Update build

[towoe]

@widlarizer, I reused some of your commits (also merged a few things together) from #12
My goal would be to bring this up-to-date, and then also have the changes in CIRCT which we also want to have upstream, and maybe leave out the "experimental" things.
So updating the build in here, and then follow up with the features in another PR.

[towoe]

I think the things missing from #12 are the attributes and the bytecode output @widlarizer?

[widlarizer]

Sorry, I don't understand the plan. Is this #12 rebased but you removed some things so they're missing now?

[towoe]

Basically yes, this is now only including the stuff for the build system, to get this updated.
I think there are some other things in PR #12 which might need some more changes, but so make this a bit easier I wanted to do unrelated things in #13. Does that sound okay to you?

[widlarizer]

Right, so the CIRCT bump includes none of the actual CIRCT changes, I'll see when I can get to rebase all that then

[towoe]

The CIRCT bump should include the existing RTLIL stuff with some rebase adoptions, but none of the change from you fork.
@widlarizer what do you mean with "rebase all that"?

[widlarizer]

I see, thanks. Is this PR buildable as-is? I tried moving all of #12 on top of this PR but ran into:

CMake Error at llvm/build/lib/cmake/llvm/AddLLVM.cmake:1133 (add_dependencies):
  The dependency target "MLIRRegisterAllDialects" of target
  "circt-lsp-server" does not exist.
Call Stack (most recent call first):
  cmake/modules/AddCIRCT.cmake:50 (add_llvm_executable)
  cmake/modules/AddCIRCT.cmake:59 (add_circt_executable)
  tools/circt-lsp-server/CMakeLists.txt:44 (add_circt_tool)

Which seems quite unrelated to any of the changes I did. But also I may have messed up the rebase. You can look at that rebase here

[towoe]

I tested the PR before I opened it. It should work...
Your error looks suspiciously like an outdated dependency.
Could you try a clean build? With both, circt and llvm, submodules updated.

[widlarizer]

I rechecked without any of my changes. Even if I have no nix flake bump, with this PR as-is, I still get the same build error when clean building. I don't know what's up with that yet