Re: [Libjit-developers] libjit vs LLVM

[Chris Lattner]

On Sat, 29 May 2004, Tim Jansen wrote:

> On Friday 28 May 2004 08:20, Chris Lattner wrote:
> > It's not that.  The problem is that there is a limited marked for this
> > kind of thing.  Open source is really bad because everyone reinvents the
> > wheel.
>
> If I interpret LLVM's license correctly, it's BSD with advertising clause and
> thus incompatible with the GPL. That would be a major obstacle for many
> people who would want to use it as a library.

No, it is a standard OSI approved 3-clause BSD license, not the
advertising clause one.

> > The primary advantage that libjit has over LLVM seems to be the
> > availability of a C API.
>
> Which is quite useful if you want to run the VM in your target language
> and use libjit as the only native code. (You need an interpreter in
> order to start/bootstrap the VM though, or it would be desirable to save
> a native program like llvm does).

I'm not sure that I understand what you mean here.  In any case, it would
be pretty trivial to write a C wrapper library around the LLVM interface,
it's just that noone has had the desire to do so yet.

> Another libjit advantage is that there are very few dependencies, which
> can be useful if your target platform is new.

LLVM has very few dependencies as well the big extra one is the
requirement for a C++ compiler.  The other nice thing about LLVM is that
since it's completely modular, you would only link in the portions that
you need.  If you were building a JIT application like libjit would be
used for, you would choose the core library, the JIT library, a code
generator for the current target and that's about it.  You could choose to
add a bytecode reader or .ll file parser if you wanted to, but as we've
discussed to death, that is not required.

-Chris

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