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Yap. And ARM has the advantage of requiring a smaller frontend. Especially when one looks at wider decoders. On the other hand if your ISA is the micro-ops dir
by sharpneli 6y ago
Yap. And ARM has the advantage of requiring a smaller frontend. Especially when one looks at wider decoders.
On the other hand if your ISA is the micro-ops directly then the instructions start to take ridiculous amounts of space. It's a balancing act between instruction size (to save instruction cache) and the complexity of decoding them.
And it's not just about being 1:1. It's also about how wide you can go. And variable length encodings simply are fundamentally more hard to parse in parallel fashion. That means a wider unit is harder to achieve, needing more space and power.