[plt-scheme] GNU Lightning (was: Re: Improving mzc output)

On Mon, 2005-01-10 at 16:04 -0500, Eli Barzilay wrote in
http://list.cs.brown.edu/pipermail/plt-scheme/2005-January/007644.html
Message-ID: <16866.60900.887441.73781 at mojave.cs.cornell.edu>
> > > > Why go through all the work of writing a JIT compiler when
> > > > they are entirely CPU specific?
> > >
> > > There is a library that we're using that implements a portable
> > > assembly layer.
> > 
> > I'm interested in this.  What library is it?  Can I get a copy?
> 
> Google for "GNU lightning".

Pardon my idle curiousity.  I'm wondering if you have had a chance to
try GNU Lightning out yet, and if you have, what do you think of it so
far?

I hadn't heard of it until you mentioned it.  So, I asked around and
got a response along the following lines.

  | The interface presented by GNU Lightning is pretty low-level.
  | It's a register machine and all instructions are immediately
  | translated to machine code via C macros.
  | 
  | Bad for two reasons:
  | 
  |   (a) too low-level to be a good JIT in its own right.
  | 
  |   (b) too high-level as a code generation tool -- abstracts the real
  |       CPU too much.
  | 
  | Any of the following would be a better choice:
  | 
  |   - LLVM
  |   - Mono's JIT
  |   - Intel's ORP (x86 only)


Personally, I'm not qualified to have an opinion one way or the other,
but I'd be curious to hear yours.  How's GNU Lightning stacking up
against the competition?


Thanks,
Vadim