P4 ➡ LLVM IR ➡ JSON

P4LLVM is an LLVM based compiler for P4, a networking language.

This project is built upon open-source P4 compiler called p4c. The LLVM IR emitter is a pass over p4c IR. We reuse the p4c front-end and translate p4c IR to LLVM IR.

If you use P4LLVM, please cite the following paper:

@inproceedings{2018p4llvm,
  title={P4LLVM: An LLVM Based P4 Compiler},
  author={Dangeti, Tharun Kumar and S, Venkata Keerthy and Upadrasta, Ramakrishna},
  booktitle={2018 IEEE 26th International Conference on Network Protocols (ICNP)},
  pages={424--429},
  year={2018},
  organization={IEEE}
}

Supporting materials can be found here

Getting started

Install LLVM from source. We are using LLVM 7.0, not tested on the other versions.

• git clone https://llvm.org/git/llvm.git
• git checkout 04bf737a84687a17137cc39da1f2e15ee74f1a4c
• cd llvm && mkdir build && cd build
• cmake ../
• make

Either do make install after make or export the path of llvm binaries.

Clone the P4lang repository. It includes submodules, so be sure to use --recursive to pull them in:

git clone --recursive https://github.com/IITH-Compilers/p4lang.git

If you forget to use --recursive, you can update the submodules at any time using:

git submodule update --init --recursive

Install dependencies.

Dependencies for this repository are same as the p4c compiler. We are listing them here for ease.

• A C++11 compiler. GCC 4.9 or later or Clang 3.3 or later is required.
• git for version control
• GNU autotools for the build process
• CMake 3.0.2 or higher
• Boehm-Weiser garbage-collector C++ library
• GNU Bison and Flex for the parser and lexical analyzer generators.
• Google Protocol Buffers 3.0 or higher for control plane API generation
• GNU multiple precision library GMP
• C++ boost library (minimally used)
• Python 2.7 for scripting and running tests

On Ubuntu you can use:

sudo apt-get install g++ git automake libtool libgc-dev bison flex libfl-dev libgmp-dev libboost-dev libboost-iostreams-dev libboost-graph-dev pkg-config python python-scapy python-ipaddr tcpdump cmake

Install protobuf 3.2.0

• git clone https://github.com/google/protobuf.git
• git checkout v3.2.0
• ./autogen.sh
• ./configure
• make
• make check
• sudo make install
• sudo ldconfig # refresh shared library cache.

Build P4LLVM in a subdirectory named build.

• mkdir build && cd build
• cmake ..
• make -j4

How to run?

Once make is successful, execute p4c-llbm2-ss in build directory to run the code. For example,

./p4c-llbm2-ss ../p4lang/testdata/p4_16_samples/arith-bmv2.p4

This would create arith2-bmv2.p4.ll, a file with LLVM IR equivalent of arith2-bmv2.p4 and arith2-bmv2.p4.ll.json, a JSON file to target BMV2 compiler. arith2-bmv2.p4.ll.json file would be found under P4_16_sample directory.

Running with optimization

While running p4c-llbm2-ss, --optimize flag can be used to perform oz optimization of LLVM. For example,

./p4c-llbm2-ss --optimize ../p4lang/testdata/p4_16_samples/arith-bmv2.p4