Allow JS -> native dependencies to be specified in __deps. NFC (#18849)

Now that LLD_REPORT_UNDEFINED is always on, we can depend on JS library
processing before link time.  Extend the existing symbol list to be
a list of symbols + native dependencies.

This way we can begin to move reverse dependencies out of deps_info.py
and potentially one day completely remove that file.  For now it is
still needed because indirect dependencies can't be specified in the JS
library code yet.

Replaces (and inspired by): #15982

emcc.py

@@ -50,6 +50,7 @@
 from tools.minimal_runtime_shell import generate_minimal_runtime_html
 import tools.line_endings
 from tools import feature_matrix
+from tools import deps_info
 from tools import js_manipulation
 from tools import wasm2c
 from tools import webassembly
@@ -542,14 +543,28 @@ def build_symbol_list(filename):
     """Only called when there is no existing symbol list for a given content hash.
     """
     library_syms = generate_js_symbols()
-    write_file(filename, '\n'.join(library_syms) + '\n')
+    lines = []
+
+    for name, deps in library_syms.items():
+      if deps:
+        lines.append('%s: %s' % (name, ','.join(deps)))
+      else:
+        lines.append(name)
+    write_file(filename, '\n'.join(lines) + '\n')
 
   # We need to use a separate lock here for symbol lists because, unlike with system libraries,
   # it's normally for these file to get pruned as part of normal operation.  This means that it
   # can be deleted between the `cache.get()` then the `read_file`.
   with filelock.FileLock(cache.get_path(cache.get_path('symbol_lists.lock'))):
     filename = cache.get(f'symbol_lists/{content_hash}.txt', build_symbol_list)
-    library_syms = read_file(filename).splitlines()
+    lines = read_file(filename).splitlines()
+    library_syms = {}
+    for line in lines:
+      if ':' in line:
+        name, deps = line.split(':')
+        library_syms[name] = deps.strip().split(',')
+      else:
+        library_syms[line] = []
 
     # Limit of the overall size of the cache to 100 files.
     # This code will get test coverage since a full test run of `other` or `core`
@@ -1315,9 +1330,14 @@ def run(args):
     logger.debug('stopping after linking to object file')
     return 0
 
+  js_syms = {}
+  if not settings.SIDE_MODULE:
+    js_syms = get_all_js_syms()
+    deps_info.append_deps_info(js_syms)
+
   phase_calculate_system_libraries(state, linker_arguments, linker_inputs, newargs)
 
-  phase_link(linker_arguments, wasm_target)
+  phase_link(linker_arguments, wasm_target, js_syms)
 
   # Special handling for when the user passed '-Wl,--version'.  In this case the linker
   # does not create the output file, but just prints its version and exits with 0.
@@ -3062,7 +3082,7 @@ def phase_calculate_system_libraries(state, linker_arguments, linker_inputs, new
 
 
 @ToolchainProfiler.profile_block('link')
-def phase_link(linker_arguments, wasm_target):
+def phase_link(linker_arguments, wasm_target, js_syms):
   logger.debug(f'linking: {linker_arguments}')
 
   # Make a final pass over settings.EXPORTED_FUNCTIONS to remove any
@@ -3072,13 +3092,6 @@ def phase_link(linker_arguments, wasm_target):
   settings.REQUIRED_EXPORTS = dedup_list(settings.REQUIRED_EXPORTS)
   settings.EXPORT_IF_DEFINED = dedup_list(settings.EXPORT_IF_DEFINED)
 
-  # if  EMCC_DEBUG=2  then we must link now, so the temp files are complete.
-  # if using the wasm backend, we might be using vanilla LLVM, which does not allow our
-  # fastcomp deferred linking opts.
-  # TODO: we could check if this is a fastcomp build, and still speed things up here
-  js_syms = None
-  if settings.ERROR_ON_UNDEFINED_SYMBOLS and not settings.SIDE_MODULE:
-    js_syms = get_all_js_syms()
   building.link_lld(linker_arguments, wasm_target, external_symbols=js_syms)
 
