oh the theatrics

if you love all of those and holding your breath, try underwater rugby

*machine-IR like

but maybe one could dream up an MLIR dialect that preserves high level structure after lowering to a machine-like IR dialect?

I think it’s more fundamental than that: SSA form is nice for optimizations, but not great for code size estimation.

so you either have to guess about code size via heuristics, or you’ve already lowered past a representation that makes optimizations easy

the “too complex” part of the problem is that often the IR you’d want to operate on for optimization decisions is a bit higher level than the one where you’d have precise code size information.

I can think of a couple different places in clang where we do something like that, but not for that reason: if-conversion, and outlining.