--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/hotspot/share/gc/g1/g1MarkSweep.cpp	Tue Sep 12 19:03:39 2017 +0200
@@ -0,0 +1,381 @@
+/*
+ * Copyright (c) 2001, 2017, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ *
+ */
+
+#include "precompiled.hpp"
+#include "classfile/javaClasses.hpp"
+#include "classfile/symbolTable.hpp"
+#include "classfile/systemDictionary.hpp"
+#include "classfile/vmSymbols.hpp"
+#include "code/codeCache.hpp"
+#include "code/icBuffer.hpp"
+#include "gc/g1/g1FullGCScope.hpp"
+#include "gc/g1/g1MarkSweep.hpp"
+#include "gc/g1/g1RootProcessor.hpp"
+#include "gc/g1/g1StringDedup.hpp"
+#include "gc/serial/markSweep.inline.hpp"
+#include "gc/shared/gcHeapSummary.hpp"
+#include "gc/shared/gcLocker.hpp"
+#include "gc/shared/gcTimer.hpp"
+#include "gc/shared/gcTrace.hpp"
+#include "gc/shared/gcTraceTime.inline.hpp"
+#include "gc/shared/genCollectedHeap.hpp"
+#include "gc/shared/modRefBarrierSet.hpp"
+#include "gc/shared/referencePolicy.hpp"
+#include "gc/shared/space.hpp"
+#include "oops/instanceRefKlass.hpp"
+#include "oops/oop.inline.hpp"
+#include "prims/jvmtiExport.hpp"
+#include "runtime/atomic.hpp"
+#include "runtime/biasedLocking.hpp"
+#include "runtime/synchronizer.hpp"
+#include "runtime/thread.hpp"
+#include "runtime/vmThread.hpp"
+#include "utilities/copy.hpp"
+#include "utilities/events.hpp"
+
+class HeapRegion;
+
+void G1MarkSweep::invoke_at_safepoint(ReferenceProcessor* rp,
+                                      bool clear_all_softrefs) {
+  assert(SafepointSynchronize::is_at_safepoint(), "must be at a safepoint");
+  HandleMark hm;  // Discard invalid handles created during gc
+
+#if defined(COMPILER2) || INCLUDE_JVMCI
+  DerivedPointerTable::clear();
+#endif
+#ifdef ASSERT
+  if (G1CollectedHeap::heap()->collector_policy()->should_clear_all_soft_refs()) {
+    assert(clear_all_softrefs, "Policy should have been checked earler");
+  }
+#endif
+  // hook up weak ref data so it can be used during Mark-Sweep
+  assert(GenMarkSweep::ref_processor() == NULL, "no stomping");
+  assert(rp != NULL, "should be non-NULL");
+  assert(rp == G1CollectedHeap::heap()->ref_processor_stw(), "Precondition");
+
+  GenMarkSweep::set_ref_processor(rp);
+  rp->setup_policy(clear_all_softrefs);
+
+  // When collecting the permanent generation Method*s may be moving,
+  // so we either have to flush all bcp data or convert it into bci.
+  CodeCache::gc_prologue();
+
+  bool marked_for_unloading = false;
+
+  allocate_stacks();
+
+  // We should save the marks of the currently locked biased monitors.
+  // The marking doesn't preserve the marks of biased objects.
+  BiasedLocking::preserve_marks();
+
+  // Process roots and do the marking.
+  mark_sweep_phase1(marked_for_unloading, clear_all_softrefs);
+
+  // Prepare compaction.
+  mark_sweep_phase2();
+
+#if defined(COMPILER2) || INCLUDE_JVMCI
+  // Don't add any more derived pointers during phase3
+  DerivedPointerTable::set_active(false);
+#endif
+
+  // Adjust all pointers.
+  mark_sweep_phase3();
+
+  // Do the actual compaction.
+  mark_sweep_phase4();
+
+  GenMarkSweep::restore_marks();
+  BiasedLocking::restore_marks();
+  GenMarkSweep::deallocate_stacks();
+
+#if defined(COMPILER2) || INCLUDE_JVMCI
+  // Now update the derived pointers.
