jsifier: Make JS libraries aliases work even when native export exists

Followup to #19033.

Updating the `test_closure_full_js_library` to include webgl2 caused
a lot of `JSC_REFERENCE_BEFORE_DECLARE` closure errors.

This is because we had JS aliases who's target was defined both in
JS and in native code.  In this case the jsifier was choosing not to
include the JS version, which in the case of the GL symbols not what
we want.  This is why, prior to #19033, we were duplicating the library
entries.

This this change JS symbol aliases now force the alias target to be
included from the JS library, even in the case that the native code
also emits its own version of a symbol.

This happens in the case of pthreads + MAIN_MODULE +
OFFSCREEN_FRAMEBUFFER. In this mode webgl2.c defines (and also exports)
the entire set of GL library symbols.  In this case we still want the
`emscripten_XX` aliases to point to the original JS versions, no the
natively exported version.

Sadly it looks like we have at testing gab for that particular
combination.

Author: sbc100

embuilder.py

@@ -85,8 +85,10 @@
     'libc++-mt-noexcept',
     'libdlmalloc-mt',
     'libGL-emu',
+    'libGL-emu-webgl2',
     'libGL-mt',
     'libGL-mt-emu',
+    'libGL-mt-emu-webgl2-ofb',
     'libsockets_proxy',
     'libsockets-mt',
     'crtbegin',

src/jsifier.js

@@ -228,17 +228,12 @@ function ${name}(${args}) {
       // what we just added to the library.
     }
 
-    function addFromLibrary(symbol, dependent) {
+    function addFromLibrary(symbol, dependent, force = false) {
       // dependencies can be JS functions, which we just run
       if (typeof symbol == 'function') {
         return symbol();
       }
 
-      if (symbol in addedLibraryItems) {
-        return;
-      }
-      addedLibraryItems[symbol] = true;
-
       // don't process any special identifiers. These are looked up when
       // processing the base name of the identifier.
       if (isJsLibraryConfigIdentifier(symbol)) {
@@ -257,9 +252,14 @@ function ${name}(${args}) {
 
       // if the function was implemented in compiled code, there is no need to
       // include the js version
-      if (WASM_EXPORTS.has(symbol)) {
+      if (WASM_EXPORTS.has(symbol) && !force) {
+        return;
+      }
+
+      if (symbol in addedLibraryItems) {
         return;
       }
+      addedLibraryItems[symbol] = true;
 
       // This gets set to true in the case of dynamic linking for symbols that
       // are undefined in the main module.  In this case we create a stub that
@@ -334,17 +334,19 @@ function ${name}(${args}) {
           warn(`user library symbol '${symbol}' depends on internal symbol '${dep}'`);
         }
       });
+
       let isFunction = false;
+      let aliasTarget;
 
       if (typeof snippet == 'string') {
         if (snippet[0] != '=') {
-          const target = LibraryManager.library[snippet];
-          if (target) {
-            // Redirection for aliases. We include the parent, and at runtime make ourselves equal to it.
-            // This avoid having duplicate functions with identical content.
-            const redirectedTarget = snippet;
-            deps.push(redirectedTarget);
-            snippet = mangleCSymbolName(redirectedTarget);
+          if (LibraryManager.library[snippet]) {
+            // Redirection for aliases. We include the parent, and at runtime
+            // make ourselves equal to it.  This avoid having duplicate
+            // functions with identical content.
+            aliasTarget = snippet;
+            snippet = mangleCSymbolName(aliasTarget);
+            deps.push(aliasTarget);
           }
         }
       } else if (typeof snippet == 'object') {
@@ -376,7 +378,7 @@ function ${name}(${args}) {
       const deps_list = deps.join("','");
       const identDependents = symbol + `__deps: ['${deps_list}']`;
       function addDependency(dep) {
-        return addFromLibrary(dep, `${identDependents}, referenced by ${dependent}`);
+        return addFromLibrary(dep, `${identDependents}, referenced by ${dependent}`, dep === aliasTarget);
       }
       let contentText;
       if (isFunction) {
@@ -431,8 +433,11 @@ function ${name}(${args}) {
       }
 
       let commentText = '';
+      if (force) {
+        commentText += '/** @suppress {duplicate } */\n'
+      }
       if (LibraryManager.library[symbol + '__docs']) {
-        commentText = LibraryManager.library[symbol + '__docs'] + '\n';
+        commentText += LibraryManager.library[symbol + '__docs'] + '\n';
       }
 
       const depsText = (deps ? deps.map(addDependency).filter((x) => x != '').join('\n') + '\n' : '');

src/parseTools.js

@@ -838,7 +838,7 @@ function hasExportedSymbol(sym) {
 // it is a BigInt. Otherwise, we legalize into pairs of i32s.
 function defineI64Param(name) {
   if (WASM_BIGINT) {
-    return `/** @type {!BigInt} */ ${name}`;
+    return name;
   }
   return `${name}_low, ${name}_high`;
 }

system/lib/gl/webgl2.c

@@ -131,9 +131,10 @@ ASYNC_GL_FUNCTION_5(EM_FUNC_SIG_VIIIII, void, glTexStorage2D, GLenum, GLsizei, G
 ASYNC_GL_FUNCTION_6(EM_FUNC_SIG_VIIIIII, void, glTexStorage3D, GLenum, GLsizei, GLenum, GLsizei, GLsizei, GLsizei);
 VOID_SYNC_GL_FUNCTION_5(EM_FUNC_SIG_VIIIII, void, glGetInternalformativ, GLenum, GLenum, GLenum, GLsizei, GLint *);
 
