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dart-lang / sdk

The Dart SDK, including the VM, JS and Wasm compilers, analysis, core libraries, and more.
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BSD 3-Clause "New" or "Revised" License
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Compile Dart to Wasm #32894

Closed listepo-alterpost closed 5 months ago

listepo-alterpost commented 6 years ago

It would be very cool to add support for the WebAssembly

Admin comment: For current status, see https://dart.dev/web/wasm

terrylucas commented 6 years ago

Yes it would. This is something we are looking at. Thank you.

Bohne13 commented 6 years ago

What, is the effort of webassembly and is there a timeline, for implementation?

mraleph commented 6 years ago

There is no timeline and no work is happening on this at the moment.

listepo-alterpost commented 6 years ago

@mraleph thanks for answer, but how can I know that already happening?

mraleph commented 6 years ago

@listepo-alterpost I am not sure I understand the question. Nothing is happening on this at the moment.

b-strauss commented 5 years ago

Using this in flutter apps would be a great usecase.

mraleph commented 5 years ago

@b-strauss using it in what way?

listepo-alterpost commented 5 years ago

I guess like Blazor alternative(Hummingbird)

b-strauss commented 5 years ago

@mraleph

WebAssembly is a cross platform format. If the DartVM had support for it, we could use the same WASM files on mobile Flutter apps as on web Flutter apps (with Hummingbird via calls to the JS WASM API).

mraleph commented 5 years ago

@b-strauss There is definitely no plans to support running WASM binaries on Dart VM. You can run native code on mobile platforms - which means you can run anything you want and you don't need to compile to WASM first.

b-strauss commented 5 years ago

@mraleph You're right of course. But seeingĀ that the target platforms for flutter will grow in the future (Web, Windows, macOS, fuchsia), having a single binary would make targeting these definitely easier. But I'm aware the cost for that would be high. ;)

Lelelo1 commented 5 years ago

Any news on this?

mraleph commented 5 years ago

No news.

In general if you are interested in WASM support I recommend including rationale (e.g. "I am interested in WASM because ..."). Knowing use cases that people consider would help us to prioritise things. Thanks.

Schonhoffer commented 5 years ago

I am interested in WASM because ..

TLDR: code sharing of packages between client-side web & flutter.

mraleph commented 5 years ago

@Schonhoffer You can already do this in multiple ways:

As you can see neither of these options requires any sort of WASM support from Dart.

nex3 commented 5 years ago

Dart Sass is also very interested in WebAssembly. Our biggest user base runs Dart Sass on Node.js, but we consistently hear from our users that the performance of the compiled JS output is not up to par. Our users are comparing the performance of our dart2js output to Node Sass, which is a wrapper around a C++ library. Dart Sass via dart2js is 2x slower than Node Sass in the very best cases, and almost 6x slower when compiling some real-world libraries.

On the other hand, the main reason anyone uses Dart Sass over Node Sass is that it's vastly easier to install a library that doesn't require native compilation. So users have a choice: they can have an easy installation experience or fast compilation, and whichever they choose also comes with a bunch of subtle incompatibilities. It's not a great experience.

WebAssembly would give us the best of both worlds. It would almost certainly represent a major performance boost over dart2js because we don't have to deal with the overhead of JavaScript, and it's just as portable (and thus easy to install) as plain JS. Even if it the WASM binary had to ship with a full garbage collector until WASM supported it, it would make a huge difference to me and my users.

As an aside, can we re-open this issue, since the proposal is still under consideration?

Bohne13 commented 5 years ago

For all of you: in the following link is a survey about flutter directly from the flutter developers. Because Flutter and Dart are closely linked together there are some questions about Dart and one particular about dart support for web assembly. Could be interesting?!

https://google.qualtrics.com/jfe/form/SV_3W3aVD2y9CoAe6V?Source=IntelliJ&ClientID=cc844799-def7-4db0-8e50-d20606f2af1d

alanjds commented 5 years ago

"Sorry, this survey is not active"

alanjds commented 5 years ago

@mraleph The point is about easy interoperability. I can compile Rust/C/C++ to native, but having a to deal with this for every platform is cumbersome and unecessary on early versions of my app.

Do this makes any sense?

pie-flavor commented 5 years ago

That and "it already compiles to JavaScript" is not really a big comfort because one of the main perks of using wasm instead of transpiling to JS is the incredible speed increase.

mraleph commented 5 years ago

I am reopening the issue to indicate that this is something we are considering, even though we currently have no immediate plans to work on this.

@pie-flavor

one of the main perks of using wasm instead of transpiling to JS is the incredible speed increase.

