There's no free lunch. I don't know where you're getting this "Pareto improvements" thing from because it's a much more constrained codegen framework than LLVM'

There's no free lunch. I don't know where you're getting this "Pareto improvements" thing from because it's a much more constrained codegen framework than LLVM's backend. It supports a much smaller subset, and real world code built by LLVM will use a lot of features like vectors even at -O0 for things like intrinsics. There's a maintenance cost to having a completely separate path for -O0.