[llvm] [SLP] Loop aware cost model/tree building (PR #187391)

[Elvina Yakubova via llvm-commits]

ElvinaYakubova wrote:

Sorry for the late notice. This commit introduces an 85% regression in the llvm test-suite benchmark MultiSource/Benchmarks/VersaBench/ecbdes. After your follow-up [commit](https://github.com/llvm/llvm-project/commit/34889601a9d738cd4a3049ff27479dc9c01057c9) the regression improves slightly—from 85% down to 60%— but it’s still present. I’m working on a minimal reproducer.

https://github.com/llvm/llvm-project/pull/187391