A change in the way we place TransitionElementKinds in the tree.

src/flag-definitions.h

 // Copyright 2012 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 154 matching lines @@
 // Flags for data representation optimizations
 DEFINE_bool(unbox_double_arrays, true, "automatically unbox arrays of doubles")
 DEFINE_bool(string_slices, true, "use string slices")
 
 // Flags for Crankshaft.
 DEFINE_bool(crankshaft, true, "use crankshaft")
 DEFINE_string(hydrogen_filter, "", "optimization filter")
 DEFINE_bool(use_range, true, "use hydrogen range analysis")
 DEFINE_bool(eliminate_dead_phis, true, "eliminate dead phis")
 DEFINE_bool(use_gvn, true, "use hydrogen global value numbering")
+DEFINE_bool(use_place_elements_transitions,
+            true,
+            "use optimized placement of elements transitions")
 DEFINE_bool(use_canonicalizing, true, "use hydrogen instruction canonicalizing")
 DEFINE_bool(use_inlining, true, "use function inlining")
 DEFINE_int(max_inlined_source_size, 600,
            "maximum source size in bytes considered for a single inlining")
 DEFINE_int(max_inlined_nodes, 196,
            "maximum number of AST nodes considered for a single inlining")
 DEFINE_int(max_inlined_nodes_cumulative, 196,
            "maximum cumulative number of AST nodes considered for inlining")
 DEFINE_bool(loop_invariant_code_motion, true, "loop invariant code motion")
 DEFINE_bool(collect_megamorphic_maps_from_stub_cache,
             true,
             "crankshaft harvests type feedback from stub cache")
 DEFINE_bool(hydrogen_stats, false, "print statistics for hydrogen")
 DEFINE_bool(trace_hydrogen, false, "trace generated hydrogen to file")
 DEFINE_string(trace_phase, "Z", "trace generated IR for specified phases")
 DEFINE_bool(trace_inlining, false, "trace inlining decisions")
 DEFINE_bool(trace_alloc, false, "trace register allocator")
 DEFINE_bool(trace_all_uses, false, "trace all use positions")
 DEFINE_bool(trace_range, false, "trace range analysis")
+DEFINE_bool(trace_transition_placement,
+            false,
+            "trace elementskind transition placement")
 DEFINE_bool(trace_gvn, false, "trace global value numbering")
 DEFINE_bool(trace_representation, false, "trace representation types")
 DEFINE_bool(stress_pointer_maps, false, "pointer map for every instruction")
 DEFINE_bool(stress_environments, false, "environment for every instruction")
 DEFINE_int(deopt_every_n_times,
            0,
            "deoptimize every n times a deopt point is passed")
 DEFINE_bool(trap_on_deopt, false, "put a break point before deoptimizing")
 DEFINE_bool(deoptimize_uncommon_cases, true, "deoptimize uncommon cases")
 DEFINE_bool(polymorphic_inlining, true, "polymorphic inlining")
@@ skipping 517 matching lines @@
 #undef DEFINE_bool
 #undef DEFINE_int
 #undef DEFINE_string
 #undef DEFINE_implication
 
 #undef FLAG_MODE_DECLARE
 #undef FLAG_MODE_DEFINE
 #undef FLAG_MODE_DEFINE_DEFAULTS
 #undef FLAG_MODE_META
 #undef FLAG_MODE_DEFINE_IMPLICATIONS