Remove runtime detection of Neon on ARM CPUs

Now the only way to enable Neon support is to change the mkspec.

[ChangeLog][Important Behavior Changes] Qt no longer checks for
support for the Neon FPU on ARM platforms at runtime. Code optimized
for Neon must be enabled unconditionally at compile time by ensuring
the compiler supports Neon. You may need to edit your mkspec for that.

Task-number: QTBUG-30440
Change-Id: I4df9b2bf3cd022f8ed70f02f16878cb2cb3fe6fb
Reviewed-by: Lars Knoll <lars.knoll@digia.com>

10 files changed, 42 insertions, 122 deletions

diff --git a/config.tests/unix/neon/neon.cpp b/config.tests/unix/neon/neon.cpp
deleted file mode 100644
index ccbb476367..0000000000
--- a/config.tests/unix/neon/neon.cpp
+++ /dev/null
@@ -1,51 +0,0 @@
-/****************************************************************************
-**
-** Copyright (C) 2013 Digia Plc and/or its subsidiary(-ies).
-** Contact: http://www.qt-project.org/legal
-**
-** This file is part of the config.tests of the Qt Toolkit.
-**
-** $QT_BEGIN_LICENSE:LGPL$
-** Commercial License Usage
-** Licensees holding valid commercial Qt licenses may use this file in
-** accordance with the commercial license agreement provided with the
-** Software or, alternatively, in accordance with the terms contained in
-** a written agreement between you and Digia.  For licensing terms and
-** conditions see http://qt.digia.com/licensing.  For further information
-** use the contact form at http://qt.digia.com/contact-us.
-**
-** 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, Digia gives you certain additional
-** rights.  These rights are described in the Digia Qt LGPL Exception
-** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
-**
-** GNU General Public License Usage
-** Alternatively, this file may be used under the terms of the GNU
-** General Public License version 3.0 as published by the Free Software
-** Foundation and appearing in the file LICENSE.GPL included in the
-** packaging of this file.  Please review the following information to
-** ensure the GNU General Public License version 3.0 requirements will be
-** met: http://www.gnu.org/copyleft/gpl.html.
-**
-**
-** $QT_END_LICENSE$
-**
-****************************************************************************/
-
-#include <arm_neon.h>
-
-int main(int, char**)
-{
-    int32x4_t null = vdupq_n_s32(0x0);
-
-    int result;
-    vst1q_lane_s32(&result, null, 0);
-    return result;
-}
diff --git a/config.tests/unix/neon/neon.pro b/config.tests/unix/neon/neon.pro
deleted file mode 100644
index efd608bd63..0000000000
--- a/config.tests/unix/neon/neon.pro
+++ /dev/null
@@ -1,4 +0,0 @@
-SOURCES = neon.cpp
-CONFIG -= x11 qt
-isEmpty(QMAKE_CFLAGS_NEON):error("This compiler does not support Neon")
-else:QMAKE_CXXFLAGS += $$QMAKE_CFLAGS_NEON
diff --git a/configure b/configure
index 6ec17fd258..d14422becd 100755
--- a/configure
+++ b/configure
@@ -1552,13 +1552,6 @@ while [ "$#" -gt 0 ]; do
     iwmmxt)
 	CFG_IWMMXT="yes"
 	;;
-    neon)
-        if [ "$VAL" = "no" ]; then
-            CFG_NEON="$VAL"
-        else
-            UNKNOWN_OPT=yes
-        fi
-        ;;
     mips_dsp)
         if [ "$VAL" = "no" ]; then
             CFG_MIPS_DSP="$VAL"
@@ -2283,7 +2276,6 @@ Configure options:
     -no-sse4.2 ......... Do not compile with use of SSE4.2 instructions.
     -no-avx ............ Do not compile with use of AVX instructions.
     -no-avx2 ........... Do not compile with use of AVX2 instructions.
-    -no-neon ........... Do not compile with use of NEON instructions.
     -no-mips_dsp ....... Do not compile with use of MIPS DSP instructions.
     -no-mips_dspr2 ..... Do not compile with use of MIPS DSP rev2 instructions.
 
