[llvm] [LoopInterchange] Enable it by default (PR #124911)

[Sjoerd Meijer via llvm-commits]

sjoerdmeijer wrote:

> Maybe we should modify here?
> 
> https://github.com/llvm/llvm-project/blob/80b79ce432bbe12701fd9fe495ff9feeb5e4b9ca/clang/lib/Frontend/CompilerInvocation.cpp#L1964-L1965



> Maybe we should modify here?
> 
> https://github.com/llvm/llvm-project/blob/80b79ce432bbe12701fd9fe495ff9feeb5e4b9ca/clang/lib/Frontend/CompilerInvocation.cpp#L1964-L1965

This patch needs rebasing, it's old, in the meantime, I've added support for `-floop-interchange`m and that is now interacting with this and causing me a bit of pain. I.e., we now have -floop-interchange (and -fno-loop-interchange) and `-mllvm -enable-loopinterchange` to enable/disable it, and I have to worry about the different combinations. My question is @nikic , @kasuga-fj , do we want to keep both options around? Or shall we only keep the user-facing -floop-interchange, and get rid of LLVM option -enable-interchange? That would simplify things. 

https://github.com/llvm/llvm-project/pull/124911