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

[Nikita Popov via llvm-commits]

nikic wrote:

> > Could you please provide updated compile-time and performance numbers? The implementation has changed a lot in the meantime.
> 
> Here are the new compile time numbers @nikic :
> 
> http://llvm-compile-time-tracker.com/compare.php?from=a8dacd40da0f48484bda05e066b5fa692bcddcc6&to=95270f01ac1f4f29deec6f5c29e4d7e74b4171e5&stat=instructions:u

I don't think this actually enables loop interchange? You add the extra checks for EnableLoopInterchange, but EnableLoopInterchange itself is still false.

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