On Tue, Aug 02, 2016 at 10:31:33AM -0500, Segher Boessenkool wrote: > 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?
All of yesterday's patches were from investigating https://gcc.gnu.org/bugzilla/show_bug.cgi?id=71680#c1 but that testcase isn't particularly useful past the fix for power8 SLOW_UNALIGNED_ACCESS. -- Alan Modra Australia Development Lab, IBM