For me consciousness is "the ability to analyze and influence your own thoughts".
This might not correspond 100% to what philosophers mean, but it has the immense advantage of making consciousness a well defined concept, and even measurable.
I am almost certainly wrong about this, given it is mostly idle supposition, however I think of it in terms of awareness and reflective awareness and that the ratio of reflective awareness to simple awareness in a network of neurons is very roughly to do with how much of the network is folded back on itself compared to how much reaches out to the sensory inputs.
So from this perspective, reflective awareness is what you define as consciousness, and it can be present to massively varying degrees, alongside direct awareness down to the neuron.
Well, assuming you run the JIT on its own code it could be considered conscious to a tiny degree. It can analyze it's code, but only at a very low level, with no understanding of how it works. Also it can change its own code, but only to improve speed, not to change its functionality.
But, you are right that it is possible to write quite simple self modifying programs that would be conscious with this definition. However, having consciousness without intelligence can't be very useful.
This might not correspond 100% to what philosophers mean, but it has the immense advantage of making consciousness a well defined concept, and even measurable.