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| author | Ben Pfaff <blp@nicira.com> | 2013-07-15 14:13:53 -0700 |
|---|---|---|
| committer | Ben Pfaff <blp@nicira.com> | 2013-07-31 08:56:36 -0700 |
| commit | 15248032ea9e3e88849310e8f2cef9db618fce1a (patch) | |
| tree | 5a2e5edb12f003848dbe122df9a5551c57eb9735 /m4 | |
| parent | 97be153858b4cd175cbe7862b8e1624bf22ab98a (diff) | |
| download | openvswitch-15248032ea9e3e88849310e8f2cef9db618fce1a.tar.gz | |
configure: Add configure-time check for GCC 4.0+ atomic built-ins.
We found out earlier that GCC sometimes produces an error only at link time
for atomic built-ins that are not supported on a platform. This actually
tries the link at configure time and should thus reliably detect whether
the atomic built-ins are really supported.
Signed-off-by: Ben Pfaff <blp@nicira.com>
Acked-by: Ethan Jackson <ethan@nicira.com>
Diffstat (limited to 'm4')
| -rw-r--r-- | m4/openvswitch.m4 | 72 |
1 files changed, 72 insertions, 0 deletions
diff --git a/m4/openvswitch.m4 b/m4/openvswitch.m4 index dbfc7c425..bcdb942b9 100644 --- a/m4/openvswitch.m4 +++ b/m4/openvswitch.m4 @@ -426,6 +426,78 @@ static thread_local int var;], [return var;])], fi fi]) +dnl OVS_CHECK_GCC4_ATOMICS +dnl +dnl Checks whether the compiler and linker support GCC 4.0+ atomic built-ins. +dnl A compile-time only check is not enough because the compiler defers +dnl unimplemented built-ins to libgcc, which sometimes also lacks +dnl implementations. +AC_DEFUN([OVS_CHECK_GCC4_ATOMICS], + [AC_CACHE_CHECK( + [whether $CC supports GCC 4.0+ atomic built-ins], + [ovs_cv_gcc4_atomics], + [AC_LINK_IFELSE( + [AC_LANG_PROGRAM([[#include <stdlib.h> + +#define ovs_assert(expr) if (!(expr)) abort(); +#define TEST_ATOMIC_TYPE(TYPE) \ + { \ + TYPE x = 1; \ + TYPE orig; \ + \ + __sync_synchronize(); \ + ovs_assert(x == 1); \ + \ + __sync_synchronize(); \ + x = 3; \ + __sync_synchronize(); \ + ovs_assert(x == 3); \ + \ + orig = __sync_fetch_and_add(&x, 1); \ + ovs_assert(orig == 3); \ + __sync_synchronize(); \ + ovs_assert(x == 4); \ + \ + orig = __sync_fetch_and_sub(&x, 2); \ + ovs_assert(orig == 4); \ + __sync_synchronize(); \ + ovs_assert(x == 2); \ + \ + orig = __sync_fetch_and_or(&x, 6); \ + ovs_assert(orig == 2); \ + __sync_synchronize(); \ + ovs_assert(x == 6); \ + \ + orig = __sync_fetch_and_and(&x, 10); \ + ovs_assert(orig == 6); \ + __sync_synchronize(); \ + ovs_assert(x == 2); \ + \ + orig = __sync_fetch_and_xor(&x, 10); \ + ovs_assert(orig == 2); \ + __sync_synchronize(); \ + ovs_assert(x == 8); \ + }]], [dnl +TEST_ATOMIC_TYPE(char); +TEST_ATOMIC_TYPE(unsigned char); +TEST_ATOMIC_TYPE(signed char); +TEST_ATOMIC_TYPE(short); +TEST_ATOMIC_TYPE(unsigned short); +TEST_ATOMIC_TYPE(int); +TEST_ATOMIC_TYPE(unsigned int); +TEST_ATOMIC_TYPE(long int); +TEST_ATOMIC_TYPE(unsigned long int); +TEST_ATOMIC_TYPE(long long int); +TEST_ATOMIC_TYPE(unsigned long long int); +])], + [ovs_cv_gcc4_atomics=yes], + [ovs_cv_gcc4_atomics=no])]) + if test $ovs_cv_gcc4_atomics = yes; then + AC_DEFINE([HAVE_GCC4_ATOMICS], [1], + [Define to 1 if the C compiler and linker supports the GCC 4.0+ + atomic built-ins.]) + fi]) + dnl OVS_CHECK_ATOMIC_ALWAYS_LOCK_FREE(SIZE) dnl dnl Checks __atomic_always_lock_free(SIZE, 0) |