Stop including malloc/free by default

ChangeLog.md

@@ -17,6 +17,9 @@ See docs/process.md for how version tagging works.
 
 Current Trunk
 -------------
+- Stop including `malloc` and `free` by default. If you need access to them from
+  JS, you must export them manually using
+  `-s EXPORTED_FUNCTIONS=['_malloc', ..]`.
 - Add `ERROR_ON_WASM_CHANGES_AFTER_LINK` option that errors if we need to do
   any work in `wasm-emscripten-finalize` or `wasm-opt` after linking. This
   can verify the link is maximally fast and also does no DWARF rewriting.

emcc.py

@@ -1398,12 +1398,6 @@ def check(input_file):
     if shared.Settings.EMBIND:
       forced_stdlibs.append('libembind')
 
-    if not shared.Settings.MINIMAL_RUNTIME and not shared.Settings.STANDALONE_WASM:
-      # The normal JS runtime depends on malloc and free so always keep them alive.
-      # MINIMAL_RUNTIME avoids this dependency as does STANDALONE_WASM mode (since it has no
-      # JS runtime at all).
-      shared.Settings.EXPORTED_FUNCTIONS += ['_malloc', '_free']
-
     shared.Settings.EXPORTED_FUNCTIONS += ['_stackSave', '_stackRestore', '_stackAlloc']
     # We need to preserve the __data_end symbol so that wasm-emscripten-finalize can determine
     # where static data ends (and correspondingly where the stack begins).
@@ -1532,7 +1526,7 @@ def check(input_file):
 
     if shared.Settings.USE_PTHREADS:
       # memalign is used to ensure allocated thread stacks are aligned.
-      shared.Settings.EXPORTED_FUNCTIONS += ['_memalign', '_malloc']
+      shared.Settings.EXPORTED_FUNCTIONS += ['_memalign']
 
       # dynCall is used to call pthread entry points in worker.js (as
       # metadce does not consider worker.js, which is external, we must
@@ -1754,6 +1748,26 @@ def include_and_export(name):
     if sanitize and '-g4' in args:
       shared.Settings.LOAD_SOURCE_MAP = 1
 
+    # various settings require malloc/free support from JS
+    if shared.Settings.RELOCATABLE or \
+       shared.Settings.BUILD_AS_WORKER or \
+       shared.Settings.USE_WEBGPU or \
+       shared.Settings.USE_PTHREADS or \
+       shared.Settings.OFFSCREENCANVAS_SUPPORT or \
+       shared.Settings.LEGACY_GL_EMULATION or \
+       shared.Settings.DISABLE_EXCEPTION_CATCHING != 1 or \
+       shared.Settings.ASYNCIFY or \
+       shared.Settings.ASMFS or \
+       shared.Settings.DEMANGLE_SUPPORT or \
+       shared.Settings.FORCE_FILESYSTEM or \
+       shared.Settings.STB_IMAGE or \
+       shared.Settings.EMBIND or \
+       shared.Settings.FETCH or \
+       shared.Settings.PROXY_POSIX_SOCKETS or \
+       options.memory_profiler or \
+       sanitize:
+      shared.Settings.EXPORTED_FUNCTIONS += ['_malloc', '_free']
+
     options.binaryen_passes += backend_binaryen_passes()
 
     if shared.Settings.WASM2JS and use_source_map(options):

emscripten.py

@@ -249,10 +249,6 @@ def report_missing_symbols(all_implemented, pre):
   for requested in missing:
     if ('function ' + asstr(requested)) in pre:
       continue
-    # special-case malloc, EXPORTED by default for internal use, but we bake in a
-    # trivial allocator and warn at runtime if used in ASSERTIONS
-    if missing == '_malloc':
-      continue
     diagnostics.warning('undefined', 'undefined exported function: "%s"', requested)
 