 

src/jsifier.js

@@ -68,6 +68,7 @@ function isDefined(symName) {
 
 function runJSify(symbolsOnly = false) {
   const libraryItems = [];
+  const symbolDeps = {};
   let postSets = [];
 
   LibraryManager.load();
@@ -245,9 +246,16 @@ function ${name}(${args}) {
         return;
       }
 
+      const deps = LibraryManager.library[symbol + '__deps'] || [];
+      if (!Array.isArray(deps)) {
+        error(`JS library directive ${symbol}__deps=${deps.toString()} is of type ${typeof deps}, but it should be an array!`);
+        return;
+      }
+
       if (symbolsOnly) {
         if (!isJsOnlySymbol(symbol) && LibraryManager.library.hasOwnProperty(symbol)) {
-          librarySymbols.push(symbol);
+          externalDeps = deps.filter((d) => !isJsOnlySymbol(d) && !(d in LibraryManager.library) && typeof d === 'string');
+          symbolDeps[symbol] = externalDeps;
         }
         return;
       }
@@ -319,11 +327,6 @@ function ${name}(${args}) {
 
       const original = LibraryManager.library[symbol];
       let snippet = original;
-      const deps = LibraryManager.library[symbol + '__deps'] || [];
-      if (!Array.isArray(deps)) {
-        error(`JS library directive ${symbol}__deps=${deps.toString()} is of type ${typeof deps}, but it should be an array!`);
-        return;
-      }
 
       const isUserSymbol = LibraryManager.library[symbol + '__user'];
       deps.forEach((dep) => {
@@ -542,7 +545,7 @@ function ${name}(${args}) {
   }
 
   if (symbolsOnly) {
-    print(JSON.stringify(librarySymbols));
+    print(JSON.stringify(symbolDeps));
     return;
   }
 

src/library.js

@@ -2111,7 +2111,7 @@ mergeInto(LibraryManager.library, {
     list: [],
     map: {}
   },
-  setprotoent__deps: ['$Protocols', '$writeAsciiToMemory'],
+  setprotoent__deps: ['$Protocols', '$writeAsciiToMemory', 'malloc'],
   setprotoent: function(stayopen) {
     // void setprotoent(int stayopen);
 

src/library_browser.js

@@ -804,6 +804,7 @@ var LibraryBrowser = {
   },
 
   emscripten_run_preload_plugins_data__proxy: 'sync',
+  emscripten_run_preload_plugins_data__deps: ['malloc'],
   emscripten_run_preload_plugins_data__sig: 'viiiiii',
   emscripten_run_preload_plugins_data: function(data, size, suffix, arg, onload, onerror) {
     {{{ runtimeKeepalivePush() }}}
@@ -1355,7 +1356,7 @@ var LibraryBrowser = {
     return info.awaited;
   },
 
-  emscripten_get_preloaded_image_data__deps: ['$PATH_FS'],
+  emscripten_get_preloaded_image_data__deps: ['$PATH_FS', 'malloc'],
   emscripten_get_preloaded_image_data__proxy: 'sync',
   emscripten_get_preloaded_image_data__sig: 'iiii',
   emscripten_get_preloaded_image_data: function(path, w, h) {

src/library_html5.js

@@ -2325,7 +2325,7 @@ var LibraryHTML5 = {
 
   $battery: function() { return navigator.battery || navigator.mozBattery || navigator.webkitBattery; },
 
