[LLVMdev] Scheme + LLVM JIT

[Alexander Friedman]

> llvm_function_new/llvm_value_set_name/llvm_executionengine_run_function, 
> etc.
> 
> If kept simple, standardized, and generic, I think it would be very useful 
> to people (even if incomplete).  This would allow others to build on it, 
> and we could 'ship' it as a standard llvm library.

It looks like my interface will look vaguely like this. Functions like
"llvm_make_module" will take in text representations of the
module. This seems to be the fastest way of getting our scheme
implementation to talk to the jit.

This requires being able to parse strings. The LLVM 'Parser.h'
interface (and implementation) has the built in assumptions that it
will always be parsing from the file system.

Would you guys accept a patch that makes it more general (ie, parse
from file or string)? If so, what's an easy way to do it? Is it
possible to have a "FILE" struct backed by a string?


FYI, here is a sketch of what the fib example would look like:

#include "llvm_c.h"

/*
  Everything takes and recieves void * pointers. This to avoid redefining C++
  types.

  This is the C 'version' of the Fib example, at least in spirit.
*/

char* fib_function =
 "int %fib (int %AnArg) {"

 " EntryBlock: "
 " %cond = setle int AnArg, 2"
 " branch bool %cond, label return, label recur"

 " return:"
 " ret int 1"

 " recur:"
 " %sub1 = sub int %AnArg, 1"
 " %fibx1 = call tail int %fib (int %sub1) "
 " %sub2 = sub int %AnArg, 2"
 " %fibx2 = call tail int %fib (int %sub2) "
 " %result = add int %fibx1, %fibx2"
 " ret int %result"
 "}";


void * M = llvm_make_module_from_text (program, "test") ;

// now we want to run some optimizations on this thing.
// make a pass manager
void * PM = llvm_make_pass_manager();

// add 'target data' to module
llvm_addPass(PM, make_target_data("jit-lib",M));

llvm_addPass (PM, llvm_createVerifierPass());

// add optimization passes here
// addPass (PM, ... )

llvm_run_passes(PM,M);

// merge modules - not relevant here

// make an execution engine from the module
void * JE = llvm_make_jit_engine (M);

// get a function pointer by name. If you have several functions with the same
// name, you are out of luck
int (*fib) (int) = (int (*)(int)) llvm_get_function_pointer(JE,M,"fib");

// the above cast is probably wrong.

int result =fib (24);


-- 


-Alex