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I don't think RISC-V really addresses the encoding inefficiency problem, except for the "C" extension, sorta. Though I don't think that for OoO superscalar arch
by microcolonel 11y ago
I don't think RISC-V really addresses the encoding inefficiency problem, except for the "C" extension, sorta. Though I don't think that for OoO superscalar architectures, icache pressure is as much of a problem as it is on a fancy vliw.
But yeah, would be nice to get a take on RISC-V in context of this rant.
- _chris_ 11y agoHuh? RISC-V with the compressed extension is incredibly efficient in its encoding. Better than x86 or ARM in both static and dynamic bytes per program. Also, Icache pressure is a huge problem in modern warehouse-scale computers. Any processor that cares about performance will almost certainly be implementing the C extension to RISC-V. It also enables more efficient macro-op fusion, turning common two instruction 4-byte idioms into a single, more powerful instruction.
- microcolonel 11y agoThanks for going into more detail. I was basing my assumption that it wasn't a huge problem on the fact that the only people who complain about it first seem to the folks designing the Mill. They have a ridiculous/insane/cool solution to it. Everyone else seems to first mention their cool branch predictor, or vector processor.