About the opcode constraints documentation.

[were]

Dear All,

I am hacking the RISCV codebase for my own research.
I am confused by the 4th column of the opcode definition.
I cannot find full documentation of the letters in that column in gcc internal.
Is there any material I can learn from?

Regards,
Jian

[kuanlinchentw]

Hi,

You may reference riscv_ip or validate_riscv_insn to know the letter definition.
If there is any document describing the opcode definition, I'd like to know it, too. XD

[jim-wilson]

We don't have documentation for the operand letters. You have to read the gas sources to see what they do. The ones that start with C are two letter codes for compressed instructions. The rest are one letter codes.

[were]

@kuanlinchentw @jim-wilson Thank you for your prompt response. I will be navigating the codebase then.