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SMT-based-STDCELL-Layout-Generator

1. Overview

This manual briefly summarizes the following flows to generate (i) SMT formulation file (.smt2 file) and (ii) solution files to review the cell layout result. With the given standard cell information inputs (.pinLayout file) which are extracted from the ASAP7 PDK library[1], our flow generates the SMT formulation. We provide a solution viewer to validate the transistor placement and in-cell routing result of the SMT formulation. We employ Z3 (Ver. 4.8.5) [2] as our SMT solver. Please find more details from our paper [3].

2. Our Tool-Chain Scripts and Commands with User-Specified Options

Our tool-chain scripts are written in Perl. SMT solver is Z3 (Ver. 4.8.5). For the information of the Z3 solver, please visit the following link: https://github.com/Z3Prover/z3

• Z3 Solver has been frequently updated. We recommend to use the specific version V4.8.5

(1) Input Standard Cell Information (.pinlayout)

We provide 183 standard cell information which are extracted from the ASAP7 PDK library [1]. The list of standard cells is as follows.

A2O1A1Ixp33 AOI211x1 BUFx6f INVx5 NOR5xp2 OAI32xp33 A2O1A1O1Ixp25 AOI211xp5 BUFx8 INVx6 O2A1O1Ixp33
OAI331xp33 AND2x2 AOI21x1 DFFHQNx1 INVx8 O2A1O1Ixp5 OAI332xp33 AND2x4 AOI21xp33 DFFHQNx2 INVxp33
OA211x2 OAI333xp33 AND2x6 AOI21xp5 DFFHQNx3 INVxp67 OA21x2 OR2x2 AND3x1 AOI221xp5 DFFHQx4
MAJIxp5 OA221x2 OR2x4 AND3x2 AOI222xp33 DFFLQNx1 MAJx2 OA222x2 OR2x6 AND3x4 AOI22x1 DFFLQNx2
MAJx3 OA22x2 OR3x1 AND4x1 AOI22xp33 DFFLQNx3 NAND2x1p5 OA31x2 OR3x2 AND4x2 AOI22xp5 DFFLQx4
NAND2x1 OA331x1 OR3x4 AND5x1 AOI311xp33 DHLx1 NAND2x2 OA331x2 OR4x1 AND5x2 AOI31xp33 DHLx2
NAND2xp33 OA332x1 OR4x2 AO211x2 AOI31xp67 DHLx3 NAND2xp5 OA332x2 OR5x1 AO21x1 AOI321xp33 DLLx1
NAND2xp67 OA333x1 OR5x2 AO21x2 AOI322xp5 DLLx2 NAND3x1 OA333x2 SDFHx1 AO221x1 AOI32xp33 DLLx3
NAND3x2 OA33x2 SDFHx2 AO221x2 AOI331xp33 FAx1 NAND3xp33 OAI211xp5 SDFHx3 AO222x2 AOI332xp33
HAxp5 NAND4xp25 OAI21x1 SDFHx4 AO22x1 AOI333xp33 HB1xp67 NAND4xp75 OAI21xp33 SDFLx1 AO22x2
AOI33xp33 HB2xp67 NAND5xp2 OAI21xp5 SDFLx2 AO31x2 ASYNC_DFFHx1 HB3xp67 NOR2x1p5 OAI221xp5
SDFLx3 AO322x2 BUFx10 HB4xp67 NOR2x1 OAI222xp33 SDFLx4 AO32x1 BUFx12f ICGx1 NOR2x2 OAI22x1
TIEHIx1 AO32x2 BUFx12 ICGx2 NOR2xp33 OAI22xp33 TIELOx1 AO331x1 BUFx16f ICGx3 NOR2xp67 OAI22xp5
XNOR2x1 AO331x2 BUFx24 INVx11 NOR3x1 OAI311xp33 XNOR2x2 AO332x1 BUFx2 INVx13 NOR3x2 OAI31xp33
XNOR2xp5 AO332x2 BUFx3 INVx1 NOR3xp33 OAI31xp67 XOR2x1 AO333x1 BUFx4f INVx2 NOR4xp25 OAI321xp33
XOR2x2 AO333x2 BUFx4 INVx3 NOR4xp75 OAI322xp33 XOR2xp5 AO33x2 BUFx5 INVx4 

(2) SMT Formulation Generation (genSMTinput_SPNR_Ver1.0.pl)

[Usage]

$ ./scripts/genSMTInput_Ver1.0.pl [inputfile_pinLayout] [MAR] [EOL] [VR] [PRL] [SHR] [MPO] [DBMode] [FST] [CellPartition] [CrosstalkML] [Localization] [Tolerance] [BreakingSymmetry] [ObjPartition]

