From 026b173107f19d4a1bf4e1cd05befa97c65d01f4 Mon Sep 17 00:00:00 2001 From: Christophe Lyon Date: Thu, 31 Aug 2023 13:50:16 +0000 Subject: [PATCH] libstdc++: Use GLIBCXX_CHECK_LINKER_FEATURES for cross-builds (PR111238) As discussed in PR104167 (comments #8 and below), and PR111238, using -Wl,-gc-sections in the libstdc++ testsuite for arm-eabi (cross-toolchain) avoids link failures for a few tests: 27_io/filesystem/path/108636.cc std/time/clock/gps/1.cc std/time/clock/gps/io.cc std/time/clock/tai/1.cc std/time/clock/tai/io.cc std/time/clock/utc/1.cc std/time/clock/utc/io.cc std/time/clock/utc/leap_second_info.cc std/time/exceptions.cc std/time/format.cc std/time/time_zone/get_info_local.cc std/time/time_zone/get_info_sys.cc std/time/tzdb/1.cc std/time/tzdb/leap_seconds.cc std/time/tzdb_list/1.cc std/time/zoned_time/1.cc std/time/zoned_time/custom.cc std/time/zoned_time/io.cc std/time/zoned_traits.cc This patch achieves this by calling GLIBCXX_CHECK_LINKER_FEATURES in cross-build cases, like we already do for native builds. We keep not doing so in Canadian-cross builds. However, this would hide the fact that libstdc++ somehow forces the user to use -Wl,-gc-sections to avoid undefined references to chdir, mkdir, chmod, pathconf, ... so maybe it's better to keep the status quo and not apply this patch? 2023-08-31 Christophe Lyon libstdc++-v3/ChangeLog: PR libstdc++/111238 * configure: Regenerate. * configure.ac: Call GLIBCXX_CHECK_LINKER_FEATURES in cross, non-Canadian builds. --- libstdc++-v3/configure | 154 ++++++++++++++++++++++++++++++++++++++ libstdc++-v3/configure.ac | 4 + 2 files changed, 158 insertions(+) diff --git a/libstdc++-v3/configure b/libstdc++-v3/configure index c4da56c3042..948dab4f9a0 100755 --- a/libstdc++-v3/configure +++ b/libstdc++-v3/configure @@ -29823,6 +29823,160 @@ else CANADIAN=yes else CANADIAN=no + fi + + if test $CANADIAN = no; then + + # If we're not using GNU ld, then there's no point in even trying these + # tests. Check for that first. We should have already tested for gld + # by now (in libtool), but require it now just to be safe... + test -z "$SECTION_LDFLAGS" && SECTION_LDFLAGS='' + test -z "$OPT_LDFLAGS" && OPT_LDFLAGS='' + + + + # The name set by libtool depends on the version of libtool. Shame on us + # for depending on an impl detail, but c'est la vie. Older versions used + # ac_cv_prog_gnu_ld, but now it's lt_cv_prog_gnu_ld, and is copied back on + # top of with_gnu_ld (which is also set by --with-gnu-ld, so that actually + # makes sense). We'll test with_gnu_ld everywhere else, so if that isn't + # set (hence we're using an older libtool), then set it. + if test x${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. + glibcxx_ld_is_gold=no + glibcxx_ld_is_mold=no + if test x"$with_gnu_ld" = x"yes"; then + { $as_echo "$as_me:${as_lineno-$LINENO}: checking for ld version" >&5 +$as_echo_n "checking for ld version... " >&6; } + + if $LD --version 2>/dev/null | grep 'GNU gold' >/dev/null 2>&1; then + glibcxx_ld_is_gold=yes + elif $LD --version 2>/dev/null | grep 'mold' >/dev/null 2>&1; then + glibcxx_ld_is_mold=yes + fi + ldver=`$LD --version 2>/dev/null | + sed -e 's/[. ][0-9]\{8\}$//;s/.