[jstimpfle]

Could you go into a little bit more detail regarding the movzx? Aren't 32-bit registers always zero-extended on x86-64?

[pcwalton]

Sure. Here's an in-depth explanation from Fabian Giesen: https://gist.github.com/rygorous/e0f055bfb74e3d5f0af20690759...

[jstimpfle]

Thanks, rygorous is always a great read - although sometimes a little overwhelming. If I got the gist of it, I have a small correction to your comment: the issue is about movsxd (sign extended integer indexes), not movzx (zero extension).