Minimum Vector size check added (#2428)

* Minimum size check added

* aggressive inlining added

* precision corrected

* MinVectorSize => MinInputSize

* adam approach

* tanners feedback

* increasing array sizes to test all 3 paths

* checking sse is supported is good enough check

* Test for non-accelerated path

Author: Anipik

src/Microsoft.ML.CpuMath/AvxIntrinsics.cs

@@ -466,22 +466,6 @@ public static unsafe void Scale(float scale, Span<float> dst)
                 int length = dst.Length;
                 Vector256<float> scaleVector256 = Vector256.Create(scale);
 
-                if (length < 8)
-                {
-                    // Handle cases where we have less than 256-bits total and can't ever use SIMD acceleration.
-                    switch (length)
-                    {
-                        case 7: dst[6] *= scale; goto case 6;
-                        case 6: dst[5] *= scale; goto case 5;
-                        case 5: dst[4] *= scale; goto case 4;
-                        case 4: dst[3] *= scale; goto case 3;
-                        case 3: dst[2] *= scale; goto case 2;
-                        case 2: dst[1] *= scale; goto case 1;
-                        case 1: dst[0] *= scale; break;
-                    }
-                    return;
-                }
-
                 nuint address = (nuint)(pd);
                 int misalignment = (int)(address % 32);
                 int remainder = 0;
@@ -993,27 +977,6 @@ public static unsafe float Sum(ReadOnlySpan<float> src)
             {
                 float* pValues = pSrc;
                 int length = src.Length;
-
-                if (length < 8)
-                {
-                    // Handle cases where we have less than 256-bits total and can't ever use SIMD acceleration.
-
-                    float res = 0;
-
-                    switch (length)
-                    {
-                        case 7: res += pValues[6]; goto case 6;
-                        case 6: res += pValues[5]; goto case 5;
-                        case 5: res += pValues[4]; goto case 4;
-                        case 4: res += pValues[3]; goto case 3;
-                        case 3: res += pValues[2]; goto case 2;
-                        case 2: res += pValues[1]; goto case 1;
-                        case 1: res += pValues[0]; break;
-                    }
-
-                    return res;
-                }
-
                 Vector256<float> result = Vector256<float>.Zero;
 
                 nuint address = (nuint)(pValues);