# HG changeset patch
# User rkennke
# Date 1489669171 -3600
#      Thu Mar 16 13:59:31 2017 +0100
# Node ID 57584c2a18bf1698abbbabac7b80b90a7050cec6
# Parent  366a99d8bd1b78e7ebdb852335e060d5a373f9e5
Add humongous regions support to partial GC.

diff --git a/src/share/vm/gc/shenandoah/shenandoahHeapRegion.cpp b/src/share/vm/gc/shenandoah/shenandoahHeapRegion.cpp
--- a/src/share/vm/gc/shenandoah/shenandoahHeapRegion.cpp
+++ b/src/share/vm/gc/shenandoah/shenandoahHeapRegion.cpp
@@ -49,6 +49,7 @@
   reserved(MemRegion(start, regionSizeWords)),
   _humongous_start(false),
   _humongous_continuation(false),
+  _humongous_obj_array(false),
   _recycled(true),
   _root(false),
   _new_top(NULL),
@@ -215,6 +216,18 @@
 
 void ShenandoahHeapRegion::oop_iterate(ExtendedOopClosure* blk) {
   if (is_empty()) return;
+  if (is_humongous_obj_array()) {
+    oop_iterate_humongous(blk);
+  } else {
+    oop_iterate_objects(blk);
+  }
+}
+
+void ShenandoahHeapRegion::oop_iterate_objects(ExtendedOopClosure* blk) {
+  assert(! is_humongous_obj_array(), "no humongous obj array here");
+  assert(! is_humongous_continuation(), "no humongous continuation here");
+  // Note: it is ok to have a humongous start region here, e.g. in the case
+  // of an int[]. We might want to visit its header.
   HeapWord* obj_addr = bottom() + BrooksPointer::word_size();
   HeapWord* t = top();
   // Could call objects iterate, but this is easier.
@@ -224,6 +237,21 @@
   }
 }
 
+void ShenandoahHeapRegion::oop_iterate_humongous(ExtendedOopClosure* blk) {
+  assert(is_humongous_obj_array(), "only humongous obj array here");
+  // Find head.
+  ShenandoahHeapRegionSet* regions = _heap->regions();
+  uint idx = region_number();
+  ShenandoahHeapRegion* r = regions->get(idx);
+  while (! r->is_humongous_start()) {
+    idx--;
+    r = regions->get(idx);
+  }
+  assert(r->is_humongous_start(), "need humongous head here");
+  objArrayOop array = objArrayOop(r->bottom() + BrooksPointer::word_size());
+  array->oop_iterate(blk, MemRegion(bottom(), top()));
+}
+
 void ShenandoahHeapRegion::fill_region() {
   ShenandoahHeap* sh = (ShenandoahHeap*) Universe::heap();
 
@@ -243,6 +271,10 @@
   _humongous_continuation = continuation;
 }
 
+void ShenandoahHeapRegion::set_humongous_obj_array(bool obj_array) {
+  _humongous_obj_array = obj_array;
+}
+
 bool ShenandoahHeapRegion::is_humongous() const {
   return _humongous_start || _humongous_continuation;
 }
@@ -255,11 +287,16 @@
   return _humongous_continuation;
 }
 
+bool ShenandoahHeapRegion::is_humongous_obj_array() const {
+  return _humongous_continuation;
+}
+
 void ShenandoahHeapRegion::recycle() {
   ContiguousSpace::initialize(reserved, true, false);
   clear_live_data();
   _humongous_start = false;
   _humongous_continuation = false;
+  _humongous_obj_array = false;
   _recycled = true;
   _root = false;
   set_in_collection_set(false);
diff --git a/src/share/vm/gc/shenandoah/shenandoahHeapRegion.hpp b/src/share/vm/gc/shenandoah/shenandoahHeapRegion.hpp
--- a/src/share/vm/gc/shenandoah/shenandoahHeapRegion.hpp
+++ b/src/share/vm/gc/shenandoah/shenandoahHeapRegion.hpp
@@ -44,6 +44,7 @@
 
   bool _humongous_start;
   bool _humongous_continuation;
+  bool _humongous_obj_array;
 
   bool _recycled;
   bool _root;
@@ -92,6 +93,11 @@
   HeapWord* object_iterate_careful(ObjectClosureCareful* cl);
   void oop_iterate(ExtendedOopClosure* cl);
 
+private:
+  void oop_iterate_objects(ExtendedOopClosure* cl);
+  void oop_iterate_humongous(ExtendedOopClosure* cl);
+
+public:
   HeapWord* block_start_const(const void* p) const;
 
   // Just before GC we need to fill the current region.
@@ -103,10 +109,12 @@
 
   void set_humongous_start(bool start);
   void set_humongous_continuation(bool continuation);
+  void set_humongous_obj_array(bool obj_array);
 
   bool is_humongous() const;
   bool is_humongous_start() const;
   bool is_humongous_continuation() const;
+  bool is_humongous_obj_array() const;
 
 #ifdef ASSERT
   void memProtectionOn();
diff --git a/src/share/vm/gc/shenandoah/shenandoahPartialGC.cpp b/src/share/vm/gc/shenandoah/shenandoahPartialGC.cpp
--- a/src/share/vm/gc/shenandoah/shenandoahPartialGC.cpp
+++ b/src/share/vm/gc/shenandoah/shenandoahPartialGC.cpp
@@ -194,11 +194,6 @@
       if (matrix->is_connected(from_idx, to_idx)) {
         ShenandoahHeapRegion* r = regions->get(from_idx);
         if (! r->is_root() && ! _heap->region_in_collection_set(from_idx)) {
-          // TODO: Implement support for humongous roots:
-          // - quick impl: rewind to the head of the humongous object and use that
-          // - better impl: support scanning of humongous continuation regions
-          //   and potentially avoid scanning the whole obj
-          guarantee(! r->is_humongous_continuation(), "unimplemented");
           _root_regions->add_region(r);
           r->set_root(true);
         }