User modifications with Yosys

[gudeh]

Hello everyone! I am trying to use the OpenROAD-flow and Yosys to generate some CSV data. The idea is to run Yosys with small modifications to output the data, afterwards run the OpenROAD-flow and also generate some CSV data. The OpenROAD-flow part is working fine. Although I am having some issues with Yosys.

At first I intended to run Yosys outside of OpenROAD, on a separte project and afterwards run the flow (seems easier). This is not an option because OpenROAD seems to generate its own .lib library, so I am obligated to run Yosys via the OpenROAD-flow. Do you agree with this, or is it an option to get a generated .lib from the flow so I can use it on Yosys myself? Either way this doesn't seem like the proper solution.

• A better solution is to edit the Yosys project being built by the OpenROAD-flow. I tried to do so in my fork, although I am having some issues. I don't know how to properly edit a submodule in a way that ./build_openroad.sh would still work. The only way I could make the submodule download my modifications (even with the .gitmodules file pointing to my Yosys fork) was with the command sudo git submodule foreach git pull origin master. Anyway, the real issue is when I run the build script with ./build_openroad.sh --local --latest, it seems to point to OpenROAD's git URL for Yosys, since it override my modifications.

I hope I was clear enough, buy in summary I want to build the OpenROAD-flow with my modifications on Yosys!

[maliberty]

I suggest you fork yosys and ORFS. In your ORFS you can update the submodule to point to your version of yosys with

git submodule set-url [--]

[gudeh]

I am trying to compile from my fork of ORFS, which is also up to date with ORFS: https://github.com/gudeh/OpenROAD-flow-scripts

[gudeh]

And this is the build log:
build_openroad.log

[gudeh]

The error seems to be when compiling ABC. I noticed it is using the correct version of ABC (the same as ORFS standard): Building abc/abc-bafd2a7

Although, the CFLAGS are different.

This is awkward to me since I have only a new pass on Yosys fork, and two new tcl scrips in ORFS fork, I don't understand how it generates a different CFLAGS.

[vvbandeira]

@gudeh
If you don't have any changes to abc, try removing the folder and compiling again:

rm -rf tools/yosys/abc

Or

./build_openroad.sh --clean-force [ARGS]

[gudeh]

Same error, unfortunately.

[rovinski]

OpenROAD seems to generate its own .lib library

The reason for this is because Yosys does not have any equivalent of a set_dont_use command. The only way to tell Yosys not to use cells is to edit the dont_use property directly in the .lib file which is read by Yosys. To do this, OpenROAD-flow creates a temporary copy and then edits the properties there to keep the original .lib intact.

[gudeh]

Hi @rovinski, what if I wanted to use the same library as the one used during the OR flow? Is it safe to read the one in "::env(DONT_USE_LIBS)" ?

[rovinski]

Yes. Those libraries simply have some of the dont_use properties set in accordance with what's set in the platform / user config file. You can diff the DONT_USE_LIBS with the ones in PLATFORM_DIR to see for yourself.

As a side note, ABC and Yosys recently added support for setting dont_use properties via script. Once (if) that version is upstreamed to ORFS, I believe we will simply remove the DONT_USE_LIBS because they will be obsolete.

[gudeh]

Great! Thanks a lot for clarifying.