Remove use of legacy proxy system from library_html5.js. NFC (#20031)

Author: sbc100

src/generated_struct_info32.json

@@ -231,7 +231,6 @@
         "EM_PROMISE_MATCH": 1,
         "EM_PROMISE_MATCH_RELEASE": 2,
         "EM_PROMISE_REJECT": 3,
-        "EM_PROXIED_RESIZE_OFFSCREENCANVAS": 654311424,
         "EM_TIMING_RAF": 1,
         "EM_TIMING_SETIMMEDIATE": 2,
         "EM_TIMING_SETTIMEOUT": 0,

src/generated_struct_info64.json

@@ -231,7 +231,6 @@
         "EM_PROMISE_MATCH": 1,
         "EM_PROMISE_MATCH_RELEASE": 2,
         "EM_PROMISE_REJECT": 3,
-        "EM_PROXIED_RESIZE_OFFSCREENCANVAS": 654311424,
         "EM_TIMING_RAF": 1,
         "EM_TIMING_SETIMMEDIATE": 2,
         "EM_TIMING_SETTIMEOUT": 0,

src/library_html5.js

@@ -2375,31 +2375,14 @@ var LibraryHTML5 = {
 #if OFFSCREENCANVAS_SUPPORT
   _emscripten_set_offscreencanvas_size: 'emscripten_set_canvas_element_size',
 
-  $setOffscreenCanvasSizeOnTargetThread__deps: ['$stringToNewUTF8', 'emscripten_dispatch_to_thread_', '$withStackSave'],
+  $setOffscreenCanvasSizeOnTargetThread__deps: ['$stringToNewUTF8', '_emscripten_set_offscreencanvas_size_on_thread', '$withStackSave'],
   $setOffscreenCanvasSizeOnTargetThread: (targetThread, targetCanvas, width, height) => {
     targetCanvas = targetCanvas ? UTF8ToString(targetCanvas) : '';
-    withStackSave(() => {
-      var varargs = stackAlloc(12);
-      var targetCanvasPtr = 0;
-      if (targetCanvas) {
-        targetCanvasPtr = stringToNewUTF8(targetCanvas);
-      }
-      {{{ makeSetValue('varargs', 0, 'targetCanvasPtr', 'i32')}}};
-      {{{ makeSetValue('varargs', 4, 'width', 'i32')}}};
-      {{{ makeSetValue('varargs', 8, 'height', 'i32')}}};
-      // Note: If we are also a pthread, the call below could theoretically be done synchronously. However if the target pthread is waiting for a mutex from us, then
-      // these two threads will deadlock. At the moment, we'd like to consider that this kind of deadlock would be an Emscripten runtime bug, although if
-      // emscripten_set_canvas_element_size() was documented to require running an event in the queue of thread that owns the OffscreenCanvas, then that might be ok.
-      // (safer this way however)
-      _emscripten_dispatch_to_thread_(targetThread, {{{ cDefs.EM_PROXIED_RESIZE_OFFSCREENCANVAS }}}, 0, targetCanvasPtr /* satellite data */, varargs);
-    });
-  },
-#else
-  _emscripten_set_offscreencanvas_size: (target, width, height) => {
-#if ASSERTIONS
-    err('emscripten_set_offscreencanvas_size: Build with -sOFFSCREENCANVAS_SUPPORT=1 to enable transferring canvases to pthreads.');
-#endif
-    return {{{ cDefs.EMSCRIPTEN_RESULT_NOT_SUPPORTED }}};
+    var targetCanvasPtr = 0;
+    if (targetCanvas) {
+      targetCanvasPtr = stringToNewUTF8(targetCanvas);
+    }
+    __emscripten_set_offscreencanvas_size_on_thread(targetThread, targetCanvasPtr, width, height);
   },
 #endif
 
