Comment by mattst88

> And that was the problem – the branch predictor would sometimes cause xdcbt instructions to be speculatively executed and that was just as bad as really executing them. One of my coworkers (thanks Tracy!) suggested a clever test to verify this – replace every xdcbt in the game with a breakpoint. This achieved two things: > > 1. The breakpoints were not hit, thus proving that the game was not executing xdcbt instructions. > 2. The crashes went away.

I love the simplicity and the genius behind this idea.