Hi,
In this new version the most significant change is in patch 6,
where a new hflag allows us to not call the instruction helper
inside translate.c unless we're absolutely certain that there
is an instruction count event being sampled and active in the
PMU. This change turned out to be a big boost in performance
in the PMU emulation overall, most notably when dealing with
cycle events that were calling the helper needlessly.
This and all other changes were suggested by David in his review
of the previous version.
Changes from v8:
- patch 5:
* overflow timer of PMC5 is now marked as NULL instead of absent
- patch 6:
* new hflags HFLAGS_INSN_CNT added to track instruction count state
* previous HFLAGS_MMCR0FC flag removed
* pmu_count_insns() now works partially with user mode
- patch 9:
* fixed interrupt comment
- v8 link: https://lists.gnu.org/archive/html/qemu-devel/2021-11/msg05160.html