WASM is not some pixie dust that makes your code magically faster. I actually have some serious doubts that compiling Dart to WASM would bring any speed increase, and in fact expect worse performance due to the lack of dynamic optimizations, insulation from underlying native architecture and inability to rely on builtin optimised primitives and standard library. The only performance characteristic that can potentially be improved by targeting WASM is startup latency. Additionally you will get somewhat predictable performance - but again, I actually doubt it would be better than peak performance you will get from good dart2js code.

b-strauss commented 5 years ago

I am reopening the issue to indicate that this is something we are considering, even though we currently have no immediate plans to work on this.

@mraleph Are you talking about running WASM binaries on Dart VM, or compiling Dart to WASM?

mraleph commented 5 years ago

@b-strauss renamed issue to make it clear.

b-strauss commented 5 years ago

@mraleph Is running WASM on the Dart VM also something that is considered? Should there be a separate issue for that?

mraleph commented 5 years ago

@b-strauss nothing has changed since my comment in January. There are no immediate plans for running WASM on Dart VM - because so far there was no strong demand or persuasive use case which would warrant adding such complexity to the VM.

alanjds commented 5 years ago

Is running WASM on the Dart VM also something that is considered? Should there be a separate issue for that?

There are no immediate plans for running WASM on Dart VM - because so far there was no strong demand or persuasive use case which would warrant adding such complexity to the VM.

What about being able to reuse already-existing business logic coded in a wasm-compilable language? Compiling to native in 2 or 3 platforms (iOS, Android, Web) is way harder then compile to WASM only and use it on the 3.

To be clear: Your team can have a stance against doing it or even doing it right now. But in no way there is "no use case" for running WASM along Dart code, in my opinion.

alanjds commented 5 years ago

(cc: @mesquitaa)

nex3 commented 5 years ago

Although my primary interest here is being able to compile Dart to WASM, I think @alanjds makes a really good point. I expect we're going to be seeing a lot more shared libraries targeting WASM in the next few years, and either Dart's support for that could be a feature that sets it apart from other language options, or its lack of support could be another drawback that makes JS more appealing.

pie-flavor commented 5 years ago

@mraleph

WASM is not some pixie dust that makes your code magically faster.

Isn't it? That's pretty much the whole point of using a compiled instead of interpreted language. But that's just startup time; the real speedup is in not using a language where you can redefine anything anywhere at any moment, because that's the primary thing holding back the JIT. It's not necessarily that the WASM format is special; it's that its end format isn't JS.

mraleph commented 5 years ago

@pie-flavor It is without doubt that WASM is a better compilation target than JS for languages like C/C++ and Rust - languages where you manage your memory manually, where your calls are most often statically dispatched and primitive types are unboxed.

However if you start moving away from this kind of languages towards languages like Dart - which are full of dynamic behaviour, boxed primitive types and GC you will discover it becomes harder to claim with absolute certainty that WASM is a better compilation target than JS - because you would be forced to compile various runtime components (e.g. method dispatch implementation) into WASM - while in JS you get those things from underlying JS runtime and they are implemented natively and heavily optimised.

Another interesting thing to consider is that dart2js essentially benefits from two compilation steps - AOT compilation to JS and dynamic optimisation of this JS later by JS JIT. If AOT compiler fails to statically specialise some call site, there is still a chance that JS VM would manage to do that. You don't get such luxury with WASM.

There are a lot of other factors to consider (e.g. builtin libraries - do you want to implement your own array like structure in WASM with associated performance penalty, or do you just want to use heavily optimised native array?), etc, etc.

That said - I don't doubt that there are workloads and programs that would benefit from Dart targeting WASM. All I am saying is that expecting all Dart programs to magically get faster is incorrect.

swissonid commented 5 years ago

@pie-flavor here is very good Google I/O talkt about js and WAM. If you don't wanna watch the whole talk. Just jump to 17:38 https://youtu.be/njt-Qzw0mVY

armacoty commented 5 years ago

WASM will speed up webgl-based applications.

sffc commented 5 years ago

In the Google i18n team, we are considering options to build a single shared library that targets multiple runtimes. We are evaluating WebAssembly as a compile target, such that our i18n library can be invoked from any VMs that support WASM. Support for WASM on the Dart VM would be a boon to the impact of our i18n-on-WebAssembly proposal.

vsmenon commented 5 years ago

Let's use #37355 for interop with WASM and keep this one for compilation to WASM.

Dart Sass is also very interested in WebAssembly. Our biggest user base runs Dart Sass on Node.js, but we consistently hear from our users that the performance of the compiled JS output is not up to par. Our users are comparing the performance of our dart2js output to Node Sass, which is a wrapper around a C++ library. Dart Sass via dart2js is 2x slower than Node Sass in the very best cases, and almost 6x slower when compiling some real-world libraries.

