Use ELF symbol versioning

At the same time, we must bump the (major) ABI version.  This needed to be
done anyway due to ABI breakage in the AArch64 port (see 12cf89ee and the
corresponding GCC PR70024).

1 files changed, 381 insertions, 0 deletions

diff --git a/acinclude.m4 b/acinclude.m4
index 3e8f8ba..5df37a8 100644
--- a/acinclude.m4
+++ b/acinclude.m4
@@ -90,3 +90,384 @@ if test $ac_cv_func_mmap_anon = yes; then
 	    [Define if mmap with MAP_ANON(YMOUS) works.])
 fi
 ])
+
+dnl ----------------------------------------------------------------------
+dnl This whole bit snagged from libstdc++-v3, via libatomic.
+
+dnl
+dnl LIBFFI_ENABLE
+dnl    (FEATURE, DEFAULT, HELP-ARG, HELP-STRING)
+dnl    (FEATURE, DEFAULT, HELP-ARG, HELP-STRING, permit a|b|c)
+dnl    (FEATURE, DEFAULT, HELP-ARG, HELP-STRING, SHELL-CODE-HANDLER)
+dnl
+dnl See docs/html/17_intro/configury.html#enable for documentation.
+dnl
+m4_define([LIBFFI_ENABLE],[dnl
+m4_define([_g_switch],[--enable-$1])dnl
+m4_define([_g_help],[AC_HELP_STRING(_g_switch$3,[$4 @<:@default=$2@:>@])])dnl
+ AC_ARG_ENABLE($1,_g_help,
+  m4_bmatch([$5],
+   [^permit ],
+     [[
+      case "$enableval" in
+       m4_bpatsubst([$5],[permit ])) ;;
+       *) AC_MSG_ERROR(Unknown argument to enable/disable $1) ;;
+          dnl Idea for future:  generate a URL pointing to
+          dnl "onlinedocs/configopts.html#whatever"
+      esac
+     ]],
+   [^$],
+     [[
+      case "$enableval" in
+       yes|no) ;;
+       *) AC_MSG_ERROR(Argument to enable/disable $1 must be yes or no) ;;
+      esac
+     ]],
+   [[$5]]),
+  [enable_]m4_bpatsubst([$1],-,_)[=][$2])
+m4_undefine([_g_switch])dnl
+m4_undefine([_g_help])dnl
+])
+
+dnl
+dnl If GNU ld is in use, check to see if tricky linker opts can be used.  If
+dnl the native linker is in use, all variables will be defined to something
+dnl safe (like an empty string).
+dnl
+dnl Defines:
+dnl  SECTION_LDFLAGS='-Wl,--gc-sections' if possible
+dnl  OPT_LDFLAGS='-Wl,-O1' if possible
+dnl  LD (as a side effect of testing)
+dnl Sets:
+dnl  with_gnu_ld
+dnl  libat_ld_is_gold (possibly)
+dnl  libat_gnu_ld_version (possibly)
+dnl
+dnl The last will be a single integer, e.g., version 1.23.45.0.67.89 will
+dnl set libat_gnu_ld_version to 12345.  Zeros cause problems.
+dnl
+AC_DEFUN([LIBFFI_CHECK_LINKER_FEATURES], [
+  # If we're not using GNU ld, then there's no point in even trying these
+  # tests.  Check for that first.  We should have already tested for gld
+  # by now (in libtool), but require it now just to be safe...
+  test -z "$SECTION_LDFLAGS" && SECTION_LDFLAGS=''
+  test -z "$OPT_LDFLAGS" && OPT_LDFLAGS=''
+  AC_REQUIRE([AC_PROG_LD])
+  AC_REQUIRE([AC_PROG_AWK])
+
+  # The name set by libtool depends on the version of libtool.  Shame on us
+  # for depending on an impl detail, but c'est la vie.  Older versions used
+  # ac_cv_prog_gnu_ld, but now it's lt_cv_prog_gnu_ld, and is copied back on
+  # top of with_gnu_ld (which is also set by --with-gnu-ld, so that actually
+  # makes sense).  We'll test with_gnu_ld everywhere else, so if that isn't
+  # set (hence we're using an older libtool), then set it.
+  if test x${with_gnu_ld+set} != xset; then
+    if test x${ac_cv_prog_gnu_ld+set} != xset; then
+      # We got through "ac_require(ac_prog_ld)" and still not set?  Huh?
+      with_gnu_ld=no
+    else
+      with_gnu_ld=$ac_cv_prog_gnu_ld
+    fi
+  fi
+
+  # Start by getting the version number.  I think the libtool test already
+  # does some of this, but throws away the result.
