Improve threading support further

third_party/chibicc/test/spinlock_test.c

@@ -15,12 +15,66 @@
 
 #define SPUNLOCK(lock) __sync_lock_release(lock)
 
+////////////////////////////////////////////////////////////////////////////////
+
+#define SPINLOCK2(lock)                                           \
+  do {                                                            \
+    for (;;) {                                                    \
+      typeof(*(lock)) x;                                          \
+      __atomic_load(lock, &x, __ATOMIC_RELAXED);                  \
+      if (!x && !__atomic_test_and_set(lock, __ATOMIC_SEQ_CST)) { \
+        break;                                                    \
+      } else {                                                    \
+        __builtin_ia32_pause();                                   \
+      }                                                           \
+    }                                                             \
+  } while (0)
+
+#define SPUNLOCK2(lock) __sync_lock_release(lock)
+
+////////////////////////////////////////////////////////////////////////////////
+
 _Alignas(64) char lock;
 
 main() {
+  int x, y;
+
   ASSERT(0, lock);
   SPINLOCK(&lock);
   ASSERT(1, lock);
   SPUNLOCK(&lock);
   ASSERT(0, lock);
+
+  ASSERT(0, lock);
+  SPINLOCK2(&lock);
+  ASSERT(1, lock);
+  SPUNLOCK2(&lock);
+  ASSERT(0, lock);
+
+  x = 0;
+  y = 7;
+  ASSERT(0, x);
+  ASSERT(7, y);
+  __atomic_store(&x, &y, __ATOMIC_RELAXED);
+  ASSERT(7, x);
+  ASSERT(7, y);
+
+  x = 0;
+  y = 7;
+  ASSERT(0, x);
+  ASSERT(7, y);
+  __atomic_store(&x, &y, __ATOMIC_SEQ_CST);
+  ASSERT(7, x);
+  ASSERT(7, y);
+
+  x = 5;
+  y = __atomic_test_and_set(&x, __ATOMIC_SEQ_CST);
+  ASSERT(1, x);
+  ASSERT(5, y);
+
+  x = 5;
+  __atomic_clear(&x, __ATOMIC_SEQ_CST);
+  ASSERT(0, x);
+
+  //
 }