On October 28, 2019 6:18:26 PM GMT+01:00, Segher Boessenkool <seg...@kernel.crashing.org> wrote: >On Mon, Oct 28, 2019 at 09:08:04AM +0100, Richard Biener wrote: >> On Fri, 25 Oct 2019, Jiufu Guo wrote: >> > On powerpc64le, for O2 , enable -funroll-loops and limit >> > PARAM_MAX_UNROLL_TIMES=2 and PARAM_MAX_UNROLLED_INSNS=20, we can >see >2% >> > overall improvement for SPEC2017. >> >> Note the behavior with LTO will be surprising (and generally when >> functions are compiled with different -O level via the optimize >> attribute). It's a bad idea to base --param values on the value >> of a global optimization option that can be set per function >> (see PR92046). >> >> A better patch would have been to adjust via the target hooks for >> unroll adjust. > >So we should add target hooks for all params, to have them work sanely >with LTO?
No. There are existing target hooks for the unroller though. >What makes params special, different from normal command line options? They use a different machinery. They should be moved over to the general options handling so that per-function settings work. Richard. > >Segher
