text: echo "Deleting old gf2x files."
  rm -f "$SAGE_LOCAL"/lib/libgf2x*
  rm -rf "$SAGE_LOCAL"/include/gf2x*
  
  cd src
  
  # Use newer version of config.guess and config.sub (see Trac #19727)
  cp "$SAGE_ROOT"/config/config.* config
  
  if [ "$SAGE_DEBUG" = "yes" ]; then
      echo "Building a debug version of gf2x."
      export CFLAGS="-O0 -g $CFLAGS"
  elif $CC --version 2>/dev/null |grep 'gcc.* 5[.][12]' >/dev/null; then
      echo "Using compiler flags to work around problems with GCC 5.1/5.2 (Trac #18580,#18978)"
      export CFLAGS="-O2 -fno-forward-propagate -g $CFLAGS"
  else
      export CFLAGS="-O2 -g $CFLAGS"
  fi
  
  if [ "$SAGE_FAT_BINARY" = "yes" ]; then
      echo "Building a generic gf2x library."
      GF2X_CONFIGURE="--disable-hardware-specific-code $GF2X_CONFIGURE"
      SAGE_TUNE_GF2X="no"
  fi
  
  sdh_configure $GF2X_CONFIGURE
  sdh_make
  
  case "$SAGE_TUNE_GF2X" in
      "full")
          echo "Complete tuning of gf2x."
          $MAKE tune-lowlevel && $MAKE tune-toom && $MAKE tune-fft
          if [ $? -ne 0 ]; then
              echo >&2 "Error: Failed to tune gf2x."
              exit 1
          fi
          ;;
      "no")
          echo "Skipping tuning of gf2x."
          echo "You can set SAGE_TUNE_GF2X to yes or full to turn it on."
          ;;
      *)
          echo "Fast tuning of gf2x."
          echo "You can set SAGE_TUNE_GF2X to full to run a complete tuning."
          $MAKE tune-lowlevel && $MAKE tune-toom
          if [ $? -ne 0 ]; then
              echo >&2 "Error: Failed to tune gf2x."
              exit 1
          fi
          ;;
  esac
  
  sdh_make_install
  