How many other NOP opcodes in @risc_v ?https://twitter.com/babbageboole/status/1054144450342006785 …
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I wonder how many EXACTLY NOPs in the ISA. I counted RV32I = 3945472 ; RV64I adds : 142336 ; Here is my formulahttps://beta.observablehq.com/@drom/nop-v
Missing afaict: AUIPC with Rd=0, branches to the next address, jump to next address, AND/OR of A with A written to A, LD to x0 (only NOP from valid non-io addr), CSR-based nops (i.e. Rd to x0, ignored writes)
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if you count 2-opcode sequences the amount of nops becomes even larger...
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I also thought about that but to me it doesn't feel like it's a proper nop if there's an observable changed in-between state. (Also: it would mean that there are indefinitely many nops, which kind of wrecks the whole exercise. :)
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I wouldn't say LD qualifies as it could e.g. be a clear-on-read register
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Ah, you said non-IO
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I like : AND/OR of A with A written to A
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Out of your list I have added: AUIPC with Rd=0, AND/OR of A with A written to A,
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