Re: [Qemu-devel] [Aarch64] Bug in add/sub extended reg

[Peter Maydell]

On 20 February 2014 11:51, Laurent Desnogues
<address@hidden> wrote:
> Hello,
>
> there's a bug in SP handling in disas_add_sub_ext_reg:
>
>     /* non-flag setting ops may use SP */
>     if (!setflags) {
>         tcg_rn = read_cpu_reg_sp(s, rn, sf);
>         tcg_rd = cpu_reg_sp(s, rd);
>     } else {
>         tcg_rn = read_cpu_reg(s, rn, sf);
>         tcg_rd = cpu_reg(s, rd);
>     }
>
> rn can always be SP no matter whether flags are set or not.

Yep, pseudocode agrees:
    bits(datasize) operand1 = if n == 31 then SP[] else X[n];

It's only Rd that has this "31 means SP only if
we're not setting flags" behaviour.

thanks
-- PMM