[llvm] [SimplifyCFG] Not folding branch in loop header with constant iterations (PR #74268)

[via llvm-commits]

xiangzh1 wrote:

Update: add ir test llvm/test/Transforms/SimplifyCFG/simplify-cfg-unroll.ll
(not sure it is minimal, llvm-reduce does works well for it, I mannualy create it)

https://github.com/llvm/llvm-project/pull/74268