is the "start humongous" region of the series
// which this region will be part of.
void set_continues_humongous(HeapRegion* first_hr);
@@ -564,13 +526,10 @@
HeapRegion* get_next_dirty_cards_region() const { return _next_dirty_cards_region; }
HeapRegion** next_dirty_cards_region_addr() { return &_next_dirty_cards_region; }
void set_next_dirty_cards_region(HeapRegion* hr) { _next_dirty_cards_region = hr; }
bool is_on_dirty_cards_region_list() const { return get_next_dirty_cards_region() != NULL; }
- // For the start region of a humongous sequence, it's original end().
- HeapWord* orig_end() const { return _bottom + GrainWords; }
-
// Reset HR stuff to default values.
void hr_clear(bool par, bool clear_space, bool locked = false);
void par_clear();
// Get the start of the unmarked area in this region.
@@ -612,12 +571,12 @@
// Returns "false" iff no object in the region was allocated when the
// last mark phase ended.
bool is_marked() { return _prev_top_at_mark_start != bottom(); }
void reset_during_compaction() {
- assert(is_starts_humongous(),
- "should only be called for starts humongous regions");
+ assert(is_humongous(),
+ "should only be called for humongous regions");
zero_marked_bytes();
init_top_at_mark_start();
}
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