From 2c00956fd1c7219e82b999af15deb1970db3c379 Mon Sep 17 00:00:00 2001
From: Sam Clegg <sbc@chromium.org>
Date: Tue, 7 Mar 2023 15:01:06 -0800
Subject: [PATCH] Mark USE_PTHREADS as legacy. NFC

Create a new internal setting called just `PTHREADS` and use that
everywhere internally.

This allows the old setting to be marked as legacy, but still supported
in case existing use JS library code uses it.
---
 ChangeLog.md                |   3 +
 embuilder.py                |  20 +++----
 emcc.py                     |  35 +++++++-----
 emscripten.py               |   4 +-
 src/jsifier.js              |   4 +-
 src/library.js              |  14 ++---
 src/library_browser.js      |   4 +-
 src/library_dylink.js       |  10 ++--
 src/library_fetch.js        |   2 +-
 src/library_html5.js        | 108 ++++++++++++++++++------------------
 src/library_html5_webgl.js  |  18 +++---
 src/library_pipefs.js       |   4 +-
 src/library_pthread.js      |   8 +--
 src/library_pthread_stub.js |   4 +-
 src/library_sockfs.js       |   4 +-
 src/library_syscall.js      |   2 +-
 src/library_wasi.js         |   2 +-
 src/library_wasm_worker.js  |   2 +-
 src/library_webgl.js        |  14 ++---
 src/library_webgpu.js       |   2 +-
 src/library_websocket.js    |   2 +-
 src/modules.js              |   2 +-
 src/parseTools.js           |   8 +--
 src/postamble.js            |   6 +-
 src/postamble_minimal.js    |  16 +++---
 src/preamble.js             |  30 +++++-----
 src/preamble_minimal.js     |   6 +-
 src/proxyWorker.js          |  10 ++--
 src/runtime_debug.js        |   2 +-
 src/runtime_init_memory.js  |   6 +-
 src/settings.js             |   8 +--
 src/settings_internal.js    |   3 +
 src/shell.js                |  14 ++---
 src/shell_minimal.js        |  10 ++--
 test/test_other.py          |   1 +
 tools/deps_info.py          |   4 +-
 tools/feature_matrix.py     |   2 +-
 tools/ports/harfbuzz.py     |   6 +-
 tools/ports/icu.py          |   6 +-
 tools/ports/libpng.py       |   6 +-
 tools/ports/regal.py        |   6 +-
 tools/ports/sdl2.py         |   8 +--
 tools/ports/sqlite3.py      |   6 +-
 tools/settings.py           |   1 +
 tools/system_libs.py        |   2 +-
 45 files changed, 219 insertions(+), 216 deletions(-)

diff --git a/ChangeLog.md b/ChangeLog.md
index 8d696a22a96d6..c97d1efc2d169 100644
--- a/ChangeLog.md
+++ b/ChangeLog.md
@@ -20,6 +20,9 @@ See docs/process.md for more on how version tagging works.
 
 3.1.33 (in development)
 -----------------------
+- The prefered way to enable pthread is now to just the the standard `-pthread`
+  flag.  The `-sUSE_PTHREADS` setting still works but is marked a legacy and
+  will generte a warning in `-sSTRICT` mode.
 - Initial support for C++20 modules.  We have added a very simple test in form
   of `other.test_cpp_module`. (#)
 - Removed `sys/sysctl.h` compatibility header.  We don't implement the function
diff --git a/embuilder.py b/embuilder.py
index 7e2178ffad55d..488dd9ff50dc9 100755
--- a/embuilder.py
+++ b/embuilder.py
@@ -122,28 +122,22 @@ def get_help():
 
 @contextmanager
 def get_port_variant(name):
+  args = []
   if name in ports.port_variants:
-    name, extra_settings = ports.port_variants[name]
-    old_settings = settings.dict().copy()
-    for key, value in extra_settings.items():
-      setattr(settings, key, value)
-  else:
-    old_settings = None
+    name, args = ports.port_variants[name]
 
-  yield name
+  yield name, args
 
-  if old_settings:
-    settings.dict().update(old_settings)
 
 
 def clear_port(port_name):
-  with get_port_variant(port_name) as port_name:
-    ports.clear_port(port_name, settings)
+  with get_port_variant(port_name) as port_name, args:
+    ports.clear_port(port_name, args)
 
 
 def build_port(port_name):
-  with get_port_variant(port_name) as port_name:
-    ports.build_port(port_name, settings)
+  with get_port_variant(port_name) as port_name, args:
+    ports.build_port(port_name, args)
 
 
 def get_system_tasks():
diff --git a/emcc.py b/emcc.py
index 28cd5249ea651..0f411944f8669 100755
--- a/emcc.py
+++ b/emcc.py
@@ -380,7 +380,7 @@ def setup_environment_settings():
   settings.ENVIRONMENT_MAY_BE_WORKER = \
       not settings.ENVIRONMENT or \
       'worker' in environments or \
-      (settings.ENVIRONMENT_MAY_BE_NODE and settings.USE_PTHREADS)
+      (settings.ENVIRONMENT_MAY_BE_NODE and settings.PTHREADS)
 
   if not settings.ENVIRONMENT_MAY_BE_WORKER and settings.PROXY_TO_WORKER:
     exit_with_error('If you specify --proxy-to-worker and specify a "-sENVIRONMENT=" directive, it must include "worker" as a target! (Try e.g. -sENVIRONMENT=web,worker)')
@@ -1595,11 +1595,14 @@ def phase_setup(options, state, newargs):
   if settings.MAIN_MODULE or settings.SIDE_MODULE:
     settings.RELOCATABLE = 1
 
+  if 'USE_PTHREADS' in user_settings:
+    settings.PTHREADS = settings.USE_PTHREADS
+
   # Pthreads and Wasm Workers require targeting shared Wasm memory (SAB).
-  if settings.USE_PTHREADS or settings.WASM_WORKERS:
+  if settings.PTHREADS or settings.WASM_WORKERS:
     settings.SHARED_MEMORY = 1
 
-  if settings.USE_PTHREADS and '-pthread' not in newargs:
+  if settings.PTHREADS and '-pthread' not in newargs:
     newargs += ['-pthread']
   elif settings.SHARED_MEMORY:
     if '-matomics' not in newargs:
@@ -1751,7 +1754,7 @@ def include_and_export(name):
     if not settings.EXPORT_ES6 and settings.EXPORT_NAME == 'Module':
       exit_with_error('pthreads + MODULARIZE currently require you to set -sEXPORT_NAME=Something (see settings.js) to Something != Module, so that the .worker.js file can work')
 
-    # MODULARIZE+USE_PTHREADS mode requires extra exports out to Module so that worker.js
+    # MODULARIZE+PTHREADS mode requires extra exports out to Module so that worker.js
     # can access them:
 
     # general threading variables:
@@ -2099,7 +2102,7 @@ def phase_linker_setup(options, state, newargs):
       '$mergeLibSymbols',
     ]
 
-  if settings.USE_PTHREADS:
+  if settings.PTHREADS:
     settings.DEFAULT_LIBRARY_FUNCS_TO_INCLUDE += [
       '$registerTLSInit',
     ]
@@ -2210,7 +2213,7 @@ def phase_linker_setup(options, state, newargs):
     # HTML output creates a singleton instance, and it does so without the
     # Promise. However, in Pthreads mode the Promise is used for worker
     # creation.
-    if settings.MINIMAL_RUNTIME and options.oformat == OFormat.HTML and not settings.USE_PTHREADS:
+    if settings.MINIMAL_RUNTIME and options.oformat == OFormat.HTML and not settings.PTHREADS:
       settings.EXPORT_READY_PROMISE = 0
 
   if settings.LEGACY_VM_SUPPORT:
@@ -2327,7 +2330,7 @@ def phase_linker_setup(options, state, newargs):
   if settings.FETCH and final_suffix in EXECUTABLE_ENDINGS:
     state.forced_stdlibs.append('libfetch')
     settings.JS_LIBRARIES.append((0, 'library_fetch.js'))
-    if settings.USE_PTHREADS:
+    if settings.PTHREADS:
       settings.FETCH_WORKER_FILE = unsuffixed_basename(target) + '.fetch.js'
 
   if settings.DEMANGLE_SUPPORT:
@@ -2397,7 +2400,7 @@ def phase_linker_setup(options, state, newargs):
     # overrides that.
     default_setting('ABORTING_MALLOC', 0)
 
-  if settings.USE_PTHREADS:
+  if settings.PTHREADS:
     setup_pthreads(target)
     settings.JS_LIBRARIES.append((0, 'library_pthread.js'))
     if settings.PROXY_TO_PTHREAD:
@@ -2629,7 +2632,7 @@ def check_memory_setting(setting):
     # are based on experimentation with different tests/programs under asan and
     # lsan.
     settings.INITIAL_MEMORY += 50 * 1024 * 1024
-    if settings.USE_PTHREADS:
+    if settings.PTHREADS:
       settings.INITIAL_MEMORY += 50 * 1024 * 1024
 
   if settings.USE_OFFSET_CONVERTER and settings.WASM2JS:
@@ -3175,7 +3178,7 @@ def phase_final_emitting(options, state, target, wasm_target, memfile):
   # write_file(final_js, src)
 
   target_dir = os.path.dirname(os.path.abspath(target))
-  if settings.USE_PTHREADS:
+  if settings.PTHREADS:
     worker_output = os.path.join(target_dir, settings.PTHREAD_WORKER_FILE)
     contents = shared.read_and_preprocess(utils.path_from_root('src/worker.js'), expand_macros=True)
     write_file(worker_output, contents)
@@ -3576,9 +3579,11 @@ def consume_arg_file():
         options.output_eol = '\n'
       else:
         exit_with_error(f'Invalid value "{style}" to --output_eol!')
-    # Record USE_PTHREADS setting because it controls whether --shared-memory is passed to lld
+    # Record PTHREADS setting because it controls whether --shared-memory is passed to lld
     elif arg == '-pthread':
-      settings_changes.append('USE_PTHREADS=1')
+      settings.PTHREADS = 1
+      # Also set the legacy setting name, in case use JS code depends on it.
+      settings.USE_PTHREADS = 1
     elif arg == '-pthreads':
       exit_with_error('unrecognized command-line option ‘-pthreads’; did you mean ‘-pthread’?')
     elif arg in ('-fno-diagnostics-color', '-fdiagnostics-color=never'):
@@ -3706,7 +3711,7 @@ def phase_binaryen(target, options, wasm_target):
     # adds some >>> 0 things, while growth will replace a HEAP8 with a call to
     # a method to get the heap, and that call would not be recognized by the
     # unsigning pass
-    if settings.USE_PTHREADS and settings.ALLOW_MEMORY_GROWTH:
+    if settings.PTHREADS and settings.ALLOW_MEMORY_GROWTH:
       with ToolchainProfiler.profile_block('apply_wasm_memory_growth'):
         final_js = building.apply_wasm_memory_growth(final_js)
 
@@ -3880,7 +3885,7 @@ def modularize():
     'capture_module_function_for_audio_worklet': 'globalThis.AudioWorkletModule = Module;' if settings.AUDIO_WORKLET and settings.MODULARIZE else ''
   }
 
-  if settings.MINIMAL_RUNTIME and not settings.USE_PTHREADS:
+  if settings.MINIMAL_RUNTIME and not settings.PTHREADS:
     # Single threaded MINIMAL_RUNTIME programs do not need access to
     # document.currentScript, so a simple export declaration is enough.
     src = 'var %s=%s' % (settings.EXPORT_NAME, src)
@@ -3888,7 +3893,7 @@ def modularize():
     script_url_node = ''
     # When MODULARIZE this JS may be executed later,
     # after document.currentScript is gone, so we save it.
-    # In EXPORT_ES6 + USE_PTHREADS the 'thread' is actually an ES6 module webworker running in strict mode,
+    # In EXPORT_ES6 + PTHREADS the 'thread' is actually an ES6 module webworker running in strict mode,
     # so doesn't have access to 'document'. In this case use 'import.meta' instead.
     if settings.EXPORT_ES6 and settings.USE_ES6_IMPORT_META:
       script_url = 'import.meta.url'
diff --git a/emscripten.py b/emscripten.py
index f345eb0f89745..7bcf128704451 100644
--- a/emscripten.py
+++ b/emscripten.py
@@ -144,7 +144,7 @@ def update_settings_glue(wasm_file, metadata):
   if settings.ASYNCIFY == 2:
     settings.BINARYEN_FEATURES += ['--enable-reference-types']
 
