Viewing profile — cfallin

Oh goodness, that name is so good! (And thanks!)

Thanks! I haven't studied Graal's IR in detail, no. I'll add it to my reading list...

OK, cool. I was assuming "escape analysis and type inference" implied a JS JIT -- straight from your comment, no other assumptions intended. But you've got a lot of interesting exp…

Hi Fil -- thanks for the comment! I think we may be playing in slightly different spaces: unlike a JS JIT, Cranelift doesn't have "super fancy escape/type analysis". We're really t…

We have two: fuel and epochs. Fuel (analogous to "gas" as it appears in many VM platforms) is a deterministic count and epochs check an always-increasing counter in shared memory m…

No, it's still behind a flag (and so transitively, exceptions are too, because we built exception objects on top of GC). Our docs ( https://docs.wasmtime.dev/stability-tiers.html )…

> It'll be interesting to see what the second non-browser-based WASM runtime to fully support 3.0 will be (I'm guessing wasmtime will be first; ...) Wasmtime already supports every…

They're hitting another design point on the compile time vs. code-quality tradeoff curve, which is interesting. They compile 4.27x faster than Cranelift with default (higher qualit…

Indeed; the tl;dr is "yes it works on SpiderMonkey, and was designed to do so". Blog post in a few months, I promise!

> That is, if x and y are determined only at runtime for power(x, y) then I don't see what can be optimized. Yes, the example in Max's post is specifically assuming one wants to ge…

This is indeed a good point and something I want to write about when I eventually do a blog post on weval. A few counterpoints that I'd offer (and what led me to still take this ap…

weval author here (thanks Max for the blog post!). Also AMA! The talk about weval that Max mentions was at NEU and also CMU; the latter was recorded and is here: https://vimeo.com/…

The approach that Cranelift uses is what we call the "aegraph" (talk I gave about it: slides https://cfallin.org/pubs/egraphs2023_aegraphs_slides.pdf , video https://vimeo.com/8435…

We actually take a fairly unconventional approach to e-graphs: we have a few linear passes and we do all rewrites eagerly, so we use them to provide a general framework for the fix…

Right, it's about algorithmic tradeoffs throughout. A good example I wrote about is here: https://cfallin.org/blog/2021/01/22/cranelift-isel-2/ where we use a single-pass algorithm…

There are some benchmarks of Cranelift-based Wasm VMs (Wasmtime) vs. LLVM-based Wasm VMs here: https://00f.net/2023/01/04/webassembly-benchmark-2023/ The (perhaps slightly exaggera…

A small correction re: Cranelift -- I had originally prototyped with egg, but we're currently using a variant of egraphs I invented called "acyclic egraphs" after working through p…

The perf blogpost actually uses SpiderMonkey-compiled-to-Wasm as a benchmark rather than a comparison (peer) of Wasmtime. However, there are some good comparisons done by a third p…

That's a good question for bjorn3, the leader of that effort; they periodically publish status updates. Over on the Reddit discussion someone pointed to this GitHub issue too: http…