+  libat_ld_is_gold=no
+  if $LD --version 2>/dev/null | grep 'GNU gold'> /dev/null 2>&1; then
+    libat_ld_is_gold=yes
+  fi
+  changequote(,)
+  ldver=`$LD --version 2>/dev/null |
+         sed -e 's/GNU gold /GNU ld /;s/GNU ld version /GNU ld /;s/GNU ld ([^)]*) /GNU ld /;s/GNU ld \([0-9.][0-9.]*\).*/\1/; q'`
+  changequote([,])
+  libat_gnu_ld_version=`echo $ldver | \
+         $AWK -F. '{ if (NF<3) [$]3=0; print ([$]1*100+[$]2)*100+[$]3 }'`
+
+  # Set --gc-sections.
+  if test "$with_gnu_ld" = "notbroken"; then
+    # GNU ld it is!  Joy and bunny rabbits!
+
+    # All these tests are for C++; save the language and the compiler flags.
+    # Need to do this so that g++ won't try to link in libstdc++
+    ac_test_CFLAGS="${CFLAGS+set}"
+    ac_save_CFLAGS="$CFLAGS"
+    CFLAGS='-x c++  -Wl,--gc-sections'
+
+    # Check for -Wl,--gc-sections
+    # XXX This test is broken at the moment, as symbols required for linking
+    # are now in libsupc++ (not built yet).  In addition, this test has
+    # cored on solaris in the past.  In addition, --gc-sections doesn't
+    # really work at the moment (keeps on discarding used sections, first
+    # .eh_frame and now some of the glibc sections for iconv).
+    # Bzzzzt.  Thanks for playing, maybe next time.
+    AC_MSG_CHECKING([for ld that supports -Wl,--gc-sections])
+    AC_TRY_RUN([
+     int main(void)
+     {
+       try { throw 1; }
+       catch (...) { };
+       return 0;
+     }
+    ], [ac_sectionLDflags=yes],[ac_sectionLDflags=no], [ac_sectionLDflags=yes])
+    if test "$ac_test_CFLAGS" = set; then
+      CFLAGS="$ac_save_CFLAGS"
+    else
+      # this is the suspicious part
+      CFLAGS=''
+    fi
+    if test "$ac_sectionLDflags" = "yes"; then
+      SECTION_LDFLAGS="-Wl,--gc-sections $SECTION_LDFLAGS"
+    fi
+    AC_MSG_RESULT($ac_sectionLDflags)
+  fi
+
+  # Set linker optimization flags.
+  if test x"$with_gnu_ld" = x"yes"; then
+    OPT_LDFLAGS="-Wl,-O1 $OPT_LDFLAGS"
+  fi
+
+  AC_SUBST(SECTION_LDFLAGS)
+  AC_SUBST(OPT_LDFLAGS)
+])
+
+
+dnl
+dnl If GNU ld is in use, check to see if tricky linker opts can be used.  If
+dnl the native linker is in use, all variables will be defined to something
+dnl safe (like an empty string).
+dnl
+dnl Defines:
+dnl  SECTION_LDFLAGS='-Wl,--gc-sections' if possible
+dnl  OPT_LDFLAGS='-Wl,-O1' if possible
+dnl  LD (as a side effect of testing)
+dnl Sets:
+dnl  with_gnu_ld
+dnl  libat_ld_is_gold (possibly)
+dnl  libat_gnu_ld_version (possibly)
+dnl
+dnl The last will be a single integer, e.g., version 1.23.45.0.67.89 will
+dnl set libat_gnu_ld_version to 12345.  Zeros cause problems.
+dnl
+AC_DEFUN([LIBFFI_CHECK_LINKER_FEATURES], [
+  # If we're not using GNU ld, then there's no point in even trying these
+  # tests.  Check for that first.  We should have already tested for gld
+  # by now (in libtool), but require it now just to be safe...
+  test -z "$SECTION_LDFLAGS" && SECTION_LDFLAGS=''
+  test -z "$OPT_LDFLAGS" && OPT_LDFLAGS=''
+  AC_REQUIRE([AC_PROG_LD])
+  AC_REQUIRE([AC_PROG_AWK])
+
+  # The name set by libtool depends on the version of libtool.  Shame on us
+  # for depending on an impl detail, but c'est la vie.  Older versions used
+  # ac_cv_prog_gnu_ld, but now it's lt_cv_prog_gnu_ld, and is copied back on
+  # top of with_gnu_ld (which is also set by --with-gnu-ld, so that actually
+  # makes sense).  We'll test with_gnu_ld everywhere else, so if that isn't
+  # set (hence we're using an older libtool), then set it.
+  if test x${with_gnu_ld+set} != xset; then
+    if test x${ac_cv_prog_gnu_ld+set} != xset; then
+      # We got through "ac_require(ac_prog_ld)" and still not set?  Huh?
+      with_gnu_ld=no
+    else
+      with_gnu_ld=$ac_cv_prog_gnu_ld
+    fi
+  fi
+
+  # Start by getting the version number.  I think the libtool test already
+  # does some of this, but throws away the result.
