--- old/hotspot/src/share/vm/gc_implementation/parallelScavenge/psMarkSweep.cpp	2009-08-01 04:10:59.489367177 +0100
+++ new/hotspot/src/share/vm/gc_implementation/parallelScavenge/psMarkSweep.cpp	2009-08-01 04:10:59.400551143 +0100
@@ -2,7 +2,7 @@
 #pragma ident "@(#)psMarkSweep.cpp	1.92 07/06/08 23:11:01 JVM"
 #endif
 /*
- * Copyright 2001-2007 Sun Microsystems, Inc.  All Rights Reserved.
+ * Copyright 2001-2008 Sun Microsystems, Inc.  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
@@ -38,9 +38,7 @@
   _ref_processor = new ReferenceProcessor(mr,
                                           true,    // atomic_discovery
                                           false);  // mt_discovery
-  if (!UseParallelOldGC || !VerifyParallelOldWithMarkSweep) {
-    _counters = new CollectorCounters("PSMarkSweep", 1);
-  }
+  _counters = new CollectorCounters("PSMarkSweep", 1);
 }
 
 // This method contains all heap specific policy for invoking mark sweep.
@@ -101,6 +99,9 @@
   // Increment the invocation count
   heap->increment_total_collections(true /* full */);
 
+  // Save information needed to minimize mangling
+  heap->record_gen_tops_before_GC();
+
   // We need to track unique mark sweep invocations as well.
   _total_invocations++;
 
@@ -174,6 +175,7 @@
     COMPILER2_PRESENT(DerivedPointerTable::clear());
   
     ref_processor()->enable_discovery();
+    ref_processor()->setup_policy(clear_all_softrefs);
 
     mark_sweep_phase1(clear_all_softrefs);
 
@@ -190,7 +192,13 @@
     restore_marks();
     
     deallocate_stacks();
-    
+
+    if (ZapUnusedHeapArea) {
+      // Do a complete mangle (top to end) because the usage for
+      // scratch does not maintain a top pointer.
+      young_gen->to_space()->mangle_unused_area_complete();
+    }
+
     eden_empty = young_gen->eden_space()->is_empty();
     if (!eden_empty) {
       eden_empty = absorb_live_data_from_eden(size_policy, young_gen, old_gen);
@@ -200,8 +208,8 @@
     // input to soft ref clearing policy at the next gc.
     Universe::update_heap_info_at_gc();
 
-    survivors_empty = young_gen->from_space()->is_empty() && 
-      young_gen->to_space()->is_empty();
+    survivors_empty = young_gen->from_space()->is_empty() &&
+                      young_gen->to_space()->is_empty();
     young_gen_empty = eden_empty && survivors_empty;
     
     BarrierSet* bs = heap->barrier_set();
@@ -347,6 +355,11 @@
     perm_gen->verify_object_start_array();
   }
 
+  if (ZapUnusedHeapArea) {
+    old_gen->object_space()->check_mangled_unused_area_complete();
+    perm_gen->object_space()->check_mangled_unused_area_complete();
+  }
+
   NOT_PRODUCT(ref_processor()->verify_no_references_recorded());
 
   if (PrintHeapAtGC) {
@@ -379,7 +392,7 @@
   // full GC.
   const size_t alignment = old_gen->virtual_space()->alignment();
   const size_t eden_used = eden_space->used_in_bytes();
-  const size_t promoted = (size_t)(size_policy->avg_promoted()->padded_average());
+  const size_t promoted = (size_t)size_policy->avg_promoted()->padded_average();
   const size_t absorb_size = align_size_up(eden_used + promoted, alignment);
   const size_t eden_capacity = eden_space->capacity_in_bytes();
 
@@ -406,16 +419,14 @@
 
   // Fill the unused part of the old gen.
   MutableSpace* const old_space = old_gen->object_space();
-  MemRegion old_gen_unused(old_space->top(), old_space->end());
-
-  // If the unused part of the old gen cannot be filled, skip
-  // absorbing eden.
-  if (old_gen_unused.word_size() < SharedHeap::min_fill_size()) {
-    return false;
-  }
+  HeapWord* const unused_start = old_space->top();
+  size_t const unused_words = pointer_delta(old_space->end(), unused_start);
 
-  if (!old_gen_unused.is_empty()) {
-    SharedHeap::fill_region_with_object(old_gen_unused);
+  if (unused_words > 0) {
+    if (unused_words < CollectedHeap::min_fill_size()) {
+      return false;  // If the old gen cannot be filled, must give up.
+    }
+    CollectedHeap::fill_with_objects(unused_start, unused_words);
   }
 
   // Take the live data from eden and set both top and end in the old gen to
@@ -431,9 +442,8 @@
 
   // Update the object start array for the filler object and the data from eden.
   ObjectStartArray* const start_array = old_gen->start_array();
-  HeapWord* const start = old_gen_unused.start();
-  for (HeapWord* addr = start; addr < new_top; addr += oop(addr)->size()) {
-    start_array->allocate_block(addr);
+  for (HeapWord* p = unused_start; p < new_top; p += oop(p)->size()) {
+    start_array->allocate_block(p);
   }
 
   // Could update the promoted average here, but it is not typically updated at
@@ -507,24 +517,10 @@
   follow_stack();
 
   // Process reference objects found during marking
-
-  // Skipping the reference processing for VerifyParallelOldWithMarkSweep 
-  // affects the marking (makes it different).
   {
-    ReferencePolicy *soft_ref_policy;
-    if (clear_all_softrefs) {
-      soft_ref_policy = new AlwaysClearPolicy();
-    } else {
-#ifdef COMPILER2
-      soft_ref_policy = new LRUMaxHeapPolicy();
-#else
-      soft_ref_policy = new LRUCurrentHeapPolicy();
-#endif // COMPILER2
-    }
-    assert(soft_ref_policy != NULL,"No soft reference policy");
+    ref_processor()->setup_policy(clear_all_softrefs);
     ref_processor()->process_discovered_references(
-      soft_ref_policy, is_alive_closure(), mark_and_push_closure(),
-      follow_stack_closure(), NULL);
+      is_alive_closure(), mark_and_push_closure(), follow_stack_closure(), NULL);
   }
 
   // Follow system dictionary roots and unload classes