[camel-cdr]

There is an assembly manual: https://github.com/riscv-non-isa/riscv-asm-manual/blob/maste...

[IshKebab]

That's not a specification for the grammar at all. It's just a guide for how to use RISC-V assembly. Not what we're talking about.

[epcoa]

That document is grossly unfinished and doesn’t even appear to specify syntax outside pseudo ops and a few other things. In a few places it refers to the output of objdump, which I think is close enough to saying “whatever gcc does”.