AMG: Automated Efficient Approximate Multiplier Generator for FPGAs via Bayesian Optimization

how to cite

If you use this repository, we would appreciate a citation for our 2-page article:

@INPROCEEDINGS{10416134,
  author={Li, Zhen and Zhou, Hao and Wang, Lingli and Zhou, Xuegong},
  booktitle={2023 International Conference on Field Programmable Technology (ICFPT)}, 
  title={AMG: Automated Efficient Approximate Multiplier Generator for FPGAs via Bayesian Optimization}, 
  year={2023},
  volume={},
  number={},
  pages={294-295},
  keywords={Source coding;Generators;Hardware;Bayes methods;Table lookup;Optimization;Field programmable gate arrays;Approximate Multiplier;FPGA;Bayesian Optimization},
  doi={10.1109/ICFPT59805.2023.00052}}

The 7-page version is available on arxiv: https://arxiv.org/abs/2310.15495.

contents:

• src: the codes of the generator.
• multipliers: Verilog models of reproduced multipliers and our generated multipliers.
• scripts: tcl files for vivado flow and simulation.

src

Dependencies

• Python 3.9.7 (Maybe other versions also work)
• Yosys
• Hyperopt
• MongoDB (Attention for version compatibility, verified version: MongoDB 4.4.22 for pymongo 3.12.0)
• Vivado 2023.1
• Synopsys VCS

How to run

After solving the dependencies, open a terminal and follow the steps:

Step-0: compile yosys_plugins/gen_cgp/gen_cgp.cpp:

cd yosys_plugins/gen_cgp
yosys-config --build gen_cgp.so gen_cgp.cpp
cd ../../

Step-1: run gen_ha_multiplier/gen_ha_multiplier.py to generate *_ha_array.v and *_mul_top.v, for example:

cd gen_ha_multiplier
python3 gen_ha_multiplier.py unsigned -x_width 8 -y_width 8
cd ../

Step-2: translate *_ha_array.v to YAML file through yosys plugin gen_cgp.so, for example:

cd yosys_plugins/gen_cgp
yosys -Q -T -m gen_cgp.so -p "read_verilog \
../../gen_ha_multiplier/unsigned_8x8_mul_ha_array.v \
../../gen_ha_multiplier/ha_blackbox.v; \
techmap; opt -purge; \
gen_cgp unsigned_8x8_mul_ha_array.yaml"
cd ../../

• Step-3: run opt.py to search approximate multipliers, for example:

cd opt
export PYTHONPATH=../cgp2verilog:../run_vivado:../get_results
python3 opt.py \
-cgp_yaml ../yosys_plugins/gen_cgp/unsigned_8x8_mul_ha_array.yaml \
-opt_percent 0.5 \
-verilog_file unsigned_8x8_mul_ha_array.v \
-verilog_top_file ../gen_ha_multiplier/unsigned_8x8_mul_top.v \
-vivado_exe vivado \
-mae_testbench_file ../gen_lut/ubit8x8_calc_mae_tb.v \
-mse_testbench_file ../gen_lut/ubit8x8_calc_mse_tb.v
cd ../

• Step-4: run get_mongo_results.py to get multipliers:

cd opt
python3 get_mongo_results.py
cd ../

multipliers

ours

open source

• EvoApprox8b

V. Mrazek, R. Hrbacek, Z. Vasicek and L. Sekanina, "EvoApprox8b: Library of Approximate Adders and Multipliers for Circuit Design and Benchmarking of Approximation Methods," Design, Automation & Test in Europe Conference & Exhibition (DATE), 2017, 2017, pp. 258-261, doi: 10.23919/DATE.2017.7926993.

• EvoApproxLib^LITE

V. Mrazek, Z. Vasicek, L. Sekanina, H. Jiang and J. Han, "Scalable Construction of Approximate Multipliers With Formally Guaranteed Worst Case Error," in IEEE Transactions on Very Large Scale Integration (VLSI) Systems, vol. 26, no. 11, pp. 2572-2576, Nov. 2018, doi: 10.1109/TVLSI.2018.2856362.

• DRUM

S. Hashemi, R. I. Bahar and S. Reda, "DRUM: A Dynamic Range Unbiased Multiplier for approximate applications," 2015 IEEE/ACM International Conference on Computer-Aided Design (ICCAD), 2015, pp. 418-425, doi: 10.1109/ICCAD.2015.7372600.

• FPT2022

S. Yao and L. Zhang, "Hardware-Efficient FPGA-Based Approximate Multipliers for Error-Tolerant Computing," 2022 International Conference on Field-Programmable Technology (ICFPT), Hong Kong, 2022, pp. 1-8, doi: 10.1109/ICFPT56656.2022.9974399.