@@ -4338,17 +4330,6 @@ if [ "$CFG_IWMMXT" = "yes" ]; then
     fi
 fi
 
-# detect neon support
-if [ "$CFG_ARCH" = "arm" ] && [ "${CFG_NEON}" = "auto" ]; then
-    if compileTest unix/neon "neon"; then
-	CFG_NEON=yes
-    else
-	CFG_NEON=no
-    fi
-elif [ "$CFG_ARCH" != "arm" ]; then
-    CFG_NEON=no
-fi
-
 # detect mips_dsp support
 if [ "$CFG_ARCH" = "mips" ] && [ "${CFG_MIPS_DSP}" = "auto" ]; then
     if "$unixtests/compile.test" "$XQMAKESPEC" "$QMAKE_CONFIG" $OPT_VERBOSE "$relpath" "$outpath" config.tests/unix/mips_dsp "mips_dsp" $L_FLAGS $I_FLAGS $D_FLAGS $l_FLAGS; then
@@ -5799,7 +5780,6 @@ fi
 [ "$CFG_AVX" = "yes" ] && QMAKE_CONFIG="$QMAKE_CONFIG avx"
 [ "$CFG_AVX2" = "yes" ] && QMAKE_CONFIG="$QMAKE_CONFIG avx2"
 [ "$CFG_IWMMXT" = "yes" ] && QMAKE_CONFIG="$QMAKE_CONFIG iwmmxt"
-[ "$CFG_NEON" = "yes" ] && QMAKE_CONFIG="$QMAKE_CONFIG neon"
 if [ "$CFG_ARCH" = "mips" ]; then
     [ "$CFG_MIPS_DSP" = "yes" ] && QMAKE_CONFIG="$QMAKE_CONFIG mips_dsp"
     [ "$CFG_MIPS_DSPR2" = "yes" ] && QMAKE_CONFIG="$QMAKE_CONFIG mips_dspr2"
diff --git a/mkspecs/devices/linux-tegra2-g++/qmake.conf b/mkspecs/devices/linux-tegra2-g++/qmake.conf
index 320e1b8a21..adadc4d5b0 100644
--- a/mkspecs/devices/linux-tegra2-g++/qmake.conf
+++ b/mkspecs/devices/linux-tegra2-g++/qmake.conf
@@ -6,9 +6,7 @@
 # A typical configure line looks like this:
 # <path-to-qt-src>/configure -opensource -confirm-license -make libs -prefix /usr/local/Qt-5.0.0/Qt5-tegra2
 # -device tegra2 -device-option CROSS_COMPILE=<path-to-crosstoolchain>/bin/arm-none-linux-gnueabi- \
-# -sysroot <path-to-rootfs> -no-neon
-
-# CAUTION: The Tegra2 chips don't support neon, make sure it will not be used (-no-neon)
+# -sysroot <path-to-rootfs>
 
 include(../common/linux_device_pre.conf)
 
diff --git a/src/gui/image/image.pri b/src/gui/image/image.pri
index ad860ef2db..0745cc0302 100644
--- a/src/gui/image/image.pri
+++ b/src/gui/image/image.pri
@@ -78,7 +78,9 @@ contains(QT_CONFIG, jpeg):include($$PWD/qjpeghandler.pri)
 contains(QT_CONFIG, gif):include($$PWD/qgifhandler.pri)
 
 # SIMD
-NEON_SOURCES += image/qimage_neon.cpp
+contains(QT_CPU_FEATURES.$$QT_ARCH, neon) {
+    SOURCES += image/qimage_neon.cpp
+}
 contains(QT_CPU_FEATURES.$$QT_ARCH, sse2) {
     SOURCES += image/qimage_sse2.cpp
     SSSE3_SOURCES += image/qimage_ssse3.cpp
diff --git a/src/gui/image/qimage_conversions.cpp b/src/gui/image/qimage_conversions.cpp
index 317ba45dac..193ef59fcd 100644
--- a/src/gui/image/qimage_conversions.cpp
+++ b/src/gui/image/qimage_conversions.cpp
@@ -2132,14 +2132,11 @@ void qInitImageConversions()
     }
 #endif
 