• [inputfile_pinLayout] : path for input pinLayout (ex: pinLayouts/AND2x2.pinLayout)

• [MAR] : Minimum Area Rule parameter (integer)

• [EOL] : End-of-Line Rule parameter (integer)

• [VR] : VIA Rule parameter (float)

• [PRL] : Parallel Run-Length Rule parameter (integer)

• [SHR] : Step Heights Rule parameter (integer)

• [MPO] : Minimum Pin Opening parameter (integer)

• [DBMode] : Diffusion Break Mode – 0:single, 1:double, 2:mixed

  To enable mixed SDB/DDB in crossover region, FET information in crossover region should be specified in pinLayout inputs. Please refer to the sample pinLayout (DFFHQNx1.pinLayout). The FET information in crossover region is described in “i ===SDBCellInfo===” section.

• [FST] : FET Size Transition – 0:disable, 1:enable

• [CellPartition] : Cell Partitioning – 0:disable, 1:enable

  To enable Cell Partitioning Feature, partitioning information should be specified in pinLayout inputs. Please refer to the sample pinLayout (DFFHQNx1.pinLayout). The partitioning info is described in “i ===PartitionInfo===” section.

• [CrosstalkML] : Metal Length Limit for Crosstalk Mitigation

  To enable Crosstalk Mitigation Feature, special care net information should be specified in pinLayout inputs. Please refer to the sample pinLayout (DFFHQNx1.pinLayout). The net information for crosstalk mitigation is described in “i ===SpecialNetInfo===” section.

• [Localization] : Localization – 0:disable, 1:enable

• [Tolerance] : Offset Margin for Localization (integer)

• [BreakingSymmetry] : Breaking Symmetry – 0:disable, 1:enable

• [ObjPartition] : Objective Partitioning – 0:disable, 1:enable

• Please refer our paper [3] for further detailed information of each input parameters.

• Cell Partitioning and Breaking Symmetry options can not be used at the same time.

[Example] Generating the SMT formulation file (.smt2) for the AND2x2 standard cell “AND2x2.pinLayout” with the design rule parameters used in [3].

$ ./scripts/genSMTInput_SPNR_Ver1.0.pl pinLayouts/AND2x2.pinLayout 1 1 1.5 1 1 3 2 1 0 5 1 1 1 1

This will create “AND2x2.smt2” file in the inputsSMT directory. For the .smt2 file format, please visit the following link: https://rise4fun.com/z3/tutorialcontent/guide

• In our work [3], we set different parameters for combinational and sequential logic cells due to the use of cell partitioning and crosstalk mitigation features for the sequential logic cells. Please refer to the pre-described command list (cmd_gen_smt) for the parameters applied to each cell in [3].

(3) RUN SMT Solver (Z3)

[Usage] SMT Solving & Storing solution.

$ z3 inputsSMT/[inputFile(.smt2)] > RUN/[solutionName(.z3)]

[Example] Running “AND2x2.smt2” file and storing the result “AND2x2.z3” to the output directory.

$ z3 inputsSMT/AND2x2.smt2 > RUN/AND2x2.z3

(4) Solution Converter (convSMTResult_Ver1.0.pl)

[Usage]

$ ./scripts/convILPResult_Ver1.0.pl [solPath/solutionName] [inputFile_pinLayout(w/o file extension)]"

[Example] Converting “AND2x2.z3” output file generated from the input pinLayout “AND2x2.pinLayout” to the solution output directory

$ ./scripts/convSMTResult_Ver1.0.pl RUN/AND2x2.z3 AND2x2

This will create “[solutionName].conv” file in the solutionsSMT directory.

The converted solution files (.conv) can be reviewed using an excel-based solution viewer. (SolutionViewer_3F_6T.xlsm)

(5) Pre-described Command Lists

There are “cmd_conv_solution”, “cmd_gen_smt” files which consist of command lists to generate and convert the whole standard cells provided in this package. You can refer to these command file to modify the parameters or execute each cell generation or sourcing the list file to execute all cases.

3. References

[1] V. Vashishtha, M. Vangala, and L. T. Clark, “ASAP7 predictive design kit development and cell design technology co-optimization,” in 2017 IEEE/ACM International Conference on Computer-Aided Design (ICCAD), pp. 992–998, IEEE, 2017

[2] Z3, SMT Solver, https://github.com/Z3Prover/z3.

[3] D. Lee, D. Park, C.-T. Ho, I. Kang, H. Kim, S. Gao, B. Lin, C.-K. Cheng, "SP&R: SMT-based Simultaneous Place- &- Route for Standard Cell Synthesis of Advanced Nodes", IEEE Transactions on Computer-Aided Design of Integrated Circuits and Systems, 2020