[llvm] Revert "[SLP]Support revectorization of the previously vectorized scalars" (PR #134604)

[Alexey Bataev via llvm-commits]

alexey-bataev wrote:

> > > This breaks Transforms/SLPVectorizer/X86/reordered-masked-loads.ll. Apparently, the test relies on some changes in #133091.
> > 
> > 
> > Will you wait for the fix then? Will try to land it soon
> 
> We have a number of failures related to SLP vectorizer - I'll be trying to reduce and root-cause them next. As usual, it would be better to revert to green and reland with the necessary fixes.

Agree, but it may cause some other unexpected side effects already, there are some patches on top of it already :(

https://github.com/llvm/llvm-project/pull/134604