support for top-level awaits

Author: mschwarzl

Sources/Fuzzilli/Compiler/Compiler.swift

@@ -1161,9 +1161,10 @@ public class JavaScriptCompiler {
 
         case .awaitExpression(let awaitExpression):
                 // TODO await is also allowed at the top level of a module
-                if !contextAnalyzer.context.contains(.asyncFunction) {
+                /*if !contextAnalyzer.context.contains(.asyncFunction) {
                     throw CompilerError.invalidNodeError("`await` is currently only supported in async functions")
                 }
+                */
                 let argument = try compileExpression(awaitExpression.argument)
                 return emit(Await(), withInputs: [argument]).output
 

Sources/Fuzzilli/FuzzIL/Code.swift

@@ -239,9 +239,21 @@ 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")
+            
+            if instr.op is Await {
+                if !contextAnalyzer.context.contains(.asyncFunction)
+                {
+                    if contextAnalyzer.context.contains(.subroutine) {
+                        if !contextAnalyzer.context.contains(.method) && !contextAnalyzer.context.contains(.classMethod) {
+                            throw FuzzilliError.codeVerificationError("operation \(instr.op.name) inside an invalid context")
+                        }
+                    }
+                }
+                // fall-through allow top-level await
+            } else {
+                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