The aggregation repository contains a set of algorithms for grouping vertices of DAGs coming from loop-carried dependencies. Load-balance Level Coarsening (LBC) is one of the aggregation algorithms.

Hybrid Aggregation (HDagg) is another algorithm that can operate on chordal and non-chordal DAGs directly.

The algorithms in this repository can be used within code generators or libraries.

First following items should be installed:

• CMake
• C++ compiler (GCC, ICC, or CLang)
• METIS (optional) dependency for running the demo efficiently and is handled by the cmake. If you have installed the package using a packet manager (e.g., apt of homebrew), CMake should be able to detect it. Otherwise, it installs METIS from source internally.
• OpenMP (optional) for running some parts of the code in parallel. If you use GCC/ICC then OpenMP should be supported natively. If you use Apple CLang, you probably need to install OpenMP using homebrew install libomp. You can
• also install LLVM usng brew install llvm which support OpenMP natively.

Then build Aggregation, using the following:

mkdir build
cd build
cmake -DCMAKE_BUILD_TYPE=Release ..
make

You can always set -DCMAKE_CXX_COMPILER= and -DCMAKE_C_COMPILER= to use a different compiler. For example: cmake -DCMAKE_CXX_COMPILER=/usr/local/Cellar/gcc\@9/9.3.0_2/bin/g++-9 -DCMAKE_C_COMPILER=/usr/local/Cellar/gcc\@9/9.3.0_2/bin/gcc-9 ..

The example directory shows how to call LBC API and iterate over the created partitioning. For more examples on how LBC is used for making loops with sparse dependencies parallel.