How to add custom instruction to this pulp-riscv-gnu-toolchain

[20171166]

Hi.

I slightly modify the cv32e40p so I need to add custom instruction to this gcc. It is enough if I can use inline assembly which is named to be built-in in paper.

like volatile asm { instrucitons; }

I try to follow this tutorial https://nitish2112.github.io/post/adding-instruction-riscv/ but I think I don't have to use riscv-tools and It would be better if I can choose MATCH_CUSTOM and MASK_CUSTOM. It would be better if you can let me know how to fill the filed in the appropriate way.

Can you help me? or please tell me where to start.

Thanks.

[osta1]

Hello,

I am also facing the same issue; I want to add some new instructions to pulp-riscv-gnu-toolchain, but I am not able to find some satisfying answers about how to add new instructions. Thank you for informing me, in case you have solved the problem.

Thanks.

[20171166]

The above way of the question is adding custom instruction to gcc binutils. As I say, You should add and declare instruction to proper file. You can do this with trial and error looking at the rule of MASK.

I recommend using .word directive. You can use like this volatile asm{ .word 0x12345678 };

in this way, you can use custom instruction for only that part.