[llvm] [LV][IRBuilder] Allow implicit truncation of step vector (PR #173229)

[Nikita Popov via llvm-commits]

nikic wrote:

> Could you kindly add a pre-commit test so we can try to reason about the diff?

There is no diff, this only prevents an assertion failure once https://github.com/llvm/llvm-project/pull/171456 lands.

https://github.com/llvm/llvm-project/pull/173229