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The thing is, CISC vs. RISC seems to be an ideological debate more than anything else. The only reason I suggested designing a RISC CPU is because a) ARM has ma
by alanctgardner2 14y ago
The thing is, CISC vs. RISC seems to be an ideological debate more than anything else. The only reason I suggested designing a RISC CPU is because a) ARM has made RISC for servers sexy again, and b) Intel already tried a CISC chip with Itanium, and another would scare vendors pretty badly.
The big difficulty I see is designing an instruction set, architecture and compiler which can show serious performance gains for workloads that matter. Making it easy for developers to come over from x64 while juicing the performance per clock would be a big win.
P.S. I'm not a CPU expert by any means. My understanding is that x86_64 has a big legacy overhead from implementing backwards compatibility with x86, and a goal of Itanium was to reduce the amount of the die dedicated to backwards compatibility. If anyone wants to correct me, feel free.
- haberman 14y agoI don't think Itanium was CISC, they call it "EPIC" (explicitly parallel instruction computing: http://en.wikipedia.org/wiki/Explicitly_parallel_instruction_computing http://en.wikipedia.org/wiki/Explicitly_parallel_instruction...). The basic idea of this was to move logic about what could be parallelized from the CPU to the compiler, but this turned out not to work so well. In Donald Knuth's words, "The Itanium approach...was supposed to be so terrific—until it turned out that the wished-for compilers were basically impossible to write."