RFR: 8357554: Enable vectorization of Bool -> CMove with different type size (on riscv) [v2]

[Hamlin Li]

On Tue, 11 Nov 2025 13:51:01 GMT, Emanuel Peter <epeter at openjdk.org> wrote:

>> Hamlin Li has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   Update src/hotspot/share/opto/superword.cpp
>>   
>>   refactor `is_velt_basic_type_compatible_use_def`
>>   
>>   Co-authored-by: Emanuel Peter <emanuel.peter at oracle.com>
>
> src/hotspot/share/opto/superword.cpp line 2339:
> 
>> 2337:   } else if (VectorNode::is_different_use_def_size_supported()) {
>> 2338:     return use->is_CMove() && def->is_Bool();
>> 2339:   }
> 
> This looks a little tangled, and harder to extend. Can we make it linear like this?
> 
> Suggestion:
> 
>   // Input size of use equals output size of def
>   if (type2aelembytes(use_bt) == type2aelembytes(def_bt)) {
>     return true;
>   }
> 
>   // Allow CMove to have different type for comparision and moving.
>   if (VectorNode::is_different_use_def_size_supported() && return use->is_CMove() && def->is_Bool()) {
>     return true;
>   }
> 
> Because what if `is_different_use_def_size_supported` is true, but we don't have a CMove case, and then we would be able to go on with yet something else below later on?

Sure, I just committed a change as you suggested via github. :)

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PR Review Comment: https://git.openjdk.org/jdk/pull/28231#discussion_r2514371052