Comment by ashf023

In addition to godbolt and reading the output, the scalable check is just benchmarks. When you write new code that you want to autovectorize, you can check it in ways mentioned already. But then IMO the biggest downside of autovectorization is that it can suddenly disappear with seemingly minor code changes. For that you want benchmarks that run in CI or on some regular schedule. Then when you see a regression you can use a profiler plus the other mentioned tools to investigate