denozord/strongswan-ext
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

utils: Use GCC's __atomic built-ins if available

Browse Source 
These are available since GCC 4.7 and will eventually replace the __sync
operations.  They support the memory model defined by C++11. For instance,
by using __ATOMIC_RELAXED for some operations on the reference counters we
can avoid memory barriers, which are required by __sync operations (whose
memory model essentially is __ATOMIC_SEQ_CST).
This commit is contained in:
Tobias Brunner
2014-04-24 17:54:14 +02:00
parent efedd0d21e
commit 0f603d425d
3 changed files with 47 additions and 10 deletions
Download Patch File Download Diff File Expand all files Collapse all files
configure.ac
+25 -7
View File
@@ -667,21 +667,39 @@ AC_COMPILE_IFELSE(
[AC_MSG_RESULT([no])]
)
AC_MSG_CHECKING([for gcc atomic operations])
AC_MSG_CHECKING([for GCC __atomic operations])
AC_RUN_IFELSE([AC_LANG_SOURCE(
[[
int main() {
volatile int ref = 1;
__sync_fetch_and_add (&ref, 1);
__sync_sub_and_fetch (&ref, 1);
/* Make sure test fails if operations are not supported */
__sync_val_compare_and_swap(&ref, 1, 0);
int ref = 1, val;
__atomic_fetch_add(&ref, 1, __ATOMIC_RELAXED);
val = __atomic_sub_fetch(&ref, 1, __ATOMIC_RELAXED);
__atomic_compare_exchange_n(&ref, &val, 0, 0, __ATOMIC_RELAXED,
__ATOMIC_RELAXED);
return ref;
}
]])],
[AC_MSG_RESULT([yes]);
AC_DEFINE([HAVE_GCC_ATOMIC_OPERATIONS], [],
[have GCC __sync_* atomic operations])],
[have GCC __atomic_* operations])],
[AC_MSG_RESULT([no])],
[AC_MSG_RESULT([no])]
)
AC_MSG_CHECKING([for GCC __sync operations])
AC_RUN_IFELSE([AC_LANG_SOURCE(
[[
int main() {
int ref = 1;
__sync_fetch_and_add (&ref, 1);
__sync_sub_and_fetch (&ref, 1);
__sync_val_compare_and_swap(&ref, 1, 0);
return ref;
}
]])],
[AC_MSG_RESULT([yes]);
AC_DEFINE([HAVE_GCC_SYNC_OPERATIONS], [],
[have GCC __sync_* operations])],
[AC_MSG_RESULT([no])],
[AC_MSG_RESULT([no])]
)