WebAssembly Memory64

Category: WebAssembly
Type: New or changed feature
Status: Enabled by default (Chrome 133)
Intent stage: None

Breaking change: No
Enterprise impact: None
Chromium flag: enable-experimental-webassembly-features
Spec maturity: Incubation
Web Platform Tests: No

WPT details: The proposal comes with exhaustive spec tests; we pass them.

Summary

The memory64 proposal adds support for linear WebAssembly memories with size larger than 2^32 bits. It provides no new instructions, but instead extends the existing instructions to allow 64-bit indexes for memories and tables.

Motivation

This feature allows WebAssembly applications to address and use more than 4GB of memory if the system allows for it (64-bit architecture and sufficient available memory). It furthermore allows 64-bit indices to be used throughout WebAssembly (e.g. for table indices) for consistency.

Standards & signals

Specification: https://github.com/WebAssembly/memory64/blob/main/proposals/memory64/Overview.md
Firefox: Positive
Safari: In development
Web developers: Positive

Ecosystem

Web Platform Tests: https://wpt.fyi/results/?q=webassembly-memory64
Chrome Platform Showcase: https://chrome-platform-showcase.paulkinlan-ea.deno.net/features
GenDN reference: https://gendn.paulkinlan-ea.deno.net/features
chrome.dev demos search: https://www.google.com/search?q=site%3Achrome.dev+WebAssembly%20Memory64
MDN Web Docs: https://developer.mozilla.org/en-US/search?q=WebAssembly%20Memory64
Baseline status: https://webstatus.dev/?q=WebAssembly%20Memory64

Explainers: https://github.com/WebAssembly/memory64/blob/main/proposals/memory64/Overview.md

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