configure: check if -latomic is needed for __atomic_*

On some platforms, gcc generates library calls when __atomic_* functions
are used, but does not link the required library (libatomic) automatically
(supposedly to allow the app to use some other atomics implementation?).

Detect this at configure time and add the library when needed. Tested
on armel (library was added) and on x86_64 (was not, as expected).

Some documentation on this is provided in GCC wiki:
https://gcc.gnu.org/wiki/Atomic/GCCMM

Fixes: 8915f0c0 "util: use GCC atomic intrinsics with explicit memory model"
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=102573
Signed-off-by: Grazvydas Ignotas <notasas@gmail.com>
Reviewed-by: Matt Turner <mattst88@gmail.com>
Reviewed-by: Emil Velikov <emil.velikov@collabora.com>
This commit is contained in:
Grazvydas Ignotas 2017-09-18 22:11:26 +03:00
parent 6ace0b8bc8
commit 2ef7f23820
2 changed files with 15 additions and 1 deletions

View File

@ -379,8 +379,21 @@ int main() {
}]])], GCC_ATOMIC_BUILTINS_SUPPORTED=1) }]])], GCC_ATOMIC_BUILTINS_SUPPORTED=1)
if test "x$GCC_ATOMIC_BUILTINS_SUPPORTED" = x1; then if test "x$GCC_ATOMIC_BUILTINS_SUPPORTED" = x1; then
DEFINES="$DEFINES -DUSE_GCC_ATOMIC_BUILTINS" DEFINES="$DEFINES -DUSE_GCC_ATOMIC_BUILTINS"
dnl On some platforms, new-style atomics need a helper library
AC_MSG_CHECKING(whether -latomic is needed)
AC_LINK_IFELSE([AC_LANG_SOURCE([[
#include <stdint.h>
uint64_t v;
int main() {
return (int)__atomic_load_n(&v, __ATOMIC_ACQUIRE);
}]])], GCC_ATOMIC_BUILTINS_NEED_LIBATOMIC=no, GCC_ATOMIC_BUILTINS_NEED_LIBATOMIC=yes)
AC_MSG_RESULT($GCC_ATOMIC_BUILTINS_NEED_LIBATOMIC)
if test "x$GCC_ATOMIC_BUILTINS_NEED_LIBATOMIC" = xyes; then
LIBATOMIC_LIBS="-latomic"
fi
fi fi
AM_CONDITIONAL([GCC_ATOMIC_BUILTINS_SUPPORTED], [test x$GCC_ATOMIC_BUILTINS_SUPPORTED = x1]) AM_CONDITIONAL([GCC_ATOMIC_BUILTINS_SUPPORTED], [test x$GCC_ATOMIC_BUILTINS_SUPPORTED = x1])
AC_SUBST([LIBATOMIC_LIBS])
dnl Check if host supports 64-bit atomics dnl Check if host supports 64-bit atomics
dnl note that lack of support usually results in link (not compile) error dnl note that lack of support usually results in link (not compile) error

View File

@ -48,7 +48,8 @@ libmesautil_la_SOURCES = \
libmesautil_la_LIBADD = \ libmesautil_la_LIBADD = \
$(CLOCK_LIB) \ $(CLOCK_LIB) \
$(ZLIB_LIBS) $(ZLIB_LIBS) \
$(LIBATOMIC_LIBS)
libxmlconfig_la_SOURCES = $(XMLCONFIG_FILES) libxmlconfig_la_SOURCES = $(XMLCONFIG_FILES)
libxmlconfig_la_CFLAGS = \ libxmlconfig_la_CFLAGS = \