diff options
| author | Fangrui Song <maskray@google.com> | 2021-04-16 11:26:39 -0700 |
|---|---|---|
| committer | Fangrui Song <maskray@google.com> | 2021-04-16 11:26:39 -0700 |
| commit | cd6ae7ea5431c2b8f16201fb0e2c413bf8d2df06 (patch) | |
| tree | 68d5b5402097696b3e3898fad40a143720da0438 /configure.ac | |
| parent | 1a8605b6cd257e8a74e29b5b71c057211f5fb847 (diff) | |
| download | glibc-cd6ae7ea5431c2b8f16201fb0e2c413bf8d2df06.tar.gz glibc-cd6ae7ea5431c2b8f16201fb0e2c413bf8d2df06.tar.xz glibc-cd6ae7ea5431c2b8f16201fb0e2c413bf8d2df06.zip | |
Set the retain attribute on _elf_set_element if CC supports [BZ #27492]
So that text_set_element/data_set_element/bss_set_element defined variables will be retained by the linker. Note: 'used' and 'retain' are orthogonal: 'used' makes sure the variable will not be optimized out; 'retain' prevents section garbage collection if the linker support SHF_GNU_RETAIN. GNU ld 2.37 and LLD 13 will support -z start-stop-gc which allow C identifier name sections to be GCed even if there are live __start_/__stop_ references. Without the change, there are some static linking problems, e.g. _IO_cleanup (libio/genops.c) may be discarded by ld --gc-sections, so stdout is not flushed on exit. Note: GCC may warning 'retain' attribute ignored while __has_attribute(retain) is 1 (https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99587). Reviewed-by: H.J. Lu <hjl.tools@gmail.com>
Diffstat (limited to 'configure.ac')
| -rw-r--r-- | configure.ac | 21 |
1 files changed, 21 insertions, 0 deletions
diff --git a/configure.ac b/configure.ac index fce967f2c2..cc47e56e82 100644 --- a/configure.ac +++ b/configure.ac @@ -707,6 +707,23 @@ fi rm -f conftest*]) AC_SUBST(libc_cv_textrel_ifunc) +# Check if CC supports attribute retain as it is used in attribute_used_retain macro. +AC_CACHE_CHECK([for GNU attribute retain support], + libc_cv_gnu_retain, [dnl +cat > conftest.c <<EOF +static int var __attribute__ ((used, retain, section ("__libc_atexit"))); +EOF +libc_cv_gnu_retain=no +if ${CC-cc} -Werror -c conftest.c -o /dev/null 1>&AS_MESSAGE_LOG_FD \ + 2>&AS_MESSAGE_LOG_FD ; then + libc_cv_gnu_retain=yes +fi +rm -f conftest*]) +if test $libc_cv_gnu_retain = yes; then + AC_DEFINE(HAVE_GNU_RETAIN) +fi +LIBC_CONFIG_VAR([have-gnu-retain], [$libc_cv_gnu_retain]) + # Check if gcc warns about alias for function with incompatible types. AC_CACHE_CHECK([if compiler warns about alias for function with incompatible types], libc_cv_gcc_incompatible_alias, [dnl @@ -1317,6 +1334,10 @@ LIBC_LINKER_FEATURE([-z execstack], [-Wl,-z,execstack], [libc_cv_z_execstack=yes], [libc_cv_z_execstack=no]) AC_SUBST(libc_cv_z_execstack) +LIBC_LINKER_FEATURE([-z start-stop-gc], [-Wl,-z,start-stop-gc], + [libc_cv_z_start_stop_gc=yes], [libc_cv_z_start_stop_gc=no]) +LIBC_CONFIG_VAR([have-z-start-stop-gc], [$libc_cv_z_start_stop_gc]) + LIBC_LINKER_FEATURE([--no-dynamic-linker], [-Wl,--no-dynamic-linker], [libc_cv_no_dynamic_linker=yes], |