* \([^ ]\{1,\}\)$/\1/; q'` + + glibcxx_gnu_ld_version=`echo $ldver | \ + $AWK -F. '{ if (NF<3) $3=0; print ($1*100+$2)*100+$3 }'` + { $as_echo "$as_me:${as_lineno-$LINENO}: result: $glibcxx_gnu_ld_version" >&5 +$as_echo "$glibcxx_gnu_ld_version" >&6; } + fi + + # Set --gc-sections. + glibcxx_have_gc_sections=no + if test "$glibcxx_ld_is_gold" = "yes" || test "$glibcxx_ld_is_mold" = "yes" ; then + if $LD --help 2>/dev/null | grep gc-sections >/dev/null 2>&1; then + glibcxx_have_gc_sections=yes + fi + else + glibcxx_gcsections_min_ld=21602 + if test x"$with_gnu_ld" = x"yes" && + test $glibcxx_gnu_ld_version -gt $glibcxx_gcsections_min_ld ; then + glibcxx_have_gc_sections=yes + fi + fi + if test "$glibcxx_have_gc_sections" = "yes"; then + # Sufficiently young GNU ld it is! Joy and bunny rabbits! + # NB: This flag only works reliably after 2.16.1. Configure tests + # for this are difficult, so hard wire a value that should work. + + ac_test_CFLAGS="${CFLAGS+set}" + ac_save_CFLAGS="$CFLAGS" + CFLAGS='-Wl,--gc-sections' + + # Check for -Wl,--gc-sections + { $as_echo "$as_me:${as_lineno-$LINENO}: checking for ld that supports -Wl,--gc-sections" >&5 +$as_echo_n "checking for ld that supports -Wl,--gc-sections... " >&6; } + if test x$gcc_no_link = xyes; then + as_fn_error $? "Link tests are not allowed after GCC_NO_EXECUTABLES." "$LINENO" 5 +fi +cat confdefs.h - <<_ACEOF >conftest.$ac_ext +/* end confdefs.h. */ + int one(void) { return 1; } + int two(void) { return 2; } + +int +main () +{ + two(); + ; + return 0; +} +_ACEOF +if ac_fn_c_try_link "$LINENO"; then : + ac_gcsections=yes +else + ac_gcsections=no +fi +rm -f core conftest.err conftest.$ac_objext \ + conftest$ac_exeext conftest.$ac_ext + if test "$ac_gcsections" = "yes"; then + rm -f conftest.c + touch conftest.c + if $CC -c conftest.c; then + if $LD --gc-sections -o conftest conftest.o 2>&1 | \ + grep "Warning: gc-sections option ignored" > /dev/null; then + ac_gcsections=no + fi + fi + rm -f conftest.c conftest.o conftest + fi + if test "$ac_gcsections" = "yes"; then + SECTION_LDFLAGS="-Wl,--gc-sections $SECTION_LDFLAGS" + fi + { $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_gcsections" >&5 +$as_echo "$ac_gcsections" >&6; } + + if test "$ac_test_CFLAGS" = set; then + CFLAGS="$ac_save_CFLAGS" + else + # this is the suspicious part + CFLAGS='' + fi + fi + + # Set -z,relro. + # Note this is only for shared objects. + ac_ld_relro=no + if test x"$with_gnu_ld" = x"yes"; then + # cygwin and mingw uses PE, which has no ELF relro support, + # multi target ld may confuse configure machinery + case "$host" in + *-*-cygwin*) + ;; + *-*-mingw*) + ;; + *) + { $as_echo "$as_me:${as_lineno-$LINENO}: checking for ld that supports -Wl,-z,relro" >&5 +$as_echo_n "checking for ld that supports -Wl,-z,relro... " >&6; } + cxx_z_relo=`$LD -v --help 2>/dev/null | grep "z relro"` + if test -n "$cxx_z_relo"; then + OPT_LDFLAGS="-Wl,-z,relro" + ac_ld_relro=yes + fi + { $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_ld_relro" >&5 +$as_echo "$ac_ld_relro" >&6; } + esac + fi + + # Set linker optimization flags. + if test x"$with_gnu_ld" = x"yes"; then + OPT_LDFLAGS="-Wl,-O1 $OPT_LDFLAGS" + fi + + + + fi # Construct crosses by hand, eliminating bits that need ld... diff --git a/libstdc++-v3/configure.ac b/libstdc++-v3/configure.ac index fc0f2522027..49472353435 100644 --- a/libstdc++-v3/configure.ac +++ b/libstdc++-v3/configure.ac @@ -325,6 +325,10 @@ else CANADIAN=no fi + if test $CANADIAN = no; then + GLIBCXX_CHECK_LINKER_FEATURES + fi + # Construct crosses by hand, eliminating bits that need ld... # GLIBCXX_CHECK_MATH_SUPPORT -- 2.34.1