   # Special hanlding for the `_main` symbol

src/deps_info.json

@@ -4,40 +4,50 @@
   "getenv": ["malloc", "free"],
   "SDL_getenv": ["malloc", "free"],
   "dlerror": ["malloc", "free"],
-  "readdir": ["malloc"],
-  "ttyname": ["malloc"],
-  "calloc": ["malloc"],
+  "dladdr": ["malloc", "free"],
+  "readdir": ["malloc", "free"],
+  "ttyname": ["malloc", "free"],
+  "calloc": ["malloc", "free"],
   "realloc": ["malloc", "free"],
-  "getlogin": ["malloc"],
-  "tmpnam": ["malloc"],
-  "mmap": ["memalign", "memset"],
-  "realpath": ["malloc"],
-  "strerror": ["malloc"],
-  "__ctype_b_loc": ["malloc"],
-  "__ctype_tolower_loc": ["malloc"],
-  "__ctype_toupper_loc": ["malloc"],
-  "newlocale": ["malloc"],
+  "getlogin": ["malloc", "free"],
+  "tmpnam": ["malloc", "free"],
+  "mmap": ["memalign", "memset", "malloc", "free"],
+  "munmap": ["memalign", "memset", "malloc", "free"],
+  "realpath": ["malloc", "free"],
+  "strerror": ["malloc", "free"],
+  "__ctype_b_loc": ["malloc", "free"],
+  "__ctype_tolower_loc": ["malloc", "free"],
+  "__ctype_toupper_loc": ["malloc", "free"],
+  "newlocale": ["malloc", "free"],
   "freelocale": ["free"],
-  "nl_langinfo": ["malloc"],
-  "inet_ntoa": ["malloc"],
+  "nl_langinfo": ["malloc", "free"],
+  "inet_ntoa": ["malloc", "free"],
   "gethostbyname": ["malloc", "free", "htons", "ntohs", "memcpy"],
   "gethostbyname_r": ["malloc", "free", "htons", "ntohs", "memcpy"],
-  "getaddrinfo": ["malloc", "htonl", "htons", "ntohs"],
+  "getaddrinfo": ["malloc", "free", "htonl", "htons", "ntohs"],
   "getnameinfo": ["htons", "ntohs"],
   "getpeername": ["htons", "ntohs"],
   "_inet_ntop6_raw": ["ntohs"],
   "_read_sockaddr": ["ntohs"],
   "freeaddrinfo": ["free"],
-  "gai_strerror": ["malloc"],
-  "setprotoent": ["malloc"],
+  "gai_strerror": ["malloc", "free"],
+  "setprotoent": ["malloc", "free"],
   "emscripten_run_script_string": ["malloc", "free"],
   "emscripten_log": ["strlen"],
   "uuid_clear": ["memset"],
   "uuid_compare": ["memcmp", "memcpy", "memset"],
   "uuid_copy": ["memcpy"],
   "SDL_Init": ["malloc", "free", "memset", "memcpy"],
+  "SDL_PushEvent": ["malloc", "free"],
+  "SDL_OpenAudio": ["malloc", "free"],
+  "SDL_LockSurface": ["malloc", "free"],
   "SDL_GL_GetProcAddress": ["emscripten_GetProcAddress"],
+  "SDL_CreateRGBSurface": ["malloc", "free"],
+  "SDL_malloc": ["malloc", "free"],
+  "SDL_free": ["free"],
+  "emscripten_SDL_SetEventHandler": ["malloc", "free"],
   "Mix_LoadWAV_RW": ["fileno"],
+  "eglQueryString": ["malloc", "free"],
   "eglGetProcAddress": ["emscripten_GetProcAddress"],
   "glfwGetProcAddress": ["emscripten_GetProcAddress"],
   "emscripten_GetProcAddress": ["strstr"],
@@ -46,6 +56,9 @@
   "emscripten_GetAlcProcAddress": ["strcmp"],
   "emscripten_GetAlProcAddress": ["strcmp"],
   "emscripten_get_preloaded_image_data_from_FILE": ["fileno"],
+  "alGetString": ["malloc", "free"],
+  "alcGetString": ["malloc", "free"],
+  "emscripten_alcGetStringiSOFT": ["malloc", "free"],
   "__gxx_personality_v0": ["_ZSt18uncaught_exceptionv", "__cxa_find_matching_catch"],
   "__cxa_find_matching_catch": ["__cxa_is_pointer_type", "__cxa_can_catch"],
   "__cxa_find_matching_catch_0": ["__cxa_is_pointer_type", "__cxa_can_catch"],
@@ -60,36 +73,43 @@
   "__cxa_find_matching_catch_9": ["__cxa_is_pointer_type", "__cxa_can_catch"],
   "__cxa_begin_catch": ["_ZSt18uncaught_exceptionv", "setThrew"],
   "__cxa_end_catch": ["free"],
-  "__cxa_allocate_exception": ["malloc", "setThrew"],
+  "__cxa_allocate_exception": ["malloc", "free", "setThrew"],
   "__cxa_free_exception": ["free"],
