PostEmscripten: Preserve __em_js__ exports in side modules

Author: sbc100

src/passes/PostEmscripten.cpp

@@ -186,10 +186,13 @@ IString EM_JS_PREFIX("__em_js__");
 IString EM_JS_DEPS_PREFIX("__em_lib_deps_");
 
 struct EmJsWalker : public PostWalker<EmJsWalker> {
+  bool sideModule;
   std::vector<Export> toRemove;
 
+  EmJsWalker(bool sideModule) : sideModule(sideModule) {}
+
   void visitExport(Export* curr) {
-    if (curr->name.startsWith(EM_JS_PREFIX)) {
+    if (!sideModule && curr->name.startsWith(EM_JS_PREFIX)) {
       toRemove.push_back(*curr);
     }
     if (curr->name.startsWith(EM_JS_DEPS_PREFIX)) {
@@ -215,14 +218,15 @@ struct PostEmscripten : public Pass {
     auto& options = getPassOptions();
     auto sideModule = options.hasArgument("post-emscripten-side-module");
     if (!sideModule) {
+      removeData(module, segmentOffsets, "__start_em_asm", "__stop_em_asm");
+      removeData(module, segmentOffsets, "__start_em_js", "__stop_em_js");
+
       // Side modules read EM_ASM data from the module based on these exports
       // so we need to keep them around in that case.
-      removeData(module, segmentOffsets, "__start_em_asm", "__stop_em_asm");
       module.removeExport("__start_em_asm");
       module.removeExport("__stop_em_asm");
     }
 
-    removeData(module, segmentOffsets, "__start_em_js", "__stop_em_js");
     removeData(
       module, segmentOffsets, "__start_em_lib_deps", "__stop_em_lib_deps");
     module.removeExport("__start_em_js");
@@ -232,7 +236,9 @@ struct PostEmscripten : public Pass {
   }
 
   void removeEmJsExports(Module& module) {
-    EmJsWalker walker;
+    auto& options = getPassOptions();
+    auto sideModule = options.hasArgument("post-emscripten-side-module");
+    EmJsWalker walker(sideModule);
     walker.walkModule(&module);
     for (const Export& exp : walker.toRemove) {
       if (exp.kind == ExternalKind::Function) {