HeteroCL: A Multi-Paradigm Programming Infrastructure for Software-Defined Reconfigurable Computing

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Introduction

With the pursuit of improving compute performance under strict power constraints, there is an increasing need for deploying applications to heterogeneous hardware architectures with accelerators, such as GPUs and FPGAs. However, although these heterogeneous computing platforms are becoming widely available, they are very difficult to program especially with FPGAs. As a result, the use of such platforms has been limited to a small subset of programmers with specialized hardware knowledge.

To tackle this challenge, we introduce HeteroCL, a programming infrastructure comprised of a Python-based domain-specific language (DSL) and a compilation flow. The HeteroCL DSL provides a clean programming abstraction that decouples algorithm specification from hardware customizations including data and processing customizations. HeteroCL can further capture the interdependence among these different customization techniques, allowing programmers to explore various performance/area/accuracy trade-offs in a systematic and productive manner.

Language Overview

Current Compilation Flow

Install MLIR-based HeteroCL

To install the HeteroCL-MLIR dialect, please make sure you have installed the tools below:

• gcc >= 5.4
• cmake >= 3.19
• python >= 3.7

The following script shows the complete process of building the HeteroCL-MLIR dialect and connecting it with the HeteroCL frontend. It may take about 10 minutes to install the LLVM package depending on the internet connection and the hardware resource of your machine. If you are a HeteroCL developer, please refer to the guide in the HCL-MLIR repository and build the dialect with the Python binding from source.

git clone https://github.com/cornell-zhang/heterocl.git heterocl-mlir
cd heterocl-mlir
git submodule update --init --recursive
pip install . -v
# export LLVM path
export LLVM_BUILD_DIR=$(pwd)/hcl-dialect/externals/llvm-project/build
export PATH=${LLVM_BUILD_DIR}/bin:${PATH}

To verify HeteroCL is installed correctly, you can run the following test.

python3 -m pytest test

Related Publications

• Shaojie Xiang, Yi-Hsiang Lai, Yuan Zhou, Hongzheng Chen, Niansong Zhang, Debjit Pal, Zhiru Zhang. HeteroFlow: An Accelerator Programming Model with Decoupled Data Placement for Software-Defined FPGAs. In FPGA, 2022.
• Yi-Hsiang Lai, Yuze Chi, Yuwei Hu, Jie Wang, Cody Hao Yu, Yuan Zhou, Jason Cong, Zhiru Zhang. HeteroCL: A Multi-Paradigm Programming Infrastructure for Software-Defined Reconfigurable Computing. In FPGA, 2019. (Best Paper Award)

Related Work

• Stencil with Optimized Dataflow Architecture (SODA)
• Polyhedral-Based Systolic Array Auto-Compilation (PolySA)
• Merlin Compiler
• Halide
• TVM
• MLIR

Contributing to HeteroCL

Coding Style (Python)

We follow official Python coding style and use NumPy docstring style.

Coding Style (C and C++)

We follow Google coding style.

Steps

1. Use clang-format to format your C-related files. The configuration file is in docs/.clang-format. Following is a sample command to format the file in place. Note that you need to put the configuration file at the same directory you execute the command.

clang-format -i -style=file <cpp-file> 2. Use Pull Request. Remember to select the most suitable labels and put it in the title. 3. Make sure all the tests pass.