[llvm] [LoopInterchange] Bail out early if minimum loop nest is not met (PR #115128)

[Madhur Amilkanthwar via llvm-commits]

madhur13490 wrote:

Motivation for this patch. 
When loop interchange is enabled, we see an increase in instruction count http://llvm-compile-time-tracker.com/?config=stage2-O3&stat=instructions%3Au&remote=smeijer1234.
This patch aims to alleviate that impact. After this patch, we see improvement http://llvm-compile-time-tracker.com/index.php?config=stage1-O3&stat=instructions%3Au&remote=madhur13490. Lencode is improved from +1.79% to +1.28%

https://github.com/llvm/llvm-project/pull/115128