configure sets CFLAGS or how to disable default CFLAGS='-g -O2' for gcc?

[Peter Volkov]

Hello.

I'm using autoconf / automake to build my program. I'd like to set some
default CFLAGS for my project with the following variable in my
src/Makefile.am:

AM_CFLAGS = $(GLIB_CFLAGS) -O3 -Wall -ffast-math

The problem is that during compilation this default CFLAGS are hidden
with '-g -O2':

if gcc -DHAVE_CONFIG_H -I. -I. -I..    -pthread -I/usr/include/glib-2.0
-I/usr/lib/glib-2.0/include   -O3 -Wall -ffast-math -g -O2 -MT
ry-psi-function.o -MD -MP -MF ".deps/ry-psi-function.Tpo" -c -o
ry-psi-function.o ry-psi-function.c; \
then mv -f ".deps/ry-psi-function.Tpo" ".deps/ry-psi-function.Po"; else
rm -f ".deps/ry-psi-function.Tpo"; exit 1; fi

My environment does not contain any CFLAGS. echo $CFLAGS gives nothing.
I found that the problem sits in configure script itself. The following
code seems defines CFLAGS and then substitutes it in Makefile.in:

ac_cv_prog_cc_g=no
fi
rm -f conftest.err conftest.$ac_objext conftest.$ac_ext
fi
echo "$as_me:$LINENO: result: $ac_cv_prog_cc_g" >&5
echo "${ECHO_T}$ac_cv_prog_cc_g" >&6
if test "$ac_test_CFLAGS" = set; then
  CFLAGS=$ac_save_CFLAGS
elif test $ac_cv_prog_cc_g = yes; then
  if test "$GCC" = yes; then
    CFLAGS="-g -O2"
  else
    CFLAGS="-g"
  fi
else
  if test "$GCC" = yes; then
    CFLAGS="-O2"
  else
    CFLAGS=
  fi
fi

So it sets CFLAGS... But why it does not revert before making
substitutions in Makefile.in? The only thing I can think about it the
order of macroses in my configure.ac:

AC_PREREQ(2.59)
AC_INIT([Rydberg Atom], 0.0.1, address@hidden, ry-atom)
AC_LANG_C
AC_CONFIG_SRCDIR([src/ry-psi-function.h])
AC_CONFIG_HEADERS([config.h])
AC_CONFIG_AUX_DIR([aux])
AC_CANONICAL_TARGET
AM_INIT_AUTOMAKE()
AM_CONDITIONAL([I686], [test "$target_cpu" = i686])
save_prefix="$prefix"
save_exec_prefix="$exec_prefix"
test "x$prefix" = xNONE && prefix=$ac_default_prefix
test "x$exec_prefix" = xNONE && exec_prefix=$prefix
if test "$target_cpu" = i686 ; then
  ry_integ_dir=`eval echo ${datadir}/${PACKAGE}/x86`
  RY_INTEG_DIR=${ry_integ_dir}
  AC_DEFINE_UNQUOTED([RY_INTEG_DIR], "${ry_integ_dir}", [Integrals Path
Directory])
else
  echo Unknown target arch.
fi
AC_SUBST([RY_INTEG_DIR])
prefix="$save_prefix"
exec_prefix="$save_exec_prefix"
AC_PROG_CC
AC_CHECK_LIB([m],[sqrt])
AM_PATH_GLIB_2_0(2.6.0,,AC_MSG_ERROR([
*** GLib 2.6 is required to build ry-atom; please make sure you have the
GLib
*** development headers installed. The latest version of GLib is
*** always available at http://www.gtk.org/.]),[gobject gthread])
AC_C_CONST
AC_CONFIG_FILES([Makefile
                 integrals/Makefile
                 integrals/x86/Makefile
                 scripts/Makefile
                 scripts/ry-build-figures.sh
                 scripts/build-r_avr_fixed_theta-in-dep-theta.sh
                 src/Makefile])
AC_OUTPUT
echo
echo "Building for target $target_cpu $target_vendor $target_os"
echo

Does anybody see what is the problem here? I do not want to set CFLAGS
environment variable forever... Any suggestions are welcome.

Another related question is what if I want to have different CFLAGS for
release and for debugging. How should I do this? I thought about
different AM_CFLAGS in Makefile.am and chose between them with
AM_CONDITIONAL, but now I don't know what to do.

BTW. I'm using autoconf 2.59 and automake automake 1.9.6.

Thank you for your time,
Peter.

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