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What would you rather have seen ARM do for a 64-bit ISA expansion? (Genuine question; I have no opinion.)
by setpatchaddress 10y ago
What would you rather have seen ARM do for a 64-bit ISA expansion? (Genuine question; I have no opinion.)
- trsohmers 10y agoGoing through them would be a book in itself (The ARMv8 reference manual is itself a couple thousand pages, which I have only gone through a fraction of). I think RISC-V is the closest thing to what I would like in a simple general purpose ISA, even though it is not perfect (no branch delay slots, no post modifies/register writebacks, don't like the immediate encoding). It is a hell of a lot better than the mess ARM made, and the basic (IMAFD) instruction reference can be kept to a single page ;)
- rayiner 10y agoWait you like branch delay slots?!
- trsohmers 10y agoI love branch delay slots, and they are a key feature for getting highest performance in the architecture I am working on... if you have things like guaranteed latency and static scheduling (like we do with the REX Neo architecture), delay slots are VERY useful in tight loops. I understand not including them in a general purpose design with branch prediction, but I'm not a fan of branch prediction and its effects on determinism.
- coderjames 10y agoI'd never heard of the Rex Neo until your post. Looks very interesting!
- stephencanon 10y ago> no branch delay slots We fought that battle 15 years ago, and delay slots lost (for general-purpose CPUs).