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riscvarchive / riscv-binutils-gdb

RISC-V backports for binutils-gdb. Development is done upstream at the FSF.
GNU General Public License v2.0
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About the opcode constraints documentation. #243

Closed were closed 3 years ago

were commented 3 years ago

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 commented 3 years ago

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 commented 3 years ago

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 commented 3 years ago

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