+  DerivedPointerTable::update_pointers();
+#endif
+
+  CodeCache::gc_epilogue();
+  JvmtiExport::gc_epilogue();
+
+  // refs processing: clean slate
+  GenMarkSweep::set_ref_processor(NULL);
+}
+
+STWGCTimer* G1MarkSweep::gc_timer() {
+  return G1FullGCScope::instance()->timer();
+}
+
+SerialOldTracer* G1MarkSweep::gc_tracer() {
+  return G1FullGCScope::instance()->tracer();
+}
+
+void G1MarkSweep::allocate_stacks() {
+  GenMarkSweep::_preserved_count_max = 0;
+  GenMarkSweep::_preserved_marks = NULL;
+  GenMarkSweep::_preserved_count = 0;
+}
+
+void G1MarkSweep::mark_sweep_phase1(bool& marked_for_unloading,
+                                    bool clear_all_softrefs) {
+  // Recursively traverse all live objects and mark them
+  GCTraceTime(Info, gc, phases) tm("Phase 1: Mark live objects", gc_timer());
+
+  G1CollectedHeap* g1h = G1CollectedHeap::heap();
+
+  // Need cleared claim bits for the roots processing
+  ClassLoaderDataGraph::clear_claimed_marks();
+
+  MarkingCodeBlobClosure follow_code_closure(&GenMarkSweep::follow_root_closure, !CodeBlobToOopClosure::FixRelocations);
+  {
+    G1RootProcessor root_processor(g1h, 1);
+    if (ClassUnloading) {
+      root_processor.process_strong_roots(&GenMarkSweep::follow_root_closure,
+                                          &GenMarkSweep::follow_cld_closure,
+                                          &follow_code_closure);
+    } else {
+      root_processor.process_all_roots_no_string_table(
+                                          &GenMarkSweep::follow_root_closure,
+                                          &GenMarkSweep::follow_cld_closure,
+                                          &follow_code_closure);
+    }
+  }
+
+  {
+    GCTraceTime(Debug, gc, phases) trace("Reference Processing", gc_timer());
+
+    // Process reference objects found during marking
+    ReferenceProcessor* rp = GenMarkSweep::ref_processor();
+    assert(rp == g1h->ref_processor_stw(), "Sanity");
+
+    rp->setup_policy(clear_all_softrefs);
+    ReferenceProcessorPhaseTimes pt(gc_timer(), rp->num_q());
+
+    const ReferenceProcessorStats& stats =
+        rp->process_discovered_references(&GenMarkSweep::is_alive,
+                                          &GenMarkSweep::keep_alive,
+                                          &GenMarkSweep::follow_stack_closure,
+                                          NULL,
+                                          &pt);
+    gc_tracer()->report_gc_reference_stats(stats);
+    pt.print_all_references();
+  }
+
+  // This is the point where the entire marking should have completed.
+  assert(GenMarkSweep::_marking_stack.is_empty(), "Marking should have completed");
+
+  if (ClassUnloading) {
+    GCTraceTime(Debug, gc, phases) trace("Class Unloading", gc_timer());
+
+    // Unload classes and purge the SystemDictionary.
+    bool purged_class = SystemDictionary::do_unloading(&GenMarkSweep::is_alive, gc_timer());
+
+    g1h->complete_cleaning(&GenMarkSweep::is_alive, purged_class);
+  } else {
+    GCTraceTime(Debug, gc, phases) trace("Cleanup", gc_timer());
+    g1h->partial_cleaning(&GenMarkSweep::is_alive, true, true, G1StringDedup::is_enabled());
+  }
+
+  if (VerifyDuringGC) {
+    HandleMark hm;  // handle scope
+#if defined(COMPILER2) || INCLUDE_JVMCI
+    DerivedPointerTableDeactivate dpt_deact;
+#endif
+    g1h->prepare_for_verify();
+    // Note: we can verify only the heap here. When an object is
+    // marked, the previous value of the mark word (including
+    // identity hash values, ages, etc) is preserved, and the mark
+    // word is set to markOop::marked_value - effectively removing
+    // any hash values from the mark word. These hash values are
+    // used when verifying the dictionaries and so removing them
+    // from the mark word can make verification of the dictionaries
+    // fail. At the end of the GC, the original mark word values
+    // (including hash values) are restored to the appropriate
+    // objects.
+    GCTraceTime(Info, gc, verify)("During GC (full)");
+    g1h->verify(VerifyOption_G1UseMarkWord);
+  }
+
+  gc_tracer()->report_object_count_after_gc(&GenMarkSweep::is_alive);
+}
+
+
+void G1MarkSweep::mark_sweep_phase2() {
+  // Now all live objects are marked, compute the new object addresses.
+
+  // It is not required that we traverse spaces in the same order in
+  // phase2, phase3 and phase4, but the ValidateMarkSweep live oops
+  // tracking expects us to do so. See comment under phase4.
+
+  GCTraceTime(Info, gc, phases) tm("Phase 2: Compute new object addresses", gc_timer());
+
+  prepare_compaction();
+}
+
+class G1AdjustPointersClosure: public HeapRegionClosure {
+ public:
+  bool doHeapRegion(HeapRegion* r) {
+    if (r->is_humongous()) {
+      if (r->is_starts_humongous()) {
+        // We must adjust the pointers on the single H object.
+        oop obj = oop(r->bottom());
+        // point all the oops to the new location
+        MarkSweep::adjust_pointers(obj);
+      }
+    } else if (!r->is_closed_archive()) {
+      // This really ought to be "as_CompactibleSpace"...