-  if settings.USE_PTHREADS:
+  if settings.PTHREADS:
     assert '--enable-threads' in settings.BINARYEN_FEATURES
   if settings.MEMORY64:
     assert '--enable-memory64' in settings.BINARYEN_FEATURES
@@ -625,7 +625,7 @@ def add_standard_wasm_imports(send_items_map):
 
   if settings.IMPORTED_MEMORY:
     memory_import = 'wasmMemory'
-    if settings.MODULARIZE and settings.USE_PTHREADS:
+    if settings.MODULARIZE and settings.PTHREADS:
       # Pthreads assign wasmMemory in their worker startup. In MODULARIZE mode, they cannot assign inside the
       # Module scope, so lookup via Module as well.
       memory_import += " || Module['wasmMemory']"
diff --git a/src/jsifier.js b/src/jsifier.js
index 09023bfb6af40..01faabd03da42 100644
--- a/src/jsifier.js
+++ b/src/jsifier.js
@@ -159,7 +159,7 @@ function ${name}(${args}) {
           throw new Error(`Invalid proxyingMode ${symbol}__proxy: '${proxyingMode}' specified!`);
         }
         const sync = proxyingMode === 'sync';
-        if (USE_PTHREADS) {
+        if (PTHREADS) {
           snippet = modifyFunction(snippet, (name, args, body) => `
 function ${name}(${args}) {
 if (ENVIRONMENT_IS_PTHREAD)
@@ -489,7 +489,7 @@ function ${name}(${args}) {
       print(indentify(item.JS || '', 2));
     }
 
-    if (USE_PTHREADS) {
+    if (PTHREADS) {
       print('\n // proxiedFunctionTable specifies the list of functions that can be called either synchronously or asynchronously from other threads in postMessage()d or internally queued events. This way a pthread in a Worker can synchronously access e.g. the DOM on the main thread.');
       print('\nvar proxiedFunctionTable = [' + proxiedFunctionTable.join() + '];\n');
     }
diff --git a/src/library.js b/src/library.js
index d94985330cc7a..91098b9d1de6a 100644
--- a/src/library.js
+++ b/src/library.js
@@ -70,7 +70,7 @@ mergeInto(LibraryManager.library, {
     checkUnflushedContent();
 #endif // ASSERTIONS && !EXIT_RUNTIME
 
-#if USE_PTHREADS
+#if PTHREADS
     if (ENVIRONMENT_IS_PTHREAD) {
       // implict exit can never happen on a pthread
 #if ASSERTIONS
@@ -89,7 +89,7 @@ mergeInto(LibraryManager.library, {
 #if PTHREADS_DEBUG
     err('main thread called exit: keepRuntimeAlive=' + keepRuntimeAlive() + ' (counter=' + runtimeKeepaliveCounter + ')');
 #endif // PTHREADS_DEBUG
-#endif // USE_PTHREADS
+#endif // PTHREADS
 
 #if EXIT_RUNTIME
     if (!keepRuntimeAlive()) {
@@ -2357,7 +2357,7 @@ mergeInto(LibraryManager.library, {
                                "  };\n" +
                                "} else " +
 #endif
-#if USE_PTHREADS && !AUDIO_WORKLET
+#if PTHREADS && !AUDIO_WORKLET
 // Pthreads need their clocks synchronized to the execution of the main thread, so, when using them,
 // make sure to adjust all timings to the respective time origins.
                                "_emscripten_get_now = () => performance.timeOrigin + performance.now();\n",
@@ -2371,7 +2371,7 @@ mergeInto(LibraryManager.library, {
 // AudioWorkletGlobalScope does not have performance.now() (https://github.com/WebAudio/web-audio-api/issues/2527), so if building with
 // Audio Worklets enabled, do a dynamic check for its presence.
                                "if (typeof performance != 'undefined' && performance.now) {\n" +
-#if USE_PTHREADS
+#if PTHREADS
                                "  _emscripten_get_now = () => performance.timeOrigin + performance.now();\n" +
 #else
                                "  _emscripten_get_now = () => performance.now();\n" +
@@ -3044,7 +3044,7 @@ mergeInto(LibraryManager.library, {
   $runMainThreadEmAsm__sig: 'iippi',
   $runMainThreadEmAsm: function(code, sigPtr, argbuf, sync) {
     var args = readEmAsmArgs(sigPtr, argbuf);
-#if USE_PTHREADS
+#if PTHREADS
     if (ENVIRONMENT_IS_PTHREAD) {
       // EM_ASM functions are variadic, receiving the actual arguments as a buffer
       // in memory. the last parameter (argBuf) points to that data. We need to
@@ -3564,7 +3564,7 @@ mergeInto(LibraryManager.library, {
   },
 
   $maybeExit__deps: ['exit', '$handleException',
-#if USE_PTHREADS
+#if PTHREADS
     '_emscripten_thread_exit',
 #endif
   ],
@@ -3582,7 +3582,7 @@ mergeInto(LibraryManager.library, {
       dbg('maybeExit: calling exit() implicitly after user callback completed: ' + EXITSTATUS);
 #endif
       try {
-#if USE_PTHREADS
+#if PTHREADS
         if (ENVIRONMENT_IS_PTHREAD) __emscripten_thread_exit(EXITSTATUS);
         else
 #endif
diff --git a/src/library_browser.js b/src/library_browser.js
index a8160844ded6b..60ce955f6ce9c 100644
--- a/src/library_browser.js
+++ b/src/library_browser.js
@@ -846,7 +846,7 @@ var LibraryBrowser = {
     onload = {{{ makeDynCall('v', 'onload') }}};
     onerror = {{{ makeDynCall('v', 'onerror') }}};
 
-#if USE_PTHREADS
+#if PTHREADS
     if (ENVIRONMENT_IS_PTHREAD) {
       err('emscripten_async_load_script("' + UTF8ToString(url) + '") failed, emscripten_async_load_script is currently not available in pthreads!');
       return onerror ? onerror() : undefined;
@@ -1049,7 +1049,7 @@ var LibraryBrowser = {
       GL.newRenderingFrameStarted();
 #endif
 
-#if USE_PTHREADS && OFFSCREEN_FRAMEBUFFER && GL_SUPPORT_EXPLICIT_SWAP_CONTROL
+#if PTHREADS && OFFSCREEN_FRAMEBUFFER && GL_SUPPORT_EXPLICIT_SWAP_CONTROL
       // If the current GL context is a proxied regular WebGL context, and was initialized with implicit swap mode on the main thread, and we are on the parent thread,
       // perform the swap on behalf of the user.
       if (typeof GL != 'undefined' && GL.currentContext && GL.currentContextIsProxied) {
diff --git a/src/library_dylink.js b/src/library_dylink.js
index 4f9292b74c414..f114fd5fa77ab 100644
--- a/src/library_dylink.js
+++ b/src/library_dylink.js
@@ -719,7 +719,7 @@ var LibraryDylink = {
         }
 #if STACK_OVERFLOW_CHECK >= 2
         if (moduleExports['__set_stack_limits']) {
-#if USE_PTHREADS
+#if PTHREADS
           // When we are on an uninitialized pthread we delay calling
           // __set_stack_limits until $setDylinkStackLimits.
           if (!ENVIRONMENT_IS_PTHREAD || runtimeInitialized)
@@ -762,7 +762,7 @@ var LibraryDylink = {
 #endif
 
         // initialize the module
-#if USE_PTHREADS
+#if PTHREADS
         // Only one thread should call __wasm_call_ctors, but all threads need
         // to call _emscripten_tls_init
         registerTLSInit(moduleExports['_emscripten_tls_init'], instance.exports, metadata)
@@ -788,7 +788,7 @@ var LibraryDylink = {
               __ATINIT__.push(init);
             }
           }
-#if USE_PTHREADS
+#if PTHREADS
         }
 #endif
         return moduleExports;
@@ -826,8 +826,8 @@ var LibraryDylink = {
     return loadModule();
   },
 
-#if STACK_OVERFLOW_CHECK >= 2 && USE_PTHREADS
-  // With USE_PTHREADS we load libraries before we are running a pthread and
+#if STACK_OVERFLOW_CHECK >= 2 && PTHREADS
+  // With PTHREADS we load libraries before we are running a pthread and
   // therefore before we have a stack.  Instead we delay calling
   // `__set_stack_limits` until we start running a thread.  We also need to call
   // this again for each new thread that the runs on a worker (since each thread
diff --git a/src/library_fetch.js b/src/library_fetch.js
index 07b909f5994f0..44492af5a814e 100644
--- a/src/library_fetch.js
+++ b/src/library_fetch.js
@@ -7,7 +7,7 @@
 #include Fetch.js
 
 var LibraryFetch = {
-#if USE_PTHREADS
+#if PTHREADS
   $Fetch__postset: 'if (!ENVIRONMENT_IS_PTHREAD) Fetch.staticInit();',
 #else
   $Fetch__postset: 'Fetch.staticInit();',
diff --git a/src/library_html5.js b/src/library_html5.js
index df1e4a4ac92cb..68138ef5d8271 100644
--- a/src/library_html5.js
+++ b/src/library_html5.js
@@ -187,7 +187,7 @@ var LibraryHTML5 = {
       }
     },
 
-#if USE_PTHREADS
+#if PTHREADS
     queueEventHandlerOnThread_iiii: function(targetThread, eventHandlerFunc, eventTypeId, eventData, userData) {
       withStackSave(function() {
         var varargs = stackAlloc(12);
@@ -199,7 +199,7 @@ var LibraryHTML5 = {
     },
 #endif
 
-#if USE_PTHREADS
+#if PTHREADS
     getTargetThreadForEventCallback: function(targetThread) {
       switch (targetThread) {
         case {{{ cDefine('EM_CALLBACK_THREAD_CONTEXT_MAIN_RUNTIME_THREAD') }}}: return 0; // The event callback for the current event should be called on the main browser thread. (0 == don't proxy)
@@ -237,7 +237,7 @@ var LibraryHTML5 = {
 
   $registerKeyEventCallback__deps: ['$JSEvents', '$findEventTarget'],
   $registerKeyEventCallback: function(target, userData, useCapture, callbackfunc, eventTypeId, eventTypeString, targetThread) {
-#if USE_PTHREADS
+#if PTHREADS
     targetThread = JSEvents.getTargetThreadForEventCallback(targetThread);
 #endif
     if (!JSEvents.keyEvent) JSEvents.keyEvent = _malloc( {{{ C_STRUCTS.EmscriptenKeyboardEvent.__size__ }}} );
@@ -247,7 +247,7 @@ var LibraryHTML5 = {
       assert(e);
 #endif
 
-#if USE_PTHREADS
+#if PTHREADS
       var keyEventData = targetThread ? _malloc( {{{ C_STRUCTS.EmscriptenKeyboardEvent.__size__ }}} ) : JSEvents.keyEvent; // This allocated block is passed as satellite data to the proxied function call, so the call frees up the data block when done.
 #else
       var keyEventData = JSEvents.keyEvent;
@@ -270,7 +270,7 @@ var LibraryHTML5 = {
       stringToUTF8(e.char || '', keyEventData + {{{ C_STRUCTS.EmscriptenKeyboardEvent.charValue }}}, {{{ cDefine('EM_HTML5_SHORT_STRING_LEN_BYTES') }}});
       stringToUTF8(e.locale || '', keyEventData + {{{ C_STRUCTS.EmscriptenKeyboardEvent.locale }}}, {{{ cDefine('EM_HTML5_SHORT_STRING_LEN_BYTES') }}});
 
-#if USE_PTHREADS
+#if PTHREADS
       if (targetThread) JSEvents.queueEventHandlerOnThread_iiii(targetThread, callbackfunc, eventTypeId, keyEventData, userData);
       else
 #endif
@@ -302,7 +302,7 @@ var LibraryHTML5 = {
   // Users can also add more special event targets, basically by just doing something like
   //    specialHTMLTargets["!canvas"] = Module.canvas;
   // (that will let !canvas map to the canvas held in Module.canvas).
-#if ENVIRONMENT_MAY_BE_WORKER || ENVIRONMENT_MAY_BE_NODE || ENVIRONMENT_MAY_BE_SHELL || USE_PTHREADS
+#if ENVIRONMENT_MAY_BE_WORKER || ENVIRONMENT_MAY_BE_NODE || ENVIRONMENT_MAY_BE_SHELL || PTHREADS
   $specialHTMLTargets: "[0, typeof document != 'undefined' ? document : 0, typeof window != 'undefined' ? window : 0]",
 #else
   $specialHTMLTargets: "[0, document, window]",
@@ -349,7 +349,7 @@ var LibraryHTML5 = {
     // OffscreenCanvas that we can find.
      || (target == 'canvas' && Object.keys(GL.offscreenCanvases)[0])
     // If that is not found either, query via the regular DOM selector.
-#if USE_PTHREADS
+#if PTHREADS
      || (typeof document != 'undefined' && document.querySelector(target));
 #else
      || document.querySelector(target);
@@ -508,7 +508,7 @@ var LibraryHTML5 = {
 
   $registerMouseEventCallback__deps: ['$JSEvents', '$fillMouseEventData', '$findEventTarget'],
   $registerMouseEventCallback: function(target, userData, useCapture, callbackfunc, eventTypeId, eventTypeString, targetThread) {
-#if USE_PTHREADS
+#if PTHREADS
     targetThread = JSEvents.getTargetThreadForEventCallback(targetThread);
 #endif
     if (!JSEvents.mouseEvent) JSEvents.mouseEvent = _malloc( {{{ C_STRUCTS.EmscriptenMouseEvent.__size__ }}} );
@@ -518,7 +518,7 @@ var LibraryHTML5 = {
       // TODO: Make this access thread safe, or this could update live while app is reading it.
       fillMouseEventData(JSEvents.mouseEvent, e, target);
 
