On 20 December 2013 14:10, Richard Henderson <rth@xxxxxxxxxxx> wrote:
> On 12/20/2013 05:18 AM, Peter Maydell wrote:
>> On 19 December 2013 19:29, Richard Henderson <rth@xxxxxxxxxxx> wrote:
>>> On 12/17/2013 07:12 AM, Peter Maydell wrote:
>>>> + tcg_gen_mul_i64(tcg_tmp, tcg_op1, tcg_op2);
>>>> + if (is_sub) {
>>>> + tcg_gen_sub_i64(cpu_reg(s, rd), cpu_reg(s, ra), tcg_tmp);
>>>> + } else {
>>>> + tcg_gen_add_i64(cpu_reg(s, rd), cpu_reg(s, ra), tcg_tmp);
>>>> + }
>>>
>>> Perhaps worth noticing the RA=XZR special case for the MUL alias?
>>
>> Yeah, makes sense: have adjusted to:
>> + if (ra == 31) {
>> + /* We special-case rA == XZR as it is the standard MUL alias */
>> + tcg_gen_mul_i64(cpu_reg(s, rd), tcg_op1, tcg_op2);
>> + } else {
>
> You need to handle (or dismiss) is_sub.
>
> Either (ra == 31 && !is_sub) or
>
> if (is_sub) {
> tcg_gen_neg_i64(tcg_rd, tcg_rd);
> }
>
> with tcg_rd pre-loaded along with tcg_op1 and tcg_op2.
>
> That said, unlike MUL I don't expect MNEG to be common at all.
Oops. Yes, let's just have (ra == 31 && !is_sub).
thanks
-- PMM
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