RFR: 8322768: Optimize non-subword vector compress and expand APIs for AVX2 target. [v7]

[Sandhya Viswanathan]

On Fri, 19 Jan 2024 19:03:31 GMT, Jatin Bhateja <jbhateja at openjdk.org> wrote:

>> Hi,
>> 
>> Patch optimizes non-subword vector compress and expand APIs for x86 AVX2 only targets.
>> Upcoming E-core Xeons (Sierra Forest) and Hybrid CPUs only support AVX2 instruction set.
>> These are very frequently used APIs in columnar database filter operation.
>> 
>> Implementation uses a lookup table to record permute indices. Table index is computed using
>> mask argument of compress/expand operation.
>> 
>> Following are the performance number of JMH micro included with the patch.
>> 
>> 
>> System : Intel(R) Xeon(R) Platinum 8480+ (Sapphire Rapids)
>> 
>> Baseline:
>> Benchmark                                 (size)   Mode  Cnt    Score   Error   Units
>> ColumnFilterBenchmark.filterDoubleColumn    1024  thrpt    2  142.767          ops/ms
>> ColumnFilterBenchmark.filterDoubleColumn    2047  thrpt    2   71.436          ops/ms
>> ColumnFilterBenchmark.filterDoubleColumn    4096  thrpt    2   35.992          ops/ms
>> ColumnFilterBenchmark.filterFloatColumn     1024  thrpt    2  182.151          ops/ms
>> ColumnFilterBenchmark.filterFloatColumn     2047  thrpt    2   91.096          ops/ms
>> ColumnFilterBenchmark.filterFloatColumn     4096  thrpt    2   44.757          ops/ms
>> ColumnFilterBenchmark.filterIntColumn       1024  thrpt    2  184.099          ops/ms
>> ColumnFilterBenchmark.filterIntColumn       2047  thrpt    2   91.981          ops/ms
>> ColumnFilterBenchmark.filterIntColumn       4096  thrpt    2   45.170          ops/ms
>> ColumnFilterBenchmark.filterLongColumn      1024  thrpt    2  148.017          ops/ms
>> ColumnFilterBenchmark.filterLongColumn      2047  thrpt    2   73.516          ops/ms
>> ColumnFilterBenchmark.filterLongColumn      4096  thrpt    2   36.844          ops/ms
>> 
>> Withopt:
>> Benchmark                                 (size)   Mode  Cnt     Score   Error   Units
>> ColumnFilterBenchmark.filterDoubleColumn    1024  thrpt    2  2051.707          ops/ms
>> ColumnFilterBenchmark.filterDoubleColumn    2047  thrpt    2   914.072          ops/ms
>> ColumnFilterBenchmark.filterDoubleColumn    4096  thrpt    2   489.898          ops/ms
>> ColumnFilterBenchmark.filterFloatColumn     1024  thrpt    2  5324.195          ops/ms
>> ColumnFilterBenchmark.filterFloatColumn     2047  thrpt    2  2587.229          ops/ms
>> ColumnFilterBenchmark.filterFloatColumn     4096  thrpt    2  1278.665          ops/ms
>> ColumnFilterBenchmark.filterIntColumn       1024  thrpt    2  4149.384          ops/ms
>> ColumnFilterBenchmark.filterIntColumn       2047  thrpt  ...
>
> Jatin Bhateja has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Modified code comment for clarity.

src/hotspot/cpu/x86/stubGenerator_x86_64.cpp line 985:

> 983:       for (int j = 0; j < 4; j++) {
> 984:         if (mask & (1 << j)) {
> 985:           __ emit_data64(j, relocInfo::none);

This could be something like __ emit_data(2*j, relocInfo::none); __ emit_data(2*j+1, relocInfo::none) to have the double word masks in the table to begin with.
Then we don't need the extra instructions in  vector_compress_expand_avx2() to generate double word permute masks from long masks.

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PR Review Comment: https://git.openjdk.org/jdk/pull/17261#discussion_r1460113427