Re: [RFC PATCH 1/3] tcg/riscv: Fix base regsiter for qemu_ld/st

[Richard Henderson]

On 10/20/22 20:41, LIU Zhiwei wrote:
> When guest base is zero, we should use addr_regl as base regiser instead of
> the initial register TCG_REG_TMP0.
>
> Signed-off-by: LIU Zhiwei <zhiwei_liu@linux.alibaba.com>
> ---
>   tcg/riscv/tcg-target.c.inc | 4 ++++
>   1 file changed, 4 insertions(+)
>
> diff --git a/tcg/riscv/tcg-target.c.inc b/tcg/riscv/tcg-target.c.inc
> index 81a83e45b1..32f4bc7bfc 100644
> --- a/tcg/riscv/tcg-target.c.inc
> +++ b/tcg/riscv/tcg-target.c.inc
> @@ -1185,6 +1185,8 @@ static void tcg_out_qemu_ld(TCGContext *s, const TCGArg 
> *args, bool is_64)
>       }
>       if (guest_base != 0) {
>           tcg_out_opc_reg(s, OPC_ADD, base, TCG_GUEST_BASE_REG, addr_regl);
> +    } else {
> +        base = addr_regl;
>       }

You're right that there's a bug here, where TMP0 remains uninitialized.  I think it would 
be better to reorg the other direction: begin with initializeing base = addr_regl, and 
then change it away only when we make modifications.


r~