-#ifdef QT_COMPILER_SUPPORTS_NEON
-    if (qCpuHasFeature(NEON)) {
-        extern void convert_RGB888_to_RGB32_neon(QImageData *dest, const QImageData *src, Qt::ImageConversionFlags);
-        qimage_converter_map[QImage::Format_RGB888][QImage::Format_RGB32] = convert_RGB888_to_RGB32_neon;
-        qimage_converter_map[QImage::Format_RGB888][QImage::Format_ARGB32] = convert_RGB888_to_RGB32_neon;
-        qimage_converter_map[QImage::Format_RGB888][QImage::Format_ARGB32_Premultiplied] = convert_RGB888_to_RGB32_neon;
-        return;
-    }
+#ifdef __ARM_NEON__
+    extern void convert_RGB888_to_RGB32_neon(QImageData *dest, const QImageData *src, Qt::ImageConversionFlags);
+    qimage_converter_map[QImage::Format_RGB888][QImage::Format_RGB32] = convert_RGB888_to_RGB32_neon;
+    qimage_converter_map[QImage::Format_RGB888][QImage::Format_ARGB32] = convert_RGB888_to_RGB32_neon;
+    qimage_converter_map[QImage::Format_RGB888][QImage::Format_ARGB32_Premultiplied] = convert_RGB888_to_RGB32_neon;
 #endif
 }
 
diff --git a/src/gui/image/qjpeghandler.cpp b/src/gui/image/qjpeghandler.cpp
index 3ca31030c5..5187f0e9b3 100644
--- a/src/gui/image/qjpeghandler.cpp
+++ b/src/gui/image/qjpeghandler.cpp
@@ -861,7 +861,7 @@ Q_GUI_EXPORT void QT_FASTCALL qt_convert_rgb888_to_rgb32_avx(quint32 *dst, const
 QJpegHandler::QJpegHandler()
     : d(new QJpegHandlerPrivate(this))
 {
-#if defined(QT_COMPILER_SUPPORTS_NEON)
+#if defined(__ARM_NEON__)
     // from qimage_neon.cpp
 
     if (qCpuHasFeature(NEON))
diff --git a/src/gui/image/qpixmap_raster.cpp b/src/gui/image/qpixmap_raster.cpp
index be63430a78..37259adcd2 100644
--- a/src/gui/image/qpixmap_raster.cpp
+++ b/src/gui/image/qpixmap_raster.cpp
@@ -187,7 +187,7 @@ void QRasterPlatformPixmap::fill(const QColor &color)
         if (alpha != 255) {
             if (!image.hasAlphaChannel()) {
                 QImage::Format toFormat;
-#if !(defined(QT_COMPILER_SUPPORTS_NEON) || defined(__SSE2__))
+#if !(defined(__ARM_NEON__) || defined(__SSE2__))
                 if (image.format() == QImage::Format_RGB16)
                     toFormat = QImage::Format_ARGB8565_Premultiplied;
                 else if (image.format() == QImage::Format_RGB666)
@@ -316,7 +316,7 @@ void QRasterPlatformPixmap::createPixmapForImage(QImage &sourceImage, Qt::ImageC
             QImage::Format opaqueFormat = QNativeImage::systemFormat();
             QImage::Format alphaFormat = QImage::Format_ARGB32_Premultiplied;
 
