Represent implicit 'this' binding by 'super' in AST.

src/x64/full-codegen-x64.cc

Index: src/x64/full-codegen-x64.cc
diff --git a/src/x64/full-codegen-x64.cc b/src/x64/full-codegen-x64.cc
index 51b1763292cb8a947f03d24c42f9a52b31739ccb..d2cd5a5dd26d8a2cabddaabb4af9fc7c6fe36089 100644
--- a/src/x64/full-codegen-x64.cc
+++ b/src/x64/full-codegen-x64.cc
@@ -1952,7 +1952,7 @@ void FullCodeGenerator::VisitArrayLiteral(ArrayLiteral* expr) {
 
 
 void FullCodeGenerator::VisitAssignment(Assignment* expr) {
-  DCHECK(expr->target()->IsValidReferenceExpression());
+  DCHECK(expr->target()->IsValidReferenceExpressionOrThis());
 
   Comment cmnt(masm_, "[ Assignment");
   SetExpressionPosition(expr, INSERT_BREAK);
@@ -2578,7 +2578,7 @@ void FullCodeGenerator::EmitBinaryOp(BinaryOperation* expr, Token::Value op) {
 
 void FullCodeGenerator::EmitAssignment(Expression* expr,
                                        FeedbackVectorICSlot slot) {
-  DCHECK(expr->IsValidReferenceExpression());
+  DCHECK(expr->IsValidReferenceExpressionOrThis());
 
   Property* prop = expr->AsProperty();
   LhsKind assign_type = Property::GetAssignType(prop);
@@ -2720,6 +2720,19 @@ void FullCodeGenerator::EmitVariableAssignment(Variable* var, Token::Value op,
     __ bind(&const_error);
     __ CallRuntime(Runtime::kThrowConstAssignError, 0);
 
+  } else if (var->is_this() && op == Token::INIT_CONST) {
+    // Initializing assignment to const {this} needs a write barrier.
+    DCHECK(var->IsStackAllocated() || var->IsContextSlot());
+    Label uninitialized_this;
+    MemOperand location = VarOperand(var, rcx);
+    __ movp(rdx, location);
+    __ CompareRoot(rdx, Heap::kTheHoleValueRootIndex);
+    __ j(equal, &uninitialized_this);
+    __ Push(var->name());
+    __ CallRuntime(Runtime::kThrowReferenceError, 1);
+    __ bind(&uninitialized_this);
+    EmitStoreToStackLocalOrContextSlot(var, location);
+
   } else if (!var->is_const_mode() || op == Token::INIT_CONST) {
     if (var->IsLookupSlot()) {
       // Assignment to var.
@@ -3061,21 +3074,6 @@ void FullCodeGenerator::EmitResolvePossiblyDirectEval(int arg_count) {
 }
 
 
-void FullCodeGenerator::EmitInitializeThisAfterSuper(
-    SuperCallReference* super_ref, FeedbackVectorICSlot slot) {
-  Variable* this_var = super_ref->this_var()->var();
-  GetVar(rcx, this_var);
-  __ CompareRoot(rcx, Heap::kTheHoleValueRootIndex);
-  Label uninitialized_this;
-  __ j(equal, &uninitialized_this);
-  __ Push(this_var->name());
-  __ CallRuntime(Runtime::kThrowReferenceError, 1);
-  __ bind(&uninitialized_this);
-
-  EmitVariableAssignment(this_var, Token::INIT_CONST, slot);
-}
-
-
 // See http://www.ecma-international.org/ecma-262/6.0/#sec-function-calls.
 void FullCodeGenerator::PushCalleeAndWithBaseObject(Call* expr) {
   VariableProxy* callee = expr->expression()->AsVariableProxy();
@@ -3290,7 +3288,6 @@ void FullCodeGenerator::EmitSuperConstructorCall(Call* expr) {
 
   RecordJSReturnSite(expr);
 
-  EmitInitializeThisAfterSuper(super_call_ref, expr->CallFeedbackICSlot());
   context()->Plug(rax);
 }
 
@@ -4692,9 +4689,6 @@ void FullCodeGenerator::EmitCallSuperWithSpread(CallRuntime* expr) {
   // Restore context register.
   __ movp(rsi, Operand(rbp, StandardFrameConstants::kContextOffset));
   context()->DropAndPlug(1, rax);
-
-  // TODO(mvstanton): with FLAG_vector_stores this needs a slot id.
-  EmitInitializeThisAfterSuper(super_call_ref);
 }
 
 
@@ -4894,7 +4888,7 @@ void FullCodeGenerator::VisitUnaryOperation(UnaryOperation* expr) {
 
 
 void FullCodeGenerator::VisitCountOperation(CountOperation* expr) {
-  DCHECK(expr->expression()->IsValidReferenceExpression());
+  DCHECK(expr->expression()->IsValidReferenceExpressionOrThis());
 
   Comment cmnt(masm_, "[ CountOperation");