[llvm] SLPVectorizer: Avoid looking at uselists of constants (PR #134578)

[Alexander Kornienko via llvm-commits]

alexfh wrote:

After a bit more investigation I found out that the only thing this commit affects is the instrumented profile, which then leads to the crash even when compiling clang from sources before this commit. So the problem is in the SLP vectorizer, but not in this change.

Looking further...

https://github.com/llvm/llvm-project/pull/134578