[llvm] [TableGen] Improvements to Named operands in InstrInfoEmitter (PR #124960)

[Craig Topper via llvm-commits]

topperc wrote:

> Hi @jurahul ,
> 
> My downstream backend uses sentinel `OPERAND_LAST` (perhaps others do as well). It seems best to restore that line. It is pretty common for TableGen to emit sentinels in enums like this, and they can be useful.

Can you say more about what you use it for? If I understand correctly the value wasn't guaranteed to be a value that wasn't used elsewhere in the enum.

https://github.com/llvm/llvm-project/pull/124960