[brucehoult]

This is not a discussion that can be resolved in the abstract. It requires actual experimentation and data and pointing at actual physical CPUs differing only in this respect and compare the silicon area, energy use, MHz achieved, and cycles per program.

[dzaima]

It's certainly not a thing to be resolved in the abstract, but it's also far from thing to be ignored as irrelevant in the abstract.

But I have a hard time imagining that my general point of "if there's headroom for a full 64-bit adder in the AGU, adding such is very cheap and can provide a couple percent boost in applicable programs" is far from true. Though the register file port requirement might make that less trivial as I'd like it to be.