Bug 1317085 - Part 1: Handle async function flag in XDR. r=till

js/src/jit-test/tests/xdr/async.js

@@ -0,0 +1,32 @@
+load(libdir + 'bytecode-cache.js');
+
+async function f1(a, b) {
+  let x = await 10;
+  return x;
+};
+var toStringResult = f1.toString();
+
+var test = `
+async function f1(a, b) {
+  let x = await 10;
+  return x;
+};
+// toString gets unwrapped function from wrapped function.
+assertEq(f1.toString(), \`${toStringResult}\`);
+
+var ans = 0;
+f1().then(x => { ans = x; });
+drainJobQueue();
+assertEq(ans, 10);
+
+async function f2(a, b) {
+  // arguments.callee gets wrapped function from unwrapped function.
+  return arguments.callee;
+};
+
+f2().then(x => { ans = x; });
+drainJobQueue();
+assertEq(ans, f2);
+`;
+
+evalWithCache(test, { assertEqBytecode: true, checkFrozen: true});

js/src/jsscript.cpp

@@ -316,6 +316,7 @@ js::XDRScript(XDRState<mode>* xdr, HandleScope scriptEnclosingScope, HandleScrip
         IsGeneratorExp,
         IsLegacyGenerator,
         IsStarGenerator,
+        IsAsync,
         OwnSource,
         ExplicitUseStrict,
         SelfHosted,
@@ -429,6 +430,8 @@ js::XDRScript(XDRState<mode>* xdr, HandleScope scriptEnclosingScope, HandleScrip
             scriptBits |= (1 << IsLegacyGenerator);
         if (script->isStarGenerator())
             scriptBits |= (1 << IsStarGenerator);
+        if (script->asyncKind() == AsyncFunction)
+            scriptBits |= (1 << IsAsync);
         if (script->hasSingletons())
             scriptBits |= (1 << HasSingleton);
         if (script->treatAsRunOnce())
@@ -577,6 +580,9 @@ js::XDRScript(XDRState<mode>* xdr, HandleScope scriptEnclosingScope, HandleScrip
             script->setGeneratorKind(LegacyGenerator);
         } else if (scriptBits & (1 << IsStarGenerator))
             script->setGeneratorKind(StarGenerator);
+
+        if (scriptBits & (1 << IsAsync))
+            script->setAsyncKind(AsyncFunction);
     }
 
     JS_STATIC_ASSERT(sizeof(jsbytecode) == 1);