| Message ID | 1382435921-18438-1-git-send-email-peter.maydell@linaro.org |
|---|---|
| State | Accepted |
| Commit | 33effd3aab4a268fb573fd8d7e0fe0baed0cd61a |
| Headers | show |
Ping! This is needed as a build-fix for MacOSX and didn't make it into 1.7-rc0. Paolo, can I get you to review this? I did subsequently test with a Linux clang 3.3: the patch works OK on that but is not necessary because that clang doesn't define __ATOMIC_SEQ_CST, presumably because it's not recent enough. I imagine recent Linux clang still needs this fix. thanks -- PMM On 22 October 2013 10:58, Peter Maydell <peter.maydell@linaro.org> wrote: > clang defines __ATOMIC_SEQ_CST but its implementation of the > __atomic_exchange() builtin differs from that of gcc. Move the > __clang__ branch of the ifdef ladder to the top and fix its > implementation (there is no such builtin as __sync_exchange), > so we can compile with clang again. > > Signed-off-by: Peter Maydell <peter.maydell@linaro.org> > --- > I don't have access to a Linux box with clang, so this is only > tested on MacOSX clang, but I believe it to be both required > and correct for all clang platforms. > > include/qemu/atomic.h | 6 +++--- > 1 file changed, 3 insertions(+), 3 deletions(-) > > diff --git a/include/qemu/atomic.h b/include/qemu/atomic.h > index 0aa8913..492bce1 100644 > --- a/include/qemu/atomic.h > +++ b/include/qemu/atomic.h > @@ -168,14 +168,14 @@ > #endif > > #ifndef atomic_xchg > -#ifdef __ATOMIC_SEQ_CST > +#if defined(__clang__) > +#define atomic_xchg(ptr, i) __sync_swap(ptr, i) > +#elif defined(__ATOMIC_SEQ_CST) > #define atomic_xchg(ptr, i) ({ \ > typeof(*ptr) _new = (i), _old; \ > __atomic_exchange(ptr, &_new, &_old, __ATOMIC_SEQ_CST); \ > _old; \ > }) > -#elif defined __clang__ > -#define atomic_xchg(ptr, i) __sync_exchange(ptr, i) > #else > /* __sync_lock_test_and_set() is documented to be an acquire barrier only. */ > #define atomic_xchg(ptr, i) (smp_mb(), __sync_lock_test_and_set(ptr, i)) > -- > 1.7.11.4
Il 09/11/2013 19:09, Peter Maydell ha scritto: > Ping! This is needed as a build-fix for MacOSX and didn't > make it into 1.7-rc0. Paolo, can I get you to review this? I thought I already had done that, anyway: >> diff --git a/include/qemu/atomic.h b/include/qemu/atomic.h >> index 0aa8913..492bce1 100644 >> --- a/include/qemu/atomic.h >> +++ b/include/qemu/atomic.h >> @@ -168,14 +168,14 @@ >> #endif >> >> #ifndef atomic_xchg >> -#ifdef __ATOMIC_SEQ_CST >> +#if defined(__clang__) >> +#define atomic_xchg(ptr, i) __sync_swap(ptr, i) >> +#elif defined(__ATOMIC_SEQ_CST) >> #define atomic_xchg(ptr, i) ({ \ >> typeof(*ptr) _new = (i), _old; \ >> __atomic_exchange(ptr, &_new, &_old, __ATOMIC_SEQ_CST); \ >> _old; \ >> }) >> -#elif defined __clang__ >> -#define atomic_xchg(ptr, i) __sync_exchange(ptr, i) >> #else >> /* __sync_lock_test_and_set() is documented to be an acquire barrier only. */ >> #define atomic_xchg(ptr, i) (smp_mb(), __sync_lock_test_and_set(ptr, i)) Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
diff --git a/include/qemu/atomic.h b/include/qemu/atomic.h index 0aa8913..492bce1 100644 --- a/include/qemu/atomic.h +++ b/include/qemu/atomic.h @@ -168,14 +168,14 @@ #endif #ifndef atomic_xchg -#ifdef __ATOMIC_SEQ_CST +#if defined(__clang__) +#define atomic_xchg(ptr, i) __sync_swap(ptr, i) +#elif defined(__ATOMIC_SEQ_CST) #define atomic_xchg(ptr, i) ({ \ typeof(*ptr) _new = (i), _old; \ __atomic_exchange(ptr, &_new, &_old, __ATOMIC_SEQ_CST); \ _old; \ }) -#elif defined __clang__ -#define atomic_xchg(ptr, i) __sync_exchange(ptr, i) #else /* __sync_lock_test_and_set() is documented to be an acquire barrier only. */ #define atomic_xchg(ptr, i) (smp_mb(), __sync_lock_test_and_set(ptr, i))
clang defines __ATOMIC_SEQ_CST but its implementation of the __atomic_exchange() builtin differs from that of gcc. Move the __clang__ branch of the ifdef ladder to the top and fix its implementation (there is no such builtin as __sync_exchange), so we can compile with clang again. Signed-off-by: Peter Maydell <peter.maydell@linaro.org> --- I don't have access to a Linux box with clang, so this is only tested on MacOSX clang, but I believe it to be both required and correct for all clang platforms. include/qemu/atomic.h | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-)