NEON configure detection and initial blend function implementations.

Adds new NEON configure test and -no-neon configure option. NEON
implementations can also be turned off by setting the QT_NO_NEON
environment variable.

Performance improvements (in frames per second):
- Blending ARGB32 on RGB32/ARGB32, mostly opaque: 71 %
- Blending ARGB32 on RGB32/ARGB32, no opaque pixels: 108 %
- Blending ARGB32 on RGB32/ARGB32, with 0.5 opacity: 158 %
- Blending RGB32 on RGB32/ARGB32, with 0.5 opacity: 189 %

Task-number: QTBUG-6684
Reviewed-by: Gunnar Sletta
Reviewed-by: Paul Olav Tvete

5 files changed, 358 insertions, 3 deletions

diff --git a/src/gui/painting/painting.pri b/src/gui/painting/painting.pri
index 628a109c90..0b1e79ae28 100644
--- a/src/gui/painting/painting.pri
+++ b/src/gui/painting/painting.pri
@@ -379,6 +379,13 @@ symbian {
         QMAKE_CXXFLAGS.ARMCC *= -O3
 }
 
+neon {
+    DEFINES += QT_HAVE_NEON
+    HEADERS += painting/qdrawhelper_neon_p.h
+    SOURCES += painting/qdrawhelper_neon.cpp
+    QMAKE.CXXFLAGS *= -mfpu=neon
+}
+
 contains(QT_CONFIG, zlib) {
    INCLUDEPATH += ../3rdparty/zlib
 } else:!contains(QT_CONFIG, no-zlib) {
diff --git a/src/gui/painting/qblendfunctions.cpp b/src/gui/painting/qblendfunctions.cpp
index 1d15dac455..81d1515d7c 100644
--- a/src/gui/painting/qblendfunctions.cpp
+++ b/src/gui/painting/qblendfunctions.cpp
@@ -605,7 +605,7 @@ static void qt_blend_argb32_on_argb32(uchar *destPixels, int dbpl,
 }
 
 
-static void qt_blend_rgb32_on_rgb32(uchar *destPixels, int dbpl,
+void qt_blend_rgb32_on_rgb32(uchar *destPixels, int dbpl,
                              const uchar *srcPixels, int sbpl,
                              int w, int h,
                              int const_alpha)
diff --git a/src/gui/painting/qdrawhelper.cpp b/src/gui/painting/qdrawhelper.cpp
index 23236ece20..84cf5cc05a 100644
--- a/src/gui/painting/qdrawhelper.cpp
+++ b/src/gui/painting/qdrawhelper.cpp
@@ -44,6 +44,7 @@
 #include <private/qpainter_p.h>
 #include <private/qdrawhelper_x86_p.h>
 #include <private/qdrawhelper_armv6_p.h>
+#include <private/qdrawhelper_neon_p.h>
 #include <private/qmath_p.h>
 #include <qmath.h>
 
@@ -7725,7 +7726,8 @@ enum CPUFeatures {
     SSE         = 0x10,
     SSE2        = 0x20,
     CMOV        = 0x40,
-    IWMMXT      = 0x80
+    IWMMXT      = 0x80,
+    NEON        = 0x100
 };
 
