jit.opt.start(2) -- same as -O2
jit.opt.start("-dce")
jit.opt.start("hotloop=10", "hotexit=2")
</pre>
<p>
Unlike in LuaJIT 1.x, the module is built-in and
<b>optimization is turned on by default!</b>
It's no longer necessary to run <tt>require("jit.opt").start()</tt>,
which was one of the ways to enable optimization.
</p>

<h2 id="jit_util"><tt>jit.util.*</tt> &mdash; JIT compiler introspection</h2>
<p>
This submodule holds functions to introspect the bytecode, generated
traces, the IR and the generated mac