make_export_wrappers: Limit module exports to EXPORTED_FUNCTIONS

This is code size win in pretty much all cases since thee are always
a few wasm exports that don't need to be set on the module object.

ChangeLog.md

@@ -20,6 +20,11 @@ See docs/process.md for more on how version tagging works.
 
 3.1.31 (in development)
 -----------------------
+- Symbols that were previously exported from native code, but only for internal
+  reasons, are no longer exported on the `Module` object by default.  For
+  example, previously if you were using `Module._malloc` but not explicitly
+  including `_malloc` in `EXPORTED_FUNCTIONS` if might have been exported anyway
+  due to internal using of `malloc` within the JS library code. (#18564)
 - The `STACK_SIZE`, `STACK_ALIGN`, `POINTER_SIZE`, and `ASSERTIONS` JavaScript
   globals were removed by default.  In debug builds a clear error is shown if
   you try to use these. (#18503)

emscripten.py

@@ -315,6 +315,9 @@ def emscript(in_wasm, out_wasm, outfile_js, memfile):
   if settings.RELOCATABLE and settings.MEMORY64 == 2:
     metadata.imports += ['__memory_base32']
 
+  if settings.ASYNCIFY:
+    metadata.exports += ['asyncify_start_unwind', 'asyncify_stop_unwind', 'asyncify_start_rewind', 'asyncify_stop_rewind']
+
   update_settings_glue(out_wasm, metadata)
 
   if not settings.WASM_BIGINT and metadata.emJsFuncs:
@@ -391,9 +394,6 @@ def emscript(in_wasm, out_wasm, outfile_js, memfile):
 
   exports = metadata.exports
 
-  if settings.ASYNCIFY:
-    exports += ['asyncify_start_unwind', 'asyncify_stop_unwind', 'asyncify_start_rewind', 'asyncify_stop_rewind']
-
   report_missing_symbols(forwarded_json['librarySymbols'])
 
   if not outfile_js:
@@ -696,6 +696,15 @@ def make_export_wrappers(exports, delay_assignment):
     if name == '__cpp_exception':
       continue
     mangled = asmjs_mangle(name)
+    wrapper = '/** @type {function(...*):?} */\nvar %s = ' % mangled
+
+    # TODO(sbc): Can we avoid exporting the dynCall_ functions on the module.
+    if mangled in settings.EXPORTED_FUNCTIONS or name.startswith('dynCall_'):
+      exported = 'Module["%s"] = ' % mangled
+    else:
+      exported = ''
+    wrapper += exported
+
     # The emscripten stack functions are called very early (by writeStackCookie) before
     # the runtime is initialized so we can't create these wrappers that check for
     # runtimeInitialized.
@@ -705,29 +714,20 @@ def make_export_wrappers(exports, delay_assignment):
       # With assertions enabled we create a wrapper that are calls get routed through, for
       # the lifetime of the program.
       if delay_assignment:
-        wrappers.append('''\
-/** @type {function(...*):?} */
-var %(mangled)s = Module["%(mangled)s"] = createExportWrapper("%(name)s");
-''' % {'mangled': mangled, 'name': name})
+        wrapper += 'createExportWrapper("%s");' % name
       else:
-        wrappers.append('''\
-/** @type {function(...*):?} */
-var %(mangled)s = Module["%(mangled)s"] = createExportWrapper("%(name)s", asm);
-''' % {'mangled': mangled, 'name': name})
+        wrapper += 'createExportWrapper("%s", asm);' % name
     elif delay_assignment:
       # With assertions disabled the wrapper will replace the global var and Module var on
       # first use.
-      wrappers.append('''\
-/** @type {function(...*):?} */
-var %(mangled)s = Module["%(mangled)s"] = function() {
-  return (%(mangled)s = Module["%(mangled)s"] = Module["asm"]["%(name)s"]).apply(null, arguments);
+      wrapper += '''function() {
+  return (%(mangled)s = %(exported)sModule["asm"]["%(name)s"]).apply(null, arguments);
 };
-''' % {'mangled': mangled, 'name': name})
+''' % {'mangled': mangled, 'name': name, 'exported': exported}
     else:
-      wrappers.append('''\
-/** @type {function(...*):?} */
-var %(mangled)s = Module["%(mangled)s"] = asm["%(name)s"]
-''' % {'mangled': mangled, 'name': name})
+      wrapper += 'asm["%s"]' % name
+
+    wrappers.append(wrapper)
   return wrappers
 