@@ -2509,6 +2492,15 @@ var LibraryHTML5 = {
   },
 #endif
 
+#if !PTHREADS || !OFFSCREENCANVAS_SUPPORT
+  _emscripten_set_offscreencanvas_size: (target, width, height) => {
+#if ASSERTIONS
+    err('emscripten_set_offscreencanvas_size: Build with -sOFFSCREENCANVAS_SUPPORT=1 to enable transferring canvases to pthreads.');
+#endif
+    return {{{ cDefs.EMSCRIPTEN_RESULT_NOT_SUPPORTED }}};
+  },
+#endif
+
   // JavaScript-friendly API, returns pair [width, height]
   $getCanvasElementSize__deps: ['emscripten_get_canvas_element_size', '$withStackSave', '$stringToUTF8OnStack'],
   $getCanvasElementSize: (target) => withStackSave(() => {

src/struct_info.json

@@ -950,7 +950,6 @@
     {
         "file": "emscripten/threading.h",
         "defines": [
-            "EM_PROXIED_RESIZE_OFFSCREENCANVAS",
             "EM_FUNC_SIG_V",
             "EM_FUNC_SIG_VI",
             "EM_FUNC_SIG_VII",

system/include/emscripten/threading_legacy.h

@@ -118,8 +118,6 @@ typedef struct em_queued_call em_queued_call;
 #define EM_FUNC_SIG_SPECIAL_INTERNAL (1 << 24)
 #define EM_PROXIED_FUNC_SPECIAL(x) (EM_FUNC_SIG_SPECIAL_INTERNAL | ((x) << 20))
 
-#define EM_PROXIED_RESIZE_OFFSCREENCANVAS (EM_PROXIED_FUNC_SPECIAL(0) | EM_FUNC_SIG_IIII)
-
 // Runs the given function synchronously on the main Emscripten runtime thread.
 // If this thread is the main thread, the operation is immediately performed,
 // and the result is returned.

system/lib/html5/offscreencanvas.c

@@ -0,0 +1,38 @@
+#include <assert.h>
+
+#include "emscripten_internal.h"
+
+typedef struct set_cavas_size_t {
+  const char* target;
+  int width;
+  int height;
+} set_cavas_size_t;
+
+static void do_set_size(void* arg) {
+  set_cavas_size_t* args = (set_cavas_size_t*)arg;
+  _emscripten_set_offscreencanvas_size(args->target, args->width, args->height);
+  free(arg);
+}
+
+void _emscripten_set_offscreencanvas_size_on_thread(pthread_t t,
+                                                    const char* target,
+                                                    int width,
+                                                    int height) {
+  set_cavas_size_t* arg = malloc(sizeof(set_cavas_size_t));
+  arg->target = target;
+  arg->width = width;
+  arg->height = height;
+
+  em_proxying_queue* q = emscripten_proxy_get_system_queue();
+
+  // Note: If we are also a pthread, the call below could theoretically be
+  // done synchronously. However if the target pthread is waiting for a
+  // mutex from us, then these two threads will deadlock. At the moment,
+  // we'd like to consider that this kind of deadlock would be an Emscripten
+  // runtime bug, although if emscripten_set_canvas_element_size() was
+  // documented to require running an event in the queue of thread that owns
+  // the OffscreenCanvas, then that might be ok.  (safer this way however)
+  if (!emscripten_proxy_async(q, t, do_set_size, arg)) {
+    assert(false && "emscripten_proxy_async failed");
+  }
+}

system/lib/pthread/proxying_legacy.c

@@ -149,10 +149,6 @@ static void _do_call(void* arg) {
   // C function pointer
   assert(EM_FUNC_SIG_NUM_FUNC_ARGUMENTS(q->functionEnum) <= EM_QUEUED_CALL_MAX_ARGS);
   switch (q->functionEnum) {
-    case EM_PROXIED_RESIZE_OFFSCREENCANVAS:
-      q->returnValue.i =
-        _emscripten_set_offscreencanvas_size(q->args[0].cp, q->args[1].i, q->args[2].i);
-      break;
     case EM_FUNC_SIG_V:
       ((em_func_v)q->functionPtr)();
       break;

tools/system_libs.py

@@ -1910,6 +1910,7 @@ def can_use(self):
 class libhtml5(Library):
   name = 'libhtml5'
 
+  includes = ['system/lib/libc']
   cflags = ['-Oz', '-fno-inline-functions']
   src_dir = 'system/lib/html5'
   src_glob = '*.c'