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There's no way to prevent overlapping extensions. One could easily make an x86 extension that overlaps with some existing one. There's just as much an incentive
by dzaima 5y ago
There's no way to prevent overlapping extensions. One could easily make an x86 extension that overlaps with some existing one. There's just as much an incentive to not do that for x86 as there is for RISC-V.
See AMD's SSE5 vs Intel's SSE4 conflict in x86 - both have instructions that the other doesn't have, and some that both have, and, from what I understand, even the instruction formats conflict.
- saagarjha 5y ago> One could easily make an x86 extension One cannot easily make an x86 extension because there are approximately ~3 entities on the planet allowed to make x86 extensions.
- dzaima 5y agoHere's my random x86 extension: the byte sequence 0xc5,0xfd,0xd4,0x00 sorts the 64-bit floats in ymm0. It conflicts with AVX2. :)
- saagarjha 5y agoYou’ll have trouble shipping that extension. Not because it conflicts with AVX2, but because Intel will sue you for your comparability with the rest of x86.
- sudosysgen 5y agoNot really, China also added their own crypto extensions to x86 chips, though under AMD/VIA's license. I wouldn't be surprised if Sony/Microsoft did too for their consoles. It's doable if you have enough money to get AMD or VIA to make you a one-off.