[llvm] reland "[StructurizeCFG] Hoist and simplify zero-cost incoming else p… (PR #149744)

[Vigneshwar Jayakumar via llvm-commits]

VigneshwarJ wrote:

Some phi nodes that are evaluated as zero cost got hoisted, which caused the failures. added a check to prevent a phi node from hoisting 

https://github.com/llvm/llvm-project/pull/149744