https://gcc.gnu.org/bugzilla/show_bug.cgi?id=84737
Bug ID: 84737 Summary: 20% degradation in CPU2000 172.mgrid starting with r256888 Product: gcc Version: 8.0 Status: UNCONFIRMED Severity: normal Priority: P3 Component: ipa Assignee: unassigned at gcc dot gnu.org Reporter: pthaugen at gcc dot gnu.org CC: dje at gcc dot gnu.org, marxin at gcc dot gnu.org, segher at gcc dot gnu.org, wschmidt at gcc dot gnu.org Target Milestone: --- Host: powerpc64-unknown-linux-gnu Target: powerpc64-unknown-linux-gnu Build: powerpc64-unknown-linux-gnu I'm seeing a 20% degradation on 172.mgrid with r256888. Benchmark was built with "-O3 -mcpu=power7 -ffast-math". Profiling shows the difference comes from function resid() and its clone. r256887 ------- Counted PM_RUN_CYC events (Run_cycles.) with a unit mask of 0x00 (No unit mask) count 100000 samples % image name symbol name 658215 48.2563 mgrid_base.pat_test_64 .resid_ 367381 26.9341 mgrid_base.pat_test_64 .psinv_ 153587 11.2601 mgrid_base.pat_test_64 .interp_ 109785 8.0488 mgrid_base.pat_test_64 .rprj3_ 52642 3.8594 mgrid_base.pat_test_64 .comm3_ 7912 0.5801 mgrid_base.pat_test_64 .MAIN__ 3796 0.2783 libc-2.17.so .__memset_power8 r256888 ------- Counted PM_RUN_CYC events (Run_cycles.) with a unit mask of 0x00 (No unit mask) count 100000 samples % image name symbol name 1109100 59.2023 mgrid_base.gcc_hunt_64 .resid_.constprop.1 368930 19.6930 mgrid_base.gcc_hunt_64 .psinv_ 160102 8.5460 mgrid_base.gcc_hunt_64 .interp_ 114954 6.1361 mgrid_base.gcc_hunt_64 .MAIN__ 55253 2.9493 mgrid_base.gcc_hunt_64 .comm3_ 46903 2.5036 mgrid_base.gcc_hunt_64 .resid_ 5103 0.2724 libc-2.17.so .__memset_power8