Support for Cache Discard Instruction (e.g., CDISCARD) in Rocketchip

I would like to ask whether Rocketchip supports a cache discard instruction, such as `CDISCARD`. I have noticed that there is an implementation of `CFLUSH` in the project, but I could not find any reference to `CDISCARD`.

- Is there any implementation of a `CDISCARD` instruction in Rocketchip?
- If not, is there a specific reason why `CDISCARD` is not supported or adopted?

Thank you for your help!

Start by locating the existing CFLUSH implementation in Rocketchip and compare it with the issue's requested CDISCARD support. Determine whether CDISCARD is already represented and document the project's stated rationale or requirements for adding it; the issue is complete when support status and adoption rationale are clear.

Written by the indexing model from the issue text.