[llvm] prevent undefined behaviour of SPIR-V Backend non-asserts builds when dealing with token type (PR #78437)

[Vyacheslav Levytskyy via llvm-commits]

VyacheslavLevytskyy wrote:

@michalpaszkowski Can you please have a look at this one as well when you have time. Thank you!

https://github.com/llvm/llvm-project/pull/78437