[llvm] [TableGen][Decoder] Decode operands with zero width or all bits known (PR #156358)

[Sergei Barannikov via llvm-commits]

s-barannikov wrote:

> > function is now allowed to fail (should return void)
> 
> typo? _not_ allowed to ?

Yes, thanks. I was about to push a change that removes this discrepancy, since the returned status appears to be needed for ARM IT blocks.

https://github.com/llvm/llvm-project/pull/156358