[llvm] [LoopVectorize] Support vectorization of overflow intrinsics (PR #174835)

[Alexander Kornienko via llvm-commits]

alexfh wrote:

> I don't think there's an issue with the changes in this patch. It looks like it has exposed a pre-existing issue with `replicateByVF`:

That may well be the case, however, the user-visible effect of _this_ change is that the compiler started crashing on valid code. This isn't a rare situation in LLVM, unfortunately, and as in other cases, the most straightforward course of action is to revert first and figure out what needs to be done in order to prevent this problem when relanding the change. 

I've sent a PR to revert this commit to stop the bleeding: https://github.com/llvm/llvm-project/pull/179819

https://github.com/llvm/llvm-project/pull/174835