[Build, Patch, libquadmath] PR 46520 Do not call AC_CHECK_LIB for gcc_no_link

[Ralf Wildenhues]

* Tobias Burnus wrote on Sun, Dec 19, 2010 at 05:18:50PM CET:
> Ralf Wildenhues wrote:
> >Is the usage of the two HAVE_* defines for optimization only?
> 
> Yes - it's just to speed up the calculation.

Then the original patch is ok.

> >But you might still consider adding a case
> >statement in the gcc_no_link branch seeding the correct defines
> >or the respective configure cache variables (ac_cv_lib_m_cbrtl etc)
> >for targets where the functions are known to be available.
> 
> I have now use the configure cache variables; one can still add a
> version with switch, when needed.

Well, this patch is ok as well (and a bit nicer for users willing
to pass cache variables), but what I meant was something like

  # The toplevel --target becomes the --host in target libdirs.
  case $host_os in
    linux*) ac_cv_lib_m_sqrtl=yes ;;
    ...
  esac

that already seeds the variables on systems where the answer is known.
(Kind of like another step further.)

Cheers,
Ralf

> 2010-12-19  Tobias Burnus  <burnus@net-b.de>
> 
> 	PR fortran/46520
> 	* configure.ac: Do not call AC_CHECK_LIB for gcc_no_link.
> 	* configure: Regenerate
> 
> diff --git a/libquadmath/configure.ac b/libquadmath/configure.ac
> index 56b1fcb..68b5cf8 100644
> --- a/libquadmath/configure.ac
> +++ b/libquadmath/configure.ac
> @@ -109,8 +109,19 @@ esac
>  AC_SUBST(toolexecdir)
>  AC_SUBST(toolexeclibdir)
>  
> -AC_CHECK_LIB([m],[sqrtl],[AC_DEFINE([HAVE_SQRTL],[1],[libm includes sqrtl])])
> -AC_CHECK_LIB([m],[cbrtl],[AC_DEFINE([HAVE_CBRTL],[1],[libm includes cbrtl])])
> +# If available, sqrtl and cbrtl speed up the calculation -
> +# but they are not required
> +if test x$gcc_no_link != xyes; then
> +  AC_CHECK_LIB([m],[sqrtl],[AC_DEFINE([HAVE_SQRTL],[1],[libm includes sqrtl])])
> +  AC_CHECK_LIB([m],[cbrtl],[AC_DEFINE([HAVE_CBRTL],[1],[libm includes cbrtl])])
> +else
> +  if test "x$ac_cv_lib_m_sqrtl" = x""yes; then
> +    AC_DEFINE([HAVE_SQRTL],[1],[libm includes sqrtl])  
> +  fi
> +  if test "x$ac_cv_lib_m_cbrtl" = x""yes; then
> +    AC_DEFINE([HAVE_CBRTL],[1],[libm includes cbrtl])  
> +  fi
> +fi
>  
>  # Check for symbol versioning (copied from libssp).
>  AC_MSG_CHECKING([whether symbol versioning is supported])