[es6] re-implement rest parameters via desugaring

src/compiler/ast-graph-builder.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/compiler/ast-graph-builder.h"
 
 #include "src/compiler.h"
 #include "src/compiler/ast-loop-assignment-analyzer.h"
 #include "src/compiler/control-builders.h"
 #include "src/compiler/js-type-feedback.h"
@@ skipping 543 matching lines @@
   return !HasStackOverflow();
 }
 
 
 void AstGraphBuilder::CreateGraphBody(bool stack_check) {
   Scope* scope = info()->scope();
 
   // Build the arguments object if it is used.
   BuildArgumentsObject(scope->arguments());
 
-  // Build rest arguments array if it is used.
-  int rest_index;
-  Variable* rest_parameter = scope->rest_parameter(&rest_index);
-  BuildRestArgumentsArray(rest_parameter, rest_index);
-
   // Build assignment to {.this_function} variable if it is used.
   BuildThisFunctionVariable(scope->this_function_var());
 
   // Build assignment to {new.target} variable if it is used.
   BuildNewTargetVariable(scope->new_target_var());
 
   // Emit tracing call if requested to do so.
   if (FLAG_trace) {
     NewNode(javascript()->CallRuntime(Runtime::kTraceEnter, 0));
   }
@@ skipping 2629 matching lines @@
   // Assign the object to the arguments variable.
   DCHECK(arguments->IsContextSlot() || arguments->IsStackAllocated());
   // This should never lazy deopt, so it is fine to send invalid bailout id.
   FrameStateBeforeAndAfter states(this, BailoutId::None());
   BuildVariableAssignment(arguments, object, Token::ASSIGN, VectorSlotPair(),
                           BailoutId::None(), states);
   return object;
 }
 
 
-Node* AstGraphBuilder::BuildRestArgumentsArray(Variable* rest, int index) {
-  if (rest == NULL) return NULL;
-
-  DCHECK(index >= 0);
-  const Operator* op = javascript()->CallRuntime(Runtime::kNewRestParamSlow, 2);
-  Node* object = NewNode(op, jsgraph()->SmiConstant(index),
-                         jsgraph()->SmiConstant(language_mode()));
-
-  // Assign the object to the rest parameter variable.
-  DCHECK(rest->IsContextSlot() || rest->IsStackAllocated());
-  // This should never lazy deopt, so it is fine to send invalid bailout id.
-  FrameStateBeforeAndAfter states(this, BailoutId::None());
-  BuildVariableAssignment(rest, object, Token::ASSIGN, VectorSlotPair(),
-                          BailoutId::None(), states);
-  return object;
-}
-
-
 Node* AstGraphBuilder::BuildThisFunctionVariable(Variable* this_function_var) {
   if (this_function_var == nullptr) return nullptr;
 
   // Retrieve the closure we were called with.
   Node* this_function = GetFunctionClosure();
 
   // Assign the object to the {.this_function} variable.
   FrameStateBeforeAndAfter states(this, BailoutId::None());
   BuildVariableAssignment(this_function_var, this_function, Token::INIT_CONST,
                           VectorSlotPair(), BailoutId::None(), states);
@@ skipping 1043 matching lines @@
     // Phi does not exist yet, introduce one.
     value = NewPhi(inputs, value, control);
     value->ReplaceInput(inputs - 1, other);
   }
   return value;
 }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8