Add support for Wasm Workers + dlmalloc

Author: juj

emcc.py

@@ -2136,10 +2136,6 @@ def phase_linker_setup(options, state, newargs, user_settings):
       settings.WASM_WORKER_FILE = unsuffixed(os.path.basename(target)) + '.ww.js'
     settings.JS_LIBRARIES.append((0, shared.path_from_root('src', 'library_wasm_worker.js')))
 
-    if 'MALLOC' in user_settings and 'dlmalloc' in user_settings['MALLOC']:
-      exit_with_error('dlmalloc does not work with Wasm Workers! Please remove -sMALLOC=dlmalloc')
-    default_setting(user_settings, 'MALLOC', 'emmalloc')
-
   if settings.FORCE_FILESYSTEM and not settings.MINIMAL_RUNTIME:
     # when the filesystem is forced, we export by default methods that filesystem usage
     # may need, including filesystem usage from standalone file packager output (i.e.

system/lib/dlmalloc.c

@@ -19,7 +19,10 @@
 #include <emscripten/trace.h>
 
 /* Make malloc() and free() threadsafe by securing the memory allocations with pthread mutexes. */
-#if __EMSCRIPTEN_PTHREADS__
+#ifdef __EMSCRIPTEN_WASM_WORKERS__
+#define USE_LOCKS 1
+#define USE_SPIN_LOCKS 1 // Wasm Workers does not have the pthread API, so use spinwaiting
+#elif defined(__EMSCRIPTEN_PTHREADS__)
 #define USE_LOCKS 1
 #define USE_SPIN_LOCKS 0 // Ensure we use pthread_mutex_t.
 #endif

tests/test_browser.py

@@ -5290,8 +5290,12 @@ def test_wasm_worker_semaphore_try_acquire(self):
 
   # Tests that operating malloc from Wasm Workers is thread-safe.
   @also_with_minimal_runtime
-  def test_wasm_worker_thread_safe_malloc(self):
-    self.btest(test_file('wasm_worker/thread_safe_malloc.cpp'), expected='0', args=['-sWASM_WORKERS', '-DEMMALLOC'])
+  def test_wasm_worker_thread_safe_emmalloc(self):
+    self.btest(test_file('wasm_worker/thread_safe_malloc.cpp'), expected='0', args=['-sWASM_WORKERS', '-DEMMALLOC', '-sMALLOC=emmalloc-debug'])
+
+  @also_with_minimal_runtime
+  def test_wasm_worker_thread_safe_dlmalloc(self):
+    self.btest(test_file('wasm_worker/thread_safe_malloc.cpp'), expected='0', args=['-sWASM_WORKERS', '-sMALLOC=dlmalloc'])
 
   @no_firefox('no 4GB support yet')
   @require_v8

tests/test_other.py

@@ -11847,15 +11847,6 @@ def test_shared_memory_preprocessor_flags(self):
   def test_wasm_worker_preprocessor_flags(self):
     self.run_process([EMCC, '-c', test_file('wasm_worker/wasm_worker_preprocessor_flags.c'), '-sWASM_WORKERS'])
 
-  # Tests that Wasm Workers are properly detected not to (at least for now) work with dlmalloc
-  @also_with_minimal_runtime
-  def test_wasm_worker_dlmalloc_not_supported(self):
-    # Using dlmalloc should produce a build error
-    stderr = self.run_process([EMCC, test_file('hello_world.c'), '-sWASM_WORKERS', '-sMALLOC=dlmalloc'], stderr=PIPE, check=False).stderr
-    self.assertContained('dlmalloc does not work with Wasm Workers! Please remove -sMALLOC=dlmalloc', stderr)
-    # Using emmalloc should compile ok
-    self.run_process([EMCC, test_file('hello_world.c'), '-sWASM_WORKERS', '-sMALLOC=emmalloc'])
-
   def test_debug_opt_warning(self):
     err = self.expect_fail([EMCC, test_file('hello_world.c'), '-O2', '-g', '-Werror'])
     self.assertContained('error: running limited binaryen optimizations because DWARF info requested (or indirectly required) [-Wlimited-postlink-optimizations]', err)