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Evaluate JIT_MemCpy without overlap check #6701

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Evaluate JIT_MemCpy without overlap check#6701
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area-CodeGen-coreclrCLR JIT compiler in src/coreclr/src/jit and related components such as SuperPMIenhancementProduct code improvement that does NOT require public API changes/additionstenet-performancePerformance related issue
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Future

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@helloguo
helloguo
opened on Sep 21, 2016

The current implementation of JIT_MemCpy on x64 Windows checks for address overlap and different paths are taken depending on result. However, ECMA-335 mentions "The behavior of cpblk is unspecified if the source and destination areas overlap". An optimized version without overlap check may be worth evaluating and implementing. dotnet/coreclr#7198

category:cq
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  1. msftgits
    transferred this issue fromdotnet/coreclron Jan 31, 2020
  2. msftgits
    added this to the Future milestone on Jan 31, 2020
  3. BruceForstall
    added
    JitUntriagedCLR JIT issues needing additional triage
    on Oct 28, 2020

  4. TIHan commented on Nov 1, 2023

    @TIHan
    TIHan
    on Nov 1, 2023
    Contributor

    Comment regarding the overlapping buffers:

            ; Use memmove to handle overlapping buffers for better
        ; compatibility with .NET Framework. Needing to handle
        ; overlapping buffers in cpblk is undefined by the spec.

    It might be worth evaluating? Hard to tell, but keeping this as future.

  5. TIHan
    removed
    JitUntriagedCLR JIT issues needing additional triage
    on Nov 1, 2023

  6. EgorBo commented on Mar 16, 2024

    @EgorBo
    EgorBo
    on Mar 16, 2024
    Member

    Closed by #98623

  7. EgorBo
    closed this as completedon Mar 16, 2024

  8. EgorBo commented on Mar 16, 2024

    @EgorBo
    EgorBo
    on Mar 16, 2024
    Member

    Ah, sorry, it's a different issue. Although, I don't think we'll remove the overlap check

  9. EgorBo
    reopened this on Mar 16, 2024
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