Work around broken atomics in tinycc (#669)

quickjs.c

@@ -62,7 +62,10 @@
 #define NO_TM_GMTOFF
 #endif
 
-#if !defined(EMSCRIPTEN) && !defined(__wasi__) && !__STDC_NO_ATOMICS__
+// atomic_store etc. are completely busted in recent versions of tcc;
+// somehow the compiler forgets to load |ptr| into %rdi when calling
+// the __atomic_*() helpers in its lib/stdatomic.c and lib/atomic.S
+#if !defined(__TINYC__) && !defined(EMSCRIPTEN) && !defined(__wasi__) && !__STDC_NO_ATOMICS__
 #include "quickjs-c-atomics.h"
 #define CONFIG_ATOMICS
 #endif

run-test262.c

@@ -50,6 +50,14 @@ typedef pthread_t js_thread_t;
 
 #define CMD_NAME "run-test262"
 
+// not quite correct because in theory someone could compile quickjs.c
+// with a different compiler but in practice no one does that, right?
+#ifdef __TINYC__
+#define CC_IS_TCC 1
+#else
+#define CC_IS_TCC 0
+#endif
+
 typedef struct {
     js_mutex_t agent_mutex;
     js_cond_t agent_cond;
@@ -1219,7 +1227,7 @@ void load_config(const char *filename, const char *ignore)
             namelist_add(&exclude_list, base_name, p);
             break;
         case SECTION_FEATURES:
-            if (!q || str_equal(q, "yes"))
+            if (!q || str_equal(q, "yes") || (!CC_IS_TCC && str_equal(q, "!tcc")))
                 str_append(&harness_features, " ", p);
             else
                 str_append(&harness_skip_features, " ", p);

test262.conf

@@ -62,7 +62,8 @@ arraybuffer-transfer
 arrow-function
 async-functions
 async-iteration
-Atomics
+# atomics are broken in recent versions of tcc
+Atomics=!tcc
 Atomics.pause=skip
 Atomics.waitAsync=skip
 BigInt