#386 · zig-utils/zig-js

Parent: #366 Related: #264, #142 Roadmap: #134

The stable wg-3.0 tree includes seven test/core/relaxed-simd/*.wast files. zig-js now implements the complete relaxed-SIMD binary, validation, and portable execution surface against that exact corpus.

Acceptance:

Pin and inventory every relaxed-SIMD opcode and immediate from wg-3.0.
Decode and validate the full opcode set behind an explicit relaxed_simd feature gate.
Execute every allowed nondeterministic result without over-constraining platform behavior.
Preserve architecture-independent interpreter fallback and bit-exact lanes where the spec requires them.
Pass every applicable command in all seven exact wg-3.0 relaxed-SIMD files.
Add focused units, bounded CI witnesses, feature registry entries, and documentation.

Evidence:

Exact source: WebAssembly/spec@9d36019973201a19f9c9ebb0f10828b2fe2374aa (wg-3.0).
Inventory: 20 contiguous 0xfd subopcodes, 0x100 through 0x113.
Corpus: 77/77 pass, 0 fail, 0 N/A, 0 runner errors across all seven files.
Harness: 18/18 Python regression tests, including nested vector either alternatives.
Decoder slice: 38/38 pass after moving the former oversized witness from newly-valid 0x100 to 0x114.
Consolidated project run: 1,219/1,220 before that stale test expectation; the only failure was the obsolete 0x100 expectation, and its complete 38-test owning slice passed after correction.
Registry/matrix verifier: green, 14 pinned features and the unchanged 87,838-command published matrix.

Landed on main:

b1862778 feat(wasm): implement relaxed SIMD (#386)
7229d3eb ci(wasm): gate Core 3 relaxed SIMD (#386)
e99f0654 docs(wasm): publish relaxed SIMD evidence (#386)