&gt;The innovation would come in creating the optimizations in the middle-end that could not be possible in the LLVM backend<p>&gt;There is a LLVM backend that implements most if not all of the GHC &quot;middle-end&quot; optimizations<p>I&#x27;m not sure I follow, are you saying that the optimisations are possible or not in LLVM? I don&#x27;t think the LLVM optimisation passes can make guarantees such as is needed for (say) the rewrite rules that rely heavily on purity.