Add testing for compiler built-in atomic_is_lock_free API. NFC (#26646)

Author: sbc100

test/pthread/is_lock_free.c

@@ -1,9 +1,15 @@
-#include <emscripten/atomic.h>
-#include <pthread.h>
 #include <assert.h>
+#include <pthread.h>
+#include <stdatomic.h>
 #include <stdio.h>
 
-// Test emscripten_atomics_is_lock_free() functions
+#include <emscripten/atomic.h>
+
+// Test the various `is_lock_free` functions:
+//
+// - emscripten_atomics_is_lock_free
+// - __atomic_always_lock_free
+// - atomic_is_lock_free
 
 void test() {
   assert(emscripten_atomics_is_lock_free(1));
@@ -12,7 +18,30 @@ void test() {
   // Chrome is buggy, see
   // https://bugs.chromium.org/p/chromium/issues/detail?id=1167449
   //assert(emscripten_atomics_is_lock_free(8));
+  assert(!emscripten_atomics_is_lock_free(16));
   assert(!emscripten_atomics_is_lock_free(31));
+
+  // Test compiler buildin __atomic_always_lock_free version
+  assert(__atomic_always_lock_free(1, 0));
+  assert(__atomic_always_lock_free(2, 0));
+  assert(__atomic_always_lock_free(4, 0));
+  assert(__atomic_always_lock_free(8, 0));
+  assert(!__atomic_always_lock_free(16, 0));
+  assert(!__atomic_always_lock_free(31, 0));
+
+  // Test C11 atomic_is_lock_free
+  struct { char a[1]; } one;
+  struct { char a[2]; } two;
+  struct { char a[4]; } four;
+  struct { char a[8]; } eight;
+  struct { char a[16]; } sixteen;
+  struct { char a[31]; } thirty_one;
+  assert(atomic_is_lock_free(&one));
+  assert(atomic_is_lock_free(&two));
+  assert(atomic_is_lock_free(&four));
+  assert(atomic_is_lock_free(&eight));
+  assert(!atomic_is_lock_free(&sixteen));
+  assert(!atomic_is_lock_free(&thirty_one));
 }
 
 void* thread_main(void* arg) {

test/wasm_worker/hardware_concurrency_is_lock_free.c

@@ -1,6 +1,7 @@
 #include <emscripten.h>
 #include <emscripten/wasm_worker.h>
 #include <assert.h>
+#include <stdatomic.h>
 
 // Test emscripten_navigator_hardware_concurrency() and emscripten_atomics_is_lock_free() functions
 
@@ -13,7 +14,30 @@ void test() {
   // Chrome is buggy, see
   // https://bugs.chromium.org/p/chromium/issues/detail?id=1167449
   //assert(emscripten_atomics_is_lock_free(8));
+  assert(!emscripten_atomics_is_lock_free(16));
   assert(!emscripten_atomics_is_lock_free(31));
+
+  // Test compiler buildin __atomic_always_lock_free version
+  assert(__atomic_always_lock_free(1, 0));
+  assert(__atomic_always_lock_free(2, 0));
+  assert(__atomic_always_lock_free(4, 0));
+  assert(__atomic_always_lock_free(8, 0));
+  assert(!__atomic_always_lock_free(16, 0));
+  assert(!__atomic_always_lock_free(31, 0));
+
+  // Test C11 atomic_is_lock_free
+  struct { char a[1]; } one;
+  struct { char a[2]; } two;
+  struct { char a[4]; } four;
+  struct { char a[8]; } eight;
+  struct { char a[16]; } sixteen;
+  struct { char a[31]; } thirty_one;
+  assert(atomic_is_lock_free(&one));
+  assert(atomic_is_lock_free(&two));
+  assert(atomic_is_lock_free(&four));
+  assert(atomic_is_lock_free(&eight));
+  assert(!atomic_is_lock_free(&sixteen));
+  assert(!atomic_is_lock_free(&thirty_one));
 }
 
 void worker_main() {