[LLVMdev] Using JIT to construct an invocation of a non-JIT function, or how do I interface to GCC exception handling

[Tom Quarendon]

I'm just starting to have a look at LLVM, so forgive me if this is a 
simple question.

What I'd like to do is use the JIT api to construct a "program" that 
calls a series of functions. In other words I'm wanting to translate a 
scripting language into some executable assembler where each primitive 
of my scripting language is implemented with a "normal" function. That 
is, lets say I've got two primitives PUT and GET and my C++ interpretter 
goes somehting like

int doPUT() {
// Do the work of PUT
}

int doGET() {
// Do the work of GET
}

int main() {
// read in the script file and construct a Module containing a Function 
containing suitably ordered
// CallInst objects that invoke doPUT and doGET
}

Can I do that? I can't figure out how to looking at the APIs.

What I really want to do is figure out how GCC exception handling 
structures work, and I was using LLVM as an investigative tool. I'm some 
code to GCC on Linux where we "JIT" a function into memory (not using 
LLVM, I've just done it by manually generating x86 instructions) where 
that dynamically created function just consists of a series of function 
calls to other, "normal" functions that do the work. However I'm having 
trouble with getting exceptions propagated through my dynamically 
created function and I'm struggling to figure out quite what exception 
handling tables I need to generate and quite how I make the GCC 
exception handler find them. So in other words I've got

int doPUT() {
throw IOException;
}

int doGET() {
throw IOException
}

int main() {
// magic up my function in memory containing calls to doGET and doPUT.
try {
 // call my magic'd function
}
catch (IOException) {
}
}



I've found various bits of information about the structure of the 
exception handling tables that GCC uses, but so far I can't see the 
whole picture in terms of what I'd actually do with those tables in 
terms of registering them with the exception handler. I was hoping that 
I could mock up something similar using LLVM to see what it did.

Any help on this would be great thanks.

Tom Quarendon.

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