llvm-cbe

Resurrected LLVM C backend, with improvements.

Installation instructions

This version of the LLVM C backend works with LLVM 10.0.

Earlier versions are supported too (LLVM 7 and earlier should work).

Step 1: Installing LLVM

Either install the LLVM packages on your system:

On macOS, use pkgsrc and run the following commands:

    pkgin in llvm clang

On CentOS, install the llvm-devel package:

    dnf install llvm-devel clang

On Debian and derivatives, install the llvm-dev package via:

    apt install llvm-dev clang

Or compile LLVM yourself:

Note: to convert C to LLVM IR to run the tests, you will also need a C compiler using the LLVM infrastructure, such as clang.

The first step is to compile LLVM on your machine (this assumes an in-tree build, but out-of-tree will also work):

 cd $HOME
 git clone https://github.com/llvm/llvm-project.git
 cd llvm-project
 git checkout release/8.x
 mkdir llvm/build
 cd llvm/build
 cmake ..
 make

To run tests, you need to build lli.

Step 2: Compiling LLVM-CBE

Next, download and compile llvm-cbe from the same folder if you built LLVM yourself, or where you'd like in the other case:

cd $HOME/llvm-project/llvm/projects # Or any place, if you use the LLVM package of your distribution.
git clone https://github.com/JuliaComputing/llvm-cbe
cd ../build
cmake ..
make llvm-cbe

Step 3: Usage Examples

If llvm-cbe compiles, you should be able to run it with the following commands.

$ cd $HOME/llvm-project/llvm/projects/llvm-cbe/test/selectionsort
$ ls
main.c
$ clang -S -emit-llvm -g main.c
$ ls
main.c main.ll
$ $(HOME)/llvm/build/bin/llvm-cbe main.ll

Compile Generated C Code and Run

$ gcc -o main.cbe main.cbe.c
$ ls
main.c  main.cbe  main.cbe.c  main.ll
$ ./main.cbe

Running tests

Unit tests:

    $ cd $HOME/llvm-project/llvm/build
    $ make CBEUnitTests && projects/llvm-cbe/unittests/CWriterTest

Other tests:

First, compile llvm-cbe, and install pytest. Then:

    $ cd $HOME/llvm-project/llvm/projects/llvm-cbe
    $ pytest

You might have to adjust the llvm-cbe and lli paths in that configuration.