[llvm] remove 'movt' if there is no user of it (PR #136735)

[via llvm-commits]

BaoshanPang wrote:

> > I don't know how to create a end to end test case yet . Is there an example I can check with?
> 
> This one would be difficult. You could try to craft some inline assembly where a swap could form in the middle

For inline assembly, it seems this pass can't do any optimization to them. also I can't find a way that can generate such swap sequence from C code.

https://github.com/llvm/llvm-project/pull/136735