Allow partial scanning of large arrays in order to avoid

src/heap.cc

Index: src/heap.cc
===================================================================
--- src/heap.cc	(revision 12609)
+++ src/heap.cc	(working copy)
@@ -1359,11 +1359,12 @@
 
   if (external_string_table_.new_space_strings_.is_empty()) return;
 
-  Object** start = &external_string_table_.new_space_strings_[0];
-  Object** end = start + external_string_table_.new_space_strings_.length();
-  Object** last = start;
+  Object** start_slot = &external_string_table_.new_space_strings_[0];
+  Object** end_slot =
+        start_slot + external_string_table_.new_space_strings_.length();
+  Object** last = start_slot;
 
-  for (Object** p = start; p < end; ++p) {
+  for (Object** p = start_slot; p < end_slot; ++p) {
     ASSERT(InFromSpace(*p));
     String* target = updater_func(this, p);
 
@@ -1381,8 +1382,8 @@
     }
   }
 
-  ASSERT(last <= end);
-  external_string_table_.ShrinkNewStrings(static_cast<int>(last - start));
+  ASSERT(last <= end_slot);
+  external_string_table_.ShrinkNewStrings(static_cast<int>(last - start_slot));
 }
 
 
@@ -1391,9 +1392,10 @@
 
   // Update old space string references.
   if (external_string_table_.old_space_strings_.length() > 0) {
-    Object** start = &external_string_table_.old_space_strings_[0];
-    Object** end = start + external_string_table_.old_space_strings_.length();
-    for (Object** p = start; p < end; ++p) *p = updater_func(this, p);
+    Object** start_slot = &external_string_table_.old_space_strings_[0];
+    Object** end_slot =
+        start_slot + external_string_table_.old_space_strings_.length();
+    for (Object** p = start_slot; p < end_slot; ++p) *p = updater_func(this, p);
   }
 
   UpdateNewSpaceReferencesInExternalStringTable(updater_func);
@@ -6789,11 +6791,11 @@
   // Scan the object body.
   if (is_native_context && (visit_mode_ == VISIT_ONLY_STRONG)) {
     // This is specialized to scan Context's properly.
-    Object** start = reinterpret_cast<Object**>(obj->address() +
-                                                Context::kHeaderSize);
-    Object** end = reinterpret_cast<Object**>(obj->address() +
+    Object** start_slot = reinterpret_cast<Object**>(obj->address() +
+                                                     Context::kHeaderSize);
+    Object** end_slot = reinterpret_cast<Object**>(obj->address() +
         Context::kHeaderSize + Context::FIRST_WEAK_SLOT * kPointerSize);
-    mark_visitor->VisitPointers(start, end);
+    mark_visitor->VisitPointers(start_slot, end_slot);
   } else {
     obj->IterateBody(map_p->instance_type(),
                      obj->SizeFromMap(map_p),