 static uint detectCPUFeatures()
@@ -7751,6 +7753,9 @@ static uint detectCPUFeatures()
     // runtime detection only available when running as a previlegied process
     static const bool doIWMMXT = !qgetenv("QT_NO_IWMMXT").toInt();
     return doIWMMXT ? IWMMXT : 0;
+#elif defined(QT_HAVE_NEON)
+    static const bool doNEON = !qgetenv("QT_NO_NEON").toInt();
+    return doNEON ? NEON : 0;
 #else
     uint features = 0;
 #if defined(__x86_64__) || defined(Q_OS_WIN64)
@@ -8122,7 +8127,14 @@ void qInitDrawhelperAsm()
         qBlendFunctions[QImage::Format_ARGB32_Premultiplied][QImage::Format_RGB32] = qt_blend_rgb32_on_rgb32_armv6;
         qBlendFunctions[QImage::Format_RGB32][QImage::Format_ARGB32_Premultiplied] = qt_blend_argb32_on_argb32_armv6;
         qBlendFunctions[QImage::Format_ARGB32_Premultiplied][QImage::Format_ARGB32_Premultiplied] = qt_blend_argb32_on_argb32_armv6;
-#endif // Q_CC_RVCT && QT_HAVE_ARMV6
+#elif defined(QT_HAVE_NEON)
+        if (features & NEON) {
+            qBlendFunctions[QImage::Format_RGB32][QImage::Format_RGB32] = qt_blend_rgb32_on_rgb32_neon;
+            qBlendFunctions[QImage::Format_ARGB32_Premultiplied][QImage::Format_RGB32] = qt_blend_rgb32_on_rgb32_neon;
+            qBlendFunctions[QImage::Format_RGB32][QImage::Format_ARGB32_Premultiplied] = qt_blend_argb32_on_argb32_neon;
+            qBlendFunctions[QImage::Format_ARGB32_Premultiplied][QImage::Format_ARGB32_Premultiplied] = qt_blend_argb32_on_argb32_neon;
+        }
+#endif
 