 

src/library_browser.js

@@ -1379,11 +1379,11 @@ var LibraryBrowser = {
     return 0;
   },
 
-  emscripten_get_preloaded_image_data_from_FILE__deps: ['emscripten_get_preloaded_image_data'],
+  emscripten_get_preloaded_image_data_from_FILE__deps: ['emscripten_get_preloaded_image_data', 'fileno'],
   emscripten_get_preloaded_image_data_from_FILE__proxy: 'sync',
   emscripten_get_preloaded_image_data_from_FILE__sig: 'iiii',
   emscripten_get_preloaded_image_data_from_FILE: function(file, w, h) {
-    var fd = Module['_fileno'](file);
+    var fd = _fileno(file);
     var stream = FS.getStream(fd);
     if (stream) {
       return _emscripten_get_preloaded_image_data(stream.path, w, h);

src/library_sdl.js

@@ -2262,13 +2262,13 @@ var LibrarySDL = {
         }
       }
       var callStbImage = function(func, params) {
-        var x = Module['_malloc']({{{ getNativeTypeSize('i32') }}});
-        var y = Module['_malloc']({{{ getNativeTypeSize('i32') }}});
-        var comp = Module['_malloc']({{{ getNativeTypeSize('i32') }}});
+        var x = _malloc({{{ getNativeTypeSize('i32') }}});
+        var y = _malloc({{{ getNativeTypeSize('i32') }}});
+        var comp = _malloc({{{ getNativeTypeSize('i32') }}});
         addCleanup(function() {
-          Module['_free'](x);
-          Module['_free'](y);
-          Module['_free'](comp);
+          _free(x);
+          _free(y);
+          _free(comp);
           if (data) Module['_stbi_image_free'](data);
         });
         var data = Module['_' + func].apply(null, params.concat([x, y, comp, 0]));
@@ -2307,10 +2307,10 @@ var LibrarySDL = {
           if (raw === null) err('Trying to reuse preloaded image, but freePreloadedMediaOnUse is set!');
 #if STB_IMAGE
           var lengthBytes = lengthBytesUTF8(filename)+1;
-          var name = Module['_malloc'](lengthBytes);
+          var name = _malloc(lengthBytes);
           stringToUTF8(filename, name, lengthBytes);
           addCleanup(function() {
-            Module['_free'](name);
+            _free(name);
           });
           raw = callStbImage('stbi_load', [name]);
           if (!raw) return 0;
@@ -2765,7 +2765,7 @@ var LibrarySDL = {
     return 1;
   },
 
-  Mix_LoadWAV_RW__deps: ['$PATH_FS'],
+  Mix_LoadWAV_RW__deps: ['$PATH_FS', 'fileno'],
   Mix_LoadWAV_RW__proxy: 'sync',
   Mix_LoadWAV_RW__sig: 'iii',
   Mix_LoadWAV_RW__docs: '/** @param {number|boolean=} freesrc */',
@@ -2778,7 +2778,7 @@ var LibrarySDL = {
 
       if (type === 2/*SDL_RWOPS_STDFILE*/) {
         var fp = {{{ makeGetValue('rwopsID + ' + 28 /*hidden.stdio.fp*/, '0', 'i32') }}};
-        var fd = Module['_fileno'](fp);
+        var fd = _fileno(fp);
         var stream = FS.getStream(fd);
         if (stream) {
           rwops = { filename: stream.path };

test/optimizer/applyDCEGraphRemovals-output.js

@@ -13,6 +13,8 @@ var expD3 = Module["expD3"] = asm["expD3"];
 
 var expD4;
 
+var expD5;
+
 var expI1 = Module["expI1"] = function() {
  return (expI1 = Module["expI1"] = Module["asm"]["expI1"]).apply(null, arguments);
 };
@@ -27,6 +29,8 @@ var expI3 = Module["expI3"] = function() {
 
 var expI4;
 
+var expI5;
+
 expD1;
 
 Module["expD2"];

test/optimizer/applyDCEGraphRemovals.js

@@ -6,6 +6,8 @@ var expD1 = Module['expD1'] = asm['expD1'];
 var expD2 = Module['expD2'] = asm['expD2'];
 var expD3 = Module['expD3'] = asm['expD3'];
 var expD4 = Module['expD4'] = asm['expD4'];
+// Like above, but not exported on the Module
+var expD5 = asm['expD5'];
 
 // exports gotten indirectly (async compilation
 var expI1 = Module['expI1'] = (function() {
@@ -20,6 +22,10 @@ var expI3 = Module['expI3'] = (function() {
 var expI4 = Module['expI4'] = (function() {
  return (expI4 = Module['expI4'] = Module['asm']['expI4']).apply(null, arguments);
 });
+// Like above, but not exported on the Module
+var expI5 = (function() {
+ return (expI5 = Module['asm']['expI5']).apply(null, arguments);
+});
 
 // add uses for some of them, leave *4 as non-roots
 expD1;
@@ -30,4 +36,4 @@ expI1;
 Module['expI2'];
 asm['expI3'];
 
