self-modifying code and LLVM SSA form


This is a relatively basic question concerning self modification of
code expressed in bitcode. I am somewhat curious if expressing such
notions are theoretically possible. I am not sure if this is the right
place to ask this. My sense is that something like this can be quite
complex since the underlying machine code representations in different
targets are often quite distinct but I am wondering if this
possibility in theory is completely discounted.

Thanks in advance,