# HG changeset patch
# User tonyp
# Date 1391600868 -3600
# Node ID be25e3c0ae5598210f2ccbd55a307a87d90f2b77
# Parent  cae8833b9e299c260afea62d359e2b4ec106dccd
8033601: G1: Make array chunking use the same length field as the other young GCs
Summary: Use the old copy length instead of the length of the forwarded object for chunked arrays.
Reviewed-by: brutisso, tschatzl

diff -r cae8833b9e29 -r be25e3c0ae55 hotspot/src/share/vm/gc_implementation/g1/g1CollectedHeap.cpp
--- a/hotspot/src/share/vm/gc_implementation/g1/g1CollectedHeap.cpp	Wed Feb 05 10:09:54 2014 +0100
+++ b/hotspot/src/share/vm/gc_implementation/g1/g1CollectedHeap.cpp	Wed Feb 05 12:47:48 2014 +0100
@@ -4764,9 +4764,9 @@
 
     if (obj->is_objArray() && arrayOop(obj)->length() >= ParGCArrayScanChunk) {
       // We keep track of the next start index in the length field of
-      // the to-space object. The actual length can be found in the
-      // length field of the from-space object.
-      arrayOop(obj)->set_length(0);
+      // the from-space object. The actual length can be found in the
+      // length field of the to-space object.
+      arrayOop(old)->set_length(0);
       oop* old_p = set_partial_array_mask(old);
       _par_scan_state->push_on_queue(old_p);
     } else {
@@ -4840,16 +4840,16 @@
   assert(Universe::heap()->is_in_reserved(from_obj), "must be in heap.");
   assert(from_obj->is_objArray(), "must be obj array");
   objArrayOop from_obj_array = objArrayOop(from_obj);
-  // The from-space object contains the real length.
-  int length                 = from_obj_array->length();
+  // We keep track of the next start index in the length field of the
+  // from-space object.
+  int next_index             = from_obj_array->length();
 
   assert(from_obj->is_forwarded(), "must be forwarded");
   oop to_obj                 = from_obj->forwardee();
   assert(from_obj != to_obj, "should not be chunking self-forwarded objects");
   objArrayOop to_obj_array   = objArrayOop(to_obj);
-  // We keep track of the next start index in the length field of the
-  // to-space object.
-  int next_index             = to_obj_array->length();
+   // The to-space object contains the real length.
+  int length                 = to_obj_array->length();
   assert(0 <= next_index && next_index < length,
          err_msg("invariant, next index: %d, length: %d", next_index, length));
 
@@ -4859,7 +4859,7 @@
   // We'll try not to push a range that's smaller than ParGCArrayScanChunk.
   if (remainder > 2 * ParGCArrayScanChunk) {
     end = start + ParGCArrayScanChunk;
-    to_obj_array->set_length(end);
+    from_obj_array->set_length(end);
     // Push the remainder before we process the range in case another
     // worker has run out of things to do and can steal it.
     oop* from_obj_p = set_partial_array_mask(from_obj);
@@ -4868,7 +4868,7 @@
     assert(length == end, "sanity");
     // We'll process the final range for this object. Restore the length
     // so that the heap remains parsable in case of evacuation failure.
-    to_obj_array->set_length(end);
+    from_obj_array->set_length(end);
   }
   _scanner.set_region(_g1->heap_region_containing_raw(to_obj));
   // Process indexes [start,end). It will also process the header