@nex3 - a useful data point here (if possible) would be Sass with Dart AOT. A hypothetical Dart-on-WASM should be slower than that. I.e., the answer here might be that we need to focus on general Dart AOT performance first.

nex3 commented 5 years ago

We track Dart Sass benchmarks here, including running from a script snapshot, from a native executable, and from JS (our three deploy configurations). AOT performance is competitive with LibSass (written in C++) across the board so we're pretty happy with that. Node.js performance is out big pain point, ranging from about 2x slower than AOT at best to about 5x slower on one real-world benchmark. Even getting it to a consistent 2x slower would be a major improvement.

vsmenon commented 5 years ago

Thanks, @nex3 . Just to clarify, by "native executable", you mean via dart2aot and dartaotruntime?

nex3 commented 5 years ago

That's right.

iapicca commented 5 years ago

As I proposed on Flutter's Github [1] if Flutter Web would use WASM instead of dart2js it would feel "future proof"

alanjds commented 5 years ago

(Hope to not have the thread locked :)

mindplay-dk commented 4 years ago

We track Dart Sass benchmarks here, including running from a script snapshot, from a native executable, and from JS (our three deploy configurations).

@nex3 how are you benchmarking these? where's the benchmark script?

mraleph commented 4 years ago

@mindplay-dk IIRC pub run grinder benchmark runs benchmarking scripts. See https://github.com/sass/dart-sass/blob/master/tool/grind/benchmark.dart for the actual code.

insinfo commented 4 years ago

Compiling dart for webassembly would be fantastic

johnjames24 commented 4 years ago

Compiling dart VM to WASAM would also be interesting

Viacheslav-Romanov commented 4 years ago

Are there any updates here guys? šŸ¤”

nlhnt commented 4 years ago

WASM will speed up webgl-based applications.

How will it exactly speed it up? This is entirely wrong. This may be the case in some near future, but not now. Right now WASM and JS have the same peak performance.

iapicca commented 4 years ago

How will it exactly speed it up? This is entirely wrong. This may be the case in some near future, but not now. Right now WASM and JS have the same peak performance.

@nlhnt your assertion is quite debatable, today as average WASM + native (C / Rust) appears to be 20% faster than JS (source) this uplift being worth rewriting a bunch of code base is definitely up to debate, but the gain in performance is seems to be a fact.

Moreover comparing a relatively new technology against a super-optimized one one may think that there's room for this gap to widen.

I'm not implying that WASM + Dart would reach the performance of C or Rust + WASM, but a performance uplift could be expected

maks commented 4 years ago

Could the experimental work that was done for compiling Dart with LLVM be used as the basis for compiling Dart to WASM?

The kind of use case that this may be useful for is something like the new Rive wasm runtime which was written in c++, but perhaps, given the other Dart based work Rive is doing, they may have chosen to write it in Dart if there had been a Dart->WASM compiler with a low overhead runtime?

Given the Dart on LLVM work was based off of Dartino, maybe it would have such a small enough runtime?

mraleph commented 4 years ago

Could the experimental work that was done for compiling Dart with LLVM be used as the basis for compiling Dart to WASM?

Unfortunately not really for a couple of reasons - most importantly because LLVM backend would not be able to target WASM with GC, which is what we are interested in targeting - as opposed to targeting WASM linear memory and compiling our C++ runtime system to WASM. The second reason is that nothing based on Dartino should be considered usable at this point - Dartino comes from Dart 1 days and did not even entirely faithfully implement Dart 1 semantics (e.g. no support for reified generics).

That being said: given the recent effort (largely driven by V8 team) to implement and evolve GC support in WASM I would say that our interest in WASM as a target for the Dart language is also increased. I can't give any concrete timelines or promises - but I just want to say that WASM is actually starting to look like an interesting target.

On a tangential note: this was not the only experiment we have done with LLVM - we had intern project implementing LLVM backend for the Dart VM AOT compiler two years ago and most recently an engineer from Alibaba with LLVM background has implemented one as well. The practice shows that using LLVM does not really have any large benefits.

gdelgado11 commented 4 years ago

Great!!!, it would be fair and necessary

gdelgado11 commented 4 years ago

It would be interesting to perhaps redo the C / C ++ part of Dart and Flutter and bring it to Rust. So we would have something with a strong focus on security and performance. And maybe that way we would have Dart compilations in WASM that we would be sure are not going to do strange things or have security holes that make software maintenance so difficult.