Move __cxa_allocate_exception to native code. NFC (#18292)

Author: sbc100

emcc.py

@@ -2620,7 +2620,6 @@ def check_memory_setting(setting):
      settings.USE_WEBGPU or \
      settings.OFFSCREENCANVAS_SUPPORT or \
      settings.LEGACY_GL_EMULATION or \
-     not settings.DISABLE_EXCEPTION_CATCHING or \
      settings.ASYNCIFY or \
      settings.WASMFS or \
      settings.DEMANGLE_SUPPORT or \
@@ -2646,6 +2645,7 @@ def check_memory_setting(setting):
       # setThrew(). We cannot handle this using deps_info as the invokes are not
       # emitted because of library function usage, but by codegen itself.
       'setThrew',
+      '__cxa_free_exception',
     ]
 
   if settings.ASYNCIFY:

src/library_exceptions.js

@@ -163,29 +163,6 @@ var LibraryExceptions = {
     }
   },
 
-  // Exceptions
-  __cxa_allocate_exception__sig: 'pp',
-  __cxa_allocate_exception: function(size) {
-    // Thrown object is prepended by exception metadata block
-    return _malloc(size + {{{ C_STRUCTS.__cxa_exception.__size__ }}}) + {{{ C_STRUCTS.__cxa_exception.__size__ }}};
-  },
-
-  __cxa_free_exception__deps: ['$ExceptionInfo'],
-  __cxa_free_exception__sig: 'vp',
-  __cxa_free_exception: function(ptr) {
-#if ABORTING_MALLOC || ASSERTIONS
-    try {
-#endif
-      return _free(new ExceptionInfo(ptr).ptr);
-#if ABORTING_MALLOC || ASSERTIONS
-    } catch(e) {
-#if ASSERTIONS
-      err('exception during __cxa_free_exception: ' + e);
-#endif
-    }
-#endif
-  },
-
   __cxa_increment_exception_refcount__deps: ['$exception_addRef', '$ExceptionInfo'],
   __cxa_increment_exception_refcount__sig: 'vp',
   __cxa_increment_exception_refcount: function(ptr) {

system/lib/libcxxabi/src/cxa_exception_emscripten.cpp

@@ -32,9 +32,6 @@ __gxx_personality_v0(int version,
 }
 #endif // !defined(__USING_WASM_EXCEPTIONS__)
 
-#if defined(__USING_EMSCRIPTEN_EXCEPTIONS__) ||                                \
-  defined(__USING_WASM_EXCEPTIONS__)
-
 using namespace __cxxabiv1;
 
 //  Some utility routines are copied from cxa_exception.cpp
@@ -50,6 +47,9 @@ thrown_object_from_cxa_exception(__cxa_exception* exception_header) {
   return static_cast<void*>(exception_header + 1);
 }
 
+#if defined(__USING_EMSCRIPTEN_EXCEPTIONS__) ||                                \
+  defined(__USING_WASM_EXCEPTIONS__)
+
 //  Get the exception object from the unwind pointer.
 //  Relies on the structure layout, where the unwind pointer is right in
 //  front of the user's exception object
@@ -130,3 +130,21 @@ char* __get_exception_terminate_message(void* thrown_object) {
 }
 
 #endif // __USING_EMSCRIPTEN_EXCEPTIONS__ || __USING_WASM_EXCEPTIONS__
+
+#ifndef __USING_WASM_EXCEPTIONS__
+
+namespace __cxxabiv1 {
+
+void* __cxa_allocate_exception(size_t size) _NOEXCEPT {
+  // Thrown object is prepended by exception metadata block
+  __cxa_exception* ex = (__cxa_exception*)malloc(size + sizeof(__cxa_exception));
+  return thrown_object_from_cxa_exception(ex);
+}
+
+void __cxa_free_exception(void *thrown_object) _NOEXCEPT {
+  free(cxa_exception_from_thrown_object(thrown_object));
+}
+
+}
+
+#endif // !__USING_WASM_EXCEPTIONS__

test/other/metadce/test_metadce_cxx_ctors1.exports

@@ -8,7 +8,6 @@ dynCall_iiiiijj
 dynCall_jiji
 dynCall_viijii
 main
-malloc
 memory
 stackAlloc
 stackRestore

test/other/metadce/test_metadce_cxx_ctors1.imports

@@ -1,4 +1,3 @@
-env.__cxa_allocate_exception
 env.__cxa_throw
 env.abort
 env.emscripten_memcpy_big

test/other/metadce/test_metadce_cxx_ctors1.jssize

@@ -1 +1 @@
-26638
+26496

test/other/metadce/test_metadce_cxx_ctors1.sent

@@ -1,4 +1,3 @@
-__cxa_allocate_exception
 __cxa_throw
 abort
 emscripten_memcpy_big

test/other/metadce/test_metadce_cxx_ctors1.size

@@ -1 +1 @@
-123215
+123176

test/other/metadce/test_metadce_cxx_ctors2.exports

@@ -7,7 +7,6 @@ dynCall_iiiiijj
 dynCall_jiji
 dynCall_viijii
 main
-malloc
 memory
 stackAlloc
 stackRestore

test/other/metadce/test_metadce_cxx_ctors2.imports

@@ -1,4 +1,3 @@
-env.__cxa_allocate_exception
 env.__cxa_throw
 env.abort
 env.emscripten_memcpy_big