[RISCV] SiFive CPUs with CLIC CSRs

[lenary]

Which SiFive CPUs should have XSfmclic and XSfsclic?

I'm not sure there's a "good" answer here, as these are two machine/supervisor-mode extensions, but the current sifive cpus broadly only have user-mode extensions.

The answer might be "none", but I thought I'd file this to work out the right answer.

[llvmbot]

@llvm/issue-subscribers-backend-risc-v

Author: Sam Elliott (lenary)

Which SiFive CPUs should have `XSfmclic` and `XSfsclic`?

I'm not sure there's a "good" answer here, as these are two machine/supervisor-mode extensions, but the current sifive cpus broadly only have user-mode extensions.

The answer might be "none", but I thought I'd file this to work out the right answer.