[rasz]

Or you leave it as is forcing AMD to fix their shit. "fast string mode" has been strongly hinted as _the_ optimal way over 30 years ago with Pentium Pro, further enforced over 10 years ago with ERMSB and FSRM 4 years ago. AMD get with the program.

[saagarjha]

rep movsb might have been fast at one point but it definitely was not for a few decades in the middle, where vector stores were the fastest way to implement memcpy. Intel decided that they should probably make it fast again and they have slowly made it competitive with the extensions you’ve mentioned. But for processors that don’t support it, using rep movsb is going to be slow and probably not something you’d want to pick unless you have weird constraints (binary size?)