RFR: 8290322: Optimize Vector.rearrange over byte vectors for AVX512BW targets. [v2]

[Quan Anh Mai]

On Thu, 28 Jul 2022 11:04:18 GMT, Quan Anh Mai <duke at openjdk.org> wrote:

>> Jatin Bhateja has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains two additional commits since the last revision:
>> 
>>  - Merge branch 'master' of http://github.com/openjdk/jdk into JDK-8290322
>>  - 8290322: Optimize Vector.rearrange over byte vectors for AVX512BW targets.
>
> src/hotspot/cpu/x86/c2_MacroAssembler_x86.cpp line 5568:
> 
>> 5566: #endif
>> 5567: 
>> 5568: void C2_MacroAssembler::rearrange_bytes(XMMRegister dst, XMMRegister shuffle, XMMRegister src, XMMRegister xtmp1,
> 
> Can we use the same approach as that used for 256-bit vector. Something similar to:
> 
>     vpshufb(xtmp1, src, shuffle); // All elements are at the correct place modulo 16
>     vpxor(dst, dst, dst);
>     vpslld(xtmp2, shuffle, 3); // Push the digit signifying the parity of 128-bit lane to the sign digit
>     vpcmpb(ktmp, xtmp2, dst, lt);
>     vshufi32x4(xtmp2, xtmp1, xtmp1, 0b10110001); // Shuffle the 128-bit lanes to get 1 - 0 - 3 - 2
>     vpblendmb(xtmp1, ktmp, xtmp1, xtmp2); // All elements are at the correct place modulo 32
>     vpslld(xtmp2, shuffle, 2); // Push the digit signifying the parity of 256-bit lane to the sign digit
>     vpcmpb(ktmp, xtmp2, dst, lt);
>     vshufi32x4(xtmp2, xtmp1, xtmp1, 0b01001110); // Shuffle the 128-bit lanes to get 2 - 3 - 0 - 1
>     vpblendmb(dst, ktmp, xtmp1, xtmp2); // All elements are at the correct place modulo 64

Actually, it is my bad, this should not work. Sorry for the noise.

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PR: https://git.openjdk.org/jdk/pull/9498