   "__cxa_throw": ["setThrew"],
   "formatString": ["strlen"],
+  "glfwInit": ["malloc", "free"],
   "glfwSleep": ["sleep"],
   "glBegin": ["malloc", "free"],
+  "glewInit": ["malloc", "free"],
   "bind": ["htonl", "htons", "ntohs"],
   "connect": ["htonl", "htons", "ntohs"],
   "socket": ["htonl", "htons", "ntohs"],
   "socketpair": ["htons", "ntohs"],
   "sleep": ["usleep"],
   "recv": ["htons", "ntohs"],
   "send": ["htons", "ntohs"],
-  "ctime": ["_get_tzname", "_get_daylight", "_get_timezone", "malloc"],
-  "ctime_r": ["_get_tzname", "_get_daylight", "_get_timezone", "malloc"],
-  "localtime": ["_get_tzname", "_get_daylight", "_get_timezone", "malloc"],
-  "localtime_r": ["_get_tzname", "_get_daylight", "_get_timezone", "malloc"],
-  "mktime": ["_get_tzname", "_get_daylight", "_get_timezone", "malloc"],
-  "timegm": ["_get_tzname", "_get_daylight", "_get_timezone", "malloc"],
-  "tzset": ["_get_tzname", "_get_daylight", "_get_timezone", "malloc"],
+  "ctime": ["_get_tzname", "_get_daylight", "_get_timezone", "malloc", "free"],
+  "ctime_r": ["_get_tzname", "_get_daylight", "_get_timezone", "malloc", "free"],
+  "gmtime":  ["malloc", "free"],
+  "gmtime_r":  ["malloc", "free"],
+  "localtime": ["_get_tzname", "_get_daylight", "_get_timezone", "malloc", "free"],
+  "localtime_r": ["_get_tzname", "_get_daylight", "_get_timezone", "malloc", "free"],
+  "mktime": ["_get_tzname", "_get_daylight", "_get_timezone", "malloc", "free"],
+  "timegm": ["_get_tzname", "_get_daylight", "_get_timezone", "malloc", "free"],
+  "tzset": ["_get_tzname", "_get_daylight", "_get_timezone", "malloc", "free"],
   "times": ["memset"],
+  "emscripten_pc_get_function": ["malloc", "free"],
+  "emscripten_pc_get_file": ["malloc", "free"],
   "emscripten_set_canvas_element_size_calling_thread": ["_emscripten_call_on_thread"],
-  "emscripten_set_offscreencanvas_size_on_target_thread": ["_emscripten_call_on_thread"],
-  "emscripten_websocket_new": ["malloc"],
-  "emscripten_wget_data": ["malloc"],
+  "emscripten_set_offscreencanvas_size_on_target_thread": ["_emscripten_call_on_thread", "malloc", "free"],
+  "emscripten_set_offscreencanvas_size_on_target_thread_js": ["malloc", "free"],
+  "emscripten_websocket_new": ["malloc", "free"],
+  "emscripten_wget_data": ["malloc", "free"],
   "emscripten_webgl_destroy_context": ["emscripten_webgl_make_context_current", "emscripten_webgl_get_current_context"],
   "emscripten_idb_async_load": ["malloc", "free"],
   "emscripten_idb_load": ["malloc", "free"],
   "wgpuDeviceCreateBuffer": ["malloc", "free"],
-  "stringToNewUTF8": ["malloc"],
+  "stringToNewUTF8": ["malloc", "free"],
   "_embind_register_std_string": ["malloc", "free"],
   "_embind_register_std_wstring": ["malloc", "free"],
   "pthread_create": ["malloc", "free", "emscripten_main_thread_process_queued_calls"],
@@ -103,5 +123,64 @@
   "setjmp": ["setThrew", "realloc", "testSetjmp", "saveSetjmp"],
   "longjmp": ["setThrew", "realloc", "testSetjmp", "saveSetjmp"],
   "siglongjmp": ["setThrew", "realloc", "testSetjmp", "saveSetjmp"],
-  "emscripten_longjmp_jmpbuf": ["setThrew", "realloc", "testSetjmp", "saveSetjmp"]
+  "emscripten_longjmp_jmpbuf": ["setThrew", "realloc", "testSetjmp", "saveSetjmp"],
+  "emscripten_websocket_new": ["malloc", "free"],
+  "emscripten_websocket_set_onmessage_callback_on_thread": ["malloc", "free"],
+  "emscripten_websocket_set_onclose_callback_on_thread": ["malloc", "free"],
+  "emscripten_websocket_set_onerror_callback_on_thread": ["malloc", "free"],
+  "emscripten_websocket_set_onopen_callback_on_thread": ["malloc", "free"],
