I've created https://gcc.gnu.org/bugzilla/show_bug.cgi?id=88533 which provides a testcase and some performance data. On 12/17/18 11:16, Richard Biener wrote: > GCC 9 IL looks saner than the GCC 7/8 one. Note both compilers > have bound checks inside the innermost loop. The main difference > seems to be in loop header copying where GCC 9 is behaving > much "better" IMHO. It would be interesting to see whether > -fno-tree-ch brings results of the compilers in-line again (even > if it causes the code to run even more slow). I tried -fno-tree-ch as suggested, and it brings versions 7-9 in line again. However, that does not appear to be the most attractive option. I'd like to emphasize that -funroll-loops is mostly a good option here. (The resulting code still doesn't get too close to Intel or PGI, but that's a different story). > > Richard. > >> Regards >> >> Thomas > Thanks, Harald
