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OpenDP

OpenDP: Open-Source Detailed Placement Engine
Visualized detailed placement result using aes_cipher_top design with Innovus initial placement; doc/OpenDP.jpg

Features:

  • Fence region and multi-height cells. (ICCAD 2017 Contest benchmarks)
  • Fragmented ROWs.
  • Macro blocks.

Commands

The detailed_placement command performs detailed placement of instances to legal locations after global placement.

set_placement_padding -global|-instances insts|-masters masters
                      [-left pad_left] [-right pad_right]
detailed_placement [-max_displacement disp|{disp_x disp_y}]
check_placement [-verbose]
filler_placement [-prefix prefix] filler_masters
optimize_mirroring

The set_placement_padding command sets left and right padding in multiples of the row site width. Use the set_placement_padding command before legalizing placement to leave room for routing. Use the -global flag for padding that applies to all instances. Use -instances for instance-specific padding. The instances insts can be a list of instance names, or an instance object returned by the SDC get_cells command. To specify padding for all instances of a common master, use the -filter "ref_name == " option to get_cells.

The set_power_net command is used to set the power and ground special net names. The defaults are VDD and VSS.

The -max_displacement argument to detailed_placement specifies how far an instance can be moved when finding a site where it can be placed. The default values are {500 100} sites. The x/y displacement arguments are in microns.

The check_placement command checks the placement legality. It returns 0 if the placement is legal.

The filler_placement command fills gaps between detail-placed instances to connect the power and ground rails in the rows. filler_masters is a list of master/macro names to use for filling the gaps. Wildcard matching is supported, so FILL* will match, e.g., FILLCELL_X1 FILLCELL_X16 FILLCELL_X2 FILLCELL_X32 FILLCELL_X4 FILLCELL_X8. To specify a different naming prefix from FILLER_ use -prefix <new prefix>.

The optimize_mirroring command mirrors instances about the Y axis in a weak attempt to reduce total wirelength (HPWL).

Example scripts

Regression tests

Limitations

FAQs

Check out GitHub discussion about this tool.

Authors

  • SangGi Do and Mingyu Woo (respective Ph. D. advisors: Seokhyeong Kang, Andrew B. Kahng).
  • Rewrite and port to OpenDB/OpenROAD by James Cherry, Parallax Software
  • Paper reference: S. Do, M. Woo and S. Kang, "Fence-Region-Aware Mixed-Height Standard Cell Legalization", Proc. Great Lakes Symposium on VLSI, 2019, pp. 259-262. (link)

License

BSD 3-Clause License. See LICENSE file.