Re: [Qemu-devel] [PATCH 2/8] target/arm: Use generic vector infrastructure for aa64 add/sub/logic

["Alex Bennée" <alex.bennee@linaro.org>]

Richard Henderson <richard.henderson@linaro.org> writes:

> On 09/07/2017 09:58 AM, Alex Bennée wrote:
>>> +    switch (size + 4 * is_u) {
>>
>> Hmm I find this switch a little too magical. I mean I can see that the
>> encoding abuses size for the final opcode when I look at the manual but
>> it reads badly.
>>
>>> +    case 0: /* AND */
>>> +        gvec_op = tcg_gen_gvec_and8;
>>> +        goto do_gvec;
>>> +    case 1: /* BIC */
>>> +        gvec_op = tcg_gen_gvec_andc8;
>>> +        goto do_gvec;
>>> +    case 2: /* ORR */
>>> +        gvec_op = tcg_gen_gvec_or8;
>>> +        goto do_gvec;
>>> +    case 3: /* ORN */
>>> +        gvec_op = tcg_gen_gvec_orc8;
>>> +        goto do_gvec;
>>> +    case 4: /* EOR */
>>> +        gvec_op = tcg_gen_gvec_xor8;
>>> +        goto do_gvec;
>>> +    do_gvec:
>>> +        gvec_op(vec_full_reg_offset(s, rd),
>>> +                vec_full_reg_offset(s, rn),
>>> +                vec_full_reg_offset(s, rm),
>>> +                is_q ? 16 : 8, vec_full_reg_size(s));
>>> +        return;
>>
>> No default case (although I guess we just fall through). What's wrong
>> with just having a !is_u test with gvec_op = tbl[size] and skipping all
>> the goto stuff?
>
> Because that would still leave EOR out in the woods.
> I do think this is the cleanest way to filter out these 5 operations.

Is this going to look better if the other operations in this branch of
the decode are converted as well?

--
Alex Bennée