-  $registerBatteryEventCallback__deps: ['$JSEvents', '$fillBatteryEventData', '$battery', '$findEventTarget'],
+  $registerBatteryEventCallback__deps: ['$JSEvents', '$fillBatteryEventData', '$battery', '$findEventTarget', 'malloc'],
   $registerBatteryEventCallback: function(target, userData, useCapture, callbackfunc, eventTypeId, eventTypeString, targetThread) {
 #if USE_PTHREADS
     targetThread = JSEvents.getTargetThreadForEventCallback(targetThread);
@@ -2359,7 +2359,7 @@ var LibraryHTML5 = {
 
   emscripten_set_batterychargingchange_callback_on_thread__proxy: 'sync',
   emscripten_set_batterychargingchange_callback_on_thread__sig: 'iii',
-  emscripten_set_batterychargingchange_callback_on_thread__deps: ['$registerBatteryEventCallback', '$battery'],
+  emscripten_set_batterychargingchange_callback_on_thread__deps: ['$registerBatteryEventCallback', '$battery', 'malloc'],
   emscripten_set_batterychargingchange_callback_on_thread: function(userData, callbackfunc, targetThread) {
     if (!battery()) return {{{ cDefine('EMSCRIPTEN_RESULT_NOT_SUPPORTED') }}}; 
     registerBatteryEventCallback(battery(), userData, true, callbackfunc, {{{ cDefine('EMSCRIPTEN_EVENT_BATTERYCHARGINGCHANGE') }}}, "chargingchange", targetThread);
@@ -2368,7 +2368,7 @@ var LibraryHTML5 = {
 
   emscripten_set_batterylevelchange_callback_on_thread__proxy: 'sync',
   emscripten_set_batterylevelchange_callback_on_thread__sig: 'iii',
-  emscripten_set_batterylevelchange_callback_on_thread__deps: ['$registerBatteryEventCallback', '$battery'],
+  emscripten_set_batterylevelchange_callback_on_thread__deps: ['$registerBatteryEventCallback', '$battery', 'malloc'],
   emscripten_set_batterylevelchange_callback_on_thread: function(userData, callbackfunc, targetThread) {
     if (!battery()) return {{{ cDefine('EMSCRIPTEN_RESULT_NOT_SUPPORTED') }}}; 
     registerBatteryEventCallback(battery(), userData, true, callbackfunc, {{{ cDefine('EMSCRIPTEN_EVENT_BATTERYLEVELCHANGE') }}}, "levelchange", targetThread);

src/library_sdl.js

@@ -1348,7 +1348,7 @@ var LibrarySDL = {
     return SDL.version;
   },
 
-  SDL_Init__deps: ['$zeroMemory'],
+  SDL_Init__deps: ['$zeroMemory', 'malloc', 'free', 'memcpy'],
   SDL_Init__proxy: 'sync',
   SDL_Init__sig: 'ii',
   SDL_Init__docs: '/** @param{number=} initFlags */', 
@@ -1846,15 +1846,18 @@ var LibrarySDL = {
   SDL_SetError: function() {},
 
   SDL_malloc__sig: 'ii',
+  SDL_malloc__deps: ['malloc'],
   SDL_malloc: function(size) {
     return _malloc(size);
   },
 
   SDL_free__sig: 'vi',
+  SDL_free__deps: ['free'],
   SDL_free: function(ptr) {
     _free(ptr);
   },
 
+  SDL_CreateRGBSurface__deps: ['malloc', 'free'],
   SDL_CreateRGBSurface__proxy: 'sync',
   SDL_CreateRGBSurface__sig: 'iiiiiiiii',
   SDL_CreateRGBSurface: function(flags, width, height, depth, rmask, gmask, bmask, amask) {
@@ -2067,6 +2070,7 @@ var LibrarySDL = {
 
   SDL_PushEvent__proxy: 'sync',
   SDL_PushEvent__sig: 'ii',
+  SDL_PushEvent__deps: ['malloc'],
   SDL_PushEvent: function(ptr) {
     var copy = _malloc({{{ C_STRUCTS.SDL_KeyboardEvent.__size__ }}});
     _memcpy(copy, ptr, {{{ C_STRUCTS.SDL_KeyboardEvent.__size__ }}});
@@ -2117,6 +2121,7 @@ var LibrarySDL = {
   // An Emscripten-specific extension to SDL: Some browser APIs require that they are called from within an event handler function.
   // Allow recording a callback that will be called for each received event.
   emscripten_SDL_SetEventHandler__proxy: 'sync',
+  emscripten_SDL_SetEventHandler__deps: ['malloc'],
   emscripten_SDL_SetEventHandler__sig: 'vii',
   emscripten_SDL_SetEventHandler: function(handler, userdata) {
     SDL.eventHandler = handler;
@@ -2245,7 +2250,7 @@ var LibrarySDL = {
     return flags; // We support JPG, PNG, TIF because browsers do
   },
 
