NOTE: This is the current main branch, as the trunk version of LLVM-ARCompact has unsolved seg-fault issues.

ARCompact is the ISA used by the EnCore microprocessor family. This projects aims to create a working LLVM backend for the EnCore processor family, and port Clang to support the architecture as well.

As is standard for LLVM and Clang, the Clang source is kept in a different repository - Clang-ARCompact. Instructions for combining the two repositories is given below.

Note that this repository is forked from the LLVM Github mirror. Upstream changes will be fetched and merged into the arcompact branch roughly every two weeks, or when I remember.

First, get the sources:

git https://github.com/stephenmcgruer/LLVM-ARCompact-2.git llvm # Checkout LLVM
cd llvm/tools
git clone https://github.com/stephenmcgruer/Clang-ARCompact.git clang # Checkout Clang

Then it is just a case of building LLVM:

cd ../.. # Return to the top level directory
mkdir build
cd build
cmake ../llvm
make -j4

Consider the following C file:

fib.c:

int fib(int n) {
  int cur = 1;
  int prev = 1;
  for (int i = 0; i < n; i++) {
    int next = cur+prev;
    prev = cur;
    cur = next;
  }
  return cur;
}

int main(void) {
  return fib(5);
}

To compile this to ARCompact assembly, run:

bin/clang -ccc-host-triple arcompact -S fib.c -o fib.s

LLVM-ARCompact is currently only able to output assembly, and relies on the EnCore GCC Compiler to assemble and link the output assembly. This means that in order for LLVM-ARCompact to be useful, you probably want to have access to the GCC port. Currently the location that LLVM looks for GCC in is hard-coded in the Clang front-end, but in the future the aim will be to let it be set as a build or runtime flag.

Enjoy and, please, report bugs!