Use a relaxed memory ordering in dav1d_ref_inc()

Increasing a reference counter only requires atomicity, but not
ordering or synchronization.

3 files changed, 3 insertions, 1 deletions

diff --git a/include/compat/gcc/stdatomic.h b/include/compat/gcc/stdatomic.h
index 26e97d8..da38c52 100644
--- a/include/compat/gcc/stdatomic.h
+++ b/include/compat/gcc/stdatomic.h
@@ -40,6 +40,7 @@ typedef unsigned int atomic_uint;
 #define atomic_load(p_a)              __atomic_load_n(p_a, __ATOMIC_SEQ_CST)
 #define atomic_load_explicit(p_a, mo) __atomic_load_n(p_a, mo)
 #define atomic_fetch_add(p_a, inc)    __atomic_fetch_add(p_a, inc, __ATOMIC_SEQ_CST)
+#define atomic_fetch_add_explicit(p_a, inc, mo) __atomic_fetch_add(p_a, inc, mo)
 #define atomic_fetch_sub(p_a, dec)    __atomic_fetch_sub(p_a, dec, __ATOMIC_SEQ_CST)
 #define atomic_exchange(p_a, v)       __atomic_exchange_n(p_a, v, __ATOMIC_SEQ_CST)
 #define atomic_fetch_or(p_a, v)       __atomic_fetch_or(p_a, v, __ATOMIC_SEQ_CST)
diff --git a/include/compat/msvc/stdatomic.h b/include/compat/msvc/stdatomic.h
index 4154da0..cd04a38 100644
--- a/include/compat/msvc/stdatomic.h
+++ b/include/compat/msvc/stdatomic.h
@@ -62,6 +62,7 @@ typedef enum {
 #define atomic_fetch_add(p_a, inc)    InterlockedExchangeAdd(p_a, inc)
 #define atomic_fetch_sub(p_a, dec)    InterlockedExchangeAdd(p_a, -(dec))
 #define atomic_fetch_or(p_a, v)       InterlockedOr(p_a, v)
+#define atomic_fetch_add_explicit(p_a, inc, mo) atomic_fetch_add(p_a, inc)
 
 #endif /* ! stdatomic.h */
 
diff --git a/src/ref.h b/src/ref.h
index f6e3028..ec070a0 100644
--- a/src/ref.h
+++ b/src/ref.h
@@ -54,7 +54,7 @@ void dav1d_ref_dec(Dav1dRef **ref);
 int dav1d_ref_is_writable(Dav1dRef *ref);
 
 static inline void dav1d_ref_inc(Dav1dRef *const ref) {
-    atomic_fetch_add(&ref->ref_cnt, 1);
+    atomic_fetch_add_explicit(&ref->ref_cnt, 1, memory_order_relaxed);
 }
 
 #endif /* DAV1D_SRC_REF_H */