[llvm] [Mips][nanoMIPS] Add initial nanoMIPS target support (PR #223032)

[James Henderson via llvm-commits]

jh7370 wrote:

> > I'd expect to see some testing in tools/llvm-readobj, since you're adding llvm-readobj support in this PR (via the Object changes, if I'm not mistaken). There's already testing there for other MIPS relocation dumping, for example. There are probably other cases too.
> 
> Thanks for the feedback. The relocation dumping is tested in the "Add ELF and relocation support" commit (llvm/test/tools/llvm-readobj/ELF/reloc-types-nanomips.test), modelled on reloc-types-mips.test.
> 
> You do bring up an important point. We initially planned e_flags testing to be added in later stages along with the e_flags themselves, but we ended up including the e_flags in the initial batch without the tests. We had another look and it seems we also omitted an EM_NANOMIPS case in file-header-machine-types.test.
> 
> Current plan is to add the following to the PR:
> 
>     * e_flags decoding in ELFDumper plus llvm-readobj/ELF/nanomips-eflags.test
> 
>     * obj2yaml/ELF/nanomips-eflags.yaml
> 
>     * an EM_NANOMIPS case in file-header-machine-types.test
> 
> 
> Do you think these changes along with the existing reloc-types-nanomips.test would provide adequate test coverage?

Yes, this sounds like appropriate levels of coverage for the tools I maintain. (Mostly llvm-readobj and yaml2obj/obj2yaml for tools impacted by this PR).

https://github.com/llvm/llvm-project/pull/223032