Fix a bug in block reordering/block compaction.

runtime/vm/compiler.cc

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "vm/compiler.h"
 
 #include "vm/assembler.h"
 
 #include "vm/ast_printer.h"
 #include "vm/block_scheduler.h"
@@ skipping 35 matching lines @@
     "Do loop invariant code motion.");
 DEFINE_FLAG(bool, propagate_types, true, "Do static type propagation.");
 DEFINE_FLAG(bool, allocation_sinking, true,
     "Attempt to sink temporary allocations to side exits");
 DEFINE_FLAG(int, deoptimization_counter_threshold, 16,
     "How many times we allow deoptimization before we disallow optimization.");
 DEFINE_FLAG(int, deoptimization_counter_licm_threshold, 8,
     "How many times we allow deoptimization before we disable LICM.");
 DEFINE_FLAG(bool, use_inlining, true, "Enable call-site inlining");
 DEFINE_FLAG(bool, range_analysis, true, "Enable range analysis");
-DEFINE_FLAG(bool, reorder_basic_blocks, false,
-    "Enable basic-block reordering.");
+DEFINE_FLAG(bool, reorder_basic_blocks, true, "Enable basic-block reordering.");
 DEFINE_FLAG(bool, verify_compiler, false,
     "Enable compiler verification assertions");
 DECLARE_FLAG(bool, print_flow_graph);
 DECLARE_FLAG(bool, print_flow_graph_optimized);
 DECLARE_FLAG(bool, trace_failed_optimization_attempts);
 
 // Compile a function. Should call only if the function has not been compiled.
 //   Arg0: function object.
 DEFINE_RUNTIME_ENTRY(CompileFunction, 1) {
   const Function& function = Function::CheckedHandle(arguments.ArgAt(0));
@@ skipping 856 matching lines @@
       Object::Handle(isolate->object_store()->sticky_error());
     isolate->object_store()->clear_sticky_error();
     isolate->set_long_jump_base(base);
     return result.raw();
   }
   UNREACHABLE();
   return Object::null();
 }
 
 }  // namespace dart