-// EXTRA_INFO: { "unused": ["emcc$import$number", "emcc$import$name", "emcc$import$func", "emcc$export$expD4", "emcc$export$expI4"] }
+// EXTRA_INFO: { "unused": ["emcc$import$number", "emcc$import$name", "emcc$import$func", "emcc$export$expD4", "emcc$export$expD5", "emcc$export$expI4", "emcc$export$expI5"] }

test/optimizer/emitDCEGraph-output.js

@@ -100,6 +100,11 @@
   "export": "expD4",
   "reaches": []
  },
+ {
+  "name": "emcc$export$expD5",
+  "export": "expD5",
+  "reaches": []
+ },
  {
   "name": "emcc$export$expI1",
   "export": "expI1",
@@ -123,6 +128,11 @@
   "export": "expI4",
   "reaches": []
  },
+ {
+  "name": "emcc$export$expI5",
+  "export": "expI5",
+  "reaches": []
+ },
  {
   "name": "emcc$import$rootedFunc1",
   "import": [

test/optimizer/emitDCEGraph.js

@@ -49,6 +49,8 @@ var expD1 = Module['expD1'] = asm['expD1'];
 var expD2 = Module['expD2'] = asm['expD2'];
 var expD3 = Module['expD3'] = asm['expD3'];
 var expD4 = Module['expD4'] = asm['expD4'];
+// Same as above but not export on the Module
+var expD5 = asm['expD5'];
 
 // exports gotten indirectly (async compilation
 var expI1 = Module['expI1'] = function() {
@@ -63,6 +65,10 @@ var expI3 = Module['expI3'] = function() {
 var expI4 = Module['expI4'] = function() {
  return (expI4 = Module['expI4'] = Module['asm']['expI4']).apply(null, arguments);
 };
+// Same as above but not export on the Module.
+var expI5 = function() {
+ return (expI5 = Module['asm']['expI5']).apply(null, arguments);
+};
 
 // add uses for some of them
 expD1;

test/other/metadce/test_metadce_cxx_ctors1.jssize

@@ -1 +1 @@
-26600
+26008

test/other/metadce/test_metadce_cxx_ctors2.jssize

@@ -1 +1 @@
-26564
+25972

test/other/metadce/test_metadce_cxx_except.jssize

@@ -1 +1 @@
-31193
+30545

test/other/metadce/test_metadce_cxx_except_wasm.jssize

@@ -1 +1 @@
-26078
+25581

test/other/metadce/test_metadce_cxx_mangle.jssize

@@ -1 +1 @@
-31437
+30545

test/other/metadce/test_metadce_cxx_noexcept.jssize

@@ -1 +1 @@
-26600
+26008

test/other/metadce/test_metadce_hello_O0.jssize

@@ -1 +1 @@
-26963
+26284

test/other/metadce/test_metadce_hello_O1.jssize

@@ -1 +1 @@
-9214
+8678

test/other/metadce/test_metadce_hello_O2.jssize

@@ -1 +1 @@
-6610
+6138

test/other/metadce/test_metadce_hello_O3.jssize

@@ -1 +1 @@
-6060
+5968

test/other/metadce/test_metadce_hello_Os.jssize

@@ -1 +1 @@
-6060
+5968

test/other/metadce/test_metadce_hello_Oz.jssize

@@ -1 +1 @@
-6019
+5927

test/other/metadce/test_metadce_hello_export_nothing.jssize

@@ -1 +1 @@
-4740
+4648

test/other/metadce/test_metadce_libcxxabi_message_O3.jssize

@@ -1 +1 @@
-5333
+5241

test/other/metadce/test_metadce_mem_O3.jssize

@@ -1 +1 @@
-6213
+6094

test/other/metadce/test_metadce_mem_O3_grow.jssize

@@ -1 +1 @@
-6555
+6436

test/other/metadce/test_metadce_minimal_O0.jssize

@@ -1 +1 @@
-23612
+22850

test/other/metadce/test_metadce_minimal_O1.jssize

@@ -1 +1 @@
-5732
+5196

test/other/metadce/test_metadce_minimal_O2.jssize

@@ -1 +1 @@
-4447
+3975

test/other/metadce/test_metadce_minimal_O3.jssize

@@ -1 +1 @@
-3956
+3864

test/other/metadce/test_metadce_minimal_Os.jssize

@@ -1 +1 @@
-3956
+3864

test/other/metadce/test_metadce_minimal_Oz.jssize

@@ -1 +1 @@
-3956
+3864

test/other/metadce/test_metadce_minimal_pthreads.jssize

@@ -1 +1 @@
-16177
+15787

test/other/test_unoptimized_code_size.js.size

@@ -1 +1 @@
-67096
+66571

test/other/test_unoptimized_code_size_no_asserts.js.size

@@ -1 +1 @@
-38780
+38518

test/other/test_unoptimized_code_size_strict.js.size

@@ -1 +1 @@
-65962
+65437

test/test_browser.py

@@ -4392,7 +4392,7 @@ def test_small_js_flags(self):
     size = os.path.getsize('test.js')
     print('size:', size)
     # Note that this size includes test harness additions (for reporting the result, etc.).
-    self.assertLess(abs(size - 5169), 100)
+    self.assertLess(abs(size - 5059), 100)
 
   # Tests that it is possible to initialize and render WebGL content in a pthread by using OffscreenCanvas.
   # -DTEST_CHAINED_WEBGL_CONTEXT_PASSING: Tests that it is possible to transfer WebGL canvas in a chain from main thread -> thread 1 -> thread 2 and then init and render WebGL content there.