Add SVE2 BackgroundAdjustRange optimization

[ermig1979]

Summary

• Add SVE2 implementation and dispatch for SimdBackgroundAdjustRange.
• Add SVE2 coverage in the background adjust range auto test.
• Document the new SVE2 optimization in 2026 release notes.

Testing

• cmake ./prj/cmake -B build -DCMAKE_BUILD_TYPE=Release -DCMAKE_CXX_COMPILER=g++ -DCMAKE_C_COMPILER=gcc -DSIMD_TOOLCHAIN="g++" -DSIMD_TARGET="" -DSIMD_AVX512VNNI=ON -DSIMD_AMXBF16=ON -DSIMD_TEST_FLAGS="-march=native" -DSIMD_SHARED=ON
• cmake --build build --parallel$(nproc)
• export LD_LIBRARY_PATH="$(pwd):$LD_LIBRARY_PATH" && ./Test "-r=.." -fi=BackgroundAdjustRange -tt=1 -ts=1
• aarch64-linux-gnu-g++ -march=armv9-a+sve2 -msve-vector-bits=scalable -std=c++11 -I src -c src/Simd/SimdSve2Background.cpp -o /tmp/SimdSve2Background.o
• aarch64-linux-gnu-g++ -march=armv9-a+sve2 -msve-vector-bits=scalable -std=c++11 -I src -c src/Test/TestBackground.cpp -o /tmp/TestBackground.o
• git diff --check

  

[Copilot]

Pull request overview

This PR adds an ARM SVE2-optimized implementation of SimdBackgroundAdjustRange, wires it into the runtime dispatch layer, extends the existing background auto-tests to exercise the new SVE2 path, and documents the optimization in the 2026 release notes.

Changes:

• Implement Simd::Sve2::BackgroundAdjustRange using SVE2 intrinsics and proper tail handling.
• Add SVE2 dispatch for SimdBackgroundAdjustRange in the public C API entry point.
• Extend background auto-tests and 2026 release notes to include the new SVE2 optimization.

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
src/Test/TestBackground.cpp	Adds SVE2 coverage to the BackgroundAdjustRange auto-test dispatch.
src/Simd/SimdSve2Background.cpp	Introduces the SVE2 vectorized BackgroundAdjustRange implementation.
src/Simd/SimdSve2.h	Declares the new SVE2 BackgroundAdjustRange API.
src/Simd/SimdLib.cpp	Adds runtime dispatch to route SimdBackgroundAdjustRange to SVE2 when available.
docs/2026.html	Documents the new SVE2 optimization in 2026 release notes.