Module structure

Expand description

Control flow structuring: CFG of basic blocks → nested region tree.

Strategy:

Iterative dominator computation (Cooper-Harvey-Kennedy).
Exception ranges grouped by (start, end) span → try regions carved out first; bodies and handlers are structured recursively.
Inside each flow scope, walk blocks from the entry:
- loop header (back-edge target that dominates the source) → natural loop region,
- conditional terminal → If region (branches structured up to the immediate post-dominator),
- switch terminal → Switch region with per-case sub-scopes,
- forward goto within scope → continue walking at the target,
- edges that leave the scope → Goto nodes (resolved to break/continue/labels in the conversion pass).

Structs§

BUDGET_OVERRIDE: Per-method copy-budget override installed by the method size guard in classdec (pathological copy explosion retry); consumed by Structurer::with_diamonds at construction.
COPY_ALLOW_CONFLUENCE: Set while a SESE consumed-arrival copy runs: there the copy IS the arm’s only emission route (the consumed merge has no sibling owner part in this layout), so the shared-tail-confluence barrier must not truncate it (jdk11/17/26 Pattern.family: the else arm’s copy of the b13 merge tail came out stage-2-less — the bar excluded the 12-pred stage-2 switch head — and the method fell off its end, 缺少返回语句 ×3 trees). Walk-side copy sites never set this.

DOM_BLOCKS
DOM_CALLS: Perf instrumentation: how many times the walk recomputed dominators (and over how many blocks). Off by default — the unconditional atomics contended on 7M calls/run.
DOM_ON

can_reach_avoiding: True if to is reachable from from without stepping on avoid.
can_reach_cfg: Reachability from from to to via normal edges, with a work budget.
can_reach_cfg_barred: Reachability from from to to that never steps on barrier blocks (other than from itself). Follows normal AND exception successors (exc_succ), so a protected block whose normal exits all return/throw is still seen to loop back through its handler.
compute_dominators
group_exceptions
group_exceptions_with
immediate_postdom: Immediate post-dominator of entry within universe, approximated as the nearest reconvergence point: the block (other than entry) reachable from ALL of entry’s in-universe successors with the smallest total BFS distance. Blocks whose in-universe successors are empty are exits.
reachable_within: Blocks normally reachable from entry without entering stop.
reverse_postorder
set_budget_override: Install/clear the per-method copy-budget override (see BUDGET_OVERRIDE).
set_dom_counters: Enable dominator-recompute counters (diagnostics).
set_walk_deadline: Install/clear the per-method walk deadline.
set_walk_visit_budget: Install/clear the per-method walk visit budget.