[WIP] Supporting arm_neon_optional flag for blink platform.

Source/platform/graphics/cpu/arm/filters/FilterEffectNEON.h

+/*
+ * Copyright (C) 2008 Alex Mathews <possessedpenguinbob@gmail.com>
+ * Copyright (C) 2009 Dirk Schulze <krit@webkit.org>
+ * Copyright (C) Research In Motion Limited 2010. All rights reserved.
+ * Copyright (C) 2013 Google Inc. All rights reserved.
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Library General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Library General Public License for more details.
+ *
+ * You should have received a copy of the GNU Library General Public License
+ * along with this library; see the file COPYING.LIB.  If not, write to
+ * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
+ * Boston, MA 02110-1301, USA.
+ */
+
+#ifndef FilterEffectNEON_h
+#define FilterEffectNEON_h
+
+#if HAVE(ARM_NEON_INTRINSICS)
+
+#include "platform/graphics/filters/FilterEffect.h"
+#include <arm_neon.h>
+
+namespace blink {
+
+inline int FilterEffect::validPreMultipliedPixels64NEON(int pixelArrayLength, unsigned char* pixelData)
+{
+    if (pixelArrayLength >= 64) {
+        unsigned char* lastPixel = pixelData + (pixelArrayLength & ~0x3f);
+        do {
+            // Increments pixelData by 64.
+            uint8x16x4_t sixteenPixels = vld4q_u8(pixelData);
+            sixteenPixels.val[0] = vminq_u8(sixteenPixels.val[0], sixteenPixels.val[3]);
+            sixteenPixels.val[1] = vminq_u8(sixteenPixels.val[1], sixteenPixels.val[3]);
+            sixteenPixels.val[2] = vminq_u8(sixteenPixels.val[2], sixteenPixels.val[3]);
+            vst4q_u8(pixelData, sixteenPixels);
+            pixelData += 64;
+        } while (pixelData < lastPixel);
+
+        pixelArrayLength &= 0x3f;
+        if (!pixelArrayLength)
+            return pixelArrayLength;
+    }
+
+    return pixelArrayLength;
+}
+
+} // namespace blink
+
+#endif
+
+#endif // FilterEffectNEON_h