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Fix WASM stack overflow: make cek_run iterative

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The CEK evaluator's cek_run was recursive (calls itself via cek_step).
Native OCaml handles deep recursion but wasm_of_ocaml compiles to JS
which has ~10K frame stack limit. Complex expressions (bytecode compiler)
exceeded this, causing "Maximum call stack size exceeded" in all WASM
bytecode compilation.

Replace recursive cek_run with iterative while loop — same semantics,
zero stack growth. Fixes sx_build_bytecode and browser-side evaluation.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
This commit is contained in:
giles
2026-03-30 09:14:09 +00:00
parent 671d19c978
commit 7a4a6c8a85
1 changed files with 10 additions and 5 deletions
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15
hosts/ocaml/lib/sx_ref.ml
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@@ -374,11 +374,16 @@ and expand_macro mac raw_args env =
(* cek-run *) (* cek-run *)
and cek_run state = and cek_run state =
(if sx_truthy ((cek_terminal_p (state))) then (cek_value (state)) else (* Iterative loop — no stack growth. Essential for WASM where JS stack is limited. *)
try cek_run ((cek_step (state))) let s = ref state in
with Eval_error msg -> (try
(if !_last_error_kont = Nil then _last_error_kont := cek_kont state); while not (match cek_terminal_p !s with Bool true -> true | _ -> false) do
raise (Eval_error msg)) s := cek_step !s
done;
cek_value !s
with Eval_error msg ->
(if !_last_error_kont = Nil then _last_error_kont := cek_kont !s);
raise (Eval_error msg))
(* cek-step *) (* cek-step *)
and cek_step state = and cek_step state =