c11/threads: Assert that mtx is non-NULL and check return values.

Passing NULL to C11 threads functions isn't safe, so there's no need for
our implementation to handle it. Cuts about 1k of .text.

   text     data      bss      dec      hex  filename
5009514   198440    26328  5234282   4fde6a  i965_dri.so before
5008346   198440    26328  5233114   4fd9da  i965_dri.so after

Reviewed-by: Timothy Arceri <t_arceri@yahoo.com.au>
Reviewed-by: Brian Paul <brianp@vmware.com>

include/c11/threads_posix.h

@@ -102,9 +102,8 @@ call_once(once_flag *flag, void (*func)(void))
 static inline int
 cnd_broadcast(cnd_t *cond)
 {
-    if (!cond) return thrd_error;
-    pthread_cond_broadcast(cond);
-    return thrd_success;
+    assert(cond != NULL);
+    return (pthread_cond_broadcast(cond) == 0) ? thrd_success : thrd_error;
 }
 
 // 7.25.3.2
@@ -119,18 +118,16 @@ cnd_destroy(cnd_t *cond)
 static inline int
 cnd_init(cnd_t *cond)
 {
-    if (!cond) return thrd_error;
-    pthread_cond_init(cond, NULL);
-    return thrd_success;
+    assert(cond != NULL);
+    return (pthread_cond_init(cond, NULL) == 0) ? thrd_success : thrd_error;
 }
 
 // 7.25.3.4
 static inline int
 cnd_signal(cnd_t *cond)
 {
-    if (!cond) return thrd_error;
-    pthread_cond_signal(cond);
-    return thrd_success;
+    assert(cond != NULL);
+    return (pthread_cond_signal(cond) == 0) ? thrd_success : thrd_error;
 }
 
 // 7.25.3.5
@@ -139,7 +136,8 @@ cnd_timedwait(cnd_t *cond, mtx_t *mtx, const xtime *xt)
 {
     struct timespec abs_time;
     int rt;
-    if (!cond || !mtx || !xt) return thrd_error;
+    assert(mtx != NULL);
+    assert(cond != NULL);
     rt = pthread_cond_timedwait(cond, mtx, &abs_time);
     if (rt == ETIMEDOUT)
         return thrd_busy;
@@ -150,9 +148,9 @@ cnd_timedwait(cnd_t *cond, mtx_t *mtx, const xtime *xt)
 static inline int
 cnd_wait(cnd_t *cond, mtx_t *mtx)
 {
-    if (!cond || !mtx) return thrd_error;
-    pthread_cond_wait(cond, mtx);
-    return thrd_success;
+    assert(mtx != NULL);
+    assert(cond != NULL);
+    return (pthread_cond_wait(cond, mtx) == 0) ? thrd_success : thrd_error;
 }
 
 
@@ -161,7 +159,7 @@ cnd_wait(cnd_t *cond, mtx_t *mtx)
 static inline void
 mtx_destroy(mtx_t *mtx)
 {
-    assert(mtx);
+    assert(mtx != NULL);
     pthread_mutex_destroy(mtx);
 }
 
@@ -170,7 +168,7 @@ static inline int
 mtx_init(mtx_t *mtx, int type)
 {
     pthread_mutexattr_t attr;
-    if (!mtx) return thrd_error;
+    assert(mtx != NULL);
     if (type != mtx_plain && type != mtx_timed && type != mtx_try
       && type != (mtx_plain|mtx_recursive)
       && type != (mtx_timed|mtx_recursive)
@@ -188,9 +186,8 @@ mtx_init(mtx_t *mtx, int type)
 static inline int
 mtx_lock(mtx_t *mtx)
 {
-    if (!mtx) return thrd_error;
-    pthread_mutex_lock(mtx);
-    return thrd_success;
+    assert(mtx != NULL);
+    return (pthread_mutex_lock(mtx) == 0) ? thrd_success : thrd_error;
 }
 
 static inline int
@@ -203,7 +200,9 @@ thrd_yield(void);
 static inline int
 mtx_timedlock(mtx_t *mtx, const xtime *xt)
 {
-    if (!mtx || !xt) return thrd_error;
+    assert(mtx != NULL);
+    assert(xt != NULL);
+
     {
 #ifdef EMULATED_THREADS_USE_NATIVE_TIMEDLOCK
     struct timespec ts;
@@ -233,7 +232,7 @@ mtx_timedlock(mtx_t *mtx, const xtime *xt)
 static inline int
 mtx_trylock(mtx_t *mtx)
 {
-    if (!mtx) return thrd_error;
+    assert(mtx != NULL);
     return (pthread_mutex_trylock(mtx) == 0) ? thrd_success : thrd_busy;
 }
 
@@ -241,9 +240,8 @@ mtx_trylock(mtx_t *mtx)
 static inline int
 mtx_unlock(mtx_t *mtx)
 {
-    if (!mtx) return thrd_error;
-    pthread_mutex_unlock(mtx);
-    return thrd_success;
+    assert(mtx != NULL);
+    return (pthread_mutex_unlock(mtx) == 0) ? thrd_success : thrd_error;
 }
 
 
@@ -253,7 +251,7 @@ static inline int
 thrd_create(thrd_t *thr, thrd_start_t func, void *arg)
 {
     struct impl_thrd_param *pack;
-    if (!thr) return thrd_error;
+    assert(thr != NULL);
     pack = (struct impl_thrd_param *)malloc(sizeof(struct impl_thrd_param));
     if (!pack) return thrd_nomem;
     pack->func = func;
@@ -329,7 +327,7 @@ thrd_yield(void)
 static inline int
 tss_create(tss_t *key, tss_dtor_t dtor)
 {
-    if (!key) return thrd_error;
+    assert(key != NULL);
     return (pthread_key_create(key, dtor) == 0) ? thrd_success : thrd_error;
 }