-#if USE_PTHREADS
+#if PTHREADS
       if (targetThread) {
         var mouseEventData = _malloc( {{{ C_STRUCTS.EmscriptenMouseEvent.__size__ }}} ); // This allocated block is passed as satellite data to the proxied function call, so the call frees up the data block when done.
         fillMouseEventData(mouseEventData, e, target);
@@ -631,14 +631,14 @@ var LibraryHTML5 = {
 
   $registerWheelEventCallback__deps: ['$JSEvents', '$fillMouseEventData', '$findEventTarget'],
   $registerWheelEventCallback: function(target, userData, useCapture, callbackfunc, eventTypeId, eventTypeString, targetThread) {
-#if USE_PTHREADS
+#if PTHREADS
     targetThread = JSEvents.getTargetThreadForEventCallback(targetThread);
 #endif
     if (!JSEvents.wheelEvent) JSEvents.wheelEvent = _malloc( {{{ C_STRUCTS.EmscriptenWheelEvent.__size__ }}} );
 
     // The DOM Level 3 events spec event 'wheel'
     var wheelHandlerFunc = function(e = event) {
-#if USE_PTHREADS
+#if PTHREADS
       var wheelEvent = targetThread ? _malloc( {{{ C_STRUCTS.EmscriptenWheelEvent.__size__ }}} ) : JSEvents.wheelEvent; // This allocated block is passed as satellite data to the proxied function call, so the call frees up the data block when done.
 #else
       var wheelEvent = JSEvents.wheelEvent;
@@ -648,7 +648,7 @@ var LibraryHTML5 = {
       {{{ makeSetValue('wheelEvent', C_STRUCTS.EmscriptenWheelEvent.deltaY, 'e["deltaY"]', 'double') }}};
       {{{ makeSetValue('wheelEvent', C_STRUCTS.EmscriptenWheelEvent.deltaZ, 'e["deltaZ"]', 'double') }}};
       {{{ makeSetValue('wheelEvent', C_STRUCTS.EmscriptenWheelEvent.deltaMode, 'e["deltaMode"]', 'i32') }}};
-#if USE_PTHREADS
+#if PTHREADS
       if (targetThread) JSEvents.queueEventHandlerOnThread_iiii(targetThread, callbackfunc, eventTypeId, wheelEvent, userData);
       else
 #endif
@@ -708,7 +708,7 @@ var LibraryHTML5 = {
 
   $registerUiEventCallback__deps: ['$JSEvents', '$findEventTarget'],
   $registerUiEventCallback: function(target, userData, useCapture, callbackfunc, eventTypeId, eventTypeString, targetThread) {
-#if USE_PTHREADS
+#if PTHREADS
     targetThread = JSEvents.getTargetThreadForEventCallback(targetThread);
 #endif
     if (!JSEvents.uiEvent) JSEvents.uiEvent = _malloc( {{{ C_STRUCTS.EmscriptenUiEvent.__size__ }}} );
@@ -737,7 +737,7 @@ var LibraryHTML5 = {
         // During a page unload 'body' can be null, with "Cannot read property 'clientWidth' of null" being thrown
         return;
       }
-#if USE_PTHREADS
+#if PTHREADS
       var uiEvent = targetThread ? _malloc( {{{ C_STRUCTS.EmscriptenUiEvent.__size__ }}} ) : JSEvents.uiEvent;
 #else
       var uiEvent = JSEvents.uiEvent;
@@ -751,7 +751,7 @@ var LibraryHTML5 = {
       {{{ makeSetValue('uiEvent', C_STRUCTS.EmscriptenUiEvent.windowOuterHeight, 'outerHeight', 'i32') }}};
       {{{ makeSetValue('uiEvent', C_STRUCTS.EmscriptenUiEvent.scrollTop, 'pageXOffset', 'i32') }}};
       {{{ makeSetValue('uiEvent', C_STRUCTS.EmscriptenUiEvent.scrollLeft, 'pageYOffset', 'i32') }}};
-#if USE_PTHREADS
+#if PTHREADS
       if (targetThread) JSEvents.queueEventHandlerOnThread_iiii(targetThread, callbackfunc, eventTypeId, uiEvent, userData);
       else
 #endif
@@ -786,7 +786,7 @@ var LibraryHTML5 = {
 
   $registerFocusEventCallback__deps: ['$JSEvents', '$findEventTarget'],
   $registerFocusEventCallback: function(target, userData, useCapture, callbackfunc, eventTypeId, eventTypeString, targetThread) {
-#if USE_PTHREADS
+#if PTHREADS
     targetThread = JSEvents.getTargetThreadForEventCallback(targetThread);
 #endif
     if (!JSEvents.focusEvent) JSEvents.focusEvent = _malloc( {{{ C_STRUCTS.EmscriptenFocusEvent.__size__ }}} );
@@ -795,7 +795,7 @@ var LibraryHTML5 = {
       var nodeName = JSEvents.getNodeNameForTarget(e.target);
       var id = e.target.id ? e.target.id : '';
 
-#if USE_PTHREADS
+#if PTHREADS
       var focusEvent = targetThread ? _malloc( {{{ C_STRUCTS.EmscriptenFocusEvent.__size__ }}} ) : JSEvents.focusEvent;
 #else
       var focusEvent = JSEvents.focusEvent;
@@ -803,7 +803,7 @@ var LibraryHTML5 = {
       stringToUTF8(nodeName, focusEvent + {{{ C_STRUCTS.EmscriptenFocusEvent.nodeName }}}, {{{ cDefine('EM_HTML5_LONG_STRING_LEN_BYTES') }}});
       stringToUTF8(id, focusEvent + {{{ C_STRUCTS.EmscriptenFocusEvent.id }}}, {{{ cDefine('EM_HTML5_LONG_STRING_LEN_BYTES') }}});
 
-#if USE_PTHREADS
+#if PTHREADS
       if (targetThread) JSEvents.queueEventHandlerOnThread_iiii(targetThread, callbackfunc, eventTypeId, focusEvent, userData);
       else
 #endif
@@ -862,7 +862,7 @@ var LibraryHTML5 = {
 
   $registerDeviceOrientationEventCallback__deps: ['$JSEvents', '$fillDeviceOrientationEventData', '$findEventTarget'],
   $registerDeviceOrientationEventCallback: function(target, userData, useCapture, callbackfunc, eventTypeId, eventTypeString, targetThread) {
-#if USE_PTHREADS
+#if PTHREADS
     targetThread = JSEvents.getTargetThreadForEventCallback(targetThread);
 #endif
     if (!JSEvents.deviceOrientationEvent) JSEvents.deviceOrientationEvent = _malloc( {{{ C_STRUCTS.EmscriptenDeviceOrientationEvent.__size__ }}} );
@@ -870,7 +870,7 @@ var LibraryHTML5 = {
     var deviceOrientationEventHandlerFunc = function(e = event) {
       fillDeviceOrientationEventData(JSEvents.deviceOrientationEvent, e, target); // TODO: Thread-safety with respect to emscripten_get_deviceorientation_status()
 
-#if USE_PTHREADS
+#if PTHREADS
       if (targetThread) {
         var deviceOrientationEvent = _malloc( {{{ C_STRUCTS.EmscriptenDeviceOrientationEvent.__size__ }}} );
         fillDeviceOrientationEventData(deviceOrientationEvent, e, target);
@@ -935,7 +935,7 @@ var LibraryHTML5 = {
 
   $registerDeviceMotionEventCallback__deps: ['$JSEvents', '$fillDeviceMotionEventData', '$findEventTarget'],
   $registerDeviceMotionEventCallback: function(target, userData, useCapture, callbackfunc, eventTypeId, eventTypeString, targetThread) {
-#if USE_PTHREADS
+#if PTHREADS
     targetThread = JSEvents.getTargetThreadForEventCallback(targetThread);
 #endif
     if (!JSEvents.deviceMotionEvent) JSEvents.deviceMotionEvent = _malloc( {{{ C_STRUCTS.EmscriptenDeviceMotionEvent.__size__ }}} );
@@ -943,7 +943,7 @@ var LibraryHTML5 = {
     var deviceMotionEventHandlerFunc = function(e = event) {
       fillDeviceMotionEventData(JSEvents.deviceMotionEvent, e, target); // TODO: Thread-safety with respect to emscripten_get_devicemotion_status()
 
-#if USE_PTHREADS
+#if PTHREADS
       if (targetThread) {
         var deviceMotionEvent = _malloc( {{{ C_STRUCTS.EmscriptenDeviceMotionEvent.__size__ }}} );
         fillDeviceMotionEventData(deviceMotionEvent, e, target);
@@ -1005,13 +1005,13 @@ var LibraryHTML5 = {
 
   $registerOrientationChangeEventCallback__deps: ['$JSEvents', '$fillOrientationChangeEventData', '$findEventTarget'],
   $registerOrientationChangeEventCallback: function(target, userData, useCapture, callbackfunc, eventTypeId, eventTypeString, targetThread) {
-#if USE_PTHREADS
+#if PTHREADS
     targetThread = JSEvents.getTargetThreadForEventCallback(targetThread);
 #endif
     if (!JSEvents.orientationChangeEvent) JSEvents.orientationChangeEvent = _malloc( {{{ C_STRUCTS.EmscriptenOrientationChangeEvent.__size__ }}} );
 
     var orientationChangeEventHandlerFunc = function(e = event) {
-#if USE_PTHREADS
+#if PTHREADS
       var orientationChangeEvent = targetThread ? _malloc( {{{ C_STRUCTS.EmscriptenOrientationChangeEvent.__size__ }}} ) : JSEvents.orientationChangeEvent;
 #else
       var orientationChangeEvent = JSEvents.orientationChangeEvent;
@@ -1019,7 +1019,7 @@ var LibraryHTML5 = {
 
       fillOrientationChangeEventData(orientationChangeEvent);
 
-#if USE_PTHREADS
+#if PTHREADS
       if (targetThread) JSEvents.queueEventHandlerOnThread_iiii(targetThread, callbackfunc, eventTypeId, orientationChangeEvent, userData);
       else
 #endif
@@ -1129,13 +1129,13 @@ var LibraryHTML5 = {
 
   $registerFullscreenChangeEventCallback__deps: ['$JSEvents', '$fillFullscreenChangeEventData', '$findEventTarget'],
   $registerFullscreenChangeEventCallback: function(target, userData, useCapture, callbackfunc, eventTypeId, eventTypeString, targetThread) {
-#if USE_PTHREADS
+#if PTHREADS
     targetThread = JSEvents.getTargetThreadForEventCallback(targetThread);
 #endif
     if (!JSEvents.fullscreenChangeEvent) JSEvents.fullscreenChangeEvent = _malloc( {{{ C_STRUCTS.EmscriptenFullscreenChangeEvent.__size__ }}} );
 
     var fullscreenChangeEventhandlerFunc = function(e = event) {
-#if USE_PTHREADS
+#if PTHREADS
       var fullscreenChangeEvent = targetThread ? _malloc( {{{ C_STRUCTS.EmscriptenFullscreenChangeEvent.__size__ }}} ) : JSEvents.fullscreenChangeEvent;
 #else
       var fullscreenChangeEvent = JSEvents.fullscreenChangeEvent;
@@ -1143,7 +1143,7 @@ var LibraryHTML5 = {
 
       fillFullscreenChangeEventData(fullscreenChangeEvent);
 
