RFR: 8267663: AArch64: Add unsigned comparison operators on AArch64

[Andrew Haley]

On Sat, 5 Jun 2021 07:59:53 GMT, Andrew Haley <aph at openjdk.org> wrote:

>> This patch implements unsigned vector comparison on AArch64. The
>> performance of unsigned comparison improves about 4x~5x in my local with
>> Byte128Vector.java[1].
>> 
>> Before:
>> Benchmark                               Score(op/ms)     Error
>> Byte128Vector.UNSIGNED_GE#size(1024)    99.953           6.17
>> Byte128Vector.UNSIGNED_GT#size(1024)    95.334           8.865
>> Byte128Vector.UNSIGNED_LE#size(1024)    76.908           24.332
>> Byte128Vector.UNSIGNED_LT#size(1024)    78.362           23.507
>> 
>> After:
>> Benchmark                               Score(op/ms)     Error
>> Byte128Vector.UNSIGNED_GE#size(1024)    421.809          25.57
>> Byte128Vector.UNSIGNED_GT#size(1024)    420.653          26.779
>> Byte128Vector.UNSIGNED_LE#size(1024)    316.754          92.889
>> Byte128Vector.UNSIGNED_LT#size(1024)    423.683          26.508
>> 
>> [Test]
>> - All vector API test cases passed without new failure. 8265312[2] has
>>   been implemented this on x86 and supplied sufficient test cases for
>>   all kinds of vector.
>> - No performance regression for other comparisons.
>> - libjvm.so drops off about 200KB after this patch by combining those
>>   vector compare rules.
>> 
>> [1] https://github.com/openjdk/panama-vector/blob/vectorIntrinsics/test/jdk/jdk/incubator/vector/benchmark/src/main/java/benchmark/jdk/incubator/vector/Byte128Vector.java#L1198
>> [2] https://github.com/openjdk/panama-vector/pull/68
>
> src/hotspot/cpu/aarch64/aarch64_neon_ad.m4 line 889:
> 
>> 887: 
>> 888: static void neon_compare(C2_MacroAssembler masm, FloatRegister dst, BasicType bt,
>> 889:                          FloatRegister src1, FloatRegister src2, int cond, bool isX) {
> 
> Passing masm by value, rather than reference, is unconventional. There's no reason to do that.

Come to think about it, why isn't this an Assembler method?

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PR: https://git.openjdk.java.net/jdk/pull/4358