Use cmeq, cmge, cmgt (zero) when one of the operands is Vector64/128<T>.Zero #33972

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1. echesakov

   added

   arch-arm64

   area-CodeGen-coreclrCLR JIT compiler in src/coreclr/src/jit and related components such as SuperPMICLR JIT compiler in src/coreclr/src/jit and related components such as SuperPMI

   optimization

   on Mar 23, 2020
2. Dotnet-GitSync-Bot

   added

   untriagedNew issue has not been triaged by the area ownerNew issue has not been triaged by the area owner

   on Mar 23, 2020
3. Gnbrkm41 commented on Mar 31, 2020

   

   Gnbrkm41

   on Mar 31, 2020

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   runtime/src/libraries/System.Collections/src/System/Collections/BitArray.cs

   Lines 183 to 195 in c74407f

   	// JIT does not support code hoisting for SIMD yet
   	// However comparison against zero can be replaced to cmeq against zero (vceqzq_s8)
   	// See dotnet/runtime#33972 for details
   	Vector128<byte> zero = Vector128<byte>.Zero;
   	fixed (bool* ptr = values)
   	{
   	for (; (i + Vector128ByteCount * 2u) <= (uint)values.Length; i += Vector128ByteCount * 2u)
   	{
   	// Same logic as SSE2 path, however we lack MoveMask (equivalent) instruction
   	// As a workaround, mask out the relevant bit after comparison
   	// and combine by ORing all of them together (In this case, adding all of them does the same thing)
   	Vector128<byte> lowerVector = AdvSimd.LoadVector128((byte*)ptr + i);
   	Vector128<byte> lowerIsFalse = AdvSimd.CompareEqual(lowerVector, zero);
4. BruceForstall

   added this to the Future milestone on Apr 4, 2020
5. BruceForstall

   removed

   untriagedNew issue has not been triaged by the area ownerNew issue has not been triaged by the area owner

   on Apr 4, 2020
6. CarolEidt

   modified the milestones: Future, 6.0.0 on Oct 13, 2020
7. JulieLeeMSFT

   assigned

   echesakov

   on Mar 23, 2021
8. JulieLeeMSFT

   added

   needs-further-triageIssue has been initially triaged, but needs deeper consideration or reconsiderationIssue has been initially triaged, but needs deeper consideration or reconsideration

   on Mar 23, 2021
9. JulieLeeMSFT

   removed

   needs-further-triageIssue has been initially triaged, but needs deeper consideration or reconsiderationIssue has been initially triaged, but needs deeper consideration or reconsideration

   on Jun 7, 2021
10. echesakov

    modified the milestones: 6.0.0, Future on Jul 7, 2021
11. echesakov

    added

    Priority:3Work that is nice to haveWork that is nice to have

    on Jul 7, 2021
12. echesakov

    modified the milestones: Future, 7.0.0 on Oct 15, 2021
13. AndyAyersMS

    assigned

    TIHan

    on Dec 1, 2021
14. echesakov commented on Mar 15, 2022

    

    echesakov

    on Mar 15, 2022

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    I believe this item was addressed fully.
    @TIHan can you please confirm and close the issue?
15. echesakov

    removed their assignment

    on Mar 15, 2022
16. TIHan commented on Mar 15, 2022

    

    TIHan

    on Mar 15, 2022

    Contributor

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    Yes, I believe it was. There is more opportunity with other instructions like 'cmle' and 'cmlt', but based on the title of this issue, we got them covered.
17. TIHan

    closed this as completedon Mar 15, 2022
18. ghost locked as resolved and limited conversation to collaborators on Apr 15, 2022