new Array(n) above 1M is still quadratic when the array is a module-level binding #9784

The two programs below have line-for-line identical bodies. Only the binding's scope differs.

// A — inside a function: FAST
function fill(slots: number): string {
  const values: number[] = new Array(slots);
  for (let i = 0; i < slots; i++) values[i] = i;
  let s = 0; for (let i = 0; i < slots; i++) s = (s + values[i]) % 1000000007;
  return `${slots} ${s} ${values[slots-1]}`;
}
console.log(fill(1000001));

// B — at module top level: HANGS
const slots = 1000001;
const values: number[] = new Array(slots);
for (let i = 0; i < slots; i++) values[i] = i;
let s = 0; for (let i = 0; i < slots; i++) s = (s + values[i]) % 1000000007;
console.log(slots, s, values[slots-1]);

The threshold is exact: 1,000,000 elements complete in 0.44 s; 1,000,001 do not complete in 30 s.

Why this is not #9371

#9371 was closed on 2026-09-02. Its fix (#9434) is real, but its regression test crates/perry/tests/issue_9371_large_presized_array.rs fills the array inside a function, which is arm A above — the half that works. The module-scope arm was never covered, and reproduces unchanged on main@12efed1222.

Same module-global-vs-local shape as #9342.

Repro

secret-tests/scratchpad/audit0901/cliff_fn.ts and cliff_mod.ts; also secret-tests/cases/adversarial/recent/33_large_presized_array_cliff.ts, currently the adversarial suite's only timeout.

Done when

B completes in the same order of magnitude as A, case 33 matches node, and issue_9371_large_presized_array.rs grows a module-scope arm.