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DATC Robust Design Flow

Notes

Please visit new repository: https://github.com/ieee-ceda-datc/RDF-2019

Introduction

In recent years, there has been a slew of design automation contests and released benchmarks. Past examples include ISPD place & route contests, DAC placement contests, timing analysis contests at TAU, and CAD contests at ICCAD. Additional contests are planned for upcoming conferences. These are interesting and important events that stimulate the research of the target problems and advance the cutting edge technologies. Nevertheless, most contests focus only on the point tool problems and fail in addressing the design flow or co-optimization among design tools. DATC RDF platform is developed to direct attention to the overall design flow from logic design to physical synthesis to manufacturability optimization. The goals are to provide:

  1. An academic reference design flow based on past CAD contest results,
  2. The database for design benchmarks and point tool libraries
  3. Standard design input/output formats to build a customized design flow by composing point tool libraries.

Getting Started

DATC RDF consists of the following directory structure:

Flow configuration:   ./000_config
Logic synthesis:      ./100_logic_synthesis
                      ./110_remove_dangling_nets
Floorplanning:        ./200_floorplanning
                      ./210_create_def
Placement:            ./300_placement
Timing measurement:   ./310_write_def
                      ./320_timing
Gate sizing:          ./400_gate_sizing
                      ./410_write_bookshelf
                      ./420_legalization
                      ./430_write_def
                      ./440_timing
Global routing:       ./500_gr_bench_gen
                      ./510_global_route
Detaile routing:      ./600_dr_benchmark_checker
                      ./610_detail_route
Benchmarks            ./benchmarks
Binaries              ./bin
Utility scripts       ./utils

To give a first shot, please try runnning:

$ cd /path/to/your/workspace
$ git clone <this_repository>
$ cd datc_robust_design_flow
$ ./run.sh my_suite

which runs logic synthesis, placement, gate sizing, and global router with a simple test case. The result of each stage can be found under the stage's directory, e.g.,

./100_logic_synthesis/synthesis
./200_floorplanning/bookshelf
./300_placement/placement
./400_gate_sizing/sizing
./510_global_route/global_route
./610_detail_route/detail_route

Every stage has the main run script (run_suite). The configuration of design flow can be customized using the configuration script located at 000_config. We can specify logic synthesis scenario, utilization of chip floorplan, placer, gate sizer, as well as global router. You can find an example flow configuration at:

./000_config/config_simple.sh

Benchmarks

DATC RDF has 26 benchmark circuits that are taken from
TAU Contest 2017. Since TAU Contest 2017 did not release complete Liberty library, we remapped the benchmark circuits into our own technology library. The standard cell library of DATC RDF is based on the library of ISPD'12/13 Gate Sizing Contest. We took the LEF file from A2A methodology of UCSD (almost the same LEF file used in ICCAD’15 TDP contest). Please refer to the paper for more details:

A. Kahng et al., “Horizontal Benchmark Extension for Improved Assessment of Physical CAD Research,” GLSVLSI’14

Installing Benchmarks

Inside benchmarks/utils directory, theres’s a utility script named install_tau17_benchmarks.py. Run it by:

$ python install_tau17_benchmarks.py

It will (1) download the benchmarks, (2) remap the benchmarks to the RDF cell library, (3) remove the dangling wires, and (4) set up the benchmark directory.

Notes: The above python script only works with python of version greater than 3. Also, it requires an additional module requests. So, if you get an error ModuleNotFoundError: No module named ‘requests’, please install it, for example, by:

$ sudo pip install requests

Flow configuration

You can configure the DATC RDF Database with your preferred logic synthesis scenarios, placers, timers, and global routers. An example flow configuration is shown below:

#!/bin/bash

# Benchmarks
bench_suite=(
    "cordic_ispd"
)

# Logic Synthesis
synth_scenarios=(
    "st"
)
max_fanout=16

# Floorplanning
utilization=0.5

# Placement
placers=(
    "EhPlacer"
)
target_density=0.8

# Timer
timers=(
    "iTimerC2.0"
)

# Gate Sizing
run_gs=true
sizers=(
    "USizer2013"
)

# Global Routing
global_routers=(
    "NCTUgr"
)
tile_size=30
num_layer=6
adjustment=10
safety=90

# Detailed Routing
detail_routers=(
    "NCTUdr"
)

Logic Synthesis

The run_suite script sets up and runs the synthesis expriments. To launch a batch job on the full set of TAU benchmarks, the script is invoked as:

run_suite all

The script lists available benchmarks in the bench_set array. Similarly, possible synthesis "scenarios" are given in the scenario_set array. A user may fill-out the provided script variables my_suite and my_scenarios to run a customized experiment as: run_suite my_suite. (The test_suite and test_scenario variables in the script illustrate the customized setting.)

