On Thu, 2006-06-15 at 19:06 +0100, Joern RENNECKE wrote: > 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 live > > ranges, 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. >
I assume you are referring to and rtl flow pass... -ftree-live-range-split happens on trees before expand and only determines whether non-interfering ssa-names get recombined to a single variable, or are left as different variables. I suspect if you disable it you would get worse performance results, and I highly doubt it has any effect on auto increment addressing. In fact, the option is rather misnamed. It would be more correct to call it -ftree-combine-live-ranges and have it turned off by default. Im not aware of anyone turning it off for anything practical. Andrew
