Change implementation of eval to make an exact distinction between direct eva...

src/runtime.cc

Index: src/runtime.cc
===================================================================
--- src/runtime.cc	(revision 854)
+++ src/runtime.cc	(working copy)
@@ -3934,57 +3934,6 @@
 }
 
 
-static Object* EvalContext() {
-  // The topmost JS frame belongs to the eval function which called
-  // the CompileString runtime function. We need to unwind one level
-  // to get to the caller of eval.
-  StackFrameLocator locator;
-  JavaScriptFrame* frame = locator.FindJavaScriptFrame(1);
-
-  // TODO(900055): Right now we check if the caller of eval() supports
-  // eval to determine if it's an aliased eval or not. This may not be
-  // entirely correct in the unlikely case where a function uses both
-  // aliased and direct eval calls.
-  HandleScope scope;
-  if (!ScopeInfo<>::SupportsEval(frame->FindCode())) {
-    // Aliased eval: Evaluate in the global context of the eval
-    // function to support aliased, cross environment evals.
-    return *Top::global_context();
-  }
-
-  // Fetch the caller context from the frame.
-  Handle<Context> caller(Context::cast(frame->context()));
-
-  // Check for eval() invocations that cross environments. Use the
-  // context from the stack if evaluating in current environment.
-  Handle<Context> target = Top::global_context();
-  if (caller->global_context() == *target) return *caller;
-
-  // Otherwise, use the global context from the other environment.
-  return *target;
-}
-
-
-static Object* Runtime_EvalReceiver(Arguments args) {
-  ASSERT(args.length() == 1);
-  StackFrameLocator locator;
-  JavaScriptFrame* frame = locator.FindJavaScriptFrame(1);
-  // Fetch the caller context from the frame.
-  Context* caller = Context::cast(frame->context());
-
-  // Check for eval() invocations that cross environments. Use the
-  // top frames receiver if evaluating in current environment.
-  Context* global_context = Top::context()->global()->global_context();
-  if (caller->global_context() == global_context) {
-    return frame->receiver();
-  }
-
-  // Otherwise use the given argument (the global object of the
-  // receiving context).
-  return args[0];
-}
-
-
 static Object* Runtime_GlobalReceiver(Arguments args) {
   ASSERT(args.length() == 1);
   Object* global = args[0];
@@ -3995,37 +3944,112 @@
 
 static Object* Runtime_CompileString(Arguments args) {
   HandleScope scope;
-  ASSERT(args.length() == 3);
+  ASSERT(args.length() == 2);
   CONVERT_ARG_CHECKED(String, source, 0);
   CONVERT_ARG_CHECKED(Smi, line_offset, 1);
-  bool contextual = args[2]->IsTrue();
-  RUNTIME_ASSERT(contextual || args[2]->IsFalse());
 
-  // Compute the eval context.
-  Handle<Context> context;
-  if (contextual) {
-    // Get eval context. May not be available if we are calling eval
-    // through an alias, and the corresponding frame doesn't have a
-    // proper eval context set up.
-    Object* eval_context = EvalContext();
-    if (eval_context->IsFailure()) return eval_context;
-    context = Handle<Context>(Context::cast(eval_context));
-  } else {
-    context = Handle<Context>(Top::context()->global_context());
-  }
-
-
   // Compile source string.
-  bool is_global = context->IsGlobalContext();
   Handle<JSFunction> boilerplate =
-      Compiler::CompileEval(source, line_offset->value(), is_global);
+      Compiler::CompileEval(source, line_offset->value(), true);
   if (boilerplate.is_null()) return Failure::Exception();
+  Handle<Context> context(Top::context()->global_context());
   Handle<JSFunction> fun =
       Factory::NewFunctionFromBoilerplate(boilerplate, context);
   return *fun;
 }
 
 
+static Handle<JSFunction> GetBuiltinFunction(String* name) {
+  LookupResult result;
+  Top::global_context()->builtins()->LocalLookup(name, &result);
+  return Handle<JSFunction>(JSFunction::cast(result.GetValue()));
+}
+
+
+static Object* CompileDirectEval(Handle<String> source) {
+  // Compute the eval context.
+  HandleScope scope;
+  StackFrameLocator locator;
+  JavaScriptFrame* frame = locator.FindJavaScriptFrame(0);
+  Handle<Context> context(Context::cast(frame->context()));
+  bool is_global = context->IsGlobalContext();
+
+  // Compile source string.
+  Handle<JSFunction> boilerplate = Compiler::CompileEval(source, 0, is_global);
+  if (boilerplate.is_null()) return Failure::Exception();
+  Handle<JSFunction> fun =
+    Factory::NewFunctionFromBoilerplate(boilerplate, context);
+  return *fun;
+}
+
+
+static Object* Runtime_ResolvePossiblyDirectEval(Arguments args) {
+  ASSERT(args.length() == 2);
+
+  HandleScope scope;
+
+  CONVERT_ARG_CHECKED(JSFunction, callee, 0);
+
+  Handle<Object> receiver;
+
+  // Find where the 'eval' symbol is bound. It is unaliased only if
+  // it is bound in the global context.
+  StackFrameLocator locator;
+  JavaScriptFrame* frame = locator.FindJavaScriptFrame(0);
+  Handle<Context> context(Context::cast(frame->context()));
+  int index;
+  PropertyAttributes attributes;
+  while (!context.is_null()) {
+    receiver = context->Lookup(Factory::eval_symbol(), FOLLOW_PROTOTYPE_CHAIN,
+                               &index, &attributes);
+    if (attributes != ABSENT) break;
+    if (context->is_function_context()) {
+      context = Handle<Context>(Context::cast(context->closure()->context()));
+    } else {
+      context = Handle<Context>(context->previous());
+    }
+  }
+
+  if (context->IsGlobalContext()) {
+    // 'eval' is bound in the global context, but it may have been overwritten.
+    // Compare it to the builtin 'GlobalEval' function to make sure.
+    Handle<JSFunction> global_eval =
+      GetBuiltinFunction(Heap::global_eval_symbol());
+    if (global_eval.is_identical_to(callee)) {
+      // A direct eval call.
+      if (args[1]->IsString()) {
+        CONVERT_ARG_CHECKED(String, source, 1);
+        // A normal eval call on a string. Compile it and return the
+        // compiled function bound in the local context.
+        Object* compiled_source = CompileDirectEval(source);
+        if (compiled_source->IsFailure()) return compiled_source;
+        receiver = Handle<Object>(frame->receiver());
+        callee = Handle<JSFunction>(JSFunction::cast(compiled_source));
+      } else {
+        // An eval call that is not called on a string. Global eval
+        // deals better with this.
+        receiver = Handle<Object>(Top::global_context()->global());
+      }
+    } else {
+      // 'eval' is overwritten. Just call the function with the given arguments.
+      receiver = Handle<Object>(Top::global_context()->global());
+    }
+  } else {
+    // 'eval' is not bound in the global context. Just call the function
+    // with the given arguments. This is not necessarily the global eval.
+    if (receiver->IsContext()) {
+      context = Handle<Context>::cast(receiver);
+      receiver = Handle<Object>(context->get(index));
+    }
+  }
+
+  Handle<FixedArray> call = Factory::NewFixedArray(2);
+  call->set(0, *callee);
+  call->set(1, *receiver);
+  return *call;
+}
+
+
 static Object* Runtime_CompileScript(Arguments args) {
   HandleScope scope;
   ASSERT(args.length() == 4);