Emscripten, an LLVM-to-JavaScript compiler

by fredoliveira • 15 years ago

81 13 15 years ago

veyron• 15 years ago

is this what the repl.it uses?

cyrus_• 15 years ago

yes, I believe so. curious now about whether they could compile clang/llvm itself using emscripten and then pull the whole compilation stack for C into the browser...

azakai2• 15 years ago

repl.it uses Emscripten for Python, Ruby and Lua. The other languages are not compiled into JS (they are handwritten).

Xuzz• 15 years ago

Previous discussions: http://news.ycombinator.com/item?id=1644192 http://news.ycombinator.com/item?id=2428723 http://news.ycombinator.com/item?id=2600890

equark2• 15 years ago

Is there a tracing JIT that has been compiled on top of this? It would be interesting if inherent problems with Javascript as a target language could be partially avoided by implementing a tracing Javascript JIT on top of Javascript.

For instance, the simplest source-to-source transformation for operator overloading is to use function calls for all operators. But this degrades performance for the Number type. Presumably a tracing JIT could switch to native Javascript operators after observing hotspots that only use Numbers.

ootachi2• 15 years ago

Are you talking about C++ overloading? That's static, so tracing won't buy you anything.

equark2• 15 years ago

I'm talking about dynamic languages. This performance penalty is a reason why CoffeeScript has rejected adding an operator overloading mechanism:

https://github.com/jashkenas/coffee-script/issues/846

But the question is whether a tracing JIT could largely eliminate this bottleneck by noticing if inner loops are really Numeric types. I was wondering if there were any LLVM examples that show potential performance of a JIT on a JIT.

DanWaterworth2• 15 years ago

No, and there couldn't realistically be one either.

JITs compile to native machine code, but this is transforming LLVM IR, a typed assembly language.

It might be possible with http://bellard.org/jslinux/ , but I wouldn't expect great performance.

Mvandenbergh• 15 years ago

Description of how LLVM works from The Architecture of Open Source Applications: http://www.aosabook.org/en/llvm.html

ijt• 15 years ago

GHC 7 can use LLVM as a backend. That might allow generation of JavaScript code from Haskell. There's already ghcjs (https://github.com/sviperll/ghcjs), but the output from that is quite verbose from what I've seen so far.

Update: For OS X you need GHC 7.2 to use the LLVM backend. Otherwise GHC just ignores the -fllvm flag. The Haskell Platform only uses version 7.0.4.

DanWaterworth2• 15 years ago

If emscripten could run in the browser, we'd have a js-only alternative to PNaCl.

Emscripten, an LLVM-to-JavaScript compiler

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