A scenario is currently defined by the ABC AIG optmization script, int mapping command, and a Boolean indicating the use of timing assertions (provided in the <benchmark>.timing file). The name aliases for available ABC scripts and mapping commands are stored in the ./bin/abc.rc file.

The resulting verilog netlist gets stores in

synthesis/<benchmark>.<scenario>/<benchmark>.v"

Bookshelf Generation

Bookshelf files are generated given the synthesis result. You can run this stage with run_suite script, similar to logic synthesis stage, after specifying the benchmarks and logic synthesis scenario in configuration file. The results will be stored at the directory named:

bookshelf/<benchmark>.<scenario>

Placement

Currently, the following placer binaries are available:

After placement, you can see the placement plot. The plot file will be stored at:

placement/<benchmark>.<scenario>.<placer>

Timing Measurement

To measure the timing with ICCAD evaluation program, we need to generate the def files of placement results. It will be done by run_suite script inside the "310_write_def" directory.

After def file geneartion, you can measure the timing with the ICCAD evaluation program at "320_timing" directory. Currently, iTimerC2.0 and UI-Timer are available. All the files dumped by the ICCAD evaluation prgram will be stored at:

timing/<benchmark>.<scenario>.<placer>/out

Global Routing

You can generate the global routing benchmarks after placement, using the run_batch at 500_gr_bench_gen directory.

After the benchmark generation, you can now run global routing at 510_globla_route. Currently, NCTUgr, FastRoute, and BFG-R are available for global routing. After global routing, you can see the congestion map:

global_route/<benchmark>.<scenario>.<placer>.<router>/<benchmark>.Max_H.congestion.png
global_route/<benchmark>.<scenario>.<placer>.<router>/<benchmark>.Max_V.congestion.png

Detail Routing

In RDF, global routing and detailed routing read input files based on ISPD 2008 Global Routing Contest and ISPD 2018 Initial Detailed Routing Contest, respectively. Since there is no industrial standard format for connecting global routing and detailed routing, we develop a global routing guide translator to translate the output format of ISPD 2008 Global Routing Contest into the input format of routing guide used in ISPD 2018 Initial Detailed Routing Contest. In ISPD 2018 Contest, a group of design rules and routing preference metrics are defined and stored in LEF/DEF files. As in commercial routers, the output of a detailed router follows DEF format that can be read by any commercial layout tools.

Currently, NCTUdr is included, and more tools from winning teams will be included.

Gate Sizing Flow

To turn on the gate sizing flow, you need to set the run_gs flag in your flow configuration file. Note that the gate sizing takes very long time to run. It can also be executed by run_suite scripts, inside the following directories:

./400_gate_sizing
./410_write_bookshelf
./420_legalization
./430_write_def
./440_timing

References

  1. Jinwook Jung, Iris Hui-Ru Jiang, Jianli Chen, Shih-Ting Lin, Yih-Lang Li, Victor N. Kravets, and Gi-Joon Nam, "DATC RDF: An Open Design Flow from Logic Synthesis to Detailed Routing," in Proceedings of 2018 Workshop on Open-Source EDA Technology (Link to arxiv.org).
  2. Jinwook Jung, Iris Hui-Ru Jiang, Gi-Joon Nam, Victor N. Kravets, Laleh Behjat, and Yin-Lang Li, "OpenDesign flow database: the infrastructure for VLSI design and design automation research," in Proceedings of the 35th International Conference on Computer-Aided Design (ICCAD '16). (DOI: https://doi.org/10.1145/2966986.2980074)

Authors

Former Contributers