[llvm] [RISCV] Optimize conditional branches that can be statically evaluated (PR #131684)

[Michael Maitland via llvm-commits]

michaelmaitland wrote:

> 2. Have you looked at updating MachineLoopInfo instead of invalidating?  We do a bunch of this over IR Loops, but it should be doable on Machine Loops too.

@preames theres a really silly scenario where sometimes DT is not required for this pass but MLI is. We cannot update MLI without DT. Otherwise I would have.

https://github.com/llvm/llvm-project/pull/131684