[woodruffw]

I'm not saying it's impossible! They certainly have plenty of space in the EVEX scheme. But extending the GPRs is a much bigger lift, tooling-wise, than is adding a relatively disjoint ISA extension. Even if they can do it while preserving older encodings, it's just another speedbump at a time when Intel is probably anxious to make x86-64 as frictionless as possible.

Besides, register renaming seems to be working splendidly at the uarch level. Why complicate the architectural model when the gains are already present?

[monocasa]

> Even if they can do it while preserving older encodings, it's just another speedbump at a time when Intel is probably anxious to make x86-64 as frictionless as possible.

Just wanted to throw out there that it was AMD that came up with x86-64's ISA rather than Intel. Intel was still pushing Itanium hard at the time.