-#if USE_PTHREADS
+#if PTHREADS
       if (targetThread) JSEvents.queueEventHandlerOnThread_iiii(targetThread, callbackfunc, eventTypeId, fullscreenChangeEvent, userData);
       else
 #endif
@@ -1228,7 +1228,7 @@ var LibraryHTML5 = {
     currentFullscreenStrategy = strategy;
 
     if (strategy.canvasResizedCallback) {
-#if USE_PTHREADS
+#if PTHREADS
       if (strategy.canvasResizedCallbackTargetThread) JSEvents.queueEventHandlerOnThread_iiii(strategy.canvasResizedCallbackTargetThread, strategy.canvasResizedCallback, {{{ cDefine('EMSCRIPTEN_EVENT_CANVASRESIZED') }}}, 0, strategy.canvasResizedCallbackUserData);
       else
 #endif
@@ -1380,7 +1380,7 @@ var LibraryHTML5 = {
         if (canvas.GLctxObject) canvas.GLctxObject.GLctx.viewport(0, 0, oldWidth, oldHeight);
 
         if (currentFullscreenStrategy.canvasResizedCallback) {
-#if USE_PTHREADS
+#if PTHREADS
           if (currentFullscreenStrategy.canvasResizedCallbackTargetThread) JSEvents.queueEventHandlerOnThread_iiii(currentFullscreenStrategy.canvasResizedCallbackTargetThread, currentFullscreenStrategy.canvasResizedCallback, {{{ cDefine('EMSCRIPTEN_EVENT_CANVASRESIZED') }}}, 0, currentFullscreenStrategy.canvasResizedCallbackUserData);
           else
 #endif
@@ -1508,7 +1508,7 @@ var LibraryHTML5 = {
     }
 
     if (!inCenteredWithoutScalingFullscreenMode && currentFullscreenStrategy.canvasResizedCallback) {
-#if USE_PTHREADS
+#if PTHREADS
       if (currentFullscreenStrategy.canvasResizedCallbackTargetThread) JSEvents.queueEventHandlerOnThread_iiii(currentFullscreenStrategy.canvasResizedCallbackTargetThread, currentFullscreenStrategy.canvasResizedCallback, {{{ cDefine('EMSCRIPTEN_EVENT_CANVASRESIZED') }}}, 0, currentFullscreenStrategy.canvasResizedCallbackUserData);
       else
 #endif
@@ -1585,7 +1585,7 @@ var LibraryHTML5 = {
 #if HTML5_SUPPORT_DEFERRING_USER_SENSITIVE_REQUESTS
       deferUntilInEventHandler: deferUntilInEventHandler,
 #endif
-#if USE_PTHREADS
+#if PTHREADS
       canvasResizedCallbackTargetThread: {{{ makeGetValue('fullscreenStrategy', C_STRUCTS.EmscriptenFullscreenStrategy.canvasResizedCallbackTargetThread, 'i32') }}},
 #endif
       canvasResizedCallback: {{{ makeGetValue('fullscreenStrategy', C_STRUCTS.EmscriptenFullscreenStrategy.canvasResizedCallback, 'i32') }}},
@@ -1611,7 +1611,7 @@ var LibraryHTML5 = {
         filteringMode: {{{ makeGetValue('fullscreenStrategy', C_STRUCTS.EmscriptenFullscreenStrategy.filteringMode, 'i32') }}},
         canvasResizedCallback: {{{ makeGetValue('fullscreenStrategy', C_STRUCTS.EmscriptenFullscreenStrategy.canvasResizedCallback, 'i32') }}},
         canvasResizedCallbackUserData: {{{ makeGetValue('fullscreenStrategy', C_STRUCTS.EmscriptenFullscreenStrategy.canvasResizedCallbackUserData, 'i32') }}},
-#if USE_PTHREADS
+#if PTHREADS
         canvasResizedCallbackTargetThread: JSEvents.getTargetThreadForEventCallback(),
 #endif
         target: target,
@@ -1631,7 +1631,7 @@ var LibraryHTML5 = {
       restoreHiddenElements(hiddenElements);
       removeEventListener('resize', softFullscreenResizeWebGLRenderTarget);
       if (strategy.canvasResizedCallback) {
-#if USE_PTHREADS
+#if PTHREADS
         if (strategy.canvasResizedCallbackTargetThread) JSEvents.queueEventHandlerOnThread_iiii(strategy.canvasResizedCallbackTargetThread, strategy.canvasResizedCallback, {{{ cDefine('EMSCRIPTEN_EVENT_CANVASRESIZED') }}}, 0, strategy.canvasResizedCallbackUserData);
         else
 #endif
@@ -1645,7 +1645,7 @@ var LibraryHTML5 = {
 
     // Inform the caller that the canvas size has changed.
     if (strategy.canvasResizedCallback) {
-#if USE_PTHREADS
+#if PTHREADS
       if (strategy.canvasResizedCallbackTargetThread) JSEvents.queueEventHandlerOnThread_iiii(strategy.canvasResizedCallbackTargetThread, strategy.canvasResizedCallback, {{{ cDefine('EMSCRIPTEN_EVENT_CANVASRESIZED') }}}, 0, strategy.canvasResizedCallbackUserData);
       else
 #endif
@@ -1714,20 +1714,20 @@ var LibraryHTML5 = {
 
   $registerPointerlockChangeEventCallback__deps: ['$JSEvents', '$fillPointerlockChangeEventData', '$findEventTarget'],
   $registerPointerlockChangeEventCallback: function(target, userData, useCapture, callbackfunc, eventTypeId, eventTypeString, targetThread) {
-#if USE_PTHREADS
+#if PTHREADS
     targetThread = JSEvents.getTargetThreadForEventCallback(targetThread);
 #endif
     if (!JSEvents.pointerlockChangeEvent) JSEvents.pointerlockChangeEvent = _malloc( {{{ C_STRUCTS.EmscriptenPointerlockChangeEvent.__size__ }}} );
 
     var pointerlockChangeEventHandlerFunc = function(e = event) {
-#if USE_PTHREADS
+#if PTHREADS
       var pointerlockChangeEvent = targetThread ? _malloc( {{{ C_STRUCTS.EmscriptenPointerlockChangeEvent.__size__ }}} ) : JSEvents.pointerlockChangeEvent;
 #else
       var pointerlockChangeEvent = JSEvents.pointerlockChangeEvent;
 #endif
       fillPointerlockChangeEventData(pointerlockChangeEvent);
 
-#if USE_PTHREADS
+#if PTHREADS
       if (targetThread) JSEvents.queueEventHandlerOnThread_iiii(targetThread, callbackfunc, eventTypeId, pointerlockChangeEvent, userData);
       else
 #endif
@@ -1769,12 +1769,12 @@ var LibraryHTML5 = {
 
   $registerPointerlockErrorEventCallback__deps: ['$JSEvents', '$findEventTarget', '$specialHTMLTargets'],
   $registerPointerlockErrorEventCallback: function(target, userData, useCapture, callbackfunc, eventTypeId, eventTypeString, targetThread) {
-#if USE_PTHREADS
+#if PTHREADS
     targetThread = JSEvents.getTargetThreadForEventCallback(targetThread);
 #endif
 
     var pointerlockErrorEventHandlerFunc = function(e = event) {
-#if USE_PTHREADS
+#if PTHREADS
       if (targetThread) JSEvents.queueEventHandlerOnThread_iiii(targetThread, callbackfunc, eventTypeId, 0, userData);
       else
 #endif
@@ -1967,13 +1967,13 @@ var LibraryHTML5 = {
 
   $registerVisibilityChangeEventCallback__deps: ['$JSEvents', '$fillVisibilityChangeEventData', '$findEventTarget'],
   $registerVisibilityChangeEventCallback: function(target, userData, useCapture, callbackfunc, eventTypeId, eventTypeString, targetThread) {
-#if USE_PTHREADS
+#if PTHREADS
     targetThread = JSEvents.getTargetThreadForEventCallback(targetThread);
 #endif
     if (!JSEvents.visibilityChangeEvent) JSEvents.visibilityChangeEvent = _malloc( {{{ C_STRUCTS.EmscriptenVisibilityChangeEvent.__size__ }}} );
 
     var visibilityChangeEventHandlerFunc = function(e = event) {
-#if USE_PTHREADS
+#if PTHREADS
       var visibilityChangeEvent = targetThread ? _malloc( {{{ C_STRUCTS.EmscriptenVisibilityChangeEvent.__size__ }}} ) : JSEvents.visibilityChangeEvent;
 #else
       var visibilityChangeEvent = JSEvents.visibilityChangeEvent;
@@ -1981,7 +1981,7 @@ var LibraryHTML5 = {
 
       fillVisibilityChangeEventData(visibilityChangeEvent);
 
-#if USE_PTHREADS
+#if PTHREADS
       if (targetThread) JSEvents.queueEventHandlerOnThread_iiii(targetThread, callbackfunc, eventTypeId, visibilityChangeEvent, userData);
       else
 #endif
@@ -2024,7 +2024,7 @@ var LibraryHTML5 = {
 
   $registerTouchEventCallback__deps: ['$JSEvents', '$findEventTarget', '$getBoundingClientRect'],
   $registerTouchEventCallback: function(target, userData, useCapture, callbackfunc, eventTypeId, eventTypeString, targetThread) {
-#if USE_PTHREADS
+#if PTHREADS
     targetThread = JSEvents.getTargetThreadForEventCallback(targetThread);
 #endif
     if (!JSEvents.touchEvent) JSEvents.touchEvent = _malloc( {{{ C_STRUCTS.EmscriptenTouchEvent.__size__ }}} );
@@ -2058,7 +2058,7 @@ var LibraryHTML5 = {
         touches[e.targetTouches[i].identifier].onTarget = 1;
       }
 
-#if USE_PTHREADS
+#if PTHREADS
       var touchEvent = targetThread ? _malloc( {{{ C_STRUCTS.EmscriptenTouchEvent.__size__ }}} ) : JSEvents.touchEvent;
 #else
       var touchEvent = JSEvents.touchEvent;
@@ -2101,7 +2101,7 @@ var LibraryHTML5 = {
       }
       {{{ makeSetValue('touchEvent', C_STRUCTS.EmscriptenTouchEvent.numTouches, 'numTouches', 'i32') }}};
 
-#if USE_PTHREADS
+#if PTHREADS
       if (targetThread) JSEvents.queueEventHandlerOnThread_iiii(targetThread, callbackfunc, eventTypeId, touchEvent, userData);
       else
 #endif
@@ -2186,20 +2186,20 @@ var LibraryHTML5 = {
 
   $registerGamepadEventCallback__deps: ['$JSEvents', '$fillGamepadEventData', '$findEventTarget'],
   $registerGamepadEventCallback: function(target, userData, useCapture, callbackfunc, eventTypeId, eventTypeString, targetThread) {
-#if USE_PTHREADS
+#if PTHREADS
     targetThread = JSEvents.getTargetThreadForEventCallback(targetThread);
 #endif
     if (!JSEvents.gamepadEvent) JSEvents.gamepadEvent = _malloc( {{{ C_STRUCTS.EmscriptenGamepadEvent.__size__ }}} );
 
     var gamepadEventHandlerFunc = function(e = event) {
-#if USE_PTHREADS
+#if PTHREADS
       var gamepadEvent = targetThread ? _malloc( {{{ C_STRUCTS.EmscriptenGamepadEvent.__size__ }}} ) : JSEvents.gamepadEvent;
 #else
       var gamepadEvent = JSEvents.gamepadEvent;
 #endif
       fillGamepadEventData(gamepadEvent, e["gamepad"]);
 
-#if USE_PTHREADS
+#if PTHREADS
       if (targetThread) JSEvents.queueEventHandlerOnThread_iiii(targetThread, callbackfunc, eventTypeId, gamepadEvent, userData);
       else
 #endif
@@ -2327,20 +2327,20 @@ var LibraryHTML5 = {
 
   $registerBatteryEventCallback__deps: ['$JSEvents', '$fillBatteryEventData', '$battery', '$findEventTarget', 'malloc'],
   $registerBatteryEventCallback: function(target, userData, useCapture, callbackfunc, eventTypeId, eventTypeString, targetThread) {
-#if USE_PTHREADS
+#if PTHREADS
     targetThread = JSEvents.getTargetThreadForEventCallback(targetThread);
 #endif
     if (!JSEvents.batteryEvent) JSEvents.batteryEvent = _malloc( {{{ C_STRUCTS.EmscriptenBatteryEvent.__size__ }}} );
 
     var batteryEventHandlerFunc = function(e = event) {
-#if USE_PTHREADS
+#if PTHREADS
       var batteryEvent = targetThread ? _malloc( {{{ C_STRUCTS.EmscriptenBatteryEvent.__size__ }}} ) : JSEvents.batteryEvent;
 #else
       var batteryEvent = JSEvents.batteryEvent;
 #endif
       fillBatteryEventData(batteryEvent, battery());
 
-#if USE_PTHREADS
+#if PTHREADS
       if (targetThread) JSEvents.queueEventHandlerOnThread_iiii(targetThread, callbackfunc, eventTypeId, batteryEvent, userData);
       else
 #endif
@@ -2384,7 +2384,7 @@ var LibraryHTML5 = {
     return {{{ cDefine('EMSCRIPTEN_RESULT_SUCCESS') }}};
   },
 
-#if USE_PTHREADS
+#if PTHREADS
   emscripten_set_canvas_element_size_calling_thread__deps: [
     '$JSEvents',
 #if OFFSCREENCANVAS_SUPPORT
@@ -2540,7 +2540,7 @@ var LibraryHTML5 = {
     }
   },
 
-#if USE_PTHREADS
+#if PTHREADS
   emscripten_get_canvas_element_size_calling_thread__deps: ['$JSEvents', '$findCanvasEventTarget'],
   emscripten_get_canvas_element_size_calling_thread: function(target, width, height) {
     var canvas = findCanvasEventTarget(target);
diff --git a/src/library_html5_webgl.js b/src/library_html5_webgl.js
index e83389ae41a75..d2bce7fdcd2a0 100644
--- a/src/library_html5_webgl.js
+++ b/src/library_html5_webgl.js
@@ -37,7 +37,7 @@ var LibraryHtml5WebGL = {
     HEAP32[a + ({{{ C_STRUCTS.EmscriptenWebGLContextAttributes.majorVersion }}}>>2)] = 
     HEAP32[a + ({{{ C_STRUCTS.EmscriptenWebGLContextAttributes.enableExtensionsByDefault }}}>>2)] = 1;
 
-#if USE_PTHREADS
+#if PTHREADS
     // Default context initialization state (user can override):
     // - if main thread is creating the context, default to the context not being shared between threads - enabling sharing has performance overhead, because it forces the context to be OffscreenCanvas or OffscreenFramebuffer.
     // - if a web worker is creating the context, default to using OffscreenCanvas if available, or proxying via Offscreen Framebuffer if not
@@ -47,7 +47,7 @@ var LibraryHtml5WebGL = {
 
   _emscripten_webgl_power_preferences: "['default', 'low-power', 'high-performance']",
 
