On 29/08/2016 19:17, Pranith Kumar wrote:
> Use the __atomic_*_n() primitives which take the value as argument. It
> is not necessary to store the value locally before calling the
> primitive, hence saving us a stack store and load.
>
> Signed-off-by: Pranith Kumar <bobby.pr...@gmail.com>
> ---
> include/qemu/atomic.h | 24 ++++++++----------------
> 1 file changed, 8 insertions(+), 16 deletions(-)
>
> v2:
> - convert atomic_load() and atomic_compare_exchange()
>
> diff --git a/include/qemu/atomic.h b/include/qemu/atomic.h
> index 43b0645..9bb991e 100644
> --- a/include/qemu/atomic.h
> +++ b/include/qemu/atomic.h
> @@ -96,15 +96,12 @@
> #define atomic_read(ptr) \
> ({ \
> QEMU_BUILD_BUG_ON(sizeof(*ptr) > sizeof(void *)); \
> - typeof_strip_qual(*ptr) _val; \
> - __atomic_load(ptr, &_val, __ATOMIC_RELAXED); \
> - _val; \
> + __atomic_load_n(ptr, __ATOMIC_RELAXED); \
> })
>
> #define atomic_set(ptr, i) do { \
> QEMU_BUILD_BUG_ON(sizeof(*ptr) > sizeof(void *)); \
> - typeof(*ptr) _val = (i); \
> - __atomic_store(ptr, &_val, __ATOMIC_RELAXED); \
> + __atomic_store_n(ptr, i, __ATOMIC_RELAXED); \
> } while(0)
>
> /* See above: most compilers currently treat consume and acquire the
> @@ -129,8 +126,7 @@
>
> #define atomic_rcu_set(ptr, i) do { \
> QEMU_BUILD_BUG_ON(sizeof(*ptr) > sizeof(void *)); \
> - typeof(*ptr) _val = (i); \
> - __atomic_store(ptr, &_val, __ATOMIC_RELEASE); \
> + __atomic_store_n(ptr, i, __ATOMIC_RELEASE); \
> } while(0)
>
> /* atomic_mb_read/set semantics map Java volatile variables. They are
> @@ -153,9 +149,8 @@
>
> #define atomic_mb_set(ptr, i) do { \
> QEMU_BUILD_BUG_ON(sizeof(*ptr) > sizeof(void *)); \
> - typeof(*ptr) _val = (i); \
> smp_wmb(); \
> - __atomic_store(ptr, &_val, __ATOMIC_RELAXED); \
> + __atomic_store_n(ptr, i, __ATOMIC_RELAXED); \
> smp_mb(); \
> } while(0)
> #else
> @@ -169,8 +164,7 @@
>
> #define atomic_mb_set(ptr, i) do { \
> QEMU_BUILD_BUG_ON(sizeof(*ptr) > sizeof(void *)); \
> - typeof(*ptr) _val = (i); \
> - __atomic_store(ptr, &_val, __ATOMIC_SEQ_CST); \
> + __atomic_store_n(ptr, i, __ATOMIC_SEQ_CST); \
> } while(0)
> #endif
>
> @@ -179,17 +173,15 @@
>
> #define atomic_xchg(ptr, i) ({ \
> QEMU_BUILD_BUG_ON(sizeof(*ptr) > sizeof(void *)); \
> - typeof_strip_qual(*ptr) _new = (i), _old; \
> - __atomic_exchange(ptr, &_new, &_old, __ATOMIC_SEQ_CST); \
> - _old; \
> + __atomic_exchange_n(ptr, i, __ATOMIC_SEQ_CST); \
> })
>
> /* Returns the eventual value, failed or not */
> #define atomic_cmpxchg(ptr, old, new) \
> ({ \
> QEMU_BUILD_BUG_ON(sizeof(*ptr) > sizeof(void *)); \
> - typeof_strip_qual(*ptr) _old = (old), _new = (new); \
> - __atomic_compare_exchange(ptr, &_old, &_new, false, \
> + typeof_strip_qual(*ptr) _old = (old); \
> + __atomic_compare_exchange_n(ptr, &_old, new, false, \
> __ATOMIC_SEQ_CST, __ATOMIC_SEQ_CST); \
> _old; \
> })
>
Thanks, looks good.
Paolo
