JSON.stringify is a core JavaScript function for serializing data. Its performance directly affects common operations across the web, from serializing data for a network request to saving data to localStorage. A faster JSON.stringify translates to quicker page interactions and more responsive applications. That’s why we’re excited to share that a recent engineering effort has made JSON.stringify i…
In this blog post, we explain two optimizations for WebAssembly that we recently implemented in V8 and that shipped with Google Chrome M137, namely speculative call_indirect inlining and deoptimization support for WebAssembly. In combination, they allow us to generate better machine code by making assumptions based on runtime feedback. This speeds up WebAssembly execution, in particular for WasmGC…
Getting JavaScript running fast is key for a responsive web app. Even with V8's advanced optimizations, parsing and compiling critical JavaScript during startup can still create performance bottlenecks. Knowing which JavaScript functions to compile during the initial script compilation can speed up web page loading. When processing a script loaded from the network, V8 has to choose for each functi…
V8’s end-tier optimizing compiler, Turbofan, is famously one of the few large-scale production compilers to use Sea of Nodes (SoN). However, since almost 3 years ago, we’ve started to get rid of Sea of Nodes and fall back to a more traditional Control-Flow Graph (CFG) Intermediate Representation (IR), which we named Turboshaft. By now, the whole JavaScript backend of Turbofan uses Turboshaft inste…
At V8, we're constantly striving to improve JavaScript performance. As part of this effort, we recently revisited the JetStream2 benchmark suite to eliminate performance cliffs. This post details a specific optimization we made that yielded a significant 2.5x improvement in the async-fs benchmark, contributing to a noticeable boost in the overall score. The optimization was inspired by the benchma…
The JavaScript Promise Integration (JSPI) API allows WebAssembly applications that were written assuming synchronous access to external functionality to operate smoothly in an environment where the functionality is actually asynchronous. This note outlines what the core capabilities of the JSPI API are, how to access it, how to develop software for it and offers some examples to try out. What is ‘…
WebAssembly’s JavaScript Promise Integration (JSPI) API has a new API, available in Chrome release M126. We talk about what has changed, how to use it with Emscripten, and what is the roadmap for JSPI. JSPI is an API that allows WebAssembly applications that use sequential APIs to access Web APIs that are asynchronous. Many Web APIs are crafted in terms of JavaScript Promise objects: instead of im…
After almost three years since the initial design document and hundreds of CLs in the meantime, the V8 Sandbox — a lightweight, in-process sandbox for V8 — has now progressed to the point where it is no longer considered an experimental security feature. Starting today, the V8 Sandbox is included in Chrome's Vulnerability Reward Program (VRP). While there are still a number of issues to resolve be…
WebAssembly’s JavaScript Promise Integration (JSPI) API is entering an origin trial, with Chrome release M123. What that means is that you can test whether you and your users can benefit from this new API. JSPI is an API that allows so-called sequential code – that has been compiled to WebAssembly – to access Web APIs that are asynchronous. Many Web APIs are crafted in terms of JavaScript Promises…
Did you ever wonder where undefined, true, and other core JavaScript objects come from? These objects are the atoms of any user defined object and need to be there first. V8 calls them immovable immutable roots and they live in their own heap – the read-only heap. Since they are used constantly, quick access is crucial. And what could be quicker than correctly guessing their memory address at comp…