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by CalChris 2049 days ago
"Variable length CISC is fine." Well, actually, the Anandtech article points out:

"Other contemporary designs such as AMD’s Zen(1 through 3) and Intel’s µarch’s, x86 CPUs today still only feature a 4-wide decoder designs (Intel is 1+4) that is seemingly limited from going wider at this point in time due to the ISA’s inherent variable instruction length nature, making designing decoders that are able to deal with aspect of the architecture more difficult compared to the ARM ISA’s fixed-length instructions."

Given the complexity of x86, it's amazing that Intel+AMD have gotten 4-wide decoders. But the M1 has 8-wide and if they want to go wider, it's linear rather than quadratic in complexity.