LLVM Dialect for pliron

This crate provides the following functionality:

1. Dialect definitions of LLVM ops, types and attributes.
2. A wrapper around llvm-sys converting to and from our LLVM dialect. This necessitates that LLVM be installed locally.

We currently support LLVM-18, and hence LLVM-18 needs to be on your computer. On Ubuntu, this means, you require the libllvm18 and libpolly-18-dev packages.

llvm-opt tool

The llvm-opt binary is provided to enable parsing LLVM bitcode binaries into pliron's LLVM dialect and to emit LLVM bitcode back from the dialect.

Example usage:

1. Compile fib.c into LLVM-IR:

   $clang-18 -c -emit-llvm -o /tmp/fib.bc tests/resources/fib.c

2. Convert the LLVM bitcode to LLVM dialect in pliron and back to LLVM bitcode (the binary llvm-opt, produced in your cargo's target directory must be in $PATH):

   $llvm-opt -S -i /tmp/fib.bc -o /tmp/fib.opt.ll

3. Compile the output fibonacci LLVM-IR, along with a main function into a binary:

   $clang-18 -o /tmp/fib /tmp/fib.out.ll tests/resources/fib-main.c

4. Run the fibonacci binary to see the first few fibonacci numbers printed.

   $/tmp/fib

       fib(0): 0
       fib(1): 0
       fib(2): 1
       fib(3): 1
       fib(4): 2
   

Note: Implementation of the LLVM dialect is not complete, and the above is just a proof-of-concept.