ARM: Enable OSR by default.

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 116 matching lines @@
 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(process_arguments_object, true, "try to deal with arguments object")
 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")
 DEFINE_bool(aggressive_loop_invariant_motion, true,
             "aggressive motion of instructions out of loops")
-#ifdef V8_TARGET_ARCH_IA32
+#ifdef V8_TARGET_ARCH_X64
+DEFINE_bool(use_osr, false, "use on-stack replacement")
+#else
 DEFINE_bool(use_osr, true, "use on-stack replacement")
-#else
-DEFINE_bool(use_osr, false, "use on-stack replacement")
 #endif
 DEFINE_bool(trace_osr, false, "trace on-stack replacement")
 DEFINE_int(stress_runs, 0, "number of stress runs")
 DEFINE_bool(optimize_closures, true, "optimize closures")
 
 // assembler-ia32.cc / assembler-arm.cc / assembler-x64.cc
 DEFINE_bool(debug_code, false,
             "generate extra code (assertions) for debugging")
 DEFINE_bool(code_comments, false, "emit comments in code disassembly")
 DEFINE_bool(emit_branch_hints, false, "emit branch hints")
@@ skipping 388 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