[runtime] Optimize and unify 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/runtime/runtime-utils.h"
 
 #include "src/accessors.h"
 #include "src/arguments.h"
 #include "src/ast/scopeinfo.h"
 #include "src/ast/scopes.h"
@@ skipping 570 matching lines @@
     WriteBarrierMode mode = array->GetWriteBarrierMode(no_gc);
     for (int i = 0; i < argument_count; i++) {
       array->set(i, parameters[i], mode);
     }
     result->set_elements(*array);
   }
   return result;
 }
 
 
-template <typename T>
-Handle<JSObject> NewRestArguments(Isolate* isolate, Handle<JSFunction> callee,
-                                  T parameters, int argument_count,
-                                  int start_index) {
-  int num_elements = std::max(0, argument_count - start_index);
-  Handle<JSObject> result = isolate->factory()->NewJSArray(
-      FAST_ELEMENTS, num_elements, num_elements, Strength::WEAK,
-      DONT_INITIALIZE_ARRAY_ELEMENTS);
-  {
-    DisallowHeapAllocation no_gc;
-    FixedArray* elements = FixedArray::cast(result->elements());
-    WriteBarrierMode mode = result->GetWriteBarrierMode(no_gc);
-    for (int i = 0; i < num_elements; i++) {
-      elements->set(i, parameters[i + start_index], mode);
-    }
-  }
-  return result;
-}
-
-
 class HandleArguments BASE_EMBEDDED {
  public:
   explicit HandleArguments(Handle<Object>* array) : array_(array) {}
   Object* operator[](int index) { return *array_[index]; }
 
  private:
   Handle<Object>* array_;
 };
 
 
@@ skipping 30 matching lines @@
   // This generic runtime function can also be used when the caller has been
   // inlined, we use the slow but accurate {GetCallerArguments}.
   int argument_count = 0;
   base::SmartArrayPointer<Handle<Object>> arguments =
       GetCallerArguments(isolate, &argument_count);
   HandleArguments argument_getter(arguments.get());
   return *NewStrictArguments(isolate, callee, argument_getter, argument_count);
 }
 
 
-RUNTIME_FUNCTION(Runtime_NewRestArguments_Generic) {
+RUNTIME_FUNCTION(Runtime_NewRestParameter) {
   HandleScope scope(isolate);
-  DCHECK(args.length() == 2);
+  DCHECK_EQ(1, args.length());
   CONVERT_ARG_HANDLE_CHECKED(JSFunction, callee, 0)
-  CONVERT_SMI_ARG_CHECKED(start_index, 1);
+  int start_index = callee->shared()->internal_formal_parameter_count();
   // This generic runtime function can also be used when the caller has been
   // inlined, we use the slow but accurate {GetCallerArguments}.
   int argument_count = 0;
   base::SmartArrayPointer<Handle<Object>> arguments =
       GetCallerArguments(isolate, &argument_count);
-  HandleArguments argument_getter(arguments.get());
-  return *NewRestArguments(isolate, callee, argument_getter, argument_count,
-                           start_index);
+  int num_elements = std::max(0, argument_count - start_index);
+  Handle<JSObject> result = isolate->factory()->NewJSArray(
+      FAST_ELEMENTS, num_elements, num_elements, Strength::WEAK,
+      DONT_INITIALIZE_ARRAY_ELEMENTS);
+  {
+    DisallowHeapAllocation no_gc;
+    FixedArray* elements = FixedArray::cast(result->elements());
+    WriteBarrierMode mode = result->GetWriteBarrierMode(no_gc);
+    for (int i = 0; i < num_elements; i++) {
+      elements->set(i, *arguments[i + start_index], mode);
+    }
+  }
+  return *result;
 }
 
 
 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);
 #ifdef DEBUG
@@ skipping 17 matching lines @@
   // This runtime function does not materialize the correct arguments when the
   // caller has been inlined, better make sure we are not hitting that case.
   JavaScriptFrameIterator it(isolate);
   DCHECK(!it.frame()->HasInlinedFrames());
 #endif  // DEBUG
   ParameterArguments argument_getter(parameters);
   return *NewStrictArguments(isolate, callee, argument_getter, argument_count);
 }
 
 
-RUNTIME_FUNCTION(Runtime_NewRestParam) {
-  HandleScope scope(isolate);
-  DCHECK(args.length() == 3);
-  CONVERT_SMI_ARG_CHECKED(num_params, 0);
-  Object** parameters = reinterpret_cast<Object**>(args[1]);
-  CONVERT_SMI_ARG_CHECKED(rest_index, 2);
-#ifdef DEBUG
-  // This runtime function does not materialize the correct arguments when the
-  // caller has been inlined, better make sure we are not hitting that case.
-  JavaScriptFrameIterator it(isolate);
-  DCHECK(!it.frame()->HasInlinedFrames());
-#endif  // DEBUG
-  Handle<JSFunction> callee;
-  ParameterArguments argument_getter(parameters);
-  return *NewRestArguments(isolate, callee, argument_getter, num_params,
-                           rest_index);
-}
-
-
 RUNTIME_FUNCTION(Runtime_NewClosure) {
   HandleScope scope(isolate);
   DCHECK_EQ(1, args.length());
   CONVERT_ARG_HANDLE_CHECKED(SharedFunctionInfo, shared, 0);
   Handle<Context> context(isolate->context(), isolate);
   return *isolate->factory()->NewFunctionFromSharedFunctionInfo(shared, context,
                                                                 NOT_TENURED);
 }
 
 
@@ skipping 512 matching lines @@
 
   // Lookup in the initial Object.prototype object.
   Handle<Object> result;
   ASSIGN_RETURN_FAILURE_ON_EXCEPTION(
       isolate, result,
       Object::GetProperty(isolate->initial_object_prototype(), key));
   return *result;
 }
 }  // namespace internal
 }  // namespace v8