[llvm] [LLVM] Make -use-constant-fp-for-fixed-length-splat the default. (PR #193264)

[Paul Walker via llvm-commits]

paulwalker-arm wrote:

I've created https://github.com/llvm/llvm-project/pull/195090 to fix the issue.  It looks like I misinterpreted a required canonicalisation as a simple combine. I need to add some tests and then I'll send it for review.

https://github.com/llvm/llvm-project/pull/193264