Hi! On Mon, Nov 26, 2018 at 01:11:40PM +0100, Ilya Leoshkevich wrote: > In the end, the main question was: does this make the code better on > architectures other than s390? > https://gcc.gnu.org/ml/gcc-patches/2018-09/msg00993.html
Yup. > - Code size decreases in most cases. In general, the main side-effect of > this patch is that after jump threading bbro pass builds different > traces and reorders and merges basic blocks differently: It's (almost) all in the noise though. > # ppc64le-redhat-linux: > 511.povray_r -1.29% > 482.sphinx3 -0.65% > 456.hmmer -0.53% > 519.lbm_r -0.51% > # skip |dt| < 0.5% > 549.fotonik3d_r +1.13% > 403.gcc +1.76% > 500.perlbench_r +2.35% 2% degradation on gcc and perlbench isn't really acceptable. It is certainly possible this is an uarch effect of indirect jumps and we are just very unlucky now (and were lucky before), but this doesn't sound good to me :-/ What did you run this on? p8? Segher
