[llvm] Handle backedge-count logic for std::reverse like loops (PR #92560)

[Eli Friedman via llvm-commits]

efriedma-quic wrote:

Maybe you can flatten the control flow using the `if (!BECount) {` checks?

Otherwise, it's not a big deal; we can always review the diff with whitespace turned off.


https://github.com/llvm/llvm-project/pull/92560