Engineering journal

The pinned Test262 corpus passes 95,671 of 95,680 executions unmodified and 95,680 of 95,680 with five documented corrections; the DateTimeFormat shard passes 488 of 488; v0.0.18 is published.

zipp.org gains crawlable pages for the engine, Python, WebAssembly, GPU compute, Test262, benchmarks and architecture, all rendered from one JSON file, plus this journal with an RSS feed.

The experimental Python 3 frontend lands, compiling to the same register bytecode as JavaScript, together with WASM build variants, a folder-based playground, GPU graphs from Python and a Torch subset with GPU training.

Two releases close 38 tickets from the 11 September audits: VM rooting, coercion, TypedArray semantics, parser, GC and metadata, while preserving the exact 95,939 of 95,942 result on the previous corpus.

Embedding-API and host-boundary audit findings are fixed, browser Worker smoke tests and a reference host adapter land, releases are gated on the exact tagged commit, and a fresh benchmark capture shows the cost of strict call order.

Method calls now evaluate in specification order by default; the fused lowering that could be observed by a getter or proxy trap is used only where argument shapes provably cannot see it.

v0.0.14 adds the accel bridge; paired A/B measurements close five WASM interpreter pathologies, including a join with 300K retained strings from 8,423 ms to 138 ms.

v0.0.11 and v0.0.12 land register classes for tokenizer loops and inline stores into young dense arrays; the clean PGO capture at 8229b3fc becomes the public benchmark, with 21 of 30 rows faster than Node.

Six releases in one day, each raising a ceiling a real embedder had hit: a 32 MiB ArrayBuffer, a renewable instruction budget, byte-scheduled collections, a 512 MB heap.

The host boundary stops walking the whole heap per re-entry; an O(heap) walk is removed from the interpreter-only WASM build; JSON.stringify ×4000 drops from 919 ms to 8.5 ms; wasm-opt is dropped after measurement.

The first native and WebAssembly release; B249 takes bytecode-vm from 3.68× to 0.93× Node; module cycle roots restore 95,939 of 95,942; the performance ledger is archived at 881 KB.

A de-fused CallMethod lowering spikes the headline to 2.157× Node and drifts 24 Test262 rows; both are traced to one commit and reversed.

The 17-row hostile suite, built to make JavaScript stop looking like an ideal reducer, records a geomean of 0.961× Node for the first time.

The native and WebAssembly sandboxes are hardened for arbitrary hostile input, one day after ARM64 gets its first JIT tier.

Wave 19 decomposes the three rows that were 60% of the remaining gap on 23 August; the next day the headline ten rows record 0.9695× Node.

Running the same programs through the interpreter and every JIT tier and diffing the outputs finds five classes of silent wrong answers.

1.196× on the headline ten, with typedarray-math reaching Node parity for the first time.

After a two-week pause, the non-moving generational nursery is enabled by default, taking the headline capture from 1.283× to 1.212× Node.

The generational nursery's first stage is refuted by its own measurements before the third stage lands with a prover; the first landing page is committed the same day.

Profile-guided optimization takes the headline from 1.749× to 1.451× Node in one build change; two more waves the same day reach 1.330×.

Benchmark artifacts begin recording engine commit, dirty flag, competitor hashes and per-repetition schedules, after a harness was found able to name a commit it had never measured.

The README points at the repository's permanent address; the day before, the corpus refresh had left Test262 at 95,939 of 95,942.

Two phantom executions removed, then 22 of 30 remaining failures traced to the repository or runner rather than the engine; 99.995% on 95,846 executions.

Non-ISO Temporal calendars take Intl402 from 63.6% to 96.9% in a day; the core suite reaches 99.91%.

A new front end cuts parse-negative failures from 607 files to 80; honouring YAML list-form flags drops the denominator by 181 executions and the score is republished.

The WebAssembly embedding lands as a persistent VM that compiles once and re-enters later; fat LTO with one codegen unit buys about 2%; regex literals validated at compile time add 712 executions.

After six silent weeks, the Test262 runner is found to have been scoring a single execution mode; the honest pass rate is 96.97%. The same day, every crate but zipp-vm is deleted and the docs are rewritten against measurements.

The whole-function JIT tier is enabled by default (parse 4.1× → 3.3× Node) and PERF_ROADMAP.md is written as a checkable path to V8 parity. Then the log goes quiet for six weeks.

Strings gain real lone-surrogate support, BigInt gains a two-tier i128 plus num-bigint implementation, and bench/real arrives as a ten-workload five-engine suite.

Module mode lands with top-level await and a Test262 module runner; modules become runtime structures on the explicit frame stack like everything else.

Indirect and global-scope eval land, followed by ShadowRealm, both as runtime structures rather than native recursion.

A forked regress engine for regular expressions, eleven TypedArray constructors, Proxy traps, Temporal type by type, the whole Intl namespace, a mark-sweep GC, and a 17,400-line vm.rs split into a folder.

The conformance runner lands one day after the pivot, and async generators are implemented as the largest single block of failing executions.

The register VM gets an x86-64 JIT for hot integer functions, OSR loop regions, call-free inline caches, scalar replacement, rope strings and a microtask loop, and beats V8 on loop.js at 26.5 ms against 28.0.

The ES5 object model arrives, a bytecode compiler and VM are built, two engines are tried, and by evening the clean-sheet explicit-frame register VM exists. So does the first retraction of a false performance claim.

The initial commit is a tree-walking interpreter for a small typed language; by the end of the day it has a Cranelift JIT, an LLVM tier, a mark-sweep GC, a gas-metered WebAssembly profile, a zero-knowledge back end and a TypeScript front end.