https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83651
Aldy Hernandez <aldyh at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- Status|WAITING |NEW --- Comment #8 from Aldy Hernandez <aldyh at gcc dot gnu.org> --- I ran the testcase in comment #7 and can confirm that there is a 5.24% performance regression from 6.3.1 to 7.2.1, and a 2.88% regression from 6.3.1 to 8.0. I ran the test on my unloaded workstation, which is a: model name : Intel(R) Core(TM) i7-6600U CPU @ 2.60GHz Average user time of 15 runs: a.out.6.3.1 is 3.820000 Average user time of 15 runs: a.out.7.2.1 is 4.020000 Average user time of 15 runs: a.out.8.0 is 3.931333 I can also confirm that everything runs much faster with -fno-code-hoisting, but that may or may not be related: Average user time of 15 runs: a.out.8.0 -fno-code-hoisting is 3.734667 These regressions seem pretty small, though. Perhaps we could find what regressed from 6.3.1 to 7.2.1, and maybe that's still causing problems in 8 (even though other factors may be causing it to be faster in 8). Confirmed.