On Sat, 2020-02-29 at 08:47 -0700, Jeff Law wrote: > > It's almost certainly the case that the recent IRA changes are going to stress > R0 more. If I'm reading what Vlad did correctly, one of the tie-breakers its > using now is to choose the lowest numbered register when all else is equal. > So > R0 on SH is likely going to be more problematical. > > I wonder if just reordering the regs on the SH (and adjusting the debug output > to keep that working) would be enough to mitigate some of the R0 problems.
It could open a can of worms. Off the top of my head, R0 is used to hold the function return value, and R0:R1 to return structs with sizeof > 4 bytes. So if DImode is allocated to R0, it implicitly uses R0:R1, AFAIR, doesn't it? Would that kind of thing cause troubles? Cheers, Oleg
