Introduce lazy sweeping.

src/flag-definitions.h

 // Copyright 2010 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 262 matching lines @@
 #endif
 
 // macro-assembler-ia32.cc
 DEFINE_bool(native_code_counters, false,
             "generate extra code for manipulating stats counters")
 
 // mark-compact.cc
 DEFINE_bool(always_compact, false, "Perform compaction on every full GC")
 DEFINE_bool(never_compact, false,
             "Never perform compaction on full GC - testing only")
+DEFINE_bool(lazy_sweeping, true,
+            "Use lazy sweeping for old pointer and data spaces")
 DEFINE_bool(cleanup_ics_at_gc, true,
             "Flush inline caches prior to mark compact collection.")
 DEFINE_bool(cleanup_caches_in_maps_at_gc, true,
             "Flush code caches in maps during mark compact cycle.")
 DEFINE_int(random_seed, 0,
            "Default seed for initializing random generator "
            "(0, the default, means to use system random).")
 
 DEFINE_bool(canonicalize_object_literal_maps, true,
             "Canonicalize maps for object literals.")
@@ skipping 252 matching lines @@
 #undef FLAG
 
 #undef DEFINE_bool
 #undef DEFINE_int
 #undef DEFINE_string
 
 #undef FLAG_MODE_DECLARE
 #undef FLAG_MODE_DEFINE
 #undef FLAG_MODE_DEFINE_DEFAULTS
 #undef FLAG_MODE_META