[wasm][eh] Add WebAssembly.Exception.is()

R=jkummerow@chromium.org

Bug: v8:11992
Change-Id: I9fd1eabf70408f6abc4480c999ac26bf5d8ccd8d
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3067321
Commit-Queue: Thibaud Michaud <thibaudm@chromium.org>
Reviewed-by: Jakob Kummerow <jkummerow@chromium.org>
Cr-Commit-Position: refs/heads/master@{#76096}

src/wasm/wasm-js.cc

@@ -2160,6 +2160,30 @@ void WebAssemblyExceptionGetArg(
   args.GetReturnValue().Set(result);
 }
 
+void WebAssemblyExceptionIs(const v8::FunctionCallbackInfo<v8::Value>& args) {
+  v8::Isolate* isolate = args.GetIsolate();
+  HandleScope scope(isolate);
+  i::Isolate* i_isolate = reinterpret_cast<i::Isolate*>(isolate);
+  ScheduledErrorThrower thrower(i_isolate, "WebAssembly.Exception.is()");
+
+  EXTRACT_THIS(exception, WasmExceptionPackage);
+  if (thrower.error()) return;
+
+  auto tag = i::WasmExceptionPackage::GetExceptionTag(i_isolate, exception);
+  if (tag->IsUndefined()) {
+    thrower.TypeError("Expected a WebAssembly.Exception object");
+    return;
+  }
+  DCHECK(tag->IsWasmExceptionTag());
+
+  auto maybe_tag = GetFirstArgumentAsTag(args, &thrower);
+  if (thrower.error()) {
+    return;
+  }
+  auto tag_arg = maybe_tag.ToHandleChecked();
+  args.GetReturnValue().Set(tag_arg->tag() == *tag);
+}
+
 void WebAssemblyGlobalGetValueCommon(
     const v8::FunctionCallbackInfo<v8::Value>& args, const char* name) {
   v8::Isolate* isolate = args.GetIsolate();
@@ -2623,6 +2647,7 @@ void WasmJs::Install(Isolate* isolate, bool exposed_on_global_object) {
         isolate);
     InstallFunc(isolate, exception_proto, "getArg", WebAssemblyExceptionGetArg,
                 2);
+    InstallFunc(isolate, exception_proto, "is", WebAssemblyExceptionIs, 1);
     context->set_wasm_exception_constructor(*exception_constructor);
     JSFunction::SetInitialMap(isolate, exception_constructor, exception_map,
                               exception_proto);

test/mjsunit/wasm/exceptions-api.js

@@ -219,3 +219,18 @@ function TestGetArgHelper(types_str, types, values) {
   TestGetArgHelper(['externref'], [kWasmExternRef], [{val: 5}]);
   TestGetArgHelper(['i32', 'i64', 'f32', 'f64', 'externref'], [kWasmI32, kWasmI64, kWasmF32, kWasmF64, kWasmExternRef], [5, 6n, 7, 8, {val: 9}]);
 })();
+
+(function TestExceptionIs() {
+  print(arguments.callee.name);
+  let tag1 = new WebAssembly.Tag({parameters: []});
+  let tag2 = new WebAssembly.Tag({parameters: []});
+  assertThrows(() => new WebAssembly.Exception({}, []), TypeError,
+      /Argument 0 must be a WebAssembly tag/);
+
+  let exception = new WebAssembly.Exception(tag1, []);
+  assertTrue(exception.is(tag1));
+  assertFalse(exception.is(tag2));
+
+  assertThrows(() => exception.is.apply({}, tag1), TypeError,
+      /Expected a WebAssembly.Exception object/);
+})();