Implement ES6 rest parameters

src/runtime/runtime-scopes.cc

 // Copyright 2014 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/v8.h"
 
 #include "src/accessors.h"
 #include "src/arguments.h"
 #include "src/frames-inl.h"
 #include "src/runtime/runtime-utils.h"
@@ skipping 338 matching lines @@
                    Handle<JSObject>::cast(holder), name, value, attr));
 
   return *value;
 }
 
 
 static Handle<JSObject> NewSloppyArguments(Isolate* isolate,
                                            Handle<JSFunction> callee,
                                            Object** parameters,
                                            int argument_count) {
+  DCHECK(callee->is_simple_parameter_list());
   Handle<JSObject> result =
       isolate->factory()->NewArgumentsObject(callee, argument_count);
 
   // Allocate the elements if needed.
   int parameter_count = callee->shared()->formal_parameter_count();
   if (argument_count > 0) {
     if (parameter_count > 0) {
       int mapped_count = Min(argument_count, parameter_count);
       Handle<FixedArray> parameter_map =
           isolate->factory()->NewFixedArray(mapped_count + 2, NOT_TENURED);
@@ skipping 43 matching lines @@
         } else {
           // The context index goes in the parameter map with a hole in the
           // arguments array.
           int context_index = -1;
           for (int j = 0; j < context_local_count; ++j) {
             if (scope_info->ContextLocalName(j) == *name) {
               context_index = j;
               break;
             }
           }
+
           DCHECK(context_index >= 0);
           arguments->set_the_hole(index);
           parameter_map->set(
               index + 2,
               Smi::FromInt(Context::MIN_CONTEXT_SLOTS + context_index));
         }
 
         --index;
       }
     } else {
@@ skipping 38 matching lines @@
   CONVERT_ARG_HANDLE_CHECKED(JSFunction, callee, 0);
   JavaScriptFrameIterator it(isolate);
 
   // Find the frame that holds the actual arguments passed to the function.
   it.AdvanceToArgumentsFrame();
   JavaScriptFrame* frame = it.frame();
 
   // Determine parameter location on the stack and dispatch on language mode.
   int argument_count = frame->GetArgumentsLength();
   Object** parameters = reinterpret_cast<Object**>(frame->GetParameterSlot(-1));
-  return is_strict(callee->shared()->language_mode())
+
+  return (is_strict(callee->shared()->language_mode()) ||
+             !callee->is_simple_parameter_list())
              ? *NewStrictArguments(isolate, callee, parameters, argument_count)
              : *NewSloppyArguments(isolate, callee, parameters, argument_count);
 }
 
 
 RUNTIME_FUNCTION(Runtime_NewSloppyArguments) {
   HandleScope scope(isolate);
   DCHECK(args.length() == 3);
   CONVERT_ARG_HANDLE_CHECKED(JSFunction, callee, 0);
   Object** parameters = reinterpret_cast<Object**>(args[1]);
   CONVERT_SMI_ARG_CHECKED(argument_count, 2);
   return *NewSloppyArguments(isolate, callee, parameters, argument_count);
 }
 
 
 RUNTIME_FUNCTION(Runtime_NewStrictArguments) {
   HandleScope scope(isolate);
   DCHECK(args.length() == 3);
   CONVERT_ARG_HANDLE_CHECKED(JSFunction, callee, 0)
   Object** parameters = reinterpret_cast<Object**>(args[1]);
   CONVERT_SMI_ARG_CHECKED(argument_count, 2);
   return *NewStrictArguments(isolate, callee, parameters, argument_count);
 }
 
 
+static Handle<JSArray> NewRestParam(Isolate* isolate,
+                                    Object** parameters,
+                                    int num_params,
+                                    int rest_index) {
+  parameters -= rest_index;
+  int num_elements = std::max(0, num_params - rest_index);
+  Handle<FixedArray> elements =
+      isolate->factory()->NewUninitializedFixedArray(num_elements);
+  for (int i = 0; i < num_elements; ++i) {
+    elements->set(i, *--parameters);
+  }
+  return isolate->factory()->NewJSArrayWithElements(elements, FAST_ELEMENTS,
+                                                    num_elements);
+}
+
+
+RUNTIME_FUNCTION(Runtime_NewRestParam) {
+  HandleScope scope(isolate);
+  DCHECK(args.length() == 3);
+  Object** parameters = reinterpret_cast<Object**>(args[0]);
+  CONVERT_SMI_ARG_CHECKED(num_params, 1);
+  CONVERT_SMI_ARG_CHECKED(rest_index, 2);
+
+  return *NewRestParam(isolate, parameters, num_params, rest_index);
+}
+
+
+RUNTIME_FUNCTION(Runtime_NewRestParamSlow) {
+  HandleScope scope(isolate);
+  DCHECK(args.length() == 1);
+  CONVERT_SMI_ARG_CHECKED(rest_index, 0);
+
+  JavaScriptFrameIterator it(isolate);
+
+  // Find the frame that holds the actual arguments passed to the function.
+  it.AdvanceToArgumentsFrame();
+  JavaScriptFrame* frame = it.frame();
+
+  int argument_count = frame->GetArgumentsLength();
+  Object** parameters = reinterpret_cast<Object**>(frame->GetParameterSlot(-1));
+
+  return *NewRestParam(isolate, parameters, argument_count, rest_index);
+}
+
+
 RUNTIME_FUNCTION(Runtime_NewClosureFromStubFailure) {
   HandleScope scope(isolate);
   DCHECK(args.length() == 1);
   CONVERT_ARG_HANDLE_CHECKED(SharedFunctionInfo, shared, 0);
   Handle<Context> context(isolate->context());
   PretenureFlag pretenure_flag = NOT_TENURED;
   return *isolate->factory()->NewFunctionFromSharedFunctionInfo(shared, context,
                                                                 pretenure_flag);
 }
 
@@ skipping 566 matching lines @@
   return Smi::FromInt(frame->GetArgumentsLength());
 }
 
 
 RUNTIME_FUNCTION(RuntimeReference_Arguments) {
   SealHandleScope shs(isolate);
   return __RT_impl_Runtime_GetArgumentsProperty(args, isolate);
 }
 }
 }  // namespace v8::internal