[clang] [flang] [llvm] Introduce -fexperimental-loop-fuse to clang and flang (PR #142686)

[Madhur Amilkanthwar via llvm-commits]

madhur13490 wrote:

gg

> Just in case: it's not "just after LoopInterchange", it's "before LoopDeletion". If you want to run it just after LoopInterchange, please add LoopFuse after adding `LPM` to `OptimizePM`. It might be better adding some test to check the position.
> 

Yes, realized this after I pushed. 

> Also, you may want to avoid rebasing and force pushing when possible (see [Updating Pull Requests](https://llvm.org/docs/GitHub.html#updating-pull-requests)).
I prefer to test my changes with the trunk each time I push. Testing with trunk ensures reviewers are looking at the working change with the trunk. I try to minimize force pushes, but for a long-running PR, I prefer rebasing. However, the latest revision is just a fixup!

https://github.com/llvm/llvm-project/pull/142686