-#if USE_PTHREADS && OFFSCREEN_FRAMEBUFFER
+#if PTHREADS && OFFSCREEN_FRAMEBUFFER
   // In offscreen framebuffer mode, we implement a proxied version of the
   // emscripten_webgl_create_context() function in JS.
   emscripten_webgl_create_context_proxied__proxy: 'sync',
@@ -79,7 +79,7 @@ var LibraryHtml5WebGL = {
 #if LibraryManager.has('library_webgl.js')
   '$GL',
 #endif
-#if USE_PTHREADS && OFFSCREEN_FRAMEBUFFER
+#if PTHREADS && OFFSCREEN_FRAMEBUFFER
   'emscripten_webgl_create_context_proxied',
 #endif
   '$JSEvents', '_emscripten_webgl_power_preferences', '$findEventTarget', '$findCanvasEventTarget'],
@@ -115,7 +115,7 @@ var LibraryHtml5WebGL = {
     var targetStr = UTF8ToString(target);
 #endif
 
-#if USE_PTHREADS && OFFSCREEN_FRAMEBUFFER
+#if PTHREADS && OFFSCREEN_FRAMEBUFFER
     // Create a WebGL context that is proxied to main thread if canvas was not found on worker, or if explicitly requested to do so.
     if (ENVIRONMENT_IS_PTHREAD) {
       if (contextAttributes.proxyContextToMainThread === {{{ cDefine('EMSCRIPTEN_WEBGL_CONTEXT_PROXY_ALWAYS') }}} ||
@@ -214,7 +214,7 @@ var LibraryHtml5WebGL = {
     var contextHandle = GL.createContext(canvas, contextAttributes);
     return contextHandle;
   },
-#if USE_PTHREADS && OFFSCREEN_FRAMEBUFFER
+#if PTHREADS && OFFSCREEN_FRAMEBUFFER
   // Runs on the calling thread, proxies if needed.
   emscripten_webgl_make_context_current_calling_thread__sig: 'ii',
   emscripten_webgl_make_context_current_calling_thread: function(contextHandle) {
@@ -327,7 +327,7 @@ var LibraryHtml5WebGL = {
     GL.deleteContext(contextHandle);
   },
 
-#if USE_PTHREADS
+#if PTHREADS
   // Special function that will be invoked on the thread calling emscripten_webgl_destroy_context(), before routing
   // the call over to the target thread.
   emscripten_webgl_destroy_context_before_on_calling_thread__deps: ['emscripten_webgl_get_current_context', 'emscripten_webgl_make_context_current'],
@@ -409,7 +409,7 @@ var LibraryHtml5WebGL = {
 
   _registerWebGlEventCallback__deps: ['$JSEvents', '$findEventTarget'],
   _registerWebGlEventCallback: function(target, userData, useCapture, callbackfunc, eventTypeId, eventTypeString, targetThread) {
-#if USE_PTHREADS
+#if PTHREADS
     targetThread = JSEvents.getTargetThreadForEventCallback(targetThread);
 #endif
 
@@ -418,7 +418,7 @@ var LibraryHtml5WebGL = {
 #endif
 
     var webGlEventHandlerFunc = function(e = event) {
-#if USE_PTHREADS
+#if PTHREADS
       if (targetThread) JSEvents.queueEventHandlerOnThread_iiii(targetThread, callbackfunc, eventTypeId, 0, userData);
       else
 #endif
@@ -566,7 +566,7 @@ var LibraryHtml5WebGL = {
   },
 };
 
-#if USE_PTHREADS
+#if PTHREADS
 // Process 'sync_on_webgl_context_handle_thread' and 'sync_on_current_webgl_context_thread' pseudo-proxying modes
 // to appropriate proxying mechanism, either proxying on-demand, unconditionally, or never, depending on build modes.
 // 'sync_on_webgl_context_handle_thread' is used for function signatures that take a HTML5 WebGL context handle
diff --git a/src/library_pipefs.js b/src/library_pipefs.js
index c679c7e2c0f59..d2f3cac46b4fb 100644
--- a/src/library_pipefs.js
+++ b/src/library_pipefs.js
@@ -94,7 +94,7 @@ mergeInto(LibraryManager.library, {
           currentLength += bucket.offset - bucket.roffset;
         }
 
-#if USE_PTHREADS
+#if PTHREADS
         assert(buffer instanceof ArrayBuffer || buffer instanceof SharedArrayBuffer || ArrayBuffer.isView(buffer));
 #else
         assert(buffer instanceof ArrayBuffer || ArrayBuffer.isView(buffer));
@@ -151,7 +151,7 @@ mergeInto(LibraryManager.library, {
       write: function (stream, buffer, offset, length, position /* ignored */) {
         var pipe = stream.node.pipe;
 
-#if USE_PTHREADS
+#if PTHREADS
         assert(buffer instanceof ArrayBuffer || buffer instanceof SharedArrayBuffer || ArrayBuffer.isView(buffer));
 #else
         assert(buffer instanceof ArrayBuffer || ArrayBuffer.isView(buffer));
diff --git a/src/library_pthread.js b/src/library_pthread.js
index c7095badc5203..b3e5df5d8471f 100644
--- a/src/library_pthread.js
+++ b/src/library_pthread.js
@@ -7,14 +7,14 @@
  * features within this file (ES2020).
  */
 
-#if !USE_PTHREADS
-#error "Internal error! USE_PTHREADS should be enabled when including library_pthread.js."
+#if !PTHREADS
+#error "Internal error! PTHREADS should be enabled when including library_pthread.js."
 #endif
 #if !SHARED_MEMORY
 #error "Internal error! SHARED_MEMORY should be enabled when including library_pthread.js."
 #endif
-#if USE_PTHREADS == 2
-#error "USE_PTHREADS=2 is no longer supported"
+#if PTHREADS == 2
+#error "PTHREADS=2 is no longer supported"
 #endif
 #if BUILD_AS_WORKER
 #error "pthreads + BUILD_AS_WORKER require separate modes that don't work together, see https://github.com/emscripten-core/emscripten/issues/8854"
diff --git a/src/library_pthread_stub.js b/src/library_pthread_stub.js
index b18ef09eafb77..a7a10f6bb361f 100644
--- a/src/library_pthread_stub.js
+++ b/src/library_pthread_stub.js
@@ -4,8 +4,8 @@
  * SPDX-License-Identifier: MIT
  */
 
-#if USE_PTHREADS
-#error "Internal error! USE_PTHREADS should not be enabled when including library_pthread_stub.js."
+#if PTHREADS
+#error "Internal error! PTHREADS should not be enabled when including library_pthread_stub.js."
 #endif
 #if STANDALONE_WASM && SHARED_MEMORY
 #error "STANDALONE_WASM does not support shared memories yet"
diff --git a/src/library_sockfs.js b/src/library_sockfs.js
index 829ec54c6dc4d..44e653a6fa0a3 100644
--- a/src/library_sockfs.js
+++ b/src/library_sockfs.js
@@ -619,7 +619,7 @@ mergeInto(LibraryManager.library, {
         }
 
         var data;
-#if USE_PTHREADS
+#if PTHREADS
         // WebSockets .send() does not allow passing a SharedArrayBuffer, so clone the portion of the SharedArrayBuffer as a regular
         // ArrayBuffer that we want to send.
         if (buffer instanceof SharedArrayBuffer) {
@@ -627,7 +627,7 @@ mergeInto(LibraryManager.library, {
         } else {
 #endif
           data = buffer.slice(offset, offset + length);
-#if USE_PTHREADS
+#if PTHREADS
         }
 #endif
 
diff --git a/src/library_syscall.js b/src/library_syscall.js
index 677ad46bf4461..9899e9e34dd81 100644
--- a/src/library_syscall.js
+++ b/src/library_syscall.js
@@ -1087,7 +1087,7 @@ function wrapSyscallFunction(x, library, isWasi) {
   library[x] = eval('(' + t + ')');
   if (!library[x + '__deps']) library[x + '__deps'] = [];
   library[x + '__deps'].push('$SYSCALLS');
-#if USE_PTHREADS
+#if PTHREADS
   // Most syscalls need to happen on the main JS thread (e.g. because the
   // filesystem is in JS and on that thread). Proxy synchronously to there.
   // There are some exceptions, syscalls that we know are ok to just run in
diff --git a/src/library_wasi.js b/src/library_wasi.js
index 5c3484b0346d0..3aff37ecfbb4c 100644
--- a/src/library_wasi.js
+++ b/src/library_wasi.js
@@ -26,7 +26,7 @@ var WasiLibrary = {
 #endif
     EXITSTATUS = code;
     if (!keepRuntimeAlive()) {
-#if USE_PTHREADS
+#if PTHREADS
       PThread.terminateAllThreads();
 #endif
 #if expectToReceiveOnModule('onExit')
diff --git a/src/library_wasm_worker.js b/src/library_wasm_worker.js
index ef2d6df293950..e43a75eefdb06 100644
--- a/src/library_wasm_worker.js
+++ b/src/library_wasm_worker.js
@@ -70,7 +70,7 @@ mergeInto(LibraryManager.library, {
 #endif
     // Run the C side Worker initialization for stack and TLS.
     _emscripten_wasm_worker_initialize(m['sb'], m['sz']);
-#if USE_PTHREADS
+#if PTHREADS
     // Record that this Wasm Worker supports synchronous blocking in emscripten_futex_wake().
     ___set_thread_state(/*thread_ptr=*/0, /*is_main_thread=*/0, /*is_runtime_thread=*/0, /*supports_wait=*/0);
 #endif
diff --git a/src/library_webgl.js b/src/library_webgl.js
index 48b4d044035c7..5caa0b9ba819e 100644
--- a/src/library_webgl.js
+++ b/src/library_webgl.js
@@ -150,7 +150,7 @@ var LibraryGL = {
 #if GL_SUPPORT_AUTOMATIC_ENABLE_EXTENSIONS
   // If GL_SUPPORT_AUTOMATIC_ENABLE_EXTENSIONS is enabled, GL.initExtensions() will call to initialize these.
   $GL__deps: [
-#if USE_PTHREADS
+#if PTHREADS
     'malloc', // Needed by registerContext
 #endif
 #if MIN_WEBGL_VERSION == 1
@@ -195,7 +195,7 @@ var LibraryGL = {
     textures: [],
     shaders: [],
     vaos: [],
-#if USE_PTHREADS // with pthreads a context is a location in memory with some synchronized data between threads
+#if PTHREADS // with pthreads a context is a location in memory with some synchronized data between threads
     contexts: {},
 #else            // without pthreads, it's just an integer ID
     contexts: [],
@@ -972,7 +972,7 @@ var LibraryGL = {
 #endif
 
     registerContext: function(ctx, webGLContextAttributes) {
-#if USE_PTHREADS
+#if PTHREADS
       // with pthreads a context is a location in memory with some synchronized data between threads
       var handle = _malloc(8);
 #if GL_ASSERTIONS
@@ -982,10 +982,10 @@ var LibraryGL = {
       {{{ makeSetValue('handle', 0, 'webGLContextAttributes.explicitSwapControl', 'i32')}}}; // explicitSwapControl
 #endif
       {{{ makeSetValue('handle', 4, '_pthread_self()', 'i32')}}}; // the thread pointer of the thread that owns the control of the context
-#else // USE_PTHREADS
+#else // PTHREADS
       // without pthreads a context is just an integer ID
       var handle = GL.getNewId(GL.contexts);
-#endif // USE_PTHREADS
+#endif // PTHREADS
 
       var context = {
         handle: handle,
@@ -1051,7 +1051,7 @@ var LibraryGL = {
     makeContextCurrent: function(contextHandle) {
 #if GL_DEBUG
       if (contextHandle && !GL.contexts[contextHandle]) {
-#if USE_PTHREADS
+#if PTHREADS
         dbg('GL.makeContextCurrent() failed! WebGL context ' + contextHandle + ' does not exist, or was created on another thread!');
 #else
         dbg('GL.makeContextCurrent() failed! WebGL context ' + contextHandle + ' does not exist!');
@@ -1072,7 +1072,7 @@ var LibraryGL = {
       if (GL.currentContext === GL.contexts[contextHandle]) GL.currentContext = null;
       if (typeof JSEvents == 'object') JSEvents.removeAllHandlersOnTarget(GL.contexts[contextHandle].GLctx.canvas); // Release all JS event handlers on the DOM element that the GL context is associated with since the context is now deleted.
       if (GL.contexts[contextHandle] && GL.contexts[contextHandle].GLctx.canvas) GL.contexts[contextHandle].GLctx.canvas.GLctxObject = undefined; // Make sure the canvas object no longer refers to the context object so there are no GC surprises.
-#if USE_PTHREADS
+#if PTHREADS
       _free(GL.contexts[contextHandle].handle);
 #endif
       GL.contexts[contextHandle] = null;
diff --git a/src/library_webgpu.js b/src/library_webgpu.js
index c4ab3d4341550..f0a3b5237e505 100644
--- a/src/library_webgpu.js
+++ b/src/library_webgpu.js
@@ -1440,7 +1440,7 @@ var LibraryWebGPU = {
       case {{{ gpu.SType.ShaderModuleSPIRVDescriptor }}}: {
         var count = {{{ gpu.makeGetU32('nextInChainPtr', C_STRUCTS.WGPUShaderModuleSPIRVDescriptor.codeSize) }}};
         var start = {{{ makeGetValue('nextInChainPtr', C_STRUCTS.WGPUShaderModuleSPIRVDescriptor.code, '*') }}};
-#if USE_PTHREADS
+#if PTHREADS
         // Chrome can't currently handle a SharedArrayBuffer view here, so make a copy.
         desc["code"] = HEAPU32.slice(start >> 2, (start >> 2) + count);
 #else
diff --git a/src/library_websocket.js b/src/library_websocket.js
index 59ac24e0c1b00..7e56602085387 100644
--- a/src/library_websocket.js
+++ b/src/library_websocket.js
@@ -363,7 +363,7 @@ var LibraryWebSocket = {
 
     dbg('emscripten_websocket_send_binary(socketId='+socketId+',binaryData='+binaryData+ ',dataLength='+dataLength+'), ' + s);
 #endif
-#if USE_PTHREADS
+#if PTHREADS
     // TODO: This is temporary to cast a shared Uint8Array to a non-shared Uint8Array. This could be removed if WebSocket API is improved
     // to allow passing in views to SharedArrayBuffers
     socket.send(new Uint8Array({{{ makeHEAPView('U8', 'binaryData', 'binaryData+dataLength') }}}));
diff --git a/src/modules.js b/src/modules.js
index bd97f32d97416..91ecbbb13f29b 100644
--- a/src/modules.js
+++ b/src/modules.js
@@ -365,7 +365,7 @@ function exportRuntime() {
   // them via EXPORTED_RUNTIME_METHODS for backwards compat.
   runtimeElements = runtimeElements.concat(WASM_SYSTEM_EXPORTS);
 
