[WIP] Reify unstructured control-flow into `thunk` values.#39

Draft

eddyb wants to merge 7 commits intoeddyb/structurize-noretfrom

Commits on Apr 20, 2026

cf: always represent `ExitInvocation` as a node (instead of a `ControlInst`).
eddyb
committed
cf: remove phi-like limitation in favor of "BB args"-like edges-with-target-inputs.
eddyb
committed
cf: move unstructured returns from `ControlInstKind` to (per-edge) `ControlTarget`.
eddyb
committed
[TODO(eddyb) document] cf: reify `ControlEdge`s (target+inputs) into a new kind of `thunk` "value".
eddyb
committed
cf: replace `ControlInstKind::Unreachable` with branches to `undef` thunks.
eddyb
committed
cf: replace `ControlInstKind::SelectBranch` with `thunk`-valued `Select`.
eddyb
committed
cf: move the target `thunk` of each unstructured region into its `outputs`.
eddyb
committed