Rewriting MatrixConvolution image filter with SSE and AVX2

src/opts/SkMatrixConvolutionImageFilter_opts_SSE.cpp

+/*
+ * Copyright 2016 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#include "SkColor.h"
+#include "SkBitmap.h"
+#include "SkPoint.h"
+#include "SkColorPriv.h"
+
+
+namespace sk_sse {
+
+void SkMatrixConvolutionImageFilter_filterPixels_SSE(const SkBitmap& src,
+                                                     SkBitmap* result,
+                                                     const SkIRect& r,
+                                                     const SkIRect& bounds,
+                                                     bool convolveAlpha,
+                                                     SkScalar* kernel,
+                                                     const SkISize& kernelSize,
+                                                     const SkIPoint&  kernelOffset,
+                                                     SkScalar gain,
+                                                     SkScalar bias)
+{
+    SkIRect rect(r);
+    if (!rect.intersect(bounds)) {
+        return;
+    }
+    for (int y = rect.fTop; y < rect.fBottom; ++y) {
+        SkPMColor* dptr = result->getAddr32(rect.fLeft - bounds.fLeft, y - bounds.fTop);
+        for (int x = rect.fLeft; x < rect.fRight; ++x) {
+            __m128 psum = _mm_setzero_ps();
+            for (int cy = 0; cy < kernelSize.fHeight; cy++) {
+                for (int cx = 0; cx < kernelSize.fWidth; cx++) {
+                    SkPMColor s = *src.getAddr32(
+                        x + cx - kernelOffset.fX,
+                        y + cy - kernelOffset.fY);
+                    __m128 pss = _mm_cvtpu8_ps(_mm_set_pi32 (0, s));
+
+                    __m128 pk = _mm_set1_ps(kernel[cy * kernelSize.fWidth + cx]);
+
+                    psum = _mm_add_ps(psum, _mm_mul_ps(pss, pk));
+                }
+            }
+
+            union {
+                __m128 m128;
+                float f[4];
+            } conv = {psum};
+
+            SkScalar sumA, sumR, sumG, sumB;
+
+            sumA = conv.f[3];
+            sumR = conv.f[2];
+            sumG = conv.f[1];
+            sumB = conv.f[0];
+
+            int a = convolveAlpha
+                ? SkClampMax(SkScalarFloorToInt(SkScalarMul(sumA, gain) + bias), 255)

[Stephen White, 2016/04/12 20:01:59]

Using Sk4/Sk4f might also allow us to benefit from SSE2 integer ops here,
instead of resorting to scalar.

+                : 255;
+            int r = SkClampMax(SkScalarFloorToInt(SkScalarMul(sumR, gain) + bias), a);
+            int g = SkClampMax(SkScalarFloorToInt(SkScalarMul(sumG, gain) + bias), a);
+            int b = SkClampMax(SkScalarFloorToInt(SkScalarMul(sumB, gain) + bias), a);
+            if (!convolveAlpha) {
+                a = SkGetPackedA32(*src.getAddr32(x, y));
+                *dptr++ = SkPreMultiplyARGB(a, r, g, b);
+            } else {
+                *dptr++ = SkPackARGB32(a, r, g, b);
+            }
+        }
+    }
+}
+
+}