+  "emscripten_init_websocket_to_posix_socket_bridge": ["malloc", "free"],
+  "emscripten_set_keypress_callback_on_thread": ["malloc", "free"],
+  "emscripten_set_keyup_callback_on_thread": ["malloc", "free"],
+  "emscripten_set_keydown_callback_on_thread": ["malloc", "free"],
+  "emscripten_set_click_callback_on_thread": ["malloc", "free"],
+  "emscripten_set_mousedown_callback_on_thread": ["malloc", "free"],
+  "emscripten_set_mouseup_callback_on_thread": ["malloc", "free"],
+  "emscripten_set_dblclick_callback_on_thread": ["malloc", "free"],
+  "emscripten_set_mousemove_callback_on_thread": ["malloc", "free"],
+  "emscripten_set_mousemove_callback_on_thread": ["malloc", "free"],
+  "emscripten_set_mouseenter_callback_on_thread": ["malloc", "free"],
+  "emscripten_set_mouseleave_callback_on_thread": ["malloc", "free"],
+  "emscripten_set_mouseover_callback_on_thread": ["malloc", "free"],
+  "emscripten_set_mouseout_callback_on_thread": ["malloc", "free"],
+  "emscripten_set_wheel_callback_on_thread": ["malloc", "free"],
+  "emscripten_set_resize_callback_on_thread": ["malloc", "free"],
+  "emscripten_set_scroll_callback_on_thread": ["malloc", "free"],
+  "emscripten_set_blur_callback_on_thread": ["malloc", "free"],
+  "emscripten_set_focus_callback_on_thread": ["malloc", "free"],
+  "emscripten_set_focusin_callback_on_thread": ["malloc", "free"],
+  "emscripten_set_focusout_callback_on_thread": ["malloc", "free"],
+  "emscripten_set_deviceorientation_callback_on_thread": ["malloc", "free"],
+  "emscripten_set_orientationchange_callback_on_thread": ["malloc", "free"],
+  "emscripten_set_fullscreenchange_callback_on_thread": ["malloc", "free"],
+  "emscripten_set_pointerlockchange_callback_on_thread": ["malloc", "free"],
+  "emscripten_set_pointerlockerror_callback_on_thread": ["malloc", "free"],
+  "emscripten_set_visibilitychange_callback_on_thread": ["malloc", "free"],
+  "emscripten_set_touchstart_callback_on_thread": ["malloc", "free"],
+  "emscripten_set_touchend_callback_on_thread": ["malloc", "free"],
+  "emscripten_set_touchmove_callback_on_thread": ["malloc", "free"],
+  "emscripten_set_touchcancel_callback_on_thread": ["malloc", "free"],
+  "emscripten_set_gamepadconnected_callback_on_thread": ["malloc", "free"],
+  "emscripten_set_gamepaddisconnected_callback_on_thread": ["malloc", "free"],
+  "emscripten_set_beforeunload_callback_on_thread": ["malloc", "free"],
+  "emscripten_set_batterychargingchange_callback_on_thread": ["malloc", "free"],
+  "emscripten_set_batterylevelchange_callback_on_thread": ["malloc", "free"],
+  "emscripten_set_devicemotion_callback_on_thread": ["malloc", "free"],
+  "emscripten_run_preload_plugins_data": ["malloc", "free"],
+  "emscripten_async_wget_data": ["malloc", "free"],
+  "emscripten_async_wget2_data": ["malloc", "free"],
+  "emscripten_get_window_title": ["malloc", "free"],
+  "emscripten_get_compiler_setting": ["malloc", "free"],
+  "emscripten_create_worker": ["malloc", "free"],
+  "emscripten_get_preloaded_image_data": ["malloc", "free"],
+  "emscripten_webgl_get_supported_extensions": ["malloc", "free"],
+  "emscripten_webgl_get_program_info_log_utf8": ["malloc", "free"],
+  "emscripten_webgl_get_shader_info_log_utf8": ["malloc", "free"],
+  "emscripten_webgl_get_shader_source_utf8": ["malloc", "free"],
+  "emscripten_webgl_get_parameter_utf8": ["malloc", "free"],
+  "emscripten_webgl_create_context": ["malloc", "free"],
+  "glMapBufferRange": ["malloc", "free"],
+  "glGetString": ["malloc", "free"],
+  "glGetStringi": ["malloc", "free"],
+  "syslog": ["malloc", "free"]
 }

