[llvm] [LoongArch] Pre-commit test for loop term fold pass & vector sext, zext (PR #131742)

[Lu Weining via llvm-commits]

https://github.com/SixWeining commented:

Could you add a test like the comment:
https://github.com/llvm/llvm-project/pull/129485/files#diff-47299c232403370e6e02355713cf717324051be6fbaa48257087ebdf0d46ae37R579

https://github.com/llvm/llvm-project/pull/131742