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0 pointshajile4y ago0 comments

It's not too surprising. Load, store, move, add, subtract, shift, branch, jump. These are definitely the most common instructions used.

Put it side-by-side with Thumb and it also looks pretty similar (thumb has a multiply instruction IIRC).

Put it side-by-side with short x86 instructions accounting for the outdated ones and the list is pretty similar (down to having 8 registers).

All in all, when old and new instruction sets are taking the same approach, you can be reasonably sure it's not the absolute worst choice.

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zamadatix4y ago

It was more a question of the way it was handled (i.e. it's not a different mode and can be mixed) than what the opcode list looked like.

hajileOP4y ago

Mode switching bloats the instruction count by shifting in and out. RISC-V does well here.

If there's a criticism, it's that the two bytes on 32-bit instructions mean the total instruction range is MUCH smaller overall until you switch to 48-bit instructions which are then much bigger.

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