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* [gcc r14-3660] libstdc++: Use GLIBCXX_CHECK_LINKER_FEATURES for cross-builds (PR111238)
@ 2023-09-04 20:44 Christophe Lyon
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From: Christophe Lyon @ 2023-09-04 20:44 UTC (permalink / raw)
To: gcc-cvs, libstdc++-cvs
https://gcc.gnu.org/g:56d0592db19b69e3cc217fabe5c2f8be3a75a8cf
commit r14-3660-g56d0592db19b69e3cc217fabe5c2f8be3a75a8cf
Author: Christophe Lyon <christophe.lyon@linaro.org>
Date: Thu Aug 31 13:50:16 2023 +0000
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 <christophe.lyon@linaro.org>
libstdc++-v3/ChangeLog:
PR libstdc++/111238
* configure: Regenerate.
* configure.ac: Call GLIBCXX_CHECK_LINKER_FEATURES in cross,
non-Canadian builds.
Diff:
---
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 db1932300c01..830c25fe8b13 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 fc0f25220277..494723534358 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
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