3 ms·
This is entirely anecdotal, but a coworker of mine worked at amd, and he once told me that amd did a study and found that instructions needed for backwards comp
by muricula 9y ago
This is entirely anecdotal, but a coworker of mine worked at amd, and he once told me that amd did a study and found that instructions needed for backwards compatibility accounted for less than 1% of CPU die space. Big silicon manufacturers are pretty price sensitive and the decision to break backwards compatibility is a clear cut economic one. Clearly they have chosen not to break old software at the expense of continued architectural complexity and maintenance.
- Symmetry 9y agoThe problem isn't the hardware devoted to decoding or even executing instructions so much as the overall design and verification complexity. The existence of 286 call gates has implications throughout the memory subsystem and now when you're adding your TSX transactional memory instructions you have to think carefully about how they interact with call gates and whether you could be introducing bugs and make sure you have unit tests to uncover those bugs.