On Wed, Aug 03, 2016 at 12:05:07AM +0930, Alan Modra wrote: > As noted in the last patch, rs6000_rtx_costs ought to cost slow > unaligned mems. This stops combine merging loads/stores with a > mode-changing SET subreg, if the load/store in the subreg mode would > be slow. Costing slow mems at 100 insns is just an order of magnitude > estimate. (The alignment interrupt does cost quite a lot. > Experiments on power8 with a misaligned lwarx showed taking the > alignment interrupt cost roughly 300 insns.)
Okay for trunk. Do you have a testcase, too? Segher
