[LLVMdev] lli in interpreter mode and external native libraries

[Chris Lattner]

On Wed, 25 Oct 2006, Sarah Thompson wrote:
> Is there any way to support calling external libraries from interpreted
> code (*not* JITted code) within lli?

Sure.

> I am looking at the external functions implementation, and it seems just
> to wrap back onto its own library, looking up lli_X_... prefixed
> functions. It would (for obvious reasons) be incredibly useful not to be
> restricted to the (tiny) set of supplied functions.

There are three ways to do this:

1. Ugly: teach the interpreter about every function you care about, in
    ExternalFunctions.cpp.
2. Less Ugly: refactor the interpreter to think about things in terms of
    their prototype instead of their name.  All external functions of the
    same prototype use the same calling sequence.  Add code for each
    prototype you care about.
3. Best: Find a "foreign function interface" library, and use that to
    interface to native code.

> PS: I'm attempting to extend the interpreter to implement threads
> (mostly working), and will shortly attempt to rip out its state handling
> in order to build an explicit state model checker. So far, it looks like
> LLVM will do very nicely, and though supporting native code external
> functions isn't essential for my purposes, it would be extremely useful.

Cool!

-Chris

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