Add detection of AVX and AVX2 support in the compiler.

Intel CC 12.1 supports AVX2 but only with -march=core-avx2. The -mavx2
option produces a warning.

GCC 4.6 does not recognise any option.

GCC 4.7 recognises both -mavx2 and -march=core-avx2 so let's use the
latter for now. We may need to change to -mavx2 when there's an AMD
processor that supports AVX2 too.

Change-Id: I529240e6e6c2c0e3942d357e0320212d954fe4de
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@nokia.com>

config.tests/unix/avx2/avx2.cpp

@@ -0,0 +1,55 @@
+/****************************************************************************
+**
+** Copyright (C) 2012 Intel Corporation.
+** Contact: http://www.qt-project.org/
+**
+** This file is part of the configuration of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:LGPL$
+** GNU Lesser General Public License Usage
+** 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.
+**
+** 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.
+**
+** Other Usage
+** Alternatively, this file may be used in accordance with the terms and
+** conditions contained in a signed written agreement between you and Nokia.
+**
+**
+**
+**
+**
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#include <immintrin.h>
+
+int main(int, char**)
+{
+    /* AVX */
+    _mm256_zeroall();
+    volatile __m256i a = _mm256_setzero_si256();
+
+    /* AVX2 */
+    volatile __m256i b = _mm256_and_si256(a, a);
+    volatile __m256i result = _mm256_add_epi8(a, b);
+    (void)result;
+    return 0;
+}

config.tests/unix/avx2/avx2.pro

@@ -0,0 +1,3 @@
+SOURCES = avx2.cpp
+CONFIG -= x11 qt
+mac:CONFIG -= app_bundle

configure

@@ -731,6 +731,7 @@ CFG_SSSE3=auto
 CFG_SSE4_1=auto
 CFG_SSE4_2=auto
 CFG_AVX=auto
+CFG_AVX2=auto
 CFG_REDUCE_RELOCATIONS=auto
 CFG_NAS=no
 CFG_ACCESSIBILITY=auto
@@ -1510,6 +1511,13 @@ while [ "$#" -gt 0 ]; do
             UNKNOWN_OPT=yes
         fi
         ;;
+    avx2)
+        if [ "$VAL" = "no" ]; then
+            CFG_AVX2="$VAL"
+        else
+            UNKNOWN_OPT=yes
+        fi
+        ;;
     iwmmxt)
 	CFG_IWMMXT="yes"
 	;;
@@ -3081,6 +3089,7 @@ cat << EOF
     -no-sse4.1.......... Do not compile with use of SSE4.1 instructions.
     -no-sse4.2.......... Do not compile with use of SSE4.2 instructions.
     -no-avx ............ Do not compile with use of AVX instructions.
+    -no-avx2 ........... Do not compile with use of AVX2 instructions.
     -no-neon ........... Do not compile with use of NEON instructions.
     -no-mips_dsp ....... Do not compile with use of MIPS DSP instructions.
     -no-mips_dspr2 ..... Do not compile with use of MIPS DSP rev2 instructions.
@@ -3990,6 +3999,15 @@ if [ "${CFG_AVX}" = "auto" ]; then
     fi
 fi
 
+# detect avx2 support
+if [ "${CFG_AVX2}" = "auto" ]; then
+    if "$unixtests/compile.test" "$XQMAKESPEC" "$QMAKE_CONFIG" $OPT_VERBOSE "$relpath" "$outpath" config.tests/unix/avx2 "avx2" $L_FLAGS $I_FLAGS $l_FLAGS "-march=core-avx2"; then
+       CFG_AVX2=yes
+    else
+       CFG_AVX2=no
+    fi
+fi
+
 # check iWMMXt support
 if [ "$CFG_IWMMXT" = "yes" ]; then
     "$unixtests/compile.test" "$XQMAKESPEC" "$QMAKE_CONFIG" $OPT_VERBOSE "$relpath" "$outpath" config.tests/unix/iwmmxt "iwmmxt" $L_FLAGS $I_FLAGS $l_FLAGS "-mcpu=iwmmxt"
@@ -5555,6 +5573,7 @@ fi
 [ "$CFG_SSE4_1" = "yes" ] && QMAKE_CONFIG="$QMAKE_CONFIG sse4_1"
 [ "$CFG_SSE4_2" = "yes" ] && QMAKE_CONFIG="$QMAKE_CONFIG sse4_2"
 [ "$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
@@ -6510,7 +6529,7 @@ echo "PCH support ............ $CFG_PRECOMPILE"
 if [ "$CFG_ARCH" = "i386" -o "$CFG_ARCH" = "x86_64" ]; then
     echo "SSE2/SSE3/SSSE3......... ${CFG_SSE2}/${CFG_SSE3}/${CFG_SSSE3}"
     echo "SSE4.1/SSE4.2........... ${CFG_SSSE3}/${CFG_SSE4_1}/${CFG_SSE4_2}"
-    echo "AVX..................... ${CFG_AVX}"
+    echo "AVX/AVX2................ ${CFG_AVX}/${CFG_AVX2}"
 elif [ "$CFG_ARCH" = "arm" ]; then
     echo "iWMMXt support ......... ${CFG_IWMMXT}"
     echo "NEON support ........... ${CFG_NEON}"

mkspecs/features/qt.prf

@@ -210,4 +210,5 @@ ssse3:DEFINES += QT_HAVE_SSSE3
 sse4_1:DEFINES += QT_HAVE_SSE4_1
 sse4_2:DEFINES += QT_HAVE_SSE4_2
 avx:DEFINES += QT_HAVE_AVX
+avx2:DEFINES += QT_HAVE_AVX2
 iwmmxt:DEFINES += QT_HAVE_IWMMXT