-  IMG_Load_RW__deps: ['SDL_LockSurface', 'SDL_FreeRW', '$PATH_FS'],
+  IMG_Load_RW__deps: ['SDL_LockSurface', 'SDL_FreeRW', '$PATH_FS', 'malloc'],
   IMG_Load_RW__proxy: 'sync',
   IMG_Load_RW__sig: 'iii',
   IMG_Load_RW: function(rwopsID, freeSrc) {
@@ -2413,7 +2418,7 @@ var LibrarySDL = {
 
   // SDL_Audio
 
-  SDL_OpenAudio__deps: ['$autoResumeAudioContext', '$safeSetTimeout'],
+  SDL_OpenAudio__deps: ['$autoResumeAudioContext', '$safeSetTimeout', 'malloc'],
   SDL_OpenAudio__proxy: 'sync',
   SDL_OpenAudio__sig: 'iii',
   SDL_OpenAudio: function(desired, obtained) {

src/library_uuid.js

@@ -24,6 +24,7 @@ mergeInto(LibraryManager.library, {
   },
 
   // Copies the 'compact' UUID variable from src to dst.
+  uuid_copy__deps: ['memcpy'],
   uuid_copy: function(dst, src) {
     // void uuid_copy(uuid_t dst, const uuid_t src);
     _memcpy(dst, src, 16);

src/library_webgpu.js

@@ -1851,7 +1851,7 @@ var LibraryWebGPU = {
 
   // In webgpu.h offset and size are passed in as size_t.
   // And library_webgpu assumes that size_t is always 32bit in emscripten.
-  wgpuBufferGetConstMappedRange__deps: ['$warnOnce'],
+  wgpuBufferGetConstMappedRange__deps: ['$warnOnce', 'malloc', 'free'],
   wgpuBufferGetConstMappedRange: function(bufferId, offset, size) {
     var bufferWrapper = WebGPU.mgrBuffer.objects[bufferId];
     {{{ gpu.makeCheckDefined('bufferWrapper') }}}
@@ -1882,7 +1882,7 @@ var LibraryWebGPU = {
 
   // In webgpu.h offset and size are passed in as size_t.
   // And library_webgpu assumes that size_t is always 32bit in emscripten.
-  wgpuBufferGetMappedRange__deps: ['$warnOnce'],
+  wgpuBufferGetMappedRange__deps: ['$warnOnce', 'malloc', 'free'],
   wgpuBufferGetMappedRange: function(bufferId, offset, size) {
     var bufferWrapper = WebGPU.mgrBuffer.objects[bufferId];
     {{{ gpu.makeCheckDefined('bufferWrapper') }}}

test/test_other.py

@@ -6782,26 +6782,22 @@ def test_no_missing_symbols(self): # simple hello world should not show any miss
 mergeInto(LibraryManager.library, {
   my_js__deps: ['main'],
   my_js: (function() {
-      return function() {
-        console.log("hello " + _nonexistingvariable);
-      };
+      return () => console.log("hello " + _nonexistingvariable);
   }()),
 });
 ''')
-    create_file('test.cpp', '''\
+    create_file('test.c', '''\
 #include <stdio.h>
 #include <stdlib.h>
 
-extern "C" {
-  extern void my_js();
-}
+void my_js();
 
 int main() {
   my_js();
   return EXIT_SUCCESS;
 }
 ''')
-    self.run_process([EMXX, 'test.cpp', '--js-library', 'library_foo.js'])
+    self.run_process([EMCC, 'test.c', '--js-library', 'library_foo.js'])
 
