Re: Pengine - the Prolog engine running SWISH

On 08/19/2013 01:03 AM, Richard A. O'Keefe wrote:
> Step 1.  Compile the C code to LLVM bitcode using clang.
> Step 2.  Compile the LLVM bitcode to JavaScript using emscripten
>           (http://en.wikipedia.org/wiki/Emscripten).
> Step 3.  Asm.js (asmjs.org) is a sublanguage of JavaScript.  An
>           Asm.js-aware JavaScript implementation (such as a recent
>           versions of FireFox) can compile it to native code that's
>           within hailing distance of C->native direct compilation.
>
> Of course, with JavaScript having no threads, some things wouldn't
> port.  I've never used emscripten or asm.js myself, but I'm led to
> believe that it would be more like a port to a new (and crippled)
> operating system than anything else.
>
> Some of the libraries wouldn't port, and the top level driver might
> be different, but I would expect that the compiler and the emulator
> would be OK.

Cool. I wonder how that would work security-wise though. After all,
things on the stack are intptr_t objects that go through some math
before it is used as a pointer. Nobody can prove that this is a pointer
into an allocated stack. Either you need expensive checks or you need a
separate process and use the VM manager to make sure nothing outside
allocated memory is touched.

... and the single-threaded version no longer compiles :-(  Shouldn't
be too hard to fix that.

	Cheers --- Jan