I am not sure I would call cranelift "substantial" in terms of exposure/usage. From what I gather, it's not used at all
for normal, everyday Javascript.
I stand corrected though, every little bit helps. Here's hope they'll start using Rust in more places where it counts.
I suppose "substantial" is subjective, but I really do thing it counts. Certainly their are unfortunately frequent vulnerabilities in the code it intends to replace. For example:
To be fair I'm not actually sure rust would fix either of the CVEs I linked. Both being about problems in the generated code (as I understand them from a glance), which is something inherently unsafe to do.
Edit: I realized you might be picking out the word "ARM" on that page. I know Crainlift also works on x86, and I assume it's intended to replace IonMonkey everywhere, not just on ARM chips.
I stand corrected though, every little bit helps. Here's hope they'll start using Rust in more places where it counts.