Arrays longer than 2^20 kept every element beyond the cutoff in a sorted
side store, and each indexed write to an existing entry deleted and
reinserted it, so fill + indexed read/write loops went quadratic
(n=1.2M: 10.4s on macOS arm64, 12.6s on Linux x64).
- Rewrite existing sparse entries in place.
- Let dense storage grow past the cutoff for contiguous extension of a
populated prefix, bulk range writes, and sparse tails that reach 3/16
density, migrating side-store entries so index < cap stays dense.
- Make the side store a deque with front slack so descending first-touch
writes and prefix migration are amortized O(1).
- Bound range-derived slice/splice capacity hints for hole runs.
scr_arr_new now reserves the live count, so a 2^20+3 element Set
converts into dense storage instead of a sparse tail; the white-box
test_lib check that pinned the old policy now asserts dense storage.
- Sort primitive arrays with stable native ordering and pure conversion keys.
- Preserve sparse semantics and argument effects while avoiding callback overhead.
- Verify Unicode ordering and ownership across native and WASI paths.
- Share dense array storage and move owned ranges without rebuilding containers.
- Batch array construction and insertion while preserving evaluation order and bounded temporary storage.
- Lower indexed mutations natively and preserve typed-array reversal across numeric element types.
- Combine bounded string concatenations while preserving evaluation and ownership.
- Build array joins and raw strings directly in their final storage.
- Support literal null and undefined string conversions with preserved effects.
- Reduce allocation and reference-management overhead in native array loops.
- Enable vectorization while preserving numeric behavior.
- Preserve live tuple iteration and cover reference lifetimes and missing values.
Represent ordinary JavaScript arrays with hole, value, and explicit-undefined states; add sparse side storage and carry missing values through the frontend, native backends, runtime, and Node-facing consumers.
- Lower unshift and reverse through the C and LLVM backends.
- Preserve spread, mutation, evaluation-order, and reference-counting semantics.
- Add runtime, differential, and surface-manifest coverage.
Malte Ubl