Re: [ARM/FDPIC v5 02/21] [ARM] FDPIC: Handle arm*-*-uclinuxfdpiceabi in configure scripts

[Richard Sandiford <richard.sandiford@arm.com>]

Christophe Lyon <christophe.lyon@st.com> writes:
> The new arm-uclinuxfdpiceabi target behaves pretty much like
> arm-linux-gnueabi. In order the enable the same set of features, we
> have to update several configure scripts that generally match targets
> like *-*-linux*: in most places, we add *-uclinux* where there is
> already *-linux*, or uclinux* when there is already linux*.
>
> In gcc/config.gcc and libgcc/config.host we use *-*-uclinuxfdpiceabi
> because there is already a different behaviour for *-*uclinux* target.
>
> In libtool.m4, we use uclinuxfdpiceabi in cases where ELF shared
> libraries support is required, as uclinux does not guarantee that.
>
> 2019-XX-XX  Christophe Lyon  <christophe.lyon@st.com>
>
> 	config/
> 	* futex.m4: Handle *-uclinux*.
> 	* tls.m4 (GCC_CHECK_TLS): Likewise.
>
> 	gcc/
> 	* config.gcc: Handle *-*-uclinuxfdpiceabi.
>
> 	libatomic/
> 	* configure.tgt: Handle arm*-*-uclinux*.
> 	* configure: Regenerate.
>
> 	libgcc/
> 	* config.host: Handle *-*-uclinuxfdpiceabi.
>
> 	libitm/
> 	* configure.tgt: Handle *-*-uclinux*.
> 	* configure: Regenerate.
>
> 	libstdc++-v3/
> 	* acinclude.m4: Handle uclinux*.
> 	* configure: Regenerate.
> 	* configure.host: Handle uclinux*
>
> 	* libtool.m4: Handle uclinux*.

Has the libtool.m4 patch been submitted to upstream libtool?
I think this is supposed to be handled by submitting there first
and then cherry-picking into gcc, so that the change isn't lost
by a future import.

> [...]
>
> diff --git a/config/tls.m4 b/config/tls.m4
> index 1a5fc59..a487aa4 100644
> --- a/config/tls.m4
> +++ b/config/tls.m4
> @@ -76,7 +76,7 @@ AC_DEFUN([GCC_CHECK_TLS], [
>  	  dnl Shared library options may depend on the host; this check
>  	  dnl is only known to be needed for GNU/Linux.
>  	  case $host in
> -	    *-*-linux*)
> +	    *-*-linux* | -*-uclinux*)
>  	      LDFLAGS="-shared -Wl,--no-undefined $LDFLAGS"
>  	      ;;
>  	  esac

Is this right for all uclinux targets?  

> diff --git a/libstdc++-v3/acinclude.m4 b/libstdc++-v3/acinclude.m4
> index 84258d8..cb0fdc5 100644
> --- a/libstdc++-v3/acinclude.m4
> +++ b/libstdc++-v3/acinclude.m4

It'd probably be worth splitting out the libstdc++-v3 bits and
submitting them separately, cc:ing libstdc++@gcc.gnu.org.  But...

> @@ -1404,7 +1404,7 @@ AC_DEFUN([GLIBCXX_ENABLE_LIBSTDCXX_TIME], [
>          ac_has_nanosleep=yes
>          ac_has_sched_yield=yes
>          ;;
> -      gnu* | linux* | kfreebsd*-gnu | knetbsd*-gnu)
> +      gnu* | linux* | kfreebsd*-gnu | knetbsd*-gnu | uclinux*)
>          AC_MSG_CHECKING([for at least GNU libc 2.17])
>          AC_TRY_COMPILE(
>            [#include <features.h>],

is this the right thing to do?  It seems odd to be testing the glibc
version for uclibc.

Do you want to support multiple possible settings of
ac_has_clock_monotonic and ac_has_clock_realtime?  Or could you just
hard-code the values, given particular baseline assumptions about the
version of uclibc etc.?  Hard-coding would then make....

> @@ -1526,7 +1526,7 @@ AC_DEFUN([GLIBCXX_ENABLE_LIBSTDCXX_TIME], [
>  
>    if test x"$ac_has_clock_monotonic" != x"yes"; then
>      case ${target_os} in
> -      linux*)
> +      linux* | uclinux*)
>  	AC_MSG_CHECKING([for clock_gettime syscall])
>  	AC_TRY_COMPILE(
>  	  [#include <unistd.h>

...this redundant.

> @@ -2415,7 +2415,7 @@ AC_DEFUN([GLIBCXX_ENABLE_CLOCALE], [
>    # Default to "generic".
>    if test $enable_clocale_flag = auto; then
>      case ${target_os} in
> -      linux* | gnu* | kfreebsd*-gnu | knetbsd*-gnu)
> +      linux* | gnu* | kfreebsd*-gnu | knetbsd*-gnu | uclinux*)
>  	enable_clocale_flag=gnu
>  	;;
>        darwin*)

This too seems to be choosing a glibc setting for a uclibc target.

> @@ -2661,7 +2661,7 @@ AC_DEFUN([GLIBCXX_ENABLE_ALLOCATOR], [
>    # Default to "new".
>    if test $enable_libstdcxx_allocator_flag = auto; then
>      case ${target_os} in
> -      linux* | gnu* | kfreebsd*-gnu | knetbsd*-gnu)
> +      linux* | gnu* | kfreebsd*-gnu | knetbsd*-gnu | uclinux*)
>  	enable_libstdcxx_allocator_flag=new
>  	;;
>        *)

The full case is:

  # Probe for host-specific support if no specific model is specified.
  # Default to "new".
  if test $enable_libstdcxx_allocator_flag = auto; then
    case ${target_os} in
      linux* | gnu* | kfreebsd*-gnu | knetbsd*-gnu)
	enable_libstdcxx_allocator_flag=new
	;;
      *)
	enable_libstdcxx_allocator_flag=new
	;;
    esac
  fi

which looks a bit redundant :-)

Thanks,
Richard