-  if (USE_PTHREADS && ALLOW_MEMORY_GROWTH) {
+  if (PTHREADS && ALLOW_MEMORY_GROWTH) {
     runtimeElements = runtimeElements.concat([
       'GROWABLE_HEAP_I8',
       'GROWABLE_HEAP_U8',
diff --git a/src/parseTools.js b/src/parseTools.js
index 931963072f0c7..49d569ad55290 100644
--- a/src/parseTools.js
+++ b/src/parseTools.js
@@ -705,11 +705,11 @@ function modifyFunction(text, func) {
 }
 
 function runIfMainThread(text) {
-  if (WASM_WORKERS && USE_PTHREADS) {
+  if (WASM_WORKERS && PTHREADS) {
     return 'if (!ENVIRONMENT_IS_WASM_WORKER && !ENVIRONMENT_IS_PTHREAD) { ' + text + ' }';
   } else if (WASM_WORKERS) {
     return 'if (!ENVIRONMENT_IS_WASM_WORKER) { ' + text + ' }';
-  } else if (USE_PTHREADS) {
+  } else if (PTHREADS) {
     return 'if (!ENVIRONMENT_IS_PTHREAD) { ' + text + ' }';
   } else {
     return text;
@@ -936,7 +936,7 @@ function makeMalloc(source, param) {
 // We skip this completely in MINIMAL_RUNTIME and also in builds that
 // don't ever need to exit the runtime.
 function runtimeKeepalivePush() {
-  if (MINIMAL_RUNTIME || (EXIT_RUNTIME == 0 && USE_PTHREADS == 0)) return '';
+  if (MINIMAL_RUNTIME || (EXIT_RUNTIME == 0 && PTHREADS == 0)) return '';
   return 'runtimeKeepalivePush();';
 }
 
@@ -945,7 +945,7 @@ function runtimeKeepalivePush() {
 // We skip this completely in MINIMAL_RUNTIME and also in builds that
 // don't ever need to exit the runtime.
 function runtimeKeepalivePop() {
-  if (MINIMAL_RUNTIME || (EXIT_RUNTIME == 0 && USE_PTHREADS == 0)) return '';
+  if (MINIMAL_RUNTIME || (EXIT_RUNTIME == 0 && PTHREADS == 0)) return '';
   return 'runtimeKeepalivePop();';
 }
 
diff --git a/src/postamble.js b/src/postamble.js
index b5bb3b4feec20..12adf97cf2e96 100644
--- a/src/postamble.js
+++ b/src/postamble.js
@@ -117,7 +117,7 @@ function stackCheckInit() {
   // This is normally called automatically during __wasm_call_ctors but need to
   // get these values before even running any of the ctors so we call it redundantly
   // here.
-#if ASSERTIONS && USE_PTHREADS
+#if ASSERTIONS && PTHREADS
   // See $establishStackSpace for the equivelent code that runs on a thread
   assert(!ENVIRONMENT_IS_PTHREAD);
 #endif
@@ -152,7 +152,7 @@ function run() {
   }
 
 #if STACK_OVERFLOW_CHECK
-#if USE_PTHREADS
+#if PTHREADS
   if (!ENVIRONMENT_IS_PTHREAD)
 #endif
     stackCheckInit();
@@ -188,7 +188,7 @@ function run() {
   }
 #endif
 
-#if USE_PTHREADS
+#if PTHREADS
   if (ENVIRONMENT_IS_PTHREAD) {
 #if MODULARIZE
     // The promise resolve function typically gets called as part of the execution
diff --git a/src/postamble_minimal.js b/src/postamble_minimal.js
index 7a4bdbb805149..396d955b43ef6 100644
--- a/src/postamble_minimal.js
+++ b/src/postamble_minimal.js
@@ -26,7 +26,7 @@ function run() {
 #if EXIT_RUNTIME
   callRuntimeCallbacks(__ATEXIT__);
   <<< ATEXITS >>>
-#if USE_PTHREADS
+#if PTHREADS
   PThread.terminateAllThreads();
 #endif
 
@@ -53,7 +53,7 @@ function initRuntime(asm) {
   runtimeInitialized = true;
 #endif
 
-#if USE_PTHREADS
+#if PTHREADS
   if (ENVIRONMENT_IS_PTHREAD) {
     // Export needed variables that worker.js needs to Module.
     Module['HEAPU32'] = HEAPU32;
@@ -76,7 +76,7 @@ function initRuntime(asm) {
 #endif
 #endif
 
-#if USE_PTHREADS
+#if PTHREADS
   PThread.tlsInitFunctions.push(asm['_emscripten_tls_init']);
 #endif
 
@@ -104,7 +104,7 @@ var imports = {
 var asm;
 #endif
 
-#if USE_PTHREADS
+#if PTHREADS
 var wasmModule;
 #endif
 
@@ -151,14 +151,14 @@ WebAssembly.instantiate(Module['wasm'], imports).then(function(output) {
   // output.module objects. But if Module['wasm'] is an already compiled
   // WebAssembly module, then output is the WebAssembly instance itself.
   // Depending on the build mode, Module['wasm'] can mean a different thing.
-#if MINIMAL_RUNTIME_STREAMING_WASM_COMPILATION || MINIMAL_RUNTIME_STREAMING_WASM_INSTANTIATION || USE_PTHREADS
+#if MINIMAL_RUNTIME_STREAMING_WASM_COMPILATION || MINIMAL_RUNTIME_STREAMING_WASM_INSTANTIATION || PTHREADS
   // https://caniuse.com/#feat=wasm and https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/WebAssembly/instantiateStreaming
   // Firefox 52 added Wasm support, but only Firefox 58 added compileStreaming &
   // instantiateStreaming.
   // Chrome 57 added Wasm support, but only Chrome 61 added compileStreaming &
   // instantiateStreaming.
   // Node.js and Safari do not support compileStreaming or instantiateStreaming.
-#if MIN_FIREFOX_VERSION < 58 || MIN_CHROME_VERSION < 61 || ENVIRONMENT_MAY_BE_NODE || MIN_SAFARI_VERSION != TARGET_NOT_SUPPORTED || USE_PTHREADS
+#if MIN_FIREFOX_VERSION < 58 || MIN_CHROME_VERSION < 61 || ENVIRONMENT_MAY_BE_NODE || MIN_SAFARI_VERSION != TARGET_NOT_SUPPORTED || PTHREADS
   // In pthreads, Module['wasm'] is an already compiled WebAssembly.Module. In
   // that case, 'output' is a WebAssembly.Instance.
   // In main thread, Module['wasm'] is either a typed array or a fetch stream.
@@ -176,7 +176,7 @@ WebAssembly.instantiate(Module['wasm'], imports).then(function(output) {
 #endif
 
 #if USE_OFFSET_CONVERTER
-#if USE_PTHREADS
+#if PTHREADS
   if (!ENVIRONMENT_IS_PTHREAD)
 #endif
     wasmOffsetConverter = new WasmOffsetConverter(Module['wasm'], output.module);
@@ -227,7 +227,7 @@ WebAssembly.instantiate(Module['wasm'], imports).then(function(output) {
 #endif
 
   initRuntime(asm);
-#if USE_PTHREADS
+#if PTHREADS
   // Export Wasm module for pthread creation to access.
   wasmModule = output.module || Module['wasm'];
   PThread.loadWasmModuleToAllWorkers(ready);
diff --git a/src/preamble.js b/src/preamble.js
index f0ffc881719fa..69b09341662ec 100644
--- a/src/preamble.js
+++ b/src/preamble.js
@@ -202,7 +202,7 @@ function keepRuntimeAlive() {
 }
 
 function preRun() {
-#if ASSERTIONS && USE_PTHREADS
+#if ASSERTIONS && PTHREADS
   assert(!ENVIRONMENT_IS_PTHREAD); // PThreads reuse the runtime from the main thread.
 #endif
 #if expectToReceiveOnModule('preRun')
@@ -226,7 +226,7 @@ function initRuntime() {
   if (ENVIRONMENT_IS_WASM_WORKER) return __wasm_worker_initializeRuntime();
 #endif
 
-#if USE_PTHREADS
+#if PTHREADS
   if (ENVIRONMENT_IS_PTHREAD) return;
 #endif
 
@@ -252,7 +252,7 @@ function preMain() {
 #if STACK_OVERFLOW_CHECK
   checkStackCookie();
 #endif
-#if USE_PTHREADS
+#if PTHREADS
   if (ENVIRONMENT_IS_PTHREAD) return; // PThreads reuse the runtime from the main thread.
 #endif
   <<< ATMAINS >>>
@@ -275,7 +275,7 @@ function exitRuntime() {
 #if STACK_OVERFLOW_CHECK
   checkStackCookie();
 #endif
-#if USE_PTHREADS
+#if PTHREADS
   if (ENVIRONMENT_IS_PTHREAD) return; // PThreads reuse the runtime from the main thread.
 #endif
 #if !STANDALONE_WASM
@@ -283,7 +283,7 @@ function exitRuntime() {
 #endif
   callRuntimeCallbacks(__ATEXIT__);
   <<< ATEXITS >>>
-#if USE_PTHREADS
+#if PTHREADS
   PThread.terminateAllThreads();
 #endif
   runtimeExited = true;
@@ -294,7 +294,7 @@ function postRun() {
 #if STACK_OVERFLOW_CHECK
   checkStackCookie();
 #endif
-#if USE_PTHREADS
+#if PTHREADS
   if (ENVIRONMENT_IS_PTHREAD) return; // PThreads reuse the runtime from the main thread.
 #endif
 
@@ -991,7 +991,7 @@ function createWasm() {
 
     Module['asm'] = exports;
 
-#if USE_PTHREADS
+#if PTHREADS
 #if MAIN_MODULE
     registerTLSInit(Module['asm']['_emscripten_tls_init'], instance.exports, metadata);
 #else
@@ -1046,16 +1046,16 @@ function createWasm() {
     exportAsmFunctions(exports);
 #endif
 
-#if USE_PTHREADS || WASM_WORKERS
+#if PTHREADS || WASM_WORKERS
     // We now have the Wasm module loaded up, keep a reference to the compiled module so we can post it to the workers.
     wasmModule = module;
 #endif
 
