[llvm] [SLP]Reduce number of alternate instruction, where possible (PR #128907)

[Alexey Bataev via llvm-commits]

alexey-bataev wrote:

> @alexey-bataev, I am seeing an assertion in SLP with this patch even after the latest reland [7de895f](https://github.com/llvm/llvm-project/commit/7de895ff1146c17ec78877900c01c09f4140e692).
> 
> I opened #130972 with an IR reproducer. Reverting [7de895f](https://github.com/llvm/llvm-project/commit/7de895ff1146c17ec78877900c01c09f4140e692) "fixes" the issue.
> 
> The original crash I saw was in a Fortran application compiled with flang.
> 
> Can you have a look or revert?

It is reverted already, the fixed version will be landed soon

https://github.com/llvm/llvm-project/pull/128907