src/library_fs.js

@@ -2025,10 +2025,14 @@ FS.staticInit();` +
     // Allocate memory for an mmap operation. This allocates space of the right
     // page-aligned size, and clears the padding.
     mmapAlloc: function(size) {
+#if '_malloc' in IMPLEMENTED_FUNCTIONS
       var alignedSize = alignMemory(size, {{{ POSIX_PAGE_SIZE }}});
       var ptr = _malloc(alignedSize);
       while (size < alignedSize) HEAP8[ptr + size++] = 0;
       return ptr;
+#else
+      {{{ makeMallocAbort("mmapAlloc") }}}
+#endif
     }
   }
 });

src/library_sdl.js

@@ -1846,10 +1846,14 @@ var LibrarySDL = {
   SDL_SetError: function() {},
 
   SDL_malloc__sig: 'ii',
-  SDL_malloc: 'malloc',
+  SDL_malloc: function(size) {
+    return _malloc(size);
+  },
 
   SDL_free__sig: 'vi',
-  SDL_free: 'free',
+  SDL_free: function(ptr) {
+    _free(ptr);
+  },
 
   SDL_CreateRGBSurface__proxy: 'sync',
   SDL_CreateRGBSurface__sig: 'iiiiiiiii',
@@ -2653,7 +2657,7 @@ var LibrarySDL = {
     SDL.audio.paused = pauseOn;
   },
 