     # but we do error on a missing js var
     create_file('library_foo_missing.js', '''
@@ -6814,16 +6810,16 @@ def test_no_missing_symbols(self): # simple hello world should not show any miss
   }()),
 });
 ''')
-    err = self.expect_fail([EMXX, 'test.cpp', '--js-library', 'library_foo_missing.js'])
-    self.assertContained('undefined symbol: nonexistingvariable', err)
+    err = self.expect_fail([EMCC, 'test.c', '--js-library', 'library_foo_missing.js'])
+    self.assertContained('wasm-ld: error: symbol exported via --export not found: nonexistingvariable', err)
 
     # and also for missing C code, of course (without the --js-library, it's just a missing C method)
-    err = self.expect_fail([EMXX, 'test.cpp'])
+    err = self.expect_fail([EMCC, 'test.c'])
     self.assertContained('undefined symbol: my_js', err)
 
-  def test_js_lib_to_system_lib(self):
-    # memset is in compiled code, so a js library __deps can't access it. it
-    # would need to be in deps_info.json or EXPORTED_FUNCTIONS
+  def test_js_lib_native_deps(self):
+    # Verify that memset (which lives in compiled code), can be specified as a JS library
+    # dependency.
     create_file('lib.js', r'''
 mergeInto(LibraryManager.library, {
   depper__deps: ['memset'],
@@ -6832,38 +6828,19 @@ def test_js_lib_to_system_lib(self):
   },
 });
 ''')
-    create_file('test.cpp', r'''
-#include <string.h>
+    create_file('test.c', r'''
 #include <stdio.h>
 
-extern "C" {
-extern void depper(char*);
-}
+void depper(char*);
 
 int main(int argc, char** argv) {
-  char buffer[11];
-  buffer[10] = '\0';
-  // call by a pointer, to force linking of memset, no llvm intrinsic here
-  volatile auto ptr = memset;
-  (*ptr)(buffer, 'a', 10);
+  char buffer[11] = { 0 };
   depper(buffer);
   puts(buffer);
 }
 ''')
 
-    err = self.expect_fail([EMXX, 'test.cpp', '--js-library', 'lib.js'])
-    self.assertContained('_memset may need to be added to EXPORTED_FUNCTIONS if it arrives from a system library', err)
-
-    # without the dep, and with EXPORTED_FUNCTIONS, it works ok
-    create_file('lib.js', r'''
-mergeInto(LibraryManager.library, {
-  depper: function(ptr) {
-    _memset(ptr, 'd'.charCodeAt(0), 10);
-  },
-});
-''')
-    self.run_process([EMXX, 'test.cpp', '--js-library', 'lib.js', '-sEXPORTED_FUNCTIONS=_main,_memset'])
-    self.assertContained('dddddddddd', self.run_js('a.out.js'))
+    self.do_runf('test.c', 'dddddddddd\n', emcc_args=['--js-library', 'lib.js'])
 
   def test_realpath(self):
     create_file('src.c', r'''

tools/building.py

@@ -148,7 +148,7 @@ def link_to_object(args, target):
 
 def lld_flags_for_executable(external_symbols):
   cmd = []
-  if external_symbols:
+  if settings.ERROR_ON_UNDEFINED_SYMBOLS:
     undefs = shared.get_temp_files().get('.undefined').name
     utils.write_file(undefs, '\n'.join(external_symbols))
     cmd.append('--allow-undefined-file=%s' % undefs)
@@ -176,9 +176,8 @@ def lld_flags_for_executable(external_symbols):
   # Strip the leading underscores
   c_exports = [demangle_c_symbol_name(e) for e in c_exports]
   c_exports += settings.EXPORT_IF_DEFINED
-  if external_symbols:
-    # Filter out symbols external/JS symbols
-    c_exports = [e for e in c_exports if e not in external_symbols]
+  # Filter out symbols external/JS symbols
+  c_exports = [e for e in c_exports if e not in external_symbols]
   for export in c_exports:
     cmd.append('--export-if-defined=' + export)