[llvm] [LLVM][Transforms] Correct LoopSimplify unique block placement. (PR #105538)

[Nikita Popov via llvm-commits]

nikic wrote:

The general idea here is reasonable enough, but the order of predecessors() is not going to be reliable in either way. The predecessors are computed based on the use list of the block, and that can be arbitrary and is generally not correlated with the order of the blocks themselves. It may differ depending on whether the blocks are parser from textual IR, or constructed in some other way.

https://github.com/llvm/llvm-project/pull/105538