I keep forgetting that some people actually like the reducible control flow constraint. To me, if you have that constraint then it’s not really ssa. You literal

I keep forgetting that some people actually like the reducible control flow constraint. To me, if you have that constraint then it’s not really ssa. You literally can’t represent everything that llvm IR or B3 IR could. I think you should make sure you add that caveat when making equivalence claims. That said, the key reason for my push back is the suitability of SSA for fast backends. If you can afford to run some coalescing then SSA is at least perf-neutral. If you can’t then compiling from SSA will result in crappy code. As in, probably worse than block local RA. So your best bet is to somehow avoid having to coalesce. But that probably means using SSA only for extracting liveness and then running the world’s dumbest linear scan. Even that may not be as good as block local RA.