[wasm] Fix interaction of WebAssembly.Function with globals.

This makes sure that functions constructed via {WebAssembly.Function}
can be properly stored in globals of type "funcref". For now it is not
possible to call functions in such globals, but values can be loaded and
stored.

R=ahaas@chromium.org
TEST=mjsunit/wasm/type-reflection-with-anyref
BUG=v8:7742

Change-Id: I88ad1b5a57fd50e28723430803c528e674a94321
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1876815Reviewed-by: Andreas Haas <ahaas@chromium.org>
Commit-Queue: Michael Starzinger <mstarzinger@chromium.org>
Cr-Commit-Position: refs/heads/master@{#64539}

src/runtime/runtime-wasm.cc

@@ -71,7 +71,7 @@ RUNTIME_FUNCTION(Runtime_WasmIsValidFuncRefValue) {
   if (function->IsNull(isolate)) {
     return Smi::FromInt(true);
   }
-  if (WasmExportedFunction::IsWasmExportedFunction(*function)) {
+  if (WasmExternalFunction::IsWasmExternalFunction(*function)) {
     return Smi::FromInt(true);
   }
   return Smi::FromInt(false);

src/wasm/wasm-objects-inl.h

@@ -186,7 +186,7 @@ void WasmGlobalObject::SetAnyRef(Handle<Object> value) {
 bool WasmGlobalObject::SetFuncRef(Isolate* isolate, Handle<Object> value) {
   DCHECK_EQ(type(), wasm::kWasmFuncRef);
   if (!value->IsNull(isolate) &&
-      !WasmExportedFunction::IsWasmExportedFunction(*value) &&
+      !WasmExternalFunction::IsWasmExternalFunction(*value) &&
       !WasmCapiFunction::IsWasmCapiFunction(*value)) {
     return false;
   }

test/mjsunit/wasm/type-reflection-with-anyref.js

@@ -41,6 +41,38 @@ load('test/mjsunit/wasm/wasm-module-builder.js');
   assertEquals(2, Object.getOwnPropertyNames(type).length);
 })();
 
+(function TestFunctionGlobalGetAndSet() {
+  let builder = new WasmModuleBuilder();
+  let fun1 = new WebAssembly.Function({parameters:[], results:["i32"]}, _ => 7);
+  let fun2 = new WebAssembly.Function({parameters:[], results:["i32"]}, _ => 9);
+  builder.addGlobal(kWasmAnyFunc, true).exportAs("f");
+  builder.addFunction('get_global', kSig_a_v)
+      .addBody([
+        kExprGlobalGet, 0,
+      ])
+      .exportFunc();
+  builder.addFunction('set_global', kSig_v_a)
+      .addBody([
+        kExprLocalGet, 0,
+        kExprGlobalSet, 0,
+      ])
+      .exportFunc();
+  let instance = builder.instantiate();
+
+  // Test getting and setting "funcref" global via WebAssembly.
+  assertEquals(null, instance.exports.get_global());
+  instance.exports.set_global(fun1);
+  assertEquals(fun1, instance.exports.get_global());
+
+  // Test getting and setting "funcref" global via JavaScript.
+  assertEquals(fun1, instance.exports.f.value);
+  instance.exports.f.value = fun2;
+  assertEquals(fun2, instance.exports.f.value);
+
+  // Test the full round-trip of an "funcref" global.
+  assertEquals(fun2, instance.exports.get_global());
+})();
+
 // This is an extension of "type-reflection.js/TestFunctionTableSetAndCall" to
 // multiple table indexes. If --experimental-wasm-anyref is enabled by default
 // this test case can supersede the other one.