RePlAce

RePlAce: Advancing Solution Quality and Routability Validation in Global Placement

Features:

• Analytic and nonlinear placement algorithm. Solves electrostatic force equations using Nesterov's method. (link)
• Verified with various commercial technologies and research enablements using OpenDB (7/14/16/28/45/55/65nm).
• Verified deterministic solution generation with various compilers and OS.
• Supports Mixed-size placement mode.
• Supports fast image drawing modes with CImg library.

Visualized examples from ISPD 2006 contest; adaptec2.inf	Real-world Design: Coyote (TSMC16 7.5T)

Commands

global_placement
    [-timing_driven]
    [-routability_driven]
    [-skip_initial_place]
    [-disable_timing_driven]
    [-disable_routability_driven]
    [-incremental]
    [-bin_grid_count grid_count]
    [-density target_density]
    [-init_density_penalty init_density_penalty]
    [-init_wirelength_coef init_wirelength_coef]
    [-min_phi_coef min_phi_conef]
    [-max_phi_coef max_phi_coef]
    [-overflow overflow]
    [-initial_place_max_iter initial_place_max_iter]
    [-initial_place_max_fanout initial_place_max_fanout]
    [-routability_check_overflow routability_check_overflow]
    [-routability_max_density routability_max_density]
    [-routability_max_bloat_iter routability_max_bloat_iter]
    [-routability_max_inflation_iter routability_max_inflation_iter]
    [-routability_target_rc_metric routability_target_rc_metric]
    [-routability_inflation_ratio_coef routability_inflation_ratio_coef]
    [-routability_pitch_scale routability_pitch_scale]
    [-routability_max_inflation_ratio routability_max_inflation_ratio]
    [-routability_rc_coefficients routability_rc_coefficients]
    [-timing_driven_net_reweight_overflow]
    [-pad_left pad_left]
    [-pad_right pad_right]
    [-verbose_level level]

Tuning Parameters

• -timing_driven: Enable timing-driven mode
• -skip_initial_place : Skip the initial placement (BiCGSTAB solving) before Nesterov placement. IP improves HPWL by ~5% on large designs. Equal to '-initial_place_max_iter 0'
• -incremental : Enable the incremental global placement. Users would need to tune other parameters (e.g., init_density_penalty) with pre-placed solutions.
• -bin_grid_count: set bin grid's counts. Default value is defined by internal heuristic. Allowed values are [64,128,256,512,..., int].
• -density: set target density. Default value is 0.70. Allowed values are [0-1, float].
• -init_density_penalty: set initial density penalty. Default value is 8e-5. Allowed values are [1e-6 - 1e6, float].
• -init_wirelength_coef: set initial wirelength coefficient. Default value is 0.25. Allowed values are [unlimited, float].
• -min_phi_coef: set pcof_min(µ_k Lower Bound). Default value is 0.95. Allowed values are [0.95-1.05, float].
• -max_phi_coef: set pcof_max(µ_k Upper Bound). Default value is 1.05. Allowed values are [1.00-1.20, float].
• -overflow: set target overflow for termination condition. Default value is 0.1. Allowed values are [0-1, float].
• -initial_place_max_iter: set maximum iterations in initial place. Default value is 20. Allowed values are [0-MAX_INT, int].
• -initial_place_max_fanout: set net escape condition in initial place when 'fanout >= initial_place_max_fanout'. Default value is 200. Allowed values are [1-MAX_INT, int].
• -timing_driven_net_reweight_overflow: set overflow threshold for timing-driven net reweighting. Allowed values are tcl list of [0-100, int].
• -verbose_level: set verbose level for RePlAce. Default value is 1. Allowed values are [0-5, int].

-timing_driven does a virtual repair_design to find slacks and weight nets with low slack. Use the set_wire_rc command to set resistance and capacitance of estimated wires used for timing.

Example scripts

Regression tests

Limitations

FAQs

Check out GitHub discussion about this tool.

External references

• C.-K. Cheng, A. B. Kahng, I. Kang and L. Wang, "RePlAce: Advancing Solution Quality and Routability Validation in Global Placement", IEEE Transactions on Computer-Aided Design of Integrated Circuits and Systems, 38(9) (2019), pp. 1717-1730.

• J. Lu, P. Chen, C.-C. Chang, L. Sha, D. J.-H. Huang, C.-C. Teng and C.-K. Cheng, "ePlace: Electrostatics based Placement using Fast Fourier Transform and Nesterov's Method", ACM TODAES 20(2) (2015), article 17.

• J. Lu, H. Zhuang, P. Chen, H. Chang, C.-C. Chang, Y.-C. Wong, L. Sha, D. J.-H. Huang, Y. Luo, C.-C. Teng and C.-K. Cheng, "ePlace-MS: Electrostatics based Placement for Mixed-Size Circuits", IEEE TCAD 34(5) (2015), pp. 685-698.

• The timing-driven mode has been implemented by Mingyu Woo (only available in legacy repo in standalone branch.)

• The routability-driven mode has been implemented by Mingyu Woo.

• Timing-driven mode re-implementation is ongoing with the current clean-code structure.

Authors

• Authors/maintainer since Jan 2020: Mingyu Woo (Ph.D. Advisor: Andrew. B. Kahng)
• Original open-sourcing of RePlAce: August 2018, by Ilgweon Kang (Ph.D. Advisor: Chung-Kuan Cheng), Lutong Wang (Ph.D. Advisor: Andrew B. Kahng), and Mingyu Woo (Ph.D. Advisor: Andrew B. Kahng).
• Also thanks to Dr. Jingwei Lu for open-sourcing the previous ePlace-MS/ePlace project code.

License

BSD 3-Clause License. See LICENSE file.