On 01/25/2018 09:03 AM, Peter Maydell wrote:
> On 17 January 2018 at 16:14, Richard Henderson
> <richard.hender...@linaro.org> wrote:
>> Signed-off-by: Richard Henderson <richard.hender...@linaro.org>
>> ---
>> target/arm/translate-a64.c | 386
>> ++++++++++++++++++++++++++++++++++++++-------
>> 1 file changed, 329 insertions(+), 57 deletions(-)
>>
>> diff --git a/target/arm/translate-a64.c b/target/arm/translate-a64.c
>> index 2495414603..1b5005637d 100644
>> --- a/target/arm/translate-a64.c
>> +++ b/target/arm/translate-a64.c
>> @@ -6489,17 +6489,6 @@ static void handle_shri_with_rndacc(TCGv_i64 tcg_res,
>> TCGv_i64 tcg_src,
>> }
>> }
>>
>> -/* Common SHL/SLI - Shift left with an optional insert */
>> -static void handle_shli_with_ins(TCGv_i64 tcg_res, TCGv_i64 tcg_src,
>> - bool insert, int shift)
>> -{
>> - if (insert) { /* SLI */
>> - tcg_gen_deposit_i64(tcg_res, tcg_res, tcg_src, shift, 64 - shift);
>> - } else { /* SHL */
>> - tcg_gen_shli_i64(tcg_res, tcg_src, shift);
>> - }
>> -}
>> -
>> /* SRI: shift right with insert */
>> static void handle_shri_with_ins(TCGv_i64 tcg_res, TCGv_i64 tcg_src,
>> int size, int shift)
>> @@ -6603,7 +6592,11 @@ static void handle_scalar_simd_shli(DisasContext *s,
>> bool insert,
>> tcg_rn = read_fp_dreg(s, rn);
>> tcg_rd = insert ? read_fp_dreg(s, rd) : tcg_temp_new_i64();
>>
>> - handle_shli_with_ins(tcg_rd, tcg_rn, insert, shift);
>> + if (insert) {
>> + tcg_gen_deposit_i64(tcg_rd, tcg_rd, tcg_rn, shift, 64 - shift);
>> + } else {
>> + tcg_gen_shli_i64(tcg_rd, tcg_rn, shift);
>> + }
>
> It looks like you're folding handle_shli_with_ins() into its
> now only callsite, but handle_shri_with_ins() has been left as
> its own function?
I didn't notice that. I'll have a look.
>> +static void gen_shr8_ins_i64(TCGv_i64 d, TCGv_i64 a, int64_t shift)
>> +{
>> + uint64_t mask = (0xff >> shift) * (-1ull / 0xff);
>> + TCGv_i64 t = tcg_temp_new_i64();
>> +
>> + tcg_gen_shri_i64(t, a, shift);
>> + tcg_gen_andi_i64(t, t, mask);
>> + tcg_gen_andi_i64(d, d, ~mask);
>> + tcg_gen_or_i64(d, d, t);
>> + tcg_temp_free_i64(t);
>
> The previous code was able to work with just shifts and deposits --
> why do we need to open-code this kind of mask-and-or now? Is this
> because we now operate an i64 at a time when we used to operate
> on smaller quantities at once?
Yes, exactly. It's now 4 total operations instead of 16.
I should also tidy this to use a new dup_const function that's been introduced
since I first wrote this code...
r~
