allow async on the top level

Author: mschwarzl

Sources/Fuzzilli/Compiler/Compiler.swift

@@ -1160,10 +1160,8 @@ public class JavaScriptCompiler {
             fatalError("V8IntrinsicIdentifiers must be handled as part of their surrounding CallExpression")
 
         case .awaitExpression(let awaitExpression):
-                // TODO await is also allowed at the top level of a module
-                if !contextAnalyzer.context.contains(.asyncFunction) {
-                    throw CompilerError.invalidNodeError("`await` is currently only supported in async functions")
-                }
+                // Await is also allowed at the top level of a module
+                // workerd requires that support
                 let argument = try compileExpression(awaitExpression.argument)
                 return emit(Await(), withInputs: [argument]).output
 

Sources/Fuzzilli/Compiler/Parser/parser.js

@@ -34,7 +34,7 @@ function tryReadFile(path) {
 
 // Parse the given JavaScript script and return an AST compatible with Fuzzilli's protobuf-based AST format.
 function parse(script, proto) {
-    let ast = Parser.parse(script, { plugins: ["v8intrinsic"] });
+    let ast = Parser.parse(script, { allowAwaitOutsideFunction: true, plugins: ["topLevelAwait","v8intrinsic"] });
 
     function assertNoError(err) {
         if (err) throw err;

Sources/Fuzzilli/FuzzIL/Code.swift

@@ -239,9 +239,12 @@ public struct Code: Collection {
                     throw FuzzilliError.codeVerificationError("variable \(input) is not visible anymore")
                 }
             }
-
-            guard instr.op.requiredContext.isSubset(of: contextAnalyzer.context) else {
-                throw FuzzilliError.codeVerificationError("operation \(instr.op.name) inside an invalid context")
+            
+            // allow top-level await
+            if !instr.op is Await {
+                guard instr.op.requiredContext.isSubset(of: contextAnalyzer.context) else {
+                    throw FuzzilliError.codeVerificationError("operation \(instr.op.name) inside an invalid context")
+                }
             }
 
             // Ensure that the instruction exists in the right context