-#if USE_PTHREADS
+#if PTHREADS
     PThread.loadWasmModuleToAllWorkers(() => removeRunDependency('wasm-instantiate'));
 #else // singlethreaded build:
     removeRunDependency('wasm-instantiate');
-#endif // ~USE_PTHREADS
+#endif // ~PTHREADS
 
     return exports;
   }
@@ -1085,7 +1085,7 @@ function createWasm() {
     receiveInstance(result['instance'], result['module']);
 #else
     // TODO: Due to Closure regression https://github.com/google/closure-compiler/issues/3193, the above line no longer optimizes out down to the following line.
-    // When the regression is fixed, can restore the above USE_PTHREADS-enabled path.
+    // When the regression is fixed, can restore the above PTHREADS-enabled path.
     receiveInstance(result['instance']);
 #endif
   }
@@ -1098,7 +1098,7 @@ function createWasm() {
   // Also pthreads and wasm workers initialize the wasm instance through this path.
   if (Module['instantiateWasm']) {
 #if USE_OFFSET_CONVERTER
-#if ASSERTIONS && USE_PTHREADS
+#if ASSERTIONS && PTHREADS
     if (ENVIRONMENT_IS_PTHREAD) {
       assert(Module['wasmOffsetData'], 'wasmOffsetData not found on Module object');
     }
@@ -1106,7 +1106,7 @@ function createWasm() {
     wasmOffsetConverter = resetPrototype(WasmOffsetConverter, Module['wasmOffsetData']);
 #endif
 #if LOAD_SOURCE_MAP
-#if ASSERTIONS && USE_PTHREADS
+#if ASSERTIONS && PTHREADS
     if (ENVIRONMENT_IS_PTHREAD) {
       assert(Module['wasmSourceMapData'], 'wasmSourceMapData not found on Module object');
     }
@@ -1143,7 +1143,7 @@ function createWasm() {
   return {}; // no exports yet; we'll fill them in later
 #else
   var result = instantiateSync(wasmBinaryFile, info);
-#if USE_PTHREADS || MAIN_MODULE
+#if PTHREADS || MAIN_MODULE
   return receiveInstance(result[0], result[1]);
 #else
   // TODO: Due to Closure regression https://github.com/google/closure-compiler/issues/3193,
@@ -1173,7 +1173,7 @@ function getCompilerSetting(name) {
 var memoryInitializer = <<< MEM_INITIALIZER >>>;
 
 function runMemoryInitializer() {
-#if USE_PTHREADS
+#if PTHREADS
   if (ENVIRONMENT_IS_PTHREAD) return;
 #endif
   if (!isDataURI(memoryInitializer)) {
diff --git a/src/preamble_minimal.js b/src/preamble_minimal.js
index bedb131ac189f..dc6ea52ad9e6b 100644
--- a/src/preamble_minimal.js
+++ b/src/preamble_minimal.js
@@ -94,7 +94,7 @@ function updateMemoryViews() {
 }
 
 #if IMPORTED_MEMORY
-#if USE_PTHREADS
+#if PTHREADS
 if (!ENVIRONMENT_IS_PTHREAD) {
 #endif
   wasmMemory =
@@ -110,14 +110,14 @@ if (!ENVIRONMENT_IS_PTHREAD) {
     , 'shared': true
 #endif
     });
-#if USE_PTHREADS
+#if PTHREADS
 }
 #if MODULARIZE
 else {
   wasmMemory = Module['wasmMemory'];
 }
 #endif // MODULARIZE
-#endif // USE_PTHREADS
+#endif // PTHREADS
 
 updateMemoryViews();
 #endif // IMPORTED_MEMORY
diff --git a/src/proxyWorker.js b/src/proxyWorker.js
index ec92a51b6edf7..c70aaa90b1d2a 100644
--- a/src/proxyWorker.js
+++ b/src/proxyWorker.js
@@ -382,12 +382,12 @@ Module['postMainLoop'] = function() {
 
 // Wait to start running until we receive some info from the client
 
-#if USE_PTHREADS
+#if PTHREADS
 if (!ENVIRONMENT_IS_PTHREAD) {
 #endif
   addRunDependency('gl-prefetch');
   addRunDependency('worker-init');
-#if USE_PTHREADS
+#if PTHREADS
 }
 #endif
 
@@ -484,7 +484,7 @@ function onMessageFromMainEmscriptenThread(message) {
       screen.height = Module.canvas.height_ = message.data.height;
       Module.canvas.boundingClientRect = message.data.boundingClientRect;
       document.URL = message.data.URL;
-#if USE_PTHREADS
+#if PTHREADS
       currentScriptUrl = message.data.currentScriptUrl;
 #endif
       window.fireEvent({ type: 'load' });
@@ -507,11 +507,11 @@ function onMessageFromMainEmscriptenThread(message) {
   }
 };
 
-#if USE_PTHREADS
+#if PTHREADS
 if (!ENVIRONMENT_IS_PTHREAD) {
 #endif
   onmessage = onMessageFromMainEmscriptenThread;
-#if USE_PTHREADS
+#if PTHREADS
 }
 #endif
 
diff --git a/src/runtime_debug.js b/src/runtime_debug.js
index 89cebe542b536..96663a21659d9 100644
--- a/src/runtime_debug.js
+++ b/src/runtime_debug.js
@@ -129,7 +129,7 @@ function prettyPrint(arg) {
 #if ASSERTIONS || RUNTIME_DEBUG
 // Used by XXXXX_DEBUG settings to output debug messages.
 function dbg(text) {
-#if ENVIRONMENT_MAY_BE_NODE && USE_PTHREADS
+#if ENVIRONMENT_MAY_BE_NODE && PTHREADS
   // Avoid using the console for debugging in multi-threaded node applications
   // See https://github.com/emscripten-core/emscripten/issues/14804
   if (ENVIRONMENT_IS_NODE) {
diff --git a/src/runtime_init_memory.js b/src/runtime_init_memory.js
index 4b87f96c02322..a22027493755c 100644
--- a/src/runtime_init_memory.js
+++ b/src/runtime_init_memory.js
@@ -15,11 +15,11 @@ assert(INITIAL_MEMORY >= {{{STACK_SIZE}}}, 'INITIAL_MEMORY should be larger than
 
 // check for full engine support (use string 'subarray' to avoid closure compiler confusion)
 
-#if USE_PTHREADS
+#if PTHREADS
 if (ENVIRONMENT_IS_PTHREAD) {
   wasmMemory = Module['wasmMemory'];
 } else {
-#endif // USE_PTHREADS
+#endif // PTHREADS
 
 #if expectToReceiveOnModule('wasmMemory')
   if (Module['wasmMemory']) {
@@ -55,7 +55,7 @@ if (ENVIRONMENT_IS_PTHREAD) {
 #endif
   }
 
-#if USE_PTHREADS
+#if PTHREADS
 }
 #endif
 
diff --git a/src/settings.js b/src/settings.js
index 957ace4412cc6..1a9c436f0a3f9 100644
--- a/src/settings.js
+++ b/src/settings.js
@@ -1516,11 +1516,6 @@ var USE_SQLITE3 = false;
 // [compile+link] - affects user code at compile and system libraries at link.
 var SHARED_MEMORY = false;
 
-// If true, enables support for pthreads. This implies SHARED_MEMORY.
-// This setting is equivalent to `-pthread`, which should be preferred.
-// [compile+link] - affects user code at compile and system libraries at link.
-var USE_PTHREADS = false;
-
 // If true, enables support for Wasm Workers. Wasm Workers enable applications
 // to create threads using a lightweight web-specific API that builds on top
 // of Wasm SharedArrayBuffer + Atomics API.
@@ -2015,7 +2010,7 @@ var PURE_WASI = false;
 // it to JavaScript.
 // Use of the following settings will enable this settings since they
 // depend on being able to define the memory in JavaScript:
-// - USE_PTHREADS
+// - -pthread
 // - RELOCATABLE
 // - ASYNCIFY_LAZY_LOAD_CODE
 // - WASM2JS (WASM=0)
@@ -2178,4 +2173,5 @@ var LEGACY_SETTINGS = [
   ['SHELL_FILE', [''], 'No longer supported'],
   ['LLD_REPORT_UNDEFINED', [1], 'Disabling is no longer supported'],
   ['MEM_INIT_METHOD', [0], 'No longer supported'],
+  ['USE_PTHREADS', [0, 1], 'No longer needed. Use -pthread instead'],
 ];
diff --git a/src/settings_internal.js b/src/settings_internal.js
index 65a26eb8e44d3..fb0271691c580 100644
--- a/src/settings_internal.js
+++ b/src/settings_internal.js
@@ -256,3 +256,6 @@ var HAVE_EM_ASM = true;
 var PRE_JS_FILES = [];
 
 var POST_JS_FILES = [];
+
+// Set when -pthread / -sPTHREADS is passed
+var PTHREADS = false;
diff --git a/src/shell.js b/src/shell.js
index 33763dec4c4b5..5375e1daa5799 100644
--- a/src/shell.js
+++ b/src/shell.js
@@ -98,7 +98,7 @@ var ENVIRONMENT_IS_AUDIO_WORKLET = typeof AudioWorkletGlobalScope !== 'undefined
 
 #if ENVIRONMENT && !ENVIRONMENT.includes(',')
 var ENVIRONMENT_IS_WEB = {{{ ENVIRONMENT === 'web' }}};
-#if USE_PTHREADS && ENVIRONMENT_MAY_BE_NODE
+#if PTHREADS && ENVIRONMENT_MAY_BE_NODE
 // node+pthreads always supports workers; detect which we are at runtime
 var ENVIRONMENT_IS_WORKER = typeof importScripts == 'function';
 #else
@@ -126,7 +126,7 @@ if (Module['ENVIRONMENT']) {
 }
 #endif
 
-#if USE_PTHREADS
+#if PTHREADS
 // Three configurations we can be running in:
 // 1) We could be the application main() thread running in the main JS UI thread. (ENVIRONMENT_IS_WORKER == false and ENVIRONMENT_IS_PTHREAD == false)
 // 2) We could be the application main() thread proxied to worker. (with Emscripten -sPROXY_TO_WORKER) (ENVIRONMENT_IS_WORKER == true, ENVIRONMENT_IS_PTHREAD == false)
@@ -262,7 +262,7 @@ if (ENVIRONMENT_IS_NODE) {
 
   Module['inspect'] = function () { return '[Emscripten Module object]'; };
 
-#if USE_PTHREADS
+#if PTHREADS
   let nodeWorkerThreads;
   try {
     nodeWorkerThreads = require('worker_threads');
@@ -408,7 +408,7 @@ if (ENVIRONMENT_IS_WEB || ENVIRONMENT_IS_WORKER) {
 
   // Differentiate the Web Worker from the Node Worker case, as reading must
   // be done differently.
-#if USE_PTHREADS && ENVIRONMENT_MAY_BE_NODE
+#if PTHREADS && ENVIRONMENT_MAY_BE_NODE
   if (!ENVIRONMENT_IS_NODE)
 #endif
   {
@@ -427,7 +427,7 @@ if (!ENVIRONMENT_IS_AUDIO_WORKLET)
 #endif // ASSERTIONS
 }
 
-#if ENVIRONMENT_MAY_BE_NODE && USE_PTHREADS
+#if ENVIRONMENT_MAY_BE_NODE && PTHREADS
 if (ENVIRONMENT_IS_NODE) {
   // Polyfill the performance object, which emscripten pthreads support
   // depends on for good timing.
@@ -495,14 +495,14 @@ assert(typeof Module['TOTAL_MEMORY'] == 'undefined', 'Module.TOTAL_MEMORY has be
 {{{ makeRemovedFSAssert('NODEFS') }}}
 #endif
 
-#if USE_PTHREADS
+#if PTHREADS
 assert(
 #if AUDIO_WORKLET
   ENVIRONMENT_IS_AUDIO_WORKLET ||
 #endif
   ENVIRONMENT_IS_WEB || ENVIRONMENT_IS_WORKER || ENVIRONMENT_IS_NODE, 'Pthreads do not work in this environment yet (need Web Workers, or an alternative to them)');
 #else
-#endif // USE_PTHREADS
+#endif // PTHREADS
 
 #if !ENVIRONMENT_MAY_BE_WEB
 assert(!ENVIRONMENT_IS_WEB, "web environment detected but not enabled at build time.  Add 'web' to `-sENVIRONMENT` to enable.");
diff --git a/src/shell_minimal.js b/src/shell_minimal.js
index 2729c608d8c67..d019d388ffd6b 100644
--- a/src/shell_minimal.js
+++ b/src/shell_minimal.js
@@ -56,7 +56,7 @@ var ENVIRONMENT_IS_SHELL = typeof read == 'function';
 var ENVIRONMENT_IS_AUDIO_WORKLET = typeof AudioWorkletGlobalScope !== 'undefined';
 #endif
 
-#if ASSERTIONS || USE_PTHREADS
+#if ASSERTIONS || PTHREADS
 #if !ENVIRONMENT_MAY_BE_NODE && !ENVIRONMENT_MAY_BE_SHELL
 var ENVIRONMENT_IS_WEB = true
 #elif ENVIRONMENT && !ENVIRONMENT.includes(',')
@@ -68,7 +68,7 @@ var ENVIRONMENT_IS_WEB = !ENVIRONMENT_IS_SHELL;
 #else
 var ENVIRONMENT_IS_WEB = !ENVIRONMENT_IS_NODE;
 #endif
-#endif // ASSERTIONS || USE_PTHREADS
+#endif // ASSERTIONS || PTHREADS
 
 #if WASM_WORKERS
 var ENVIRONMENT_IS_WASM_WORKER = Module['$ww'];
@@ -138,7 +138,7 @@ function ready() {
 #elif ASSERTIONS
   out('ready() called, and INVOKE_RUN=0. The runtime is now ready for you to call run() to invoke application _main(). You can also override ready() in a --pre-js file to get this signal as a callback')
 #endif
-#if USE_PTHREADS
+#if PTHREADS
   // This Worker is now ready to host pthreads, tell the main thread we can proceed.
   if (ENVIRONMENT_IS_PTHREAD) {
     startWorker(Module);
@@ -157,7 +157,7 @@ function ready() {
 // refer to Module (if they choose; they can also define Module)
 {{{ preJS() }}}
 
