Re: [RFC PATCH 1/8] riscv: Add RV64I instructions description

[Richard Henderson]

On 4/30/20 12:21 AM, LIU Zhiwei wrote:
> +LUI RISCV imm:20 rd:5 0110111 \
> +!constraints { $rd != 2 && $rd != 3 && $rd != 4 }

I think it would be helpful to add a function for this.  e.g. greg($rd) and
gbase($rs1) (including $0).  It would keep the constraints smaller, and avoid
mistakes.

These functions would go into risugen_riscv.pm.

> +ADDI RISCV imm:12 rs1:5 000 rd:5 0010011 \
> +!constraints { $rd != 2 && $rd != 3 && $rd != 4 && $rs1 != 2 }

Since all of sp, gp, tp are not in risu's control, why is rs1 only excluding
sp, and not gp and tp as well?


r~