[llvm] [LSR] Optimize lsr-term-fold if the operand of condition is PHINode (PR #96048)

[Zhijin Zeng via llvm-commits]

zengdage wrote:

I think the two pr should be reviewed together. https://github.com/llvm/llvm-project/pull/96044. After the two pr, it can reduce dynamic instruction counts for function `__find_if`  in `stl_algobase.h`.

https://github.com/llvm/llvm-project/pull/96048