     if (functionForModeSolidAsm) {
         const int destinationMode = QPainter::CompositionMode_Destination;
diff --git a/src/gui/painting/qdrawhelper_neon.cpp b/src/gui/painting/qdrawhelper_neon.cpp
new file mode 100644
index 0000000000..7fe11bf4e3
--- /dev/null
+++ b/src/gui/painting/qdrawhelper_neon.cpp
@@ -0,0 +1,260 @@
+/****************************************************************************
+**
+** Copyright (C) 2009 Nokia Corporation and/or its subsidiary(-ies).
+** All rights reserved.
+** Contact: Nokia Corporation (qt-info@nokia.com)
+**
+** This file is part of the QtGui module of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:LGPL$
+** No Commercial Usage
+** This file contains pre-release code and may not be distributed.
+** You may use this file in accordance with the terms and conditions
+** contained in the Technology Preview License Agreement accompanying
+** this package.
+**
+** GNU Lesser General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU Lesser
+** General Public License version 2.1 as published by the Free Software
+** Foundation and appearing in the file LICENSE.LGPL included in the
+** packaging of this file.  Please review the following information to
+** ensure the GNU Lesser General Public License version 2.1 requirements
+** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
+**
+** In addition, as a special exception, Nokia gives you certain additional
+** rights.  These rights are described in the Nokia Qt LGPL Exception
+** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
+**
+** If you have questions regarding the use of this file, please contact
+** Nokia at qt-info@nokia.com.
+**
+**
+**
+**
+**
+**
+**
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#include <private/qdrawhelper_p.h>
+
+#ifdef QT_HAVE_NEON
+
+#include <private/qdrawhelper_neon_p.h>
+#include <arm_neon.h>
+
+QT_BEGIN_NAMESPACE
+
+static inline int16x8_t qvdiv_255_s16(int16x8_t x, int16x8_t half)
+{
+    // result = (x + (x >> 8) + 0x80) >> 8
+
+    const int16x8_t temp = vshrq_n_s16(x, 8); // x >> 8
+    const int16x8_t sum_part = vaddq_s16(x, half); // x + 0x80
+    const int16x8_t sum = vaddq_s16(temp, sum_part);
+
+    return vreinterpretq_s16_u16(vshrq_n_u16(vreinterpretq_u16_s16(sum), 8));
+}
+
+static inline int16x8_t qvbyte_mul_s16(int16x8_t x, int16x8_t alpha, int16x8_t half)
+{
+    // t = qRound(x * alpha / 255.0)
+
+    const int16x8_t t = vmulq_s16(x, alpha); // t
+    return qvdiv_255_s16(t, half);
+}
+
+static inline int16x8_t qvinterpolate_pixel_255(int16x8_t x, int16x8_t a, int16x8_t y, int16x8_t b, int16x8_t half)
+{
+    // t = x * a + y * b
+
+    const int16x8_t ta = vmulq_s16(x, a);
+    const int16x8_t tb = vmulq_s16(y, b);
+
+    return qvdiv_255_s16(vaddq_s16(ta, tb), half);
+}
+
+static inline int16x8_t qvsource_over_s16(int16x8_t src16, int16x8_t dst16, int16x8_t half, int16x8_t full)
+{
+    const int16x4_t alpha16_high = vdup_lane_s16(vget_high_s16(src16), 3);
+    const int16x4_t alpha16_low = vdup_lane_s16(vget_low_s16(src16), 3);
+
+    const int16x8_t alpha16 = vsubq_s16(full, vcombine_s16(alpha16_low, alpha16_high));
+
+    return vaddq_s16(src16, qvbyte_mul_s16(dst16, alpha16, half));
+}
+
+void qt_blend_argb32_on_argb32_neon(uchar *destPixels, int dbpl,
+                                    const uchar *srcPixels, int sbpl,
+                                    int w, int h,
+                                    int const_alpha)
+{
+    const uint *src = (const uint *) srcPixels;
+    uint *dst = (uint *) destPixels;
+    int16x8_t half = vdupq_n_s16(0x80);
+    int16x8_t full = vdupq_n_s16(0xff);
+    if (const_alpha == 256) {
+        for (int y = 0; y < h; ++y) {
+            int x = 0;
+            for (; x < w-3; x += 4) {
+                int32x4_t src32 = vld1q_s32((int32_t *)&src[x]);
+                if ((src[x] & src[x+1] & src[x+2] & src[x+3]) >= 0xff000000) {
+                    // all opaque
+                    vst1q_s32((int32_t *)&dst[x], src32);
+                } else if (src[x] | src[x+1] | src[x+2] | src[x+3]) {
+                    int32x4_t dst32 = vld1q_s32((int32_t *)&dst[x]);
+
+                    const uint8x16_t src8 = vreinterpretq_u8_s32(src32);
+                    const uint8x16_t dst8 = vreinterpretq_u8_s32(dst32);
+
+                    const uint8x8_t src8_low = vget_low_u8(src8);
+                    const uint8x8_t dst8_low = vget_low_u8(dst8);
+
+                    const uint8x8_t src8_high = vget_high_u8(src8);
+                    const uint8x8_t dst8_high = vget_high_u8(dst8);
+
+                    const int16x8_t src16_low = vreinterpretq_s16_u16(vmovl_u8(src8_low));