-#endif // ~__EMSCRIPTEN_PTHREADS__
-
-// Extensions:
+// Extensions that are aliases for the proxying functions defined above.
+// Normally these aliases get defined in library_webgl.js but when building with
+// __EMSCRIPTEN_OFFSCREEN_FRAMEBUFFER__ we want to intercept them in native
+// code and redirect them to thier proxying couterparts.
 GL_APICALL void GL_APIENTRY glVertexAttribDivisorNV(GLuint index, GLuint divisor) { glVertexAttribDivisor(index, divisor); }
 GL_APICALL void GL_APIENTRY glVertexAttribDivisorEXT(GLuint index, GLuint divisor) { glVertexAttribDivisor(index, divisor); }
 GL_APICALL void GL_APIENTRY glVertexAttribDivisorARB(GLuint index, GLuint divisor) { glVertexAttribDivisor(index, divisor); }
@@ -153,6 +154,8 @@ GL_APICALL GLboolean GL_APIENTRY glIsVertexArrayOES(GLuint array) { return glIsV
 GL_APICALL void GL_APIENTRY glDrawBuffersEXT(GLsizei n, const GLenum *bufs) { glDrawBuffers(n, bufs); }
 GL_APICALL void GL_APIENTRY glDrawBuffersWEBGL(GLsizei n, const GLenum *bufs) { glDrawBuffers(n, bufs); }
 
+#endif // ~__EMSCRIPTEN_PTHREADS__) && __EMSCRIPTEN_OFFSCREEN_FRAMEBUFFER__
+
 // Returns a function pointer to the given WebGL 2 extension function, when queried without
 // a GL extension suffix such as "EXT", "OES", or "ANGLE". This function is used by
 // emscripten_GetProcAddress() to implement legacy GL emulation semantics for portability.

system/lib/gl/webgl_internal.h

@@ -7,6 +7,8 @@ EMSCRIPTEN_RESULT emscripten_webgl_do_commit_frame(void);
 EM_BOOL emscripten_supports_offscreencanvas(void);
 void _emscripten_proxied_gl_context_activated_from_main_browser_thread(EMSCRIPTEN_WEBGL_CONTEXT_HANDLE context);
 
+#if defined(__EMSCRIPTEN_PTHREADS__) && defined(__EMSCRIPTEN_OFFSCREEN_FRAMEBUFFER__)
+
 #ifdef EMSCRIPTEN_WEBGL_TRACE
 #define GL_FUNCTION_TRACE(func) printf(#func "\n")
 #else
@@ -52,8 +54,6 @@ void _emscripten_proxied_gl_context_activated_from_main_browser_thread(EMSCRIPTE
 #define VOID_SYNC_GL_FUNCTION_10(sig, ret, functionName, t0, t1, t2, t3, t4, t5, t6, t7, t8, t9) ret functionName(t0 p0, t1 p1, t2 p2, t3 p3, t4 p4, t5 p5, t6 p6, t7 p7, t8 p8, t9 p9) { GL_FUNCTION_TRACE(functionName); if (pthread_getspecific(currentThreadOwnsItsWebGLContext)) emscripten_##functionName(p0, p1, p2, p3, p4, p5, p6, p7, p8, p9); else emscripten_sync_run_in_main_runtime_thread(sig, &emscripten_##functionName, p0, p1, p2, p3, p4, p5, p6, p7, p8, p9); }
 #define VOID_SYNC_GL_FUNCTION_11(sig, ret, functionName, t0, t1, t2, t3, t4, t5, t6, t7, t8, t9, t10) ret functionName(t0 p0, t1 p1, t2 p2, t3 p3, t4 p4, t5 p5, t6 p6, t7 p7, t8 p8, t9 p9, t10 p10) { GL_FUNCTION_TRACE(functionName); if (pthread_getspecific(currentThreadOwnsItsWebGLContext)) emscripten_##functionName(p0, p1, p2, p3, p4, p5, p6, p7, p8, p9, p10); else emscripten_sync_run_in_main_runtime_thread(sig, &emscripten_##functionName, p0, p1, p2, p3, p4, p5, p6, p7, p8, p9, p10); }
 
-#if defined(__EMSCRIPTEN_PTHREADS__) && defined(__EMSCRIPTEN_OFFSCREEN_FRAMEBUFFER__)
-
 #include <pthread.h>
 
 extern pthread_key_t currentActiveWebGLContext;

test/test_other.py

@@ -8685,6 +8685,7 @@ def test_full_js_library_minimal_runtime(self):
     # binaryen tools get run, which can affect how debug info is kept around
     'bigint': [['-sWASM_BIGINT']],
     'pthread': [['-pthread', '-Wno-experimental']],
+    'pthread_offscreen': [['-pthread', '-Wno-experimental', '-sOFFSCREEN_FRAMEBUFFER']],
   })
   def test_closure_full_js_library(self, args):
     # Test for closure errors and warnings in the entire JS library.
@@ -8698,6 +8699,7 @@ def test_closure_full_js_library(self, args):
       '-sFETCH',
       '-sFETCH_SUPPORT_INDEXEDDB',
       '-sLEGACY_GL_EMULATION',
+      '-sMAX_WEBGL_VERSION=2',
     ] + args)
 
   def test_closure_webgpu(self):