[llvm] Move SI Lower Control Flow Up (PR #159557)

[Patrick Simmons via llvm-commits]

linuxrocks123 wrote:

@arsenm we are planning to move forward with this.  The current approach is similar to the first one, but we are updating our target hooks instead of attempting to use bundles to change the IR format.

https://github.com/llvm/llvm-project/pull/159557