+                    const int16x8_t dst16_low = vreinterpretq_s16_u16(vmovl_u8(dst8_low));
+
+                    const int16x8_t src16_high = vreinterpretq_s16_u16(vmovl_u8(src8_high));
+                    const int16x8_t dst16_high = vreinterpretq_s16_u16(vmovl_u8(dst8_high));
+
+                    const int16x8_t result16_low = qvsource_over_s16(src16_low, dst16_low, half, full);
+                    const int16x8_t result16_high = qvsource_over_s16(src16_high, dst16_high, half, full);
+
+                    const int32x2_t result32_low = vreinterpret_s32_s8(vmovn_s16(result16_low));
+                    const int32x2_t result32_high = vreinterpret_s32_s8(vmovn_s16(result16_high));
+
+                    vst1q_s32((int32_t *)&dst[x], vcombine_s32(result32_low, result32_high));
+                }
+            }
+            for (; x<w; ++x) {
+                uint s = src[x];
+                if (s >= 0xff000000)
+                    dst[x] = s;
+                else if (s != 0)
+                    dst[x] = s + BYTE_MUL(dst[x], qAlpha(~s));
+            }
+            dst = (quint32 *)(((uchar *) dst) + dbpl);
+            src = (const quint32 *)(((const uchar *) src) + sbpl);
+        }
+    } else if (const_alpha != 0) {
+        const_alpha = (const_alpha * 255) >> 8;
+        int16x8_t const_alpha16 = vdupq_n_s16(const_alpha);
+        for (int y = 0; y < h; ++y) {
+            int x = 0;
+            for (; x < w-3; x += 4) {
+                if (src[x] | src[x+1] | src[x+2] | src[x+3]) {
+                    int32x4_t src32 = vld1q_s32((int32_t *)&src[x]);
+                    int32x4_t dst32 = vld1q_s32((int32_t *)&dst[x]);
+
+                    const uint8x16_t src8 = vreinterpretq_u8_s32(src32);
+                    const uint8x16_t dst8 = vreinterpretq_u8_s32(dst32);
+
+                    const uint8x8_t src8_low = vget_low_u8(src8);
+                    const uint8x8_t dst8_low = vget_low_u8(dst8);
+
+                    const uint8x8_t src8_high = vget_high_u8(src8);
+                    const uint8x8_t dst8_high = vget_high_u8(dst8);
+
+                    const int16x8_t src16_low = vreinterpretq_s16_u16(vmovl_u8(src8_low));
+                    const int16x8_t dst16_low = vreinterpretq_s16_u16(vmovl_u8(dst8_low));
+
+                    const int16x8_t src16_high = vreinterpretq_s16_u16(vmovl_u8(src8_high));
+                    const int16x8_t dst16_high = vreinterpretq_s16_u16(vmovl_u8(dst8_high));
+
+                    const int16x8_t srcalpha16_low = qvbyte_mul_s16(src16_low, const_alpha16, half);
+                    const int16x8_t srcalpha16_high = qvbyte_mul_s16(src16_high, const_alpha16, half);
+
+                    const int16x8_t result16_low = qvsource_over_s16(srcalpha16_low, dst16_low, half, full);
+                    const int16x8_t result16_high = qvsource_over_s16(srcalpha16_high, dst16_high, half, full);
+
+                    const int32x2_t result32_low = vreinterpret_s32_s8(vmovn_s16(result16_low));
+                    const int32x2_t result32_high = vreinterpret_s32_s8(vmovn_s16(result16_high));
+
+                    vst1q_s32((int32_t *)&dst[x], vcombine_s32(result32_low, result32_high));
+                }
+            }
+            for (; x<w; ++x) {
+                uint s = src[x];
+                if (s != 0) {
+                    s = BYTE_MUL(s, const_alpha);
+                    dst[x] = s + BYTE_MUL(dst[x], qAlpha(~s));
+                }
+            }
+            dst = (quint32 *)(((uchar *) dst) + dbpl);
+            src = (const quint32 *)(((const uchar *) src) + sbpl);
+        }
+    }
+}
+
+// qblendfunctions.cpp
+void qt_blend_rgb32_on_rgb32(uchar *destPixels, int dbpl,
+                             const uchar *srcPixels, int sbpl,
+                             int w, int h,
+                             int const_alpha);
+
+void qt_blend_rgb32_on_rgb32_neon(uchar *destPixels, int dbpl,
+                                  const uchar *srcPixels, int sbpl,
+                                  int w, int h,
+                                  int const_alpha)
+{
+    if (const_alpha != 256) {
+        if (const_alpha != 0) {
+            const uint *src = (const uint *) srcPixels;
+            uint *dst = (uint *) destPixels;
+            int16x8_t half = vdupq_n_s16(0x80);
+            const_alpha = (const_alpha * 255) >> 8;
+            int one_minus_const_alpha = 255 - const_alpha;
+            int16x8_t const_alpha16 = vdupq_n_s16(const_alpha);
+            int16x8_t one_minus_const_alpha16 = vdupq_n_s16(255 - const_alpha);
+            for (int y = 0; y < h; ++y) {
+                int x = 0;
+                for (; x < w-3; x += 4) {
+                    int32x4_t src32 = vld1q_s32((int32_t *)&src[x]);
