Massive: The asm.js Benchmark

You don't have to choose one or the other. I'm comparing technical merits.

> Strength 1 means that old browsers or browsers from uncooperative vendors can still run applications at some level of performance (which might or might not be a usable level).

It's more than just "usable". Chrome doesn't support asm.js, but it runs asm.js apps just dandy, albeit not quite as fast as Firefox.

> As to point 2, the fact that asm.js means that authors and tools don't have to target a new runtime language is a pretty mixed blessing, because perforce it means that they have to continue targeting the old one, which is JS.

I said runtime/API, not "runtime language". I'm referring to the DOM and other Web APIs here, vs. Chrome's Pepper. It means browsers don't need yet another set of APIs, and you get access to all the benefits of the existing set of APIs.

OK, you might not find the high-level DOM and the Web APIs that nice, but you get OpenGL ES and direct blitting, raw audio, raw controller input, and so on as well.

> When did "here, compile to a subset of this old high-level scripting language and we'll try to get the performance back using the latest in JIT and specialisation" become a reasonable candidate for a portable assembler system?

I don't see how the syntax really matters. asm.js is essentially a well-supported portable bytecode. The fact it happens to be a subset of JavaScript doesn't make it bad.

> Like a dog walking on its hind legs, it's impressive that asm.js works as well as it does, but that doesn't actually make it a reasonable approach. It only makes technical sense as part of a heroic effort to provide backwards-compatibility with JS-only browsers (see strength 1).

I don't see what's unreasonable about it. You compile native code to a portable intermediate language. It runs at near-native speed in some browsers, and reasonable speed in others. Yes, it's a subset of JS. So? Why does this bother you?

> A completely open standard? Has there been any sign that Google is frustrating or actively opposing efforts to standardise NaCl/PNaCl?

Not to my knowledge. However, NaCl implements a new set of vendor-specific APIs (Pepper) and relies on single, specific implementations (LLVM, Pepper), making it difficult, if not impossible, for other browser vendors to implement it. You can't really standardise PNaCl for the same reason you could't reasonably standardise WebSQL.

Chrome is hardly the most likely problem child; older versions of IE are more likely to taking up the rear when it comes to performance.

> I don't see what's unreasonable about it. You compile native code to a portable intermediate language. It runs at near-native speed in some browsers, and reasonable speed in others. Yes, it's a subset of JS. So? Why does this bother you?

Well, the biggest and most obvious reason to be bothered (though not the only one) is the concern that the journey through JS (as opposed to generating slightly-shackled native code and running that on the client) is going to impose a performance burden that the browser's JS engine won't be able to fully eliminate, at least in some cases. If you're telling me that asm.js now consistently runs at roughly-as-good-as-native-code speeds across the board, then that is surprising but great news. It certainly didn't seem to be the case three years ago, when we were assured that it was impossible to efficiently implement bignums in code compiled to JS, but I suppose things have been moving quickly in this area. Unfortunately OP doesn't seem to fully support that idea, as it seems to imply that IonMonkey requires significant processor time to make the JS run fast. (Shuffling that overhead off to another thread may effectively remove the performance burden when running single-threaded code on a machine which has two or more idle cores and is plugged into the wall, but it comes back in other cases, including the case where several tabs are all running asm.js programs at the same time.)

...what? asm.js is a compiler target for C code. It's not intended to be hand-written. It's also the default compiler target for C code on the web. You wouldn't really want to compile to anything else, except NaCl I suppose (though that requires more porting effort).

I don't get what you mean by "going through the trouble of compiling their application to asm.js" versus ""normal" javascript wasn't good enough for them.". Why would they compile to normal JS? There's no reason to: Their codebase is in C, C++, or some other native code language. If they compile to asm.js, they get a free performance boost. If they compile to JS, they just get horrible slowness. The only difference between them, here, is a single compiler flag. I don't understand.

> Hell, elm/cljs/scala.js/js_of_ocaml/etc wasn't good enough. How many asm.js developers do you know that will go through the trouble of compiling a codebase to asm.js, without putting up an alert('This app works best on Firefox');?

Why would normal JS developers be writing in asm.js? Do you even understand why asm.js exists?

> Unless the barriers to entry for compiling to asm.js can be very significantly reduced, it will become a Mozilla-only ecosystem.

What barriers to entry? You download the emscripten SDK and you compile your existing C/C++ app to asm.js.

> I'm a huge Mozilla fanboy, but I feel like they bit off more than they could chew here, and I think the effort would be better spent on standardizing a spec for a true VM instead of trying to back-compat-hack one into javascript.

It's not a VM, there's no JIT involved.