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 using OpenDB (7/14/16/28/45/55/65nm).
• Verified deterministic solution generation with various compilers and OS.
  • Compiler: gcc4.8-9.1/clang-7-9/apple-clang-11
  • OS: Ubuntu 16.04-18.04 / CentOS 6-8 / OSX
• Cleanly rewritten as C++11.
• 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)

How to Download and Build?

• If you want to use this as part of the OpenROAD project you should build it and use it from inside the integrated OpenROAD app. The standalone version is available as a legacy code in standalone branch.
• For OpenROAD-flow users, manuals for released binaries are available in readthedocs. (Getting-Started)
• For developers, manuals for building a binary is available in OpenROAD app repo. (OpenROAD app)
• Note that RePlAce is a submodule of OpenROAD repo, and take a place as the "global_placement" command.

OpenROAD Tcl Usage (global_placement)

global_placement
    [-skip_initial_place]
    [-incremental]
    [-bin_grid_count grid_count]
    [-density density]
    [-init_density_penalty init_density_penalty]
    [-init_wirelength_coef init_wirelength_coef]
    [-min_phi_coef min_phi_coef]
    [-max_phi_coef max_phi_coef]
    [-overflow overflow]
    [-initial_place_max_iter max_iter]
    [-initial_place_max_fanout max_fanout]
    [-verbose_level verbose_level]

Flow Control

• 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.

Tuning Parameters

• bin_grid_count : Set bin grid's counts. Default: Defined by internal algorithm. [64,128,256,512,..., int]
• density : Set target density. Default: 0.70 [0-1, float]
• init_density_penalty : Set initial density penalty. Default: 8e-5 [1e-6 - 1e6, float]
• init_wire_length__coef : Set initial wirelength coefficient. Default: 0.25 [unlimited, float]
• min_phi_coef : Set pcof_min(µ_k Lower Bound). Default: 0.95 [0.95-1.05, float]
• max_phi_coef : Set pcof_max(µ_k Upper Bound). Default: 1.05 [1.00-1.20, float]
• overflow : Set target overflow for termination condition. Default: 0.1 [0-1, float]
• initial_place_max_iter : Set maximum iterations in initial place. Default: 20 [0-, int]
• initial_place_max_fanout : Set net escape condition in initial place when 'fanout >= initial_place_max_fanout'. Default: 200 [1-, int]

Other Options

• verbose_level : Set verbose level for RePlAce. Default: 1 [0-10, int]

Note that all of the TCL commands are defined in the replace.tcl and replace.i.

Verified/supported Technologies

• ASAP 7
• GF 14
• TSMC 16 (7.5T/9T)
• ST FDSOI 28
• TSMC 45
• Fujitsu 55
• TSMC 65

3rd Party Module List

• CImg

License

• BSD-3-clause License [Link]
• Code found under the Modules directory (e.g., submodules CImg source files) have individual copyright and license declarations at each folder.

Authors

• Paper reference: C.-K. Cheng, A. B. Kahng, I. Kang and L. Wang, "RePlAce: Advancing Solution Quality and Routability Validation in Global Placement", to appear in IEEE Transactions on Computer-Aided Design of Integrated Circuits and Systems, 2018. (Digital Object Identifier: 10.1109/TCAD.2018.2859220)
• Mingyu Woo rewrites the whole RePlAce with a clean C++11 structure.
• The timing-Driven mode has been implemented by Mingyu Woo (only available in standalone branch.)
• Timing-Driven and Routability-Driven mode are ongoing with the clean-code structure (in openroad branch.)