atomic: remove __atomic builtin usage

Using these was a temporary solution while some compilers implemented
the underlying atomic mechanisms, but not the C11 language parts (or
that's what I guess). Not really useful for us anymore. Also, there is
the slight risk of having subtly incorrect semantics by using
potentially changing compiler internals and such.

3 files changed, 10 insertions, 41 deletions

diff --git a/osdep/atomic.h b/osdep/atomic.h
index 50f4f403da..1d3e158afa 100644
--- a/osdep/atomic.h
+++ b/osdep/atomic.h
@@ -27,15 +27,14 @@
 #else
 
 // Emulate the parts of C11 stdatomic.h needed by mpv.
-// Still relies on gcc/clang atomic builtins.
 
-typedef struct { volatile unsigned long v;      } atomic_ulong;
-typedef struct { volatile int v;                } atomic_int;
-typedef struct { volatile unsigned int v;       } atomic_uint;
-typedef struct { volatile _Bool v;              } atomic_bool;
-typedef struct { volatile long long v;          } atomic_llong;
-typedef struct { volatile uint_least32_t v;     } atomic_uint_least32_t;
-typedef struct { volatile unsigned long long v; } atomic_ullong;
+typedef struct { unsigned long v;      } atomic_ulong;
+typedef struct { int v;                } atomic_int;
+typedef struct { unsigned int v;       } atomic_uint;
+typedef struct { _Bool v;              } atomic_bool;
+typedef struct { long long v;          } atomic_llong;
+typedef struct { uint_least32_t v;     } atomic_uint_least32_t;
+typedef struct { unsigned long long v; } atomic_ullong;
 
 #define ATOMIC_VAR_INIT(x) \
     {.v = (x)}
@@ -45,24 +44,6 @@ typedef struct { volatile unsigned long long v; } atomic_ullong;
 
 #define atomic_load_explicit(p, e) atomic_load(p)
 
-#if HAVE_ATOMIC_BUILTINS
-
-#define atomic_load(p) \
-    __atomic_load_n(&(p)->v, __ATOMIC_SEQ_CST)
-#define atomic_store(p, val) \
-    __atomic_store_n(&(p)->v, val, __ATOMIC_SEQ_CST)
-#define atomic_fetch_add(a, b) \
-    __atomic_fetch_add(&(a)->v, b, __ATOMIC_SEQ_CST)
-#define atomic_fetch_and(a, b) \
-    __atomic_fetch_and(&(a)->v, b, __ATOMIC_SEQ_CST)
-#define atomic_fetch_or(a, b) \
-    __atomic_fetch_or(&(a)->v, b, __ATOMIC_SEQ_CST)
-#define atomic_compare_exchange_strong(a, b, c) \
-    __atomic_compare_exchange_n(&(a)->v, b, c, 0, __ATOMIC_SEQ_CST, \
-    __ATOMIC_SEQ_CST)
-
-#elif defined(__GNUC__)
-
 #include <pthread.h>
 
 extern pthread_mutex_t mp_atomic_mutex;
@@ -104,10 +85,6 @@ extern pthread_mutex_t mp_atomic_mutex;
        pthread_mutex_unlock(&mp_atomic_mutex);          \
        res; })
 
-#else
-# error "this should have been a configuration error, report a bug please"
-#endif /* no atomics */
-
 #endif /* else HAVE_STDATOMIC */
 
 #endif
diff --git a/player/main.c b/player/main.c
index 87ec1ab70b..3f5e5abe59 100644
--- a/player/main.c
+++ b/player/main.c
@@ -74,7 +74,7 @@ static const char def_config[] =
 #define FULLCONFIG "(missing)\n"
 #endif
 
-#if !(HAVE_STDATOMIC || HAVE_ATOMIC_BUILTINS || HAVE_SYNC_BUILTINS)
+#if !HAVE_STDATOMIC
 pthread_mutex_t mp_atomic_mutex = PTHREAD_MUTEX_INITIALIZER;
 #endif
 
diff --git a/wscript b/wscript
index e660ff7003..aefa6dd82b 100644
--- a/wscript
+++ b/wscript
@@ -171,19 +171,11 @@ main_dependencies = [
                 'atomic_int_least64_t test = ATOMIC_VAR_INIT(123);'
                 'atomic_fetch_add(&test, 1)'))
     }, {
-        'name': 'atomic-builtins',
-        'desc': 'compiler support for __atomic built-ins',
-        'func': check_libs(['atomic'],
-            check_statement('stdint.h',
-                'int64_t test = 0;'
-                'test = __atomic_add_fetch(&test, 1, __ATOMIC_SEQ_CST)')),
-        'deps_neg': [ 'stdatomic' ],
-    }, {
         'name': 'atomics',
-        'desc': 'stdatomic.h support or emulation',
+        'desc': 'stdatomic.h support or slow emulation',
         'func': check_true,
         'req': True,
-        'deps_any': ['stdatomic', 'atomic-builtins', 'gnuc'],
+        'deps_any': ['stdatomic', 'gnuc'],
     }, {
         'name': 'c11-tls',
         'desc': 'C11 TLS support',