-#if !defined(QT_COMPILER_SUPPORTS_NEON) && !defined(__SSE2__)
+#if !defined(__ARM_NEON__) && !defined(__SSE2__)
             switch (opaqueFormat) {
             case QImage::Format_RGB16:
                 alphaFormat = QImage::Format_ARGB8565_Premultiplied;
diff --git a/src/gui/painting/painting.pri b/src/gui/painting/painting.pri
index 271848ae73..6bf80eddbd 100644
--- a/src/gui/painting/painting.pri
+++ b/src/gui/painting/painting.pri
@@ -93,9 +93,9 @@ contains(QT_CPU_FEATURES.$$QT_ARCH, sse2) {
 }
 IWMMXT_SOURCES += painting/qdrawhelper_iwmmxt.cpp
 
-!ios {
-    NEON_SOURCES += painting/qdrawhelper_neon.cpp
-    NEON_HEADERS += painting/qdrawhelper_neon_p.h
+!ios:contains(QT_CPU_FEATURES.$$QT_ARCH, neon) {
+    SOURCES += painting/qdrawhelper_neon.cpp
+    HEADERS += painting/qdrawhelper_neon_p.h
     NEON_ASM += ../3rdparty/pixman/pixman-arm-neon-asm.S painting/qdrawhelper_neon_asm.S
 }
 
diff --git a/src/gui/painting/qdrawhelper.cpp b/src/gui/painting/qdrawhelper.cpp
index ae6a5e01e5..94ac62574b 100644
--- a/src/gui/painting/qdrawhelper.cpp
+++ b/src/gui/painting/qdrawhelper.cpp
@@ -6273,45 +6273,43 @@ void qInitDrawhelperAsm()
     }
 #endif // IWMMXT
 
-#if defined(QT_COMPILER_SUPPORTS_NEON) && !defined(Q_OS_IOS)
-    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;
-        qBlendFunctions[QImage::Format_RGB16][QImage::Format_ARGB32_Premultiplied] = qt_blend_argb32_on_rgb16_neon;
-        qBlendFunctions[QImage::Format_ARGB32_Premultiplied][QImage::Format_RGB16] = qt_blend_rgb16_on_argb32_neon;
-        qBlendFunctions[QImage::Format_RGB16][QImage::Format_RGB16] = qt_blend_rgb16_on_rgb16_neon;
+#if defined(__ARM_NEON__) && !defined(Q_OS_IOS)
+    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;
+    qBlendFunctions[QImage::Format_RGB16][QImage::Format_ARGB32_Premultiplied] = qt_blend_argb32_on_rgb16_neon;
+    qBlendFunctions[QImage::Format_ARGB32_Premultiplied][QImage::Format_RGB16] = qt_blend_rgb16_on_argb32_neon;
+    qBlendFunctions[QImage::Format_RGB16][QImage::Format_RGB16] = qt_blend_rgb16_on_rgb16_neon;
 #if Q_BYTE_ORDER == Q_LITTLE_ENDIAN
-        qBlendFunctions[QImage::Format_RGBX8888][QImage::Format_RGBX8888] = qt_blend_rgb32_on_rgb32_neon;
-        qBlendFunctions[QImage::Format_RGBA8888_Premultiplied][QImage::Format_RGBX8888] = qt_blend_rgb32_on_rgb32_neon;
-        qBlendFunctions[QImage::Format_RGBX8888][QImage::Format_RGBA8888_Premultiplied] = qt_blend_argb32_on_argb32_neon;
-        qBlendFunctions[QImage::Format_RGBA8888_Premultiplied][QImage::Format_RGBA8888_Premultiplied] = qt_blend_argb32_on_argb32_neon;
+    qBlendFunctions[QImage::Format_RGBX8888][QImage::Format_RGBX8888] = qt_blend_rgb32_on_rgb32_neon;
+    qBlendFunctions[QImage::Format_RGBA8888_Premultiplied][QImage::Format_RGBX8888] = qt_blend_rgb32_on_rgb32_neon;
+    qBlendFunctions[QImage::Format_RGBX8888][QImage::Format_RGBA8888_Premultiplied] = qt_blend_argb32_on_argb32_neon;
+    qBlendFunctions[QImage::Format_RGBA8888_Premultiplied][QImage::Format_RGBA8888_Premultiplied] = qt_blend_argb32_on_argb32_neon;
 #endif
 
