[vectorIntrinsics] RFR: 8284459: Add x86 back-end implementation for LEADING and TRAILING ZEROS COUNT operations [v3]

[Quan Anh Mai]

On Fri, 15 Apr 2022 21:44:53 GMT, Jatin Bhateja <jbhateja at openjdk.org> wrote:

>> Summary of changes:
>> - Patch extends auto-vectorize to vectorize following Java SE APIs.
>>      1) Integer.numberOfLeadingZeros()
>>      2) Long.numberOfLeadingZeros()
>>      3) Integer.numberOfTrailingZeros()
>>      4) Long.numberOfTrailingZeros()
>> 
>> - Adds optimized X86 backend implementation for VectorOperations.LEADING_ZERO_COUNT and VectorOperations.TRAILING_ZEROS_COUNT for AVX512 and legacy targets.
>> 
>> Kindly review and share your feedback.
>> 
>> Best Regards,
>> Jatin
>
> Jatin Bhateja has updated the pull request incrementally with one additional commit since the last revision:
> 
>   8284459: Adding auto-vectorizer and x86 backend support for TRAILING_ZERO_COUNT, also some code re-organization.

src/hotspot/cpu/x86/c2_MacroAssembler_x86.cpp line 4786:

> 4784: void C2_MacroAssembler::vector_count_leading_zeros_byte_avx(XMMRegister dst, XMMRegister src, XMMRegister xtmp1,
> 4785:                                                             XMMRegister xtmp2, XMMRegister xtmp3, Register rtmp, int vec_enc) {
> 4786:   vmovdqu(xtmp1, ExternalAddress(StubRoutines::x86::vector_count_leading_zeros_lut()));

Please pass `rtmp` here, thanks.

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PR: https://git.openjdk.java.net/panama-vector/pull/189