P4
By adding more loop opts specific stress flags, we could think about introducing a unified StressLoopOpts flag instead of having a separate StressX flag for each loop opts phase X.
We could use a bit pattern similar to what we already use for VerifyIterativeGVN
-XX:StressLoopOpts=1011
where each bit represents a stress mode for a specific loop opts phase with 0 = no stressing, 1 = stressing.
For our additional stress testing, we could use all 1s to completely randomize the choices. Or even better use -1. This will automatically enable new stress modes without an update.
Whenever we add a new stress mode for a loop optimization, we could also think about adding some additional stress testing runs only enabling this new stress mode. This often already finds new issues (see, for example, StressLoopPeeling reports). Once this stabilizes after a few months, we can remove these separate runs again.
We could use a bit pattern similar to what we already use for VerifyIterativeGVN
-XX:StressLoopOpts=1011
where each bit represents a stress mode for a specific loop opts phase with 0 = no stressing, 1 = stressing.
For our additional stress testing, we could use all 1s to completely randomize the choices. Or even better use -1. This will automatically enable new stress modes without an update.
Whenever we add a new stress mode for a loop optimization, we could also think about adding some additional stress testing runs only enabling this new stress mode. This often already finds new issues (see, for example, StressLoopPeeling reports). Once this stabilizes after a few months, we can remove these separate runs again.