-#if USE_PTHREADS
+#if PTHREADS
 
 #if !MODULARIZE
 // In MODULARIZE mode _scriptDir needs to be captured already at the very top of the page immediately when the page is parsed, so it is generated there
@@ -175,4 +175,4 @@ var ENVIRONMENT_IS_WORKER = ENVIRONMENT_IS_PTHREAD = typeof importScripts == 'fu
 #endif
 
 var currentScriptUrl = typeof _scriptDir != 'undefined' ? _scriptDir : ((typeof document != 'undefined' && document.currentScript) ? document.currentScript.src : undefined);
-#endif // USE_PTHREADS
+#endif // PTHREADS
diff --git a/test/test_other.py b/test/test_other.py
index 8889b251b7017..2373915088648 100644
--- a/test/test_other.py
+++ b/test/test_other.py
@@ -186,6 +186,7 @@ def do_other_test(self, testname, emcc_args=None, **kwargs):
   def run_on_pty(self, cmd):
     master, slave = os.openpty()
     output = []
+    print(cmd)
 
     try:
       with env_modify({'TERM': 'xterm-color'}):
diff --git a/tools/deps_info.py b/tools/deps_info.py
index 8671b86b8795e..34619fa6683d0 100644
--- a/tools/deps_info.py
+++ b/tools/deps_info.py
@@ -197,11 +197,11 @@ def get_deps_info():
     _deps_info['__cxa_find_matching_catch_7'] = ['__cxa_can_catch', 'setTempRet0']
     _deps_info['__cxa_find_matching_catch_8'] = ['__cxa_can_catch', 'setTempRet0']
     _deps_info['__cxa_find_matching_catch_9'] = ['__cxa_can_catch', 'setTempRet0']
-  if settings.USE_PTHREADS and settings.OFFSCREENCANVAS_SUPPORT:
+  if settings.PTHREADS and settings.OFFSCREENCANVAS_SUPPORT:
     _deps_info['pthread_create'] = ['malloc']
   if settings.FILESYSTEM and settings.SYSCALLS_REQUIRE_FILESYSTEM:
     _deps_info['mmap'] = ['emscripten_builtin_memalign']
-  if settings.USE_PTHREADS:
+  if settings.PTHREADS:
     _deps_info['glutCreateWindow'] = ['malloc']
     _deps_info['emscripten_webgl_create_context'] = ['malloc']
     _deps_info['emscripten_webgl_destroy_context'] = ['free']
diff --git a/tools/feature_matrix.py b/tools/feature_matrix.py
index 9530d5df56c26..a20086d21ea4b 100644
--- a/tools/feature_matrix.py
+++ b/tools/feature_matrix.py
@@ -109,6 +109,6 @@ def enable_feature(feature, reason):
 def apply_min_browser_versions():
   if settings.WASM_BIGINT:
     enable_feature(Feature.JS_BIGINT_INTEGRATION, 'WASM_BIGINT')
-  if settings.USE_PTHREADS:
+  if settings.PTHREADS:
     enable_feature(Feature.THREADS, 'pthreads')
     enable_feature(Feature.BULK_MEMORY, 'pthreads')
diff --git a/tools/ports/harfbuzz.py b/tools/ports/harfbuzz.py
index ad05f9854cc23..7e1012d9aa624 100644
--- a/tools/ports/harfbuzz.py
+++ b/tools/ports/harfbuzz.py
@@ -10,7 +10,7 @@
 HASH = '2e5ab5ad83a0d8801abd3f82a276f776a0ad330edc0ab843f879dd7ad3fd2e0dc0e9a3efbb6c5f2e67d14c0e37f0d9abdb40c5e25d8231a357c0025669f219c3'
 
 deps = ['freetype']
-variants = {'harfbuzz-mt': {'USE_PTHREADS': 1}}
+variants = {'harfbuzz-mt': ['-pthread']}
 
 srcs = '''
 hb-aat-layout.cc
@@ -76,7 +76,7 @@ def needed(settings):
 
 
 def get_lib_name(settings):
-  return 'libharfbuzz' + ('-mt' if settings.USE_PTHREADS else '') + '.a'
+  return 'libharfbuzz' + ('-mt' if settings.PTHREADS else '') + '.a'
 
 
 def get(ports, settings, shared):
@@ -124,7 +124,7 @@ def create(final):
     if settings.RELOCATABLE:
       cflags.append('-fPIC')
 
-    if settings.USE_PTHREADS:
+    if settings.PTHREADS:
       cflags.append('-pthread')
       cflags.append('-DHAVE_PTHREAD')
     else:
diff --git a/tools/ports/icu.py b/tools/ports/icu.py
index 3b9bb964f0494..ca0171ba97e09 100644
--- a/tools/ports/icu.py
+++ b/tools/ports/icu.py
@@ -10,7 +10,7 @@
 VERSION = '68_2'
 HASH = '12c3db5966c234c94e7918fb8acc8bd0838edc36a620f3faa788e7ff27b06f1aa431eb117401026e3963622b9323212f444b735d5c9dd3d0b82d772a4834b993'
 
-variants = {'icu-mt': {'USE_PTHREADS': 1}}
+variants = {'icu-mt': {'PTHREADS': 1}}
 
 libname_libicu_common = 'libicu_common'
 libname_libicu_stubdata = 'libicu_stubdata'
@@ -22,7 +22,7 @@ def needed(settings):
 
 
 def get_lib_name(base_name, settings):
-  return base_name + ('-mt' if settings.USE_PTHREADS else '') + '.a'
+  return base_name + ('-mt' if settings.PTHREADS else '') + '.a'
 
 
 def get(ports, settings, shared):
@@ -53,7 +53,7 @@ def build_lib(lib_output, lib_src, other_includes, build_flags):
         # CXXFLAGS
         '-std=c++11'
     ]
-    if settings.USE_PTHREADS:
+    if settings.PTHREADS:
       additional_build_flags.append('-pthread')
 
     ports.build_port(lib_src, lib_output, 'icu', includes=other_includes, flags=build_flags + additional_build_flags)
diff --git a/tools/ports/libpng.py b/tools/ports/libpng.py
index af81e8296946e..1e9c91b3670a6 100644
--- a/tools/ports/libpng.py
+++ b/tools/ports/libpng.py
@@ -10,7 +10,7 @@
 HASH = '2ce2b855af307ca92a6e053f521f5d262c36eb836b4810cb53c809aa3ea2dcc08f834aee0ffd66137768a54397e28e92804534a74abb6fc9f6f3127f14c9c338'
 
 deps = ['zlib']
-variants = {'libpng-mt': {'USE_PTHREADS': 1}}
+variants = {'libpng-mt': {'PTHREADS': 1}}
 
 
 def needed(settings):
@@ -18,7 +18,7 @@ def needed(settings):
 
 
 def get_lib_name(settings):
-  return 'libpng' + ('-mt' if settings.USE_PTHREADS else '') + '.a'
+  return 'libpng' + ('-mt' if settings.PTHREADS else '') + '.a'
 
 
 def get(ports, settings, shared):
@@ -33,7 +33,7 @@ def create(final):
     ports.install_headers(source_path)
 
     flags = ['-sUSE_ZLIB']
-    if settings.USE_PTHREADS:
+    if settings.PTHREADS:
       flags += ['-pthread']
 
     ports.build_port(source_path, final, 'libpng', flags=flags, exclude_files=['pngtest'], exclude_dirs=['scripts', 'contrib'])
diff --git a/tools/ports/regal.py b/tools/ports/regal.py
index a70876001fc29..7b16ea523bc35 100644
--- a/tools/ports/regal.py
+++ b/tools/ports/regal.py
@@ -9,7 +9,7 @@
 TAG = 'version_7'
 HASH = 'a921dab254f21cf5d397581c5efe58faf147c31527228b4fb34aed75164c736af4b3347092a8d9ec1249160230fa163309a87a20c2b9ceef8554566cc215de9d'
 
-variants = {'regal-mt': {'USE_PTHREADS': 1}}
+variants = {'regal-mt': {'PTHREADS': 1}}
 
 
 def needed(settings):
@@ -17,7 +17,7 @@ def needed(settings):
 
 
 def get_lib_name(settings):
-  return 'libregal' + ('-mt' if settings.USE_PTHREADS else '') + '.a'
+  return 'libregal' + ('-mt' if settings.PTHREADS else '') + '.a'
 
 
 def get(ports, settings, shared):
@@ -113,7 +113,7 @@ def create(final):
       '-Wno-deprecated-register',
       '-Wno-unused-parameter'
     ]
-    if settings.USE_PTHREADS:
+    if settings.PTHREADS:
       flags += ['-pthread']
 
     ports.build_port(source_path_src, final, 'regal', srcs=srcs_regal, flags=flags)
diff --git a/tools/ports/sdl2.py b/tools/ports/sdl2.py
index a0a759366b872..24dd8757195f7 100644
--- a/tools/ports/sdl2.py
+++ b/tools/ports/sdl2.py
@@ -9,7 +9,7 @@
 HASH = 'b178bdc8f7c40271e09a72f639649d1d61953dda4dc12b77437259667b63b961fd3b2c67b0de6fdc5f9f9c80c49bfafd164e4c13715bc1056e550acc8bad5a3c'
 SUBDIR = 'SDL-' + TAG
 
-variants = {'sdl2-mt': {'USE_PTHREADS': 1}}
+variants = {'sdl2-mt': {'PTHREADS': 1}}
 
 
 def needed(settings):
@@ -17,7 +17,7 @@ def needed(settings):
 
 
 def get_lib_name(settings):
-  return 'libSDL2' + ('-mt' if settings.USE_PTHREADS else '') + '.a'
+  return 'libSDL2' + ('-mt' if settings.PTHREADS else '') + '.a'
 
 
 def get(ports, settings, shared):
@@ -64,13 +64,13 @@ def create(final):
     main/dummy/SDL_dummy_main.c locale/SDL_locale.c locale/emscripten/SDL_syslocale.c misc/SDL_url.c
     misc/emscripten/SDL_sysurl.c'''.split()
     thread_srcs = ['SDL_syscond.c', 'SDL_sysmutex.c', 'SDL_syssem.c', 'SDL_systhread.c', 'SDL_systls.c']
-    thread_backend = 'generic' if not settings.USE_PTHREADS else 'pthread'
+    thread_backend = 'generic' if not settings.PTHREADS else 'pthread'
     srcs += ['thread/%s/%s' % (thread_backend, s) for s in thread_srcs]
 
     srcs = [os.path.join(src_dir, 'src', s) for s in srcs]
     flags = ['-sUSE_SDL=0']
     includes = [ports.get_include_dir('SDL2')]
-    if settings.USE_PTHREADS:
+    if settings.PTHREADS:
       flags += ['-pthread']
     ports.build_port(src_dir, final, 'sdl2', srcs=srcs, includes=includes, flags=flags)
 
diff --git a/tools/ports/sqlite3.py b/tools/ports/sqlite3.py
index 97123e7eb1ef6..dcbb5b5b6020d 100644
--- a/tools/ports/sqlite3.py
+++ b/tools/ports/sqlite3.py
@@ -12,7 +12,7 @@
 VERSION_YEAR = 2022
 HASH = 'cbaf4adb3e404d9aa403b34f133c5beca5f641ae1e23f84dbb021da1fb9efdc7c56b5922eb533ae5cb6d26410ac60cb3f026085591bc83ebc1c225aed0cf37ca'
 
-variants = {'sqlite3-mt': {'USE_PTHREADS': 1}}
+variants = {'sqlite3-mt': {'PTHREADS': 1}}
 
 
 def needed(settings):
@@ -20,7 +20,7 @@ def needed(settings):
 
 
 def get_lib_name(settings):
-  return 'libsqlite3' + ('-mt' if settings.USE_PTHREADS else '') + '.a'
+  return 'libsqlite3' + ('-mt' if settings.PTHREADS else '') + '.a'
 
 
 def get(ports, settings, shared):
@@ -63,7 +63,7 @@ def create(final):
       '-DSQLITE_ENABLE_GEOPOLY=1',
       '-DSQLITE_OMIT_POPEN=1',
     ]
-    if settings.USE_PTHREADS:
+    if settings.PTHREADS:
       flags += [
         '-pthread',
         '-DSQLITE_THREADSAFE=1',
diff --git a/tools/settings.py b/tools/settings.py
index fd41dde2410d5..53c016a4067d6 100644
--- a/tools/settings.py
+++ b/tools/settings.py
@@ -55,6 +55,7 @@
 # Subset of settings that apply at compile time.
 # (Keep in sync with [compile] comments in settings.js)
 COMPILE_TIME_SETTINGS = {
+    'PTHREADS',
     'MEMORY64',
     'INLINING_LIMIT',
     'DISABLE_EXCEPTION_CATCHING',
diff --git a/tools/system_libs.py b/tools/system_libs.py
index 05022c7b5e0f5..8bf9bb24297d5 100644
--- a/tools/system_libs.py
+++ b/tools/system_libs.py
@@ -650,7 +650,7 @@ def vary_on(cls):
 
   @classmethod
   def get_default_variation(cls, **kwargs):
-    return super().get_default_variation(is_mt=settings.USE_PTHREADS, is_ww=settings.WASM_WORKERS and not settings.USE_PTHREADS, **kwargs)
+    return super().get_default_variation(is_mt=settings.PTHREADS, is_ww=settings.WASM_WORKERS and not settings.PTHREADS, **kwargs)
 
   @classmethod
   def variations(cls):