• CaCc

Salim Ullah, Semeen Rehman, Bharath Srinivas Prabakaran, Florian Kriebel, Muhammad Abdullah Hanif, Muhammad Shafique, and Akash Kumar. 2018. Area-optimized low-latency approximate multipliers for FPGA-based hardware accelerators. In Proceedings of the 55th Annual Design Automation Conference (DAC '18). Association for Computing Machinery, New York, NY, USA, Article 159, 1–6. https://doi.org/10.1145/3195970.3195996

• SMApproxLib

Salim Ullah, Sanjeev Sripadraj Murthy, and Akash Kumar. 2018. SMApproxlib: library of FPGA-based approximate multipliers. In Proceedings of the 55th Annual Design Automation Conference (DAC '18). Association for Computing Machinery, New York, NY, USA, Article 157, 1–6. https://doi.org/10.1145/3195970.3196115

• ApproxFPGAs

B. S. Prabakaran, V. Mrazek, Z. Vasicek, L. Sekanina and M. Shafique, "ApproxFPGAs: Embracing ASIC-Based Approximate Arithmetic Components for FPGA-Based Systems," 2020 57th ACM/IEEE Design Automation Conference (DAC), San Francisco, CA, USA, 2020, pp. 1-6, doi: 10.1109/DAC18072.2020.9218533.

• TCAD22

S. Ullah, S. Rehman, M. Shafique and A. Kumar, "High-Performance Accurate and Approximate Multipliers for FPGA-Based Hardware Accelerators," in IEEE Transactions on Computer-Aided Design of Integrated Circuits and Systems, vol. 41, no. 2, pp. 211-224, Feb. 2022, doi: 10.1109/TCAD.2021.3056337.

reproduced unsigned 8x8 multipliers

• AC

S. Venkatachalam and S. -B. Ko, "Design of Power and Area Efficient Approximate Multipliers," in IEEE Transactions on Very Large Scale Integration (VLSI) Systems, vol. 25, no. 5, pp. 1782-1786, May 2017, doi: 10.1109/TVLSI.2016.2643639.

• CR

C. Liu, J. Han and F. Lombardi, "A low-power, high-performance approximate multiplier with configurable partial error recovery," 2014 Design, Automation & Test in Europe Conference & Exhibition (DATE), 2014, pp. 1-4, doi: 10.7873/DATE.2014.108.

• KMap

P. Kulkarni, P. Gupta and M. Ercegovac, "Trading Accuracy for Power with an Underdesigned Multiplier Architecture," 2011 24th International Conference on VLSI Design, 2011, pp. 346-351, doi: 10.1109/VLSID.2011.51.

• OU

C. Chen, S. Yang, W. Qian, M. Imani, X. Yin and C. Zhuo, "Optimally Approximated and Unbiased Floating-Point Multiplier with Runtime Configurability," 2020 IEEE/ACM International Conference On Computer Aided Design (ICCAD), 2020, pp. 1-9.

• RoBA

R. Zendegani, M. Kamal, M. Bahadori, A. Afzali-Kusha and M. Pedram, "RoBA Multiplier: A Rounding-Based Approximate Multiplier for High-Speed yet Energy-Efficient Digital Signal Processing," in IEEE Transactions on Very Large Scale Integration (VLSI) Systems, vol. 25, no. 2, pp. 393-401, Feb. 2017, doi: 10.1109/TVLSI.2016.2587696.

• SDLC

I. Qiqieh, R. Shafik, G. Tarawneh, D. Sokolov and A. Yakovlev, "Energy-efficient approximate multiplier design using bit significance-driven logic compression," Design, Automation & Test in Europe Conference & Exhibition (DATE), 2017, 2017, pp. 7-12, doi: 10.23919/DATE.2017.7926950.

I. Haddadi, I. Qiqieh, R. Shafik, F. Xia, M. Al-hayanni and A. Yakovlev, "Run-time Configurable Approximate Multiplier using Significance-Driven Logic Compression," 2021 IEEE 39th International Conference on Computer Design (ICCD), 2021, pp. 117-124, doi: 10.1109/ICCD53106.2021.00029.

• TOSAM

S. Vahdat, M. Kamal, A. Afzali-Kusha and M. Pedram, "TOSAM: An Energy-Efficient Truncation- and Rounding-Based Scalable Approximate Multiplier," in IEEE Transactions on Very Large Scale Integration (VLSI) Systems, vol. 27, no. 5, pp. 1161-1173, May 2019, doi: 10.1109/TVLSI.2018.2890712.

• PPAM

G. Zervakis, K. Tsoumanis, S. Xydis, D. Soudris and K. Pekmestzi, "Design-Efficient Approximate Multiplication Circuits Through Partial Product Perforation," in IEEE Transactions on Very Large Scale Integration (VLSI) Systems, vol. 24, no. 10, pp. 3105-3117, Oct. 2016, doi: 10.1109/TVLSI.2016.2535398.

• Wallace

An exact multiplier is implemented by Wallace Tree technique.

• Star

An exact multiplier writing with a Verilog star operator, which is usually implemented by Xilinx IP.