-        qScaleFunctions[QImage::Format_RGB16][QImage::Format_ARGB32_Premultiplied] = qt_scale_image_argb32_on_rgb16_neon;
-        qScaleFunctions[QImage::Format_RGB16][QImage::Format_RGB16] = qt_scale_image_rgb16_on_rgb16_neon;
+    qScaleFunctions[QImage::Format_RGB16][QImage::Format_ARGB32_Premultiplied] = qt_scale_image_argb32_on_rgb16_neon;
+    qScaleFunctions[QImage::Format_RGB16][QImage::Format_RGB16] = qt_scale_image_rgb16_on_rgb16_neon;
 
-        qTransformFunctions[QImage::Format_RGB16][QImage::Format_ARGB32_Premultiplied] = qt_transform_image_argb32_on_rgb16_neon;
-        qTransformFunctions[QImage::Format_RGB16][QImage::Format_RGB16] = qt_transform_image_rgb16_on_rgb16_neon;
+    qTransformFunctions[QImage::Format_RGB16][QImage::Format_ARGB32_Premultiplied] = qt_transform_image_argb32_on_rgb16_neon;
+    qTransformFunctions[QImage::Format_RGB16][QImage::Format_RGB16] = qt_transform_image_rgb16_on_rgb16_neon;
 
-        qDrawHelper[QImage::Format_RGB16].alphamapBlit = qt_alphamapblit_quint16_neon;
+    qDrawHelper[QImage::Format_RGB16].alphamapBlit = qt_alphamapblit_quint16_neon;
 
-        functionForMode_C[QPainter::CompositionMode_SourceOver] = qt_blend_argb32_on_argb32_scanline_neon;
-        functionForModeSolid_C[QPainter::CompositionMode_SourceOver] = comp_func_solid_SourceOver_neon;
-        functionForMode_C[QPainter::CompositionMode_Plus] = comp_func_Plus_neon;
-        destFetchProc[QImage::Format_RGB16] = qt_destFetchRGB16_neon;
-        destStoreProc[QImage::Format_RGB16] = qt_destStoreRGB16_neon;
+    functionForMode_C[QPainter::CompositionMode_SourceOver] = qt_blend_argb32_on_argb32_scanline_neon;
+    functionForModeSolid_C[QPainter::CompositionMode_SourceOver] = comp_func_solid_SourceOver_neon;
+    functionForMode_C[QPainter::CompositionMode_Plus] = comp_func_Plus_neon;
+    destFetchProc[QImage::Format_RGB16] = qt_destFetchRGB16_neon;
+    destStoreProc[QImage::Format_RGB16] = qt_destStoreRGB16_neon;
 
-        qMemRotateFunctions[QImage::Format_RGB16][0] = qt_memrotate90_16_neon;
-        qMemRotateFunctions[QImage::Format_RGB16][2] = qt_memrotate270_16_neon;
+    qMemRotateFunctions[QImage::Format_RGB16][0] = qt_memrotate90_16_neon;
+    qMemRotateFunctions[QImage::Format_RGB16][2] = qt_memrotate270_16_neon;
         qt_memfill32 = qt_memfill32_neon;
 
-        extern const uint * QT_FASTCALL qt_fetch_radial_gradient_neon(uint *buffer, const Operator *op, const QSpanData *data,
-                                                                      int y, int x, int length);
+    extern const uint * QT_FASTCALL qt_fetch_radial_gradient_neon(uint *buffer, const Operator *op, const QSpanData *data,
+                                                                  int y, int x, int length);
 
-        qt_fetch_radial_gradient = qt_fetch_radial_gradient_neon;
-    }
+    qt_fetch_radial_gradient = qt_fetch_radial_gradient_neon;
 #endif
 
 #if defined(QT_COMPILER_SUPPORTS_MIPS_DSP)