> to my knowledge LICM doesn't cross function boundary

LICM is called with runOnLoop() but is called after function inlining. Inlining enlarges functions, possibly revealing more invariants.

Sure. Any pass that is scoped to functions (or even loops, or basic blocks) will have increased scope if run after inlining, and most passes run after inlining.

In the context of this thread, your observation is not meaningful. The point is: LICM doesn't cross function boundary and neither does regalloc, so LICM has no greater scope than regalloc.