[llvm] [IndVarSimplify] Fix `IndVarSimplify` to skip on unfolding predicates when the loop contains control convergence operations. (PR #165643)

[Sameer Sahasrabuddhe via llvm-commits]

ssahasra wrote:

#98006 was an attempt to move the basic blocks on the exit of an extended cycle into that cycle itself. When performed on a loop, this should allow any loop transform to just never worry about the loop extension, but the resulting is loop is actually not a natural loop. It will be undone when loop info is recomputed unless we fundamentally change the definition of a loop. Do you think such a long term direction might be profitable?

https://github.com/llvm/llvm-project/pull/165643