+  libat_ld_is_gold=no
+  if $LD --version 2>/dev/null | grep 'GNU gold'> /dev/null 2>&1; then
+    libat_ld_is_gold=yes
+  fi
+  changequote(,)
+  ldver=`$LD --version 2>/dev/null |
+         sed -e 's/GNU gold /GNU ld /;s/GNU ld version /GNU ld /;s/GNU ld ([^)]*) /GNU ld /;s/GNU ld \([0-9.][0-9.]*\).*/\1/; q'`
+  changequote([,])
+  libat_gnu_ld_version=`echo $ldver | \
+         $AWK -F. '{ if (NF<3) [$]3=0; print ([$]1*100+[$]2)*100+[$]3 }'`
+
+  # Set --gc-sections.
+  if test "$with_gnu_ld" = "notbroken"; then
+    # GNU ld it is!  Joy and bunny rabbits!
+
+    # All these tests are for C++; save the language and the compiler flags.
+    # Need to do this so that g++ won't try to link in libstdc++
+    ac_test_CFLAGS="${CFLAGS+set}"
+    ac_save_CFLAGS="$CFLAGS"
+    CFLAGS='-x c++  -Wl,--gc-sections'
+
+    # Check for -Wl,--gc-sections
+    # XXX This test is broken at the moment, as symbols required for linking
+    # are now in libsupc++ (not built yet).  In addition, this test has
+    # cored on solaris in the past.  In addition, --gc-sections doesn't
+    # really work at the moment (keeps on discarding used sections, first
+    # .eh_frame and now some of the glibc sections for iconv).
+    # Bzzzzt.  Thanks for playing, maybe next time.
+    AC_MSG_CHECKING([for ld that supports -Wl,--gc-sections])
+    AC_TRY_RUN([
+     int main(void)
+     {
+       try { throw 1; }
+       catch (...) { };
+       return 0;
+     }
+    ], [ac_sectionLDflags=yes],[ac_sectionLDflags=no], [ac_sectionLDflags=yes])
+    if test "$ac_test_CFLAGS" = set; then
+      CFLAGS="$ac_save_CFLAGS"
+    else
+      # this is the suspicious part
+      CFLAGS=''
+    fi
+    if test "$ac_sectionLDflags" = "yes"; then
+      SECTION_LDFLAGS="-Wl,--gc-sections $SECTION_LDFLAGS"
+    fi
+    AC_MSG_RESULT($ac_sectionLDflags)
+  fi
+
+  # Set linker optimization flags.
+  if test x"$with_gnu_ld" = x"yes"; then
+    OPT_LDFLAGS="-Wl,-O1 $OPT_LDFLAGS"
+  fi
+
+  AC_SUBST(SECTION_LDFLAGS)
+  AC_SUBST(OPT_LDFLAGS)
+])
+
+
+dnl
+dnl Add version tags to symbols in shared library (or not), additionally
+dnl marking other symbols as private/local (or not).
+dnl
+dnl --enable-symvers=style adds a version script to the linker call when
+dnl       creating the shared library.  The choice of version script is
+dnl       controlled by 'style'.
+dnl --disable-symvers does not.
+dnl  +  Usage:  LIBFFI_ENABLE_SYMVERS[(DEFAULT)]
+dnl       Where DEFAULT is either 'yes' or 'no'.  Passing `yes' tries to
+dnl       choose a default style based on linker characteristics.  Passing
+dnl       'no' disables versioning.
+dnl
+AC_DEFUN([LIBFFI_ENABLE_SYMVERS], [
+
+LIBFFI_ENABLE(symvers,yes,[=STYLE],
+  [enables symbol versioning of the shared library],
+  [permit yes|no|gnu*|sun])
+
+# If we never went through the LIBFFI_CHECK_LINKER_FEATURES macro, then we
+# don't know enough about $LD to do tricks...
+AC_REQUIRE([LIBFFI_CHECK_LINKER_FEATURES])
+
+# Turn a 'yes' into a suitable default.
+if test x$enable_symvers = xyes ; then
+  # FIXME  The following test is too strict, in theory.
+  if test $enable_shared = no || test "x$LD" = x; then
+    enable_symvers=no
+  else
+    if test $with_gnu_ld = yes ; then
+      enable_symvers=gnu
+    else
+      case ${target_os} in
+        # Sun symbol versioning exists since Solaris 2.5.
+        solaris2.[[5-9]]* | solaris2.1[[0-9]]*)
+          enable_symvers=sun ;;
+        *)
+          enable_symvers=no ;;
+      esac
+    fi
+  fi
+fi
+
+# Check if 'sun' was requested on non-Solaris 2 platforms.