+      r->adjust_pointers();
+    }
+    return false;
+  }
+};
+
+void G1MarkSweep::mark_sweep_phase3() {
+  G1CollectedHeap* g1h = G1CollectedHeap::heap();
+
+  // Adjust the pointers to reflect the new locations
+  GCTraceTime(Info, gc, phases) tm("Phase 3: Adjust pointers", gc_timer());
+
+  // Need cleared claim bits for the roots processing
+  ClassLoaderDataGraph::clear_claimed_marks();
+
+  CodeBlobToOopClosure adjust_code_closure(&GenMarkSweep::adjust_pointer_closure, CodeBlobToOopClosure::FixRelocations);
+  {
+    G1RootProcessor root_processor(g1h, 1);
+    root_processor.process_all_roots(&GenMarkSweep::adjust_pointer_closure,
+                                     &GenMarkSweep::adjust_cld_closure,
+                                     &adjust_code_closure);
+  }
+
+  assert(GenMarkSweep::ref_processor() == g1h->ref_processor_stw(), "Sanity");
+  g1h->ref_processor_stw()->weak_oops_do(&GenMarkSweep::adjust_pointer_closure);
+
+  // Now adjust pointers in remaining weak roots.  (All of which should
+  // have been cleared if they pointed to non-surviving objects.)
+  JNIHandles::weak_oops_do(&GenMarkSweep::adjust_pointer_closure);
+
+  if (G1StringDedup::is_enabled()) {
+    G1StringDedup::oops_do(&GenMarkSweep::adjust_pointer_closure);
+  }
+
+  GenMarkSweep::adjust_marks();
+
+  G1AdjustPointersClosure blk;
+  g1h->heap_region_iterate(&blk);
+}
+
+class G1SpaceCompactClosure: public HeapRegionClosure {
+public:
+  G1SpaceCompactClosure() {}
+
+  bool doHeapRegion(HeapRegion* hr) {
+    if (hr->is_humongous()) {
+      if (hr->is_starts_humongous()) {
+        oop obj = oop(hr->bottom());
+        if (obj->is_gc_marked()) {
+          obj->init_mark();
+        } else {
+          assert(hr->is_empty(), "Should have been cleared in phase 2.");
+        }
+      }
+      hr->reset_during_compaction();
+    } else if (!hr->is_pinned()) {
+      hr->compact();
+    }
+    return false;
+  }
+};
+
+void G1MarkSweep::mark_sweep_phase4() {
+  // All pointers are now adjusted, move objects accordingly
+
+  // The ValidateMarkSweep live oops tracking expects us to traverse spaces
+  // in the same order in phase2, phase3 and phase4. We don't quite do that
+  // here (code and comment not fixed for perm removal), so we tell the validate code
+  // to use a higher index (saved from phase2) when verifying perm_gen.
+  G1CollectedHeap* g1h = G1CollectedHeap::heap();
+
+  GCTraceTime(Info, gc, phases) tm("Phase 4: Move objects", gc_timer());
+
+  G1SpaceCompactClosure blk;
+  g1h->heap_region_iterate(&blk);
+
+}
+
+void G1MarkSweep::prepare_compaction_work(G1PrepareCompactClosure* blk) {
+  G1CollectedHeap* g1h = G1CollectedHeap::heap();
+  g1h->heap_region_iterate(blk);
+  blk->update_sets();
+}
+
+void G1PrepareCompactClosure::free_humongous_region(HeapRegion* hr) {
+  HeapWord* end = hr->end();
+  FreeRegionList dummy_free_list("Dummy Free List for G1MarkSweep");
+
+  hr->set_containing_set(NULL);
+  _humongous_regions_removed++;
+
+  _g1h->free_humongous_region(hr, &dummy_free_list, false /* skip_remset */);
+  prepare_for_compaction(hr, end);
+  dummy_free_list.remove_all();
+}
+
+void G1PrepareCompactClosure::prepare_for_compaction(HeapRegion* hr, HeapWord* end) {
+  // If this is the first live region that we came across which we can compact,
+  // initialize the CompactPoint.
+  if (!is_cp_initialized()) {
+    _cp.space = hr;
+    _cp.threshold = hr->initialize_threshold();
+  }
+  prepare_for_compaction_work(&_cp, hr, end);
+}
+
+void G1PrepareCompactClosure::prepare_for_compaction_work(CompactPoint* cp,
+                                                          HeapRegion* hr,
+                                                          HeapWord* end) {
+  hr->prepare_for_compaction(cp);
+  // Also clear the part of the card table that will be unused after
+  // compaction.
+  _mrbs->clear(MemRegion(hr->compaction_top(), end));
+}
+
+void G1PrepareCompactClosure::update_sets() {
+  // We'll recalculate total used bytes and recreate the free list
+  // at the end of the GC, so no point in updating those values here.
+  _g1h->remove_from_old_sets(0, _humongous_regions_removed);
+}
+
+bool G1PrepareCompactClosure::doHeapRegion(HeapRegion* hr) {
+  if (hr->is_humongous()) {
+    oop obj = oop(hr->humongous_start_region()->bottom());
+    if (hr->is_starts_humongous() && obj->is_gc_marked()) {
+      obj->forward_to(obj);
+    }
+    if (!obj->is_gc_marked()) {
+      free_humongous_region(hr);
+    }
+  } else if (!hr->is_pinned()) {
+    prepare_for_compaction(hr, hr->end());
+  }
+  return false;
+}