+dnl Check for Endianness
+AC_C_BIGENDIAN(
+ little_endian=no,
+ little_endian=yes,
+ little_endian=no,
+ little_endian=no
+)
+
+dnl Check for POWER8 Architecture
+PWR8_CFLAGS="-mpower8-vector"
+have_pwr8_intrinsics=no
+AC_MSG_CHECKING(whether gcc supports -mpower8-vector)
+save_CFLAGS=$CFLAGS
+CFLAGS="$PWR8_CFLAGS $CFLAGS"
+AC_COMPILE_IFELSE([AC_LANG_SOURCE([[
+#if defined(__GNUC__) && (__GNUC__ < 4 || (__GNUC__ == 4 && __GNUC_MINOR__ < 8))
+#error "Need GCC >= 4.8 for sane POWER8 support"
+#endif
+#include <altivec.h>
+int main () {
+ vector unsigned char r;
+ vector unsigned int v = vec_splat_u32 (1);
+ r = __builtin_vec_vgbbd ((vector unsigned char) v);
+ return 0;
+}]])], have_pwr8_intrinsics=yes)
+CFLAGS=$save_CFLAGS
+
+AC_ARG_ENABLE(pwr8,
+ [AC_HELP_STRING([--disable-pwr8-inst],
+ [disable POWER8-specific instructions])],
+ [enable_pwr8=$enableval], [enable_pwr8=auto])
+
+if test "x$enable_pwr8" = xno ; then
+ have_pwr8_intrinsics=disabled
+fi
+
+if test $have_pwr8_intrinsics = yes && test $little_endian = yes ; then
+ DEFINES="$DEFINES -D_ARCH_PWR8"
+ CXXFLAGS="$CXXFLAGS $PWR8_CFLAGS"
+ CFLAGS="$CFLAGS $PWR8_CFLAGS"
+else
+ PWR8_CFLAGS=
+fi
+
+AC_MSG_RESULT($have_pwr8_intrinsics)
+if test "x$enable_pwr8" = xyes && test $have_pwr8_intrinsics = no ; then
+ AC_MSG_ERROR([POWER8 compiler support not detected])
+fi
+
+if test $have_pwr8_intrinsics = yes && test $little_endian = no ; then
+ AC_MSG_WARN([POWER8 optimization is enabled only on POWER8 Little-Endian])
+fi
+
+AC_SUBST([PWR8_CFLAGS], $PWR8_CFLAGS)
+
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