Move __cxa_init_primary_exception to native

Given that our JS `__cxa_throw` does not depend on
`__cxa_init_primary_exception` anymore, there's no reason this function
needs to be in JS. This moves the function to the native library. Also
this changes a couple `ifdef __USING_WASM_EXCEPTIONS__`s to
`ifdef __wasm__` because Wasm's destructor type pertains to Emscripten
EH too.

Author: aheejin

src/library_exceptions.js

@@ -102,14 +102,6 @@ var LibraryExceptions = {
     }
   },
 
-  __cxa_init_primary_exception__deps: ['$ExceptionInfo'],
-  __cxa_init_primary_exception: (ptr, type, destructor) => {
-#if EXCEPTION_DEBUG
-    dbg('__cxa_init_primary_exception: ' + [ptrToString(ptr), type, ptrToString(destructor)]);
-#endif
-    return ptr;
-  },
-
   // Here, we throw an exception after recording a couple of values that we need to remember
   // We also remember that it was the last exception thrown as we need to know that later.
   __cxa_throw__deps: ['$ExceptionInfo', '$exceptionLast', '$uncaughtExceptionCount'],

src/library_sigs.js

@@ -221,7 +221,6 @@ sigs = {
   __cxa_current_primary_exception__sig: 'p',
   __cxa_end_catch__sig: 'v',
   __cxa_get_exception_ptr__sig: 'pp',
-  __cxa_init_primary_exception__sig: 'pppp',
   __cxa_rethrow__sig: 'v',
   __cxa_rethrow_primary_exception__sig: 'vp',
   __cxa_throw__sig: 'vppp',

system/lib/libcxx/include/__exception/exception_ptr.h

@@ -38,7 +38,7 @@ _LIBCPP_OVERRIDABLE_FUNC_VIS __cxa_exception* __cxa_init_primary_exception(
     std::type_info*,
 #  if defined(_WIN32)
     void(__thiscall*)(void*)) throw();
-#  elif defined(__USING_WASM_EXCEPTIONS__)
+#  elif defined(__wasm__)
     // In Wasm, a destructor returns its argument
     void* (*)(void*)) throw();
 #  else
@@ -91,14 +91,14 @@ _LIBCPP_HIDE_FROM_ABI exception_ptr make_exception_ptr(_Ep __e) _NOEXCEPT {
   using _Ep2 = __decay_t<_Ep>;
 
   void* __ex = __cxxabiv1::__cxa_allocate_exception(sizeof(_Ep));
-#      ifdef __USING_WASM_EXCEPTIONS__
+#      ifdef __wasm__
   // In Wasm, a destructor returns its argument
   (void)__cxxabiv1::__cxa_init_primary_exception(__ex, const_cast<std::type_info*>(&typeid(_Ep)), [](void* __p) -> void* {
 #      else
   (void)__cxxabiv1::__cxa_init_primary_exception(__ex, const_cast<std::type_info*>(&typeid(_Ep)), [](void* __p) {
 #      endif
     std::__destroy_at(static_cast<_Ep2*>(__p));
-#      ifdef __USING_WASM_EXCEPTIONS__
+#      ifdef __wasm__
     return __p;
 #      endif
   });

system/lib/libcxxabi/include/cxxabi.h

@@ -48,7 +48,7 @@ extern _LIBCXXABI_FUNC_VIS void
 __cxa_free_exception(void *thrown_exception) throw();
 // This function is an LLVM extension, which mirrors the same extension in libsupc++ and libcxxrt
 extern _LIBCXXABI_FUNC_VIS __cxa_exception*
-#ifdef __USING_WASM_EXCEPTIONS__
+#ifdef __wasm__
 // In Wasm, a destructor returns its argument
 __cxa_init_primary_exception(void* object, std::type_info* tinfo, void*(_LIBCXXABI_DTOR_FUNC* dest)(void*)) throw();
 #else

system/lib/libcxxabi/src/cxa_exception_emscripten.cpp

@@ -152,6 +152,15 @@ void __cxa_decrement_exception_refcount(void *thrown_object) throw() {
     }
 }
 
+__cxa_exception* __cxa_init_primary_exception(void* object, std::type_info* tinfo,
+                                              void *(_LIBCXXABI_DTOR_FUNC* dest)(void*)) throw() {
+  __cxa_exception* exception_header = cxa_exception_from_thrown_object(object);
+  exception_header->referenceCount = 0;
+  exception_header->exceptionType = tinfo;
+  exception_header->exceptionDestructor = dest;
+  return exception_header;
+}
+
 }  // extern "C"
 
 }  // abi