[Qemu-devel] [PATCH 2/3] atomics: Use __atomic_*_n() variant primitives

[Pranith Kumar]

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 <address@hidden>
---
 include/qemu/atomic.h | 16 +++++-----------
 1 file changed, 5 insertions(+), 11 deletions(-)

diff --git a/include/qemu/atomic.h b/include/qemu/atomic.h
index d313e6b..fc2309f 100644
--- a/include/qemu/atomic.h
+++ b/include/qemu/atomic.h
@@ -103,8 +103,7 @@
 
 #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 +128,7 @@
 
 #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 +151,8 @@
 
 #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 +166,7 @@
 
 #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
 
@@ -179,9 +175,7 @@
 
 #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 */
-- 
2.9.3