Routing issues

[pech1002]

Hei,

I am using RapidWright 2025.2.1 to perform both intra-site and inter-site routing on a placed DCP targeting the device xcvp1202-vsva2785-2MP-e-S. However, I am encountering several issues during the routing process.

1. When attempting intra-site routing using design.routeSites(), the routing fails with a NullPointerException.
   Routing failed: java.lang.NullPointerException: Cannot invoke "com.xilinx.rapidwright.util.Pair.getFirst()" because the return value of "com.xilinx.rapidwright.design.Cell.getFirstPhysicalPinMapping()" is null

2. I then tried routing each site individually using SiteInst.routeSite(), but the same issue persists, and multiple sites fail during routing.
   Failed to route site SLICE_X96Y106: java.lang.NullPointerException: Cannot invoke "com.xilinx.rapidwright.util.Pair.getFirst()" because the return value of "com.xilinx.rapidwright.design.Cell.getFirstPhysicalPinMapping()" is null
   Failed to route site SLICE_X96Y201: java.lang.NullPointerException

3. As a workaround, I skipped intra-site routing and attempted inter-site routing only using RWRoute.routeDesignFullNonTimingDriven(design). In this case, routing still fails, indicating that certain pins cannot be routed to an LCB.
   Routing failed: java.lang.RuntimeException: ERROR: Couldn't route pin NOC_NSU512_TOP_X25Y295/NOC_NSU512_ATOM_0_CLK_PIN to any LCB

Please advise on what might be causing these issues and how to handle routing in this scenario properly.

[clavin-xlnx]

Hi @pech1002,

I'm sorry you've run into this issue, but thank you for reporting it! We can look into the cause, but would you be willing to provide an example design and some code that can replicate the issue you are seeing?

If your design is sensitive, we do have a few tools that can help abstract away the problem. For example, we have a design obfuscator (see https://github.com/Xilinx/RapidWright/blob/master/src/com/xilinx/rapidwright/design/tools/DesignObfuscator.java).
There is also a path extraction tool that might be helpful (See #1345).

[clavin-xlnx]

Hi @pech1002 - just a quick update, I think I was able to reproduce the second issue (3 above) when routing to a NOC site with RWRoute. I've got an open PR to fix it (see #1365), please give it a try if you can.

For the first issue, it would be helpful if you can provide an example design with code to reproduce.

[pech1002]

Hi,

I’ve tested your fix, and it works well—thanks for addressing the second issue.

Regarding the first issue, I tried using the obfuscator to anonymize a DCP file, but I wasn’t able to reproduce the same error. The original design is sensitive, so I’m currently working on creating a new project that can replicate the issue without exposing any confidential data. I’ll share it with you once it’s ready.

Thanks for your understanding.