Fix references to _emscripten_main_thread_futex in comments. NFC (#18384)

Author: sbc100

system/lib/pthread/emscripten_futex_wait.c

@@ -24,16 +24,16 @@ static int futex_wait_busy(volatile void *addr, uint32_t val, double timeout) {
 
   // Register globally which address the main thread is simulating to be
   // waiting on. When zero, the main thread is not waiting on anything, and on
-  // nonzero, the contents of the address pointed by __emscripten_main_thread_futex
+  // nonzero, the contents of the address pointed by _emscripten_main_thread_futex
   // tell which address the main thread is simulating its wait on.
   // We need to be careful of recursion here: If we wait on a futex, and
   // then call _emscripten_yield() below, that will call code that takes the
   // proxying mutex - which can once more reach this code in a nested call. To
   // avoid interference between the two (there is just a single
-  // __emscripten_main_thread_futex at a time), unmark ourselves before calling
+  // _emscripten_main_thread_futex at a time), unmark ourselves before calling
   // the potentially-recursive call. See below for how we handle the case of our
   // futex being notified during the time in between when we are not set as the
-  // value of __emscripten_main_thread_futex.
+  // value of _emscripten_main_thread_futex.
   void* last_addr = a_cas_p(&_emscripten_main_thread_futex, 0, (void*)addr);
   // We must not have already been waiting.
   assert(last_addr == 0);
@@ -68,20 +68,20 @@ static int futex_wait_busy(volatile void *addr, uint32_t val, double timeout) {
     //
     //  * wait on futex A
     //  * recurse into _emscripten_yield(),
-    //    which waits on futex B. that sets the __emscripten_main_thread_futex address to
+    //    which waits on futex B. that sets the _emscripten_main_thread_futex address to
     //    futex B, and there is no longer any mention of futex A.
-    //  * a worker is done with futex A. it checks __emscripten_main_thread_futex but does
+    //  * a worker is done with futex A. it checks _emscripten_main_thread_futex but does
     //    not see A, so it does nothing special for the main thread.
     //  * a worker is done with futex B. it flips mainThreadMutex from B
     //    to 0, ending the wait on futex B.
-    //  * we return to the wait on futex A. __emscripten_main_thread_futex is 0, but that
+    //  * we return to the wait on futex A. _emscripten_main_thread_futex is 0, but that
     //    is because of futex B being done - we can't tell from
-    //    __emscripten_main_thread_futex whether A is done or not. therefore, check the
+    //    _emscripten_main_thread_futex whether A is done or not. therefore, check the
     //    memory value of the futex.
     //
     // That case motivates the design here. Given that, checking the memory
     // address is also necessary for other reasons: we unset and re-set our
-    // address in __emscripten_main_thread_futex around calls to
+    // address in _emscripten_main_thread_futex around calls to
     // _emscripten_yield(), and a worker could
     // attempt to wake us up right before/after such times.
     //

system/lib/pthread/emscripten_futex_wake.c

@@ -25,15 +25,15 @@ int emscripten_futex_wake(volatile void *addr, int count) {
     return 0;
   }
 
-  // See if main thread is waiting on this address? If so, wake it up by resetting its wake location to zero.
-  // Note that this is not a fair procedure, since we always wake main thread first before any workers, so
+  // See if main thread is waiting on this address? If so, wake it up by
+  // resetting its wake location to zero.  Note that this is not a fair
+  // procedure, since we always wake main thread first before any workers, so
   // this scheme does not adhere to real queue-based waiting.
   int main_thread_woken = 0;
   if (a_cas_p(&_emscripten_main_thread_futex, (void*)addr, 0) == addr) {
     // The main browser thread must never try to wake itself up!
     assert(!emscripten_is_main_browser_thread());
-    if (count != INT_MAX)
-    {
+    if (count != INT_MAX) {
       --count;
       main_thread_woken = 1;
       if (count <= 0) {