Remove unneeded code from library_pthread.js. NFC (#17017)

The `runWithoutMainThreadQueuedCalls` helper had exactly one callsite,
and a little refactoring makes this unnecessary.

Author: sbc100

emcc.py

@@ -1492,7 +1492,6 @@ def setup_pthreads(target):
   settings.REQUIRED_EXPORTS += [
     'emscripten_dispatch_to_thread_',
     '_emscripten_thread_free_data',
-    '_emscripten_allow_main_runtime_queued_calls',
     'emscripten_main_browser_thread_id',
     'emscripten_main_thread_process_queued_calls',
     'emscripten_run_in_main_runtime_thread_js',

src/library_pthread.js

@@ -183,41 +183,22 @@ var LibraryPThread = {
       // some operations that leave the worker queue in an invalid state until
       // we are completely done (it would be bad if free() ends up calling a
       // queued pthread_create which looks at the global data structures we are
-      // modifying).
-      PThread.runWithoutMainThreadQueuedCalls(function() {
-        delete PThread.pthreads[worker.pthread.threadInfoStruct];
-        // Note: worker is intentionally not terminated so the pool can
-        // dynamically grow.
-        PThread.unusedWorkers.push(worker);
-        PThread.runningWorkers.splice(PThread.runningWorkers.indexOf(worker), 1);
-        // Not a running Worker anymore
-        __emscripten_thread_free_data(worker.pthread.threadInfoStruct);
-        // Detach the worker from the pthread object, and return it to the
-        // worker pool as an unused worker.
-        worker.pthread = undefined;
-      });
-    },
-    // Runs a function with processing of queued calls to the main thread
-    // disabled. This is useful to avoid something like free() ending up waiting
-    // for a lock, then running processing events, and those events can end up
-    // doing things that interfere with what we were doing before (for example,
-    // if we are tearing down a thread, calling free to erase its data could
-    // end up calling a proxied pthread_create, which gets a free worker, and
-    // can interfere).
-    // This is only safe to call if we do not need queued calls to run. That is
-    // the case when doing something like free(), which just needs the malloc
-    // lock to be released.
-    runWithoutMainThreadQueuedCalls: function(func) {
-#if ASSERTIONS
-      assert(PThread.mainRuntimeThread, 'runWithoutMainThreadQueuedCalls must be done on the main runtime thread');
-      assert(__emscripten_allow_main_runtime_queued_calls);
-#endif
-      HEAP32[__emscripten_allow_main_runtime_queued_calls >> 2] = 0;
-      try {
-        func();
-      } finally {
-        HEAP32[__emscripten_allow_main_runtime_queued_calls >> 2] = 1;
-      }
+      // modifying). To achieve that, defer the free() til the very end, when
+      // we are all done.
+      var pthread_ptr = worker.pthread.threadInfoStruct;
+      delete PThread.pthreads[pthread_ptr];
+      // Note: worker is intentionally not terminated so the pool can
+      // dynamically grow.
+      PThread.unusedWorkers.push(worker);
+      PThread.runningWorkers.splice(PThread.runningWorkers.indexOf(worker), 1);
+      // Not a running Worker anymore
+      // Detach the worker from the pthread object, and return it to the
+      // worker pool as an unused worker.
+      worker.pthread = undefined;
+
+      // Finally, free the underlying (and now-unused) pthread structure in
+      // linear memory.
+      __emscripten_thread_free_data(pthread_ptr);
     },
     receiveObjectTransfer: function(data) {
 #if OFFSCREENCANVAS_SUPPORT

system/lib/pthread/library_pthread.c

@@ -496,15 +496,8 @@ void emscripten_current_thread_process_queued_calls() {
   emscripten_proxy_execute_queue(emscripten_proxy_get_system_queue());
 }
 
-// At times when we disallow the main thread to process queued calls, this will
-// be set to 0.
-int _emscripten_allow_main_runtime_queued_calls = 1;
-
 void emscripten_main_thread_process_queued_calls() {
   assert(emscripten_is_main_runtime_thread());
-  if (!_emscripten_allow_main_runtime_queued_calls)
-    return;
-
   emscripten_current_thread_process_queued_calls();
 }
 

tests/other/metadce/test_metadce_minimal_pthreads.funcs

@@ -36,9 +36,9 @@ $dlmemalign
 $do_dispatch_to_thread
 $em_queued_call_malloc
 $emscripten_async_run_in_main_thread
+$emscripten_current_thread_process_queued_calls
 $emscripten_futex_wait
 $emscripten_futex_wake
-$emscripten_main_thread_process_queued_calls
 $emscripten_proxy_main
 $emscripten_run_in_main_runtime_thread_js
 $emscripten_stack_set_limits

tests/other/metadce/test_metadce_minimal_pthreads.jssize

@@ -1 +1 @@
-13257
+13129

tests/other/metadce/test_metadce_minimal_pthreads.size

@@ -1 +1 @@
-18717
+18700