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Merged
ermig1979 merged 1 commit into from
Aug 20, 2026
Merged

Improve SVE2 optimizations of SimdSegmentationChangeIndex #895

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1 change: 1 addition & 0 deletions docs/2026.html
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Original file line number Diff line number Diff line change
Expand Up @@ -101,6 +101,7 @@ <h5>Improving</h5>
<li>SVE2 optimizations of function SobelDy.</li>
<li>SVE2 optimizations of function SobelDyAbs.</li>
<li>SVE2 optimizations of function SobelDyAbsSum.</li>
<li>SVE2 optimizations of function SegmentationChangeIndex.</li>
</ul>
<h5>Renaming</h5>
<ul>
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32 changes: 27 additions & 5 deletions src/Simd/SimdSve2Segmentation.cpp
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Expand Up @@ -58,21 +58,43 @@ namespace Simd
}
}

SIMD_INLINE void ChangeIndex(uint8_t* mask, const svuint8_t& oldIndex, const svuint8_t& newIndex, const svbool_t& tail)
SIMD_INLINE void ChangeIndex(uint8_t* mask, const svbool_t& pg, const svuint8_t& oldIndex, const svuint8_t& newIndex)
{
svuint8_t _mask = svld1_u8(tail, mask);
svst1_u8(tail, mask, svsel_u8(svcmpeq_u8(tail, _mask, oldIndex), newIndex, _mask));
const svuint8_t value = svld1_u8(pg, mask);
svst1_u8(pg, mask, svsel_u8(svcmpeq_u8(pg, value, oldIndex), newIndex, value));
}

SIMD_INLINE void ChangeIndex4(uint8_t* mask, size_t A, const svbool_t& pg, const svuint8_t& oldIndex, const svuint8_t& newIndex)
{
const svuint8_t v0 = svld1_u8(pg, mask + 0 * A);
const svuint8_t v1 = svld1_u8(pg, mask + 1 * A);
const svuint8_t v2 = svld1_u8(pg, mask + 2 * A);
const svuint8_t v3 = svld1_u8(pg, mask + 3 * A);
svst1_u8(pg, mask + 0 * A, svsel_u8(svcmpeq_u8(pg, v0, oldIndex), newIndex, v0));
svst1_u8(pg, mask + 1 * A, svsel_u8(svcmpeq_u8(pg, v1, oldIndex), newIndex, v1));
svst1_u8(pg, mask + 2 * A, svsel_u8(svcmpeq_u8(pg, v2, oldIndex), newIndex, v2));
svst1_u8(pg, mask + 3 * A, svsel_u8(svcmpeq_u8(pg, v3, oldIndex), newIndex, v3));
}

void SegmentationChangeIndex(uint8_t* mask, size_t stride, size_t width, size_t height, uint8_t oldIndex, uint8_t newIndex)
{
const size_t A = svcntb();
const size_t QA = A * 4;
const size_t widthA = AlignLo(width, A);
const size_t widthQA = AlignLo(width, QA);
const svbool_t body = svptrue_b8();
const svbool_t tail = svwhilelt_b8(widthA, width);
const svuint8_t _oldIndex = svdup_n_u8(oldIndex);
const svuint8_t _newIndex = svdup_n_u8(newIndex);
for (size_t row = 0; row < height; ++row)
{
for (size_t col = 0; col < width; col += A)
ChangeIndex(mask + col, _oldIndex, _newIndex, svwhilelt_b8(col, width));
size_t col = 0;
for (; col < widthQA; col += QA)
ChangeIndex4(mask + col, A, body, _oldIndex, _newIndex);
for (; col < widthA; col += A)
ChangeIndex(mask + col, body, _oldIndex, _newIndex);
if (col < width)
ChangeIndex(mask + col, tail, _oldIndex, _newIndex);
mask += stride;
}
}
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6 changes: 6 additions & 0 deletions src/Test/TestSegmentation.cpp
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Expand Up @@ -286,7 +286,13 @@ namespace Test

#ifdef SIMD_SVE2_ENABLE
if (Simd::Sve2::Enable && TestSve2(options))
{
const int A = (int)svcntb();
result = result && SegmentationChangeIndexAutoTest(FUNC_CI(Simd::Sve2::SegmentationChangeIndex), FUNC_CI(SimdSegmentationChangeIndex));
result = result && SegmentationChangeIndexAutoTest(A + 1, 5, FUNC_CI(Simd::Base::SegmentationChangeIndex), FUNC_CI(Simd::Sve2::SegmentationChangeIndex));
result = result && SegmentationChangeIndexAutoTest(A + 3, 7, FUNC_CI(Simd::Base::SegmentationChangeIndex), FUNC_CI(Simd::Sve2::SegmentationChangeIndex));
result = result && SegmentationChangeIndexAutoTest(3, 4, FUNC_CI(Simd::Base::SegmentationChangeIndex), FUNC_CI(Simd::Sve2::SegmentationChangeIndex));
}
#endif

return result;
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