+if test x$enable_symvers = xsun ; then
+  case ${target_os} in
+    solaris2*)
+      # All fine.
+      ;;
+    *)
+      # Unlikely to work.
+      AC_MSG_WARN([=== You have requested Sun symbol versioning, but])
+      AC_MSG_WARN([=== you are not targetting Solaris 2.])
+      AC_MSG_WARN([=== Symbol versioning will be disabled.])
+      enable_symvers=no
+      ;;
+  esac
+fi
+
+# Check to see if libgcc_s exists, indicating that shared libgcc is possible.
+if test $enable_symvers != no; then
+  AC_MSG_CHECKING([for shared libgcc])
+  ac_save_CFLAGS="$CFLAGS"
+  CFLAGS=' -lgcc_s'
+  AC_TRY_LINK(, [return 0;], libat_shared_libgcc=yes, libat_shared_libgcc=no)
+  CFLAGS="$ac_save_CFLAGS"
+  if test $libat_shared_libgcc = no; then
+    cat > conftest.c <<EOF
+int main (void) { return 0; }
+EOF
+changequote(,)dnl
+    libat_libgcc_s_suffix=`${CC-cc} $CFLAGS $CPPFLAGS $LDFLAGS \
+			     -shared -shared-libgcc -o conftest.so \
+			     conftest.c -v 2>&1 >/dev/null \
+			     | sed -n 's/^.* -lgcc_s\([^ ]*\) .*$/\1/p'`
+changequote([,])dnl
+    rm -f conftest.c conftest.so
+    if test x${libat_libgcc_s_suffix+set} = xset; then
+      CFLAGS=" -lgcc_s$libat_libgcc_s_suffix"
+      AC_TRY_LINK(, [return 0;], libat_shared_libgcc=yes)
+      CFLAGS="$ac_save_CFLAGS"
+    fi
+  fi
+  AC_MSG_RESULT($libat_shared_libgcc)
+fi
+
+# For GNU ld, we need at least this version.  The format is described in
+# LIBFFI_CHECK_LINKER_FEATURES above.
+libat_min_gnu_ld_version=21400
+# XXXXXXXXXXX libat_gnu_ld_version=21390
+
+# Check to see if unspecified "yes" value can win, given results above.
+# Change "yes" into either "no" or a style name.
+if test $enable_symvers != no && test $libat_shared_libgcc = yes; then
+  if test $with_gnu_ld = yes; then
+    if test $libat_gnu_ld_version -ge $libat_min_gnu_ld_version ; then
+      enable_symvers=gnu
+    elif test $libat_ld_is_gold = yes ; then
+      enable_symvers=gnu
+    else
+      # The right tools, the right setup, but too old.  Fallbacks?
+      AC_MSG_WARN(=== Linker version $libat_gnu_ld_version is too old for)
+      AC_MSG_WARN(=== full symbol versioning support in this release of GCC.)
+      AC_MSG_WARN(=== You would need to upgrade your binutils to version)
+      AC_MSG_WARN(=== $libat_min_gnu_ld_version or later and rebuild GCC.)
+      if test $libat_gnu_ld_version -ge 21200 ; then
+        # Globbing fix is present, proper block support is not.
+        dnl AC_MSG_WARN([=== Dude, you are soooo close.  Maybe we can fake it.])
+        dnl enable_symvers=???
+        AC_MSG_WARN([=== Symbol versioning will be disabled.])
+        enable_symvers=no
+      else
+        # 2.11 or older.
+        AC_MSG_WARN([=== Symbol versioning will be disabled.])
+        enable_symvers=no
+      fi
+    fi
+  elif test $enable_symvers = sun; then
+    : All interesting versions of Sun ld support sun style symbol versioning.
+  else
+    # just fail for now
+    AC_MSG_WARN([=== You have requested some kind of symbol versioning, but])
+    AC_MSG_WARN([=== either you are not using a supported linker, or you are])
+    AC_MSG_WARN([=== not building a shared libgcc_s (which is required).])
+    AC_MSG_WARN([=== Symbol versioning will be disabled.])
+    enable_symvers=no
+  fi
+fi
+if test $enable_symvers = gnu; then
+  AC_DEFINE(LIBFFI_GNU_SYMBOL_VERSIONING, 1,
+	    [Define to 1 if GNU symbol versioning is used for libatomic.])
+fi
+
+AM_CONDITIONAL(LIBFFI_BUILD_VERSIONED_SHLIB, test $enable_symvers != no)
+AM_CONDITIONAL(LIBFFI_BUILD_VERSIONED_SHLIB_GNU, test $enable_symvers = gnu)
+AM_CONDITIONAL(LIBFFI_BUILD_VERSIONED_SHLIB_SUN, test $enable_symvers = sun)
+AC_MSG_NOTICE(versioning on shared library symbols is $enable_symvers)
+])