-  SDL_CloseAudio__deps: ['SDL_PauseAudio', 'free'],
+  SDL_CloseAudio__deps: ['SDL_PauseAudio'],
   SDL_CloseAudio__proxy: 'sync',
   SDL_CloseAudio__sig: 'v',
   SDL_CloseAudio: function() {

src/parseTools.js

@@ -1707,3 +1707,15 @@ function addReadyPromiseAssertions(promise) {
     `;
   }).join('\n');
 }
+
+// It should be impossible to call some functions without malloc being
+// included, unless we have a deps_info.json bug. To let closure not error
+// on `_malloc` not being present, they don't call malloc and instead abort
+// with an error at runtime.
+// TODO: A more comprehensive deps system could catch this at compile time.
+function makeMallocAbort(name) {
+  if (!ASSERTIONS) {
+    return "abort();";
+  }
+  return `abort('malloc was not included, but is needed in ${name}. Adding "_malloc" to EXPORTED_FUNCTIONS should fix that. This may be a bug in the compiler, please file an issue.');`
+}

src/preamble.js

@@ -187,6 +187,22 @@ function cwrap(ident, returnType, argTypes, opts) {
   }
 }
 
+#if ASSERTIONS
+// We used to include malloc/free by default in the past. Show a helpful error in
+// builds with assertions.
+#if !('_malloc' in IMPLEMENTED_FUNCTIONS)
+function _malloc() {
+  abort("malloc() called but not included in the build - add '_malloc' to EXPORTED_FUNCTIONS");
+}
+#endif // malloc
+#if !('_free' in IMPLEMENTED_FUNCTIONS)
+function _free() {
+  // Show a helpful error since we used to include free by default in the past.
+  abort("free() called but not included in the build - add '_free' to EXPORTED_FUNCTIONS");
+}
+#endif // free
+#endif // ASSERTIONS
+
 var ALLOC_NORMAL = 0; // Tries to use _malloc()
 var ALLOC_STACK = 1; // Lives for the duration of the current function call
 var ALLOC_NONE = 2; // Do not allocate
@@ -221,7 +237,7 @@ function allocate(slab, types, allocator, ptr) {
   if (allocator == ALLOC_NONE) {
     ret = ptr;
   } else {
-    ret = [_malloc,
+    ret = [{{{ ('_malloc' in IMPLEMENTED_FUNCTIONS) ? '_malloc' : 'null' }}},
 #if DECLARE_ASM_MODULE_EXPORTS
     stackAlloc,
 #else

src/runtime_strings_extra.js

@@ -208,10 +208,14 @@ function lengthBytesUTF32(str) {
 // Allocate heap space for a JS string, and write it there.
 // It is the responsibility of the caller to free() that memory.
 function allocateUTF8(str) {
+#if '_malloc' in IMPLEMENTED_FUNCTIONS
   var size = lengthBytesUTF8(str) + 1;
   var ret = _malloc(size);
   if (ret) stringToUTF8Array(str, HEAP8, ret, size);
   return ret;
+#else
+  {{{ makeMallocAbort("allocateUTF8") }}}
+#endif
 }
 
 // Allocate stack space for a JS string, and write it there.

tests/code_size/hello_webgl2_wasm.json

@@ -4,7 +4,7 @@
   "a.js": 5035,
   "a.js.gz": 2395,
   "a.wasm": 10910,
-  "a.wasm.gz": 6930,
+  "a.wasm.gz": 6928,
   "total": 16508,
-  "total_gz": 9702
+  "total_gz": 9700
 }

tests/code_size/hello_webgl_wasm.json

@@ -4,7 +4,7 @@
   "a.js": 4519,
   "a.js.gz": 2219,
   "a.wasm": 10910,
-  "a.wasm.gz": 6930,
+  "a.wasm.gz": 6928,
   "total": 15992,
-  "total_gz": 9526
+  "total_gz": 9524
 }