On 9/15/2025 9:53 PM, Richard Henderson wrote:
> On 9/13/25 02:17, Chao Liu wrote:
>> +static void gen_check_vext_elem_mask(TCGLabel *label, TCGv_i64 mask,
>> TCGv_i64
>> mask_offs)
>> +{
>> + TCGv_i64 mask_offs_i64 = tcg_temp_new_i64();
>> + TCGv_ptr mask_offs_ptr = tcg_temp_new_ptr();
>> + TCGv_i64 mask_offs_rem = tcg_temp_new_i64();
>> + TCGv_i64 mask_elem = tcg_temp_new_i64();
>> +
>> + tcg_gen_shri_tl(mask_offs_i64, mask_offs, 3);
>> + tcg_gen_add_tl(mask_offs_i64, mask_offs_i64, mask);
>> + tcg_gen_trunc_i64_ptr(mask_offs_ptr, mask_offs_i64);
>> + tcg_gen_ld_i64(mask_elem, mask_offs_ptr, 0);
>
> You can remove the "mask" argument, simplifying the code here.
>
> tcg_gen_trunc_i64_ptr(ptr, mask_offs_i64);
> tcg_gen_add_ptr(ptr, ptr, tcg_env);
> tcg_gen_ld_i64(mask_elem, ptr, vreg_ofs(s, 0))
>
Thanks, I will try modifying it this way:
tcg_gen_shri_tl(temp, mask_offs, 3);
tcg_gen_trunc_i64_ptr(ptr, temp);
tcg_gen_add_ptr(ptr, ptr, tcg_env);
Based on your suggestion, I have removed the `mask` args.
> You can also change mask_offs to TCGv_i32, which replaces
>
> tcg_gen_extu_i32_ptr(pr, mask_offs_i32);
>
> which more obviously does not discard data from mask_offs.
>
>
>> + tcg_gen_andi_tl(mask_offs_rem, mask_offs, 7);
>> + tcg_gen_shr_tl(mask_elem, mask_elem, mask_offs_rem);
>
> The mask of 7 suggests you're only interested in the low 8 bits. Which means
> either the load is wrong (we don't need to be loading 64 bits), or the mask
> and
> shift are wrong.
>
>
Get, loading just one byte at a time is sufficient. I will modify it
accordingly:
tcg_gen_ld8u_i64(elem, ptr, 0);
tcg_gen_andi_tl(temp, mask_offs, 7);
tcg_gen_shr_tl(elem, elem, temp);
>> + tcg_gen_andi_tl(mask_elem, mask_elem, 1);
>> + tcg_gen_brcond_i64(TCG_COND_TSTNE, mask_elem, tcg_constant_i64(1),
>> label);
>
> The andi before the brcond is redundant with the TSTNE.
>
Get~
>
> r~
In addition, I also found other redundant parameters, such as the `vreg`
argument in gen_ldst_vreg(). I will remove them together in the next version of
the patch.
Thanks,
Chao