+                    int32x4_t dst32 = vld1q_s32((int32_t *)&dst[x]);
+
+                    const uint8x16_t src8 = vreinterpretq_u8_s32(src32);
+                    const uint8x16_t dst8 = vreinterpretq_u8_s32(dst32);
+
+                    const uint8x8_t src8_low = vget_low_u8(src8);
+                    const uint8x8_t dst8_low = vget_low_u8(dst8);
+
+                    const uint8x8_t src8_high = vget_high_u8(src8);
+                    const uint8x8_t dst8_high = vget_high_u8(dst8);
+
+                    const int16x8_t src16_low = vreinterpretq_s16_u16(vmovl_u8(src8_low));
+                    const int16x8_t dst16_low = vreinterpretq_s16_u16(vmovl_u8(dst8_low));
+
+                    const int16x8_t src16_high = vreinterpretq_s16_u16(vmovl_u8(src8_high));
+                    const int16x8_t dst16_high = vreinterpretq_s16_u16(vmovl_u8(dst8_high));
+
+                    const int16x8_t result16_low = qvinterpolate_pixel_255(src16_low, const_alpha16, dst16_low, one_minus_const_alpha16, half);
+                    const int16x8_t result16_high = qvinterpolate_pixel_255(src16_high, const_alpha16, dst16_high, one_minus_const_alpha16, half);
+
+                    const int32x2_t result32_low = vreinterpret_s32_s8(vmovn_s16(result16_low));
+                    const int32x2_t result32_high = vreinterpret_s32_s8(vmovn_s16(result16_high));
+
+                    vst1q_s32((int32_t *)&dst[x], vcombine_s32(result32_low, result32_high));
+                }
+                for (; x<w; ++x) {
+                    uint s = src[x];
+                    s = BYTE_MUL(s, const_alpha);
+                    dst[x] = INTERPOLATE_PIXEL_255(src[x], const_alpha, dst[x], one_minus_const_alpha);
+                }
+                dst = (quint32 *)(((uchar *) dst) + dbpl);
+                src = (const quint32 *)(((const uchar *) src) + sbpl);
+            }
+        }
+    } else {
+        qt_blend_rgb32_on_rgb32(destPixels, dbpl, srcPixels, sbpl, w, h, const_alpha);
+    }
+}
+
+QT_END_NAMESPACE
+
+#endif // QT_HAVE_NEON
+
diff --git a/src/gui/painting/qdrawhelper_neon_p.h b/src/gui/painting/qdrawhelper_neon_p.h
new file mode 100644
index 0000000000..cb9a0d69ee
--- /dev/null
+++ b/src/gui/painting/qdrawhelper_neon_p.h
@@ -0,0 +1,76 @@
+/****************************************************************************
+**
+** Copyright (C) 2009 Nokia Corporation and/or its subsidiary(-ies).
+** All rights reserved.
+** Contact: Nokia Corporation (qt-info@nokia.com)
+**
+** This file is part of the QtGui module of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:LGPL$
+** No Commercial Usage
+** This file contains pre-release code and may not be distributed.
+** You may use this file in accordance with the terms and conditions
+** contained in the Technology Preview License Agreement accompanying
+** this package.
+**
+** GNU Lesser General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU Lesser
+** General Public License version 2.1 as published by the Free Software
+** Foundation and appearing in the file LICENSE.LGPL included in the
+** packaging of this file.  Please review the following information to
+** ensure the GNU Lesser General Public License version 2.1 requirements
+** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
+**
+** In addition, as a special exception, Nokia gives you certain additional
+** rights.  These rights are described in the Nokia Qt LGPL Exception
+** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
+**
+** If you have questions regarding the use of this file, please contact
+** Nokia at qt-info@nokia.com.
+**
+**
+**
+**
+**
+**
+**
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#ifndef QDRAWHELPER_NEON_P_H
+#define QDRAWHELPER_NEON_P_H
+
+//
+//  W A R N I N G
+//  -------------
+//
+// This file is not part of the Qt API.  It exists purely as an
+// implementation detail.  This header file may change from version to
+// version without notice, or even be removed.
+//
+// We mean it.
+//
+
+#include <private/qdrawhelper_p.h>
+
+QT_BEGIN_NAMESPACE
+
+#ifdef QT_HAVE_NEON
+
+void qt_blend_argb32_on_argb32_neon(uchar *destPixels, int dbpl,
+                                            const uchar *srcPixels, int sbpl,
+                                            int w, int h,
+                                            int const_alpha);
+
+void qt_blend_rgb32_on_rgb32_neon(uchar *destPixels, int dbpl,
+                                  const uchar *srcPixels, int sbpl,
+                                  int w, int h,
+                                  int const_alpha);
+
+#endif // QT_HAVE_NEON
+
+QT_END_NAMESPACE
+
+#endif // QDRAWHELPER_NEON_P_H