In http://gcc.gnu.org/ml/gcc/2006-06/msg00549.html, you wrote:
-ftree-live-range-split splits live ranges on exit from ssa. This is on by default, and in fact it is more work to NOT split unrelated liveranges, and creates extra register pressure.
I've found that in 4.1, -fno-web is often needed in order to generate auto-increment addressing. I suppose that will be similar for any live range splitting that happens before flow.