[llvm] [Bitcode][NFC] Add abbrev for FUNC_CODE_DEBUG_LOC (PR #146497)

[Nikita Popov via llvm-commits]

nikic wrote:

I feel like we'd probably gain more long term by switching to 5 bits now and thus enabling use of more abbreviations.

But if you want to preserve the size, I strongly suspect that you can kick out FUNCTION_INST_UNOP_ABBREV and FUNCTION_INST_UNOP_FLAGS_ABBREV without much impact. These are used exclusively for encoding the fneg instruction, which shouldn't be particularly common...

https://github.com/llvm/llvm-project/pull/146497