Re: [PATCH] Fix up --enable-initfini-array autodetection in configure (PR bootstrap/50237)

[Jakub Jelinek <jakub at redhat dot com>]

On Thu, Jan 19, 2012 at 09:54:43AM +0100, Paolo Bonzini wrote:
> On 01/19/2012 12:24 AM, Jakub Jelinek wrote:
> >    if test "x${build}" = "x${target}"&&  test "x${build}" = "x${host}"; then
> 
> This test is no longer necessary, is it? ia64 does its own
> cross-compile detection via AC_RUN_IFELSE, and other hosts are
> cross-compile safe. The patch is okay if you remove it.

While the linker test is done using the target linker (it uses default
linker flags btw, so in case a linker would be buggy for one target and not
for a different target also supported by the same linker, it would be
a problem, but let's assume that the linker is either buggy or not for
all targets it supports), AC_PREPROC_IFELSE is done using the host compiler.
For cross-compiling we would need to check the target libc headers.
For glibc we could certainly do something similar to the
    case "$target" in
       *-*-linux* | *-*-kfreebsd*-gnu | *-*-knetbsd*-gnu)
      [# glibc 2.4 and later provides __stack_chk_fail and
      # either __stack_chk_guard, or TLS access to stack guard canary.
      if test -f $target_header_dir/features.h \
         && $EGREP '^[  ]*#[    ]*define[       ]+__GNU_LIBRARY__[ 	]+([1-9][0-9]|[6-9])' \
            $target_header_dir/features.h > /dev/null; then
        if $EGREP '^[   ]*#[    ]*define[       ]+__GLIBC__[ 	]+([1-9][0-9]|[3-9])' \
           $target_header_dir/features.h > /dev/null; then
          gcc_cv_libc_provides_ssp=yes
        elif $EGREP '^[         ]*#[    ]*define[       ]+__GLIBC__[    ]+2' \
             $target_header_dir/features.h > /dev/null \
             && $EGREP '^[      ]*#[    ]*define[       ]+__GLIBC_MINOR__[ 	]+([1-9][0-9]|[4-9])' \
             $target_header_dir/features.h > /dev/null; then
          gcc_cv_libc_provides_ssp=yes
        fi
      fi]
test configure already does (and glibc only supports ELF targets, so
the ELF check could be avoided).

> H.J., can ia64 fall back to the common test when cross compiling?
> Or perhaps even always?

I've kept ia64 as is because that is what we did for ia64 configure already
in 4.6 and earlier.  As ia64 was using .init_array etc. far before the
linker merging of .ctors and .init_array has been fixed, probably it just
switched over to .init_array completely many years ago or something.

	Jakub