OPTIMIZE_CFLAGS=""
OPTIMIZE_LDFLAGS=""

AC_DEFUN([check_link_flag],
 [AX_CHECK_LINK_FLAG([$1], [$2], [$3], [-Werror $4])])

# Enable -Bsymbolic
AS_IF([test "$enable_optimizations" != "no"], [
    check_link_flag([-Wl,-Bsymbolic], [OPTIMIZE_LDFLAGS="$OPTIMIZE_LDFLAGS -Wl,-Bsymbolic"])
    CFLAGS="$CFLAGS -O2"
])

# Enable Link-Time-Optimization
AS_IF([test "$enable_lto" = "yes"],
      [AS_IF([test "$c_compiler" = "gcc"],
          [AX_CHECK_COMPILE_FLAG([-flto], [OPTIMIZE_CFLAGS="$OPTIMIZE_CFLAGS -flto"])
           check_link_flag([-flto], [OPTIMIZE_LDFLAGS="$OPTIMIZE_LDFLAGS -flto"])],
          [AC_MSG_WARN([LTO is not yet available on your compiler.])])])

AC_SUBST(OPTIMIZE_CFLAGS)
AC_SUBST(OPTIMIZE_LDFLAGS)

# Add '-g' flag to gcc to build with debug symbols.
if test "$enable_debug_symbols" = "min"; then
    CFLAGS="$CFLAGS -g1"
elif test "$enable_debug_symbols" != "no"; then
    CFLAGS="$CFLAGS -g"
fi