Remove support for process-shared pthread_barrier_t (#26863)

Emscripten does not support process-shared primitives. This is a
followup to #26743 where I removed the other usages of this attr.

Author: sbc100

system/lib/libc/musl/src/thread/pthread_barrier_wait.c

@@ -1,9 +1,11 @@
 #ifdef __EMSCRIPTEN__
-#include <math.h>
+#include <assert.h> // For INFINITY
+#include <math.h> // For INFINITY
 #endif
 
 #include "pthread_impl.h"
 
+#ifndef __EMSCRIPTEN__
 static int pshared_barrier_wait(pthread_barrier_t *b)
 {
 	int limit = (b->_b_limit & INT_MAX) + 1;
@@ -52,6 +54,7 @@ static int pshared_barrier_wait(pthread_barrier_t *b)
 
 	return ret;
 }
+#endif
 
 struct instance
 {
@@ -69,8 +72,13 @@ int pthread_barrier_wait(pthread_barrier_t *b)
 	/* Trivial case: count was set at 1 */
 	if (!limit) return PTHREAD_BARRIER_SERIAL_THREAD;
 
+#ifdef __EMSCRIPTEN__
+	/* No support for process-shared barriers under emscripten */
+	assert(limit >= 0);
+#else
 	/* Process-shared barriers require a separate, inefficient wait */
 	if (limit < 0) return pshared_barrier_wait(b);
+#endif
 
 	/* Otherwise we need a lock on the barrier object */
 	while (a_swap(&b->_b_lock, 1))

system/lib/libc/musl/src/thread/pthread_barrierattr_setpshared.c

@@ -3,6 +3,9 @@
 int pthread_barrierattr_setpshared(pthread_barrierattr_t *a, int pshared)
 {
 	if (pshared > 1U) return EINVAL;
+#ifdef __EMSCRIPTEN__
+	if (pshared) return ENOTSUP;
+#endif
 	a->__attr = pshared ? INT_MIN : 0;
 	return 0;
 }

test/codesize/test_codesize_hello_dylink_all.json

@@ -1,7 +1,7 @@
 {
   "a.out.js": 244557,
-  "a.out.nodebug.wasm": 578037,
-  "total": 822594,
+  "a.out.nodebug.wasm": 578129,
+  "total": 822686,
   "sent": [
     "IMG_Init",
     "IMG_Load",
@@ -2855,7 +2855,10 @@
     "pthread_barrier_destroy",
     "pthread_barrier_init",
     "pthread_barrier_wait",
+    "pthread_barrierattr_destroy",
     "pthread_barrierattr_getpshared",
+    "pthread_barrierattr_init",
+    "pthread_barrierattr_setpshared",
     "pthread_cancel",
     "pthread_cond_broadcast",
     "pthread_cond_destroy",
@@ -4618,9 +4621,10 @@
     "$pthread_attr_setstack",
     "$pthread_attr_setstacksize",
     "$pthread_barrierattr_getpshared",
+    "$pthread_barrierattr_init",
+    "$pthread_barrierattr_setpshared",
     "$pthread_condattr_getclock",
     "$pthread_condattr_getpshared",
-    "$pthread_condattr_init",
     "$pthread_condattr_setclock",
     "$pthread_condattr_setpshared",
     "$pthread_equal",
@@ -4636,7 +4640,6 @@
     "$pthread_mutexattr_setpshared",
     "$pthread_mutexattr_settype",
     "$pthread_rwlockattr_init",
-    "$pthread_rwlockattr_setpshared",
     "$pthread_setspecific",
     "$pthread_sigmask",
     "$pthread_spin_init",

test/test_posixtest.py

@@ -71,6 +71,7 @@ def get_tests():
 
 unsupported = {
   'test_pthread_cond_init_4_2': 'PTHREAD_PROCESS_SHARED not supported',
+  'test_pthread_barrierattr_setpshared_1_1': 'PTHREAD_PROCESS_SHARED not supported',
   'test_pthread_condattr_getpshared_1_2': 'PTHREAD_PROCESS_SHARED not supported',
   'test_pthread_mutexattr_setpshared_1_1': 'PTHREAD_PROCESS_SHARED not supported',
   'test_pthread_rwlockattr_setpshared_1_1': 'PTHREAD_PROCESS_SHARED not supported',

tools/system_libs.py

@@ -1263,6 +1263,9 @@ def get_files(self):
             'pthread_attr_setscope.c',
             'pthread_attr_setstack.c',
             'pthread_attr_setstacksize.c',
+            'pthread_barrierattr_destroy.c',
+            'pthread_barrierattr_init.c',
+            'pthread_barrierattr_setpshared.c',
             'pthread_condattr_destroy.c',
             'pthread_condattr_init.c',
             'pthread_condattr_setpshared.c',