3 ms·
Would PGO figure this out?
by crazysim 2mo ago
Would PGO figure this out?
- j16sdiz 2mo agoThey could. but.... running PGO is just too much pain. We can't do it "incrementally", can we? How about combining with LTO? edit: I was thinking profiling individual module on a test driver and link them after PGO
- stkdump 2mo agoI don't know if an optimization is allowed to "invent" a write, but I would be surprised if an optimizer goes that far because I have to believe that the number of cases where more writes improve performance are pretty slim.
- rdevulap 2mo agoa simple perf stat should show that the "Keep 50% of random data" case will have insanely more branch mis-predictions that the others.
- Sesse__ 2mo agoGenerally most forms of PGO does not try to capture number of mispredicted branches (which isn't the same as how often a branch is taken).
- bjourne 2mo agoKeep in mind that this is a synthetic benchmark. The task is to remove outliers and for that the roughly 99% correct guesses of the branch predictor is perfectly fine.