[llvm] [LLVM][MC][DecoderEmitter] Add support to specialize decoder per bitwidth (PR #154865)

[Rahul Joshi via llvm-commits]

jurahul wrote:

> Do these errors make sense to you? http://45.33.8.238/macm1/113320/step_3.txt
> 
> (That bot uses the GN build; might be a bug in the GN build.)

Hmm..They don't. This seems different from the issue that @s-barannikov reported above. It looks like the .inc file is a dump of the records in the .td files, meaning that the new `-specialize-decoders-per-bitwidth` option is likely not getting recognized and then tablegen is just dumping all the class records to the output. I suspect something like that is happening. I don't see llvm-tblgen being rebuilt in the short log provided.

https://github.com/llvm/llvm-project/pull/154865