PEGO
A030: Iterative VM Frame Reuse
Iterative VM execution needs explicit call/body state. Reusing completed frames avoids a heap allocation for each step or rule call.
Mechanism and Invariants
The VM returns completed call, body, skip, longest and Operators Rule frames to parser-owned free lists. Plain calls combine invocation with a body frame, reducing push/pop dispatch. State remains live until its frame finishes, and published values are never recycled with the frame. Active growth, recovery and capture owners must stay intact.
Scope and State
Default iterative VM execution only. Closure/recursive calls use the Go stack; generated Go and TypeScript have separate frame allocation policies.
Reference Control
No universal same-source fresh-iterative-frame comparator is maintained. Stream frame controls concern another owner and boundary.
Evidence and Implementation
Records 002/013 record reduced iterative and Operators Rule allocations. Record 034 measures the one-frame plain route, including iterative JSON full parsing from 24.3 to 22.0 ms. Record 048 describes typed frame reuse with memory reduction and timing within noise. These route-specific historical effects are not additive.
Evidence records: 002, 013, 034.
Source owners: reuse, release and plainCallFrame.
The comparison policy distinguishes same-source controls, historical changes and full checkpoints.