RFR: 8354242: VectorAPI: combine vector not operation with compare [v8]

[erifan]

On Wed, 11 Jun 2025 08:47:56 GMT, Xiaohong Gong <xgong at openjdk.org> wrote:

>> erifan has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   Support negating unsigned comparison for BoolTest::mask
>>   
>>   Added a static method `negate_mask(mask btm)` into BoolTest class to
>>   negate both signed and unsigned comparison.
>
> src/hotspot/share/opto/vectornode.cpp line 2221:
> 
>> 2219:   // XorV/XorVMask is commutative, swap VectorMaskCmp/VectorMaskCast to in1.
>> 2220:   if (in2->Opcode() == Op_VectorMaskCmp ||
>> 2221:       (in2->Opcode() == Op_VectorMaskCast && in2->in(1)->Opcode() == Op_VectorMaskCmp)) {
> 
> We may need to consider cases that a `VectorMaskCast` is generated between `compare + not`, such as `compare + cast + not`. For such cases, the element size maybe different for input and output of a `cast`.  Although this patch's intention is not for the latter pattern, current change have also covered it well. Could you please add more test/jmh for all kinds of `cast` pattern here? And I think the scope of this PR could be also extended to `compare + cast + not`. WDYT?

Good catch, I'll add more tests and check the correctness. Thanks~

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PR Review Comment: https://git.openjdk.org/jdk/pull/24674#discussion_r2139615887