[llvm] [SLP] Exit early if MaxVF < MinVF (NFCI). (PR #83283)

[Florian Hahn via llvm-commits]

fhahn wrote:

> > > Hmm, I don't think this is NFC, would be good to have a test
> > 
> > 
> > Yes I think technically this could change dbg output. Let me add a test for that.
> 
> Not a debug, I think it may change vectorization output

Ah yes, I missed the updates in the outer loop. I tried to find a test case where the return changes behavior, but wasn't able to do so on X86/AArch64 in MultiSource/SPEC and a set of internal benchmarks.

But I updated the PR to use `continue` and `ScopeExit` to make sure `Operands`/`PrevDist` are updated accordingly on all early continues

https://github.com/llvm/llvm-project/pull/83283