[Interpreter] Add support for for count operations.

src/interpreter/bytecode-generator.cc

 // Copyright 2015 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/interpreter/bytecode-generator.h"
 
 #include <stack>
 
 #include "src/compiler.h"
 #include "src/interpreter/control-flow-builders.h"
@@ skipping 1131 matching lines @@
     case Token::Value::BIT_NOT:
     case Token::Value::DELETE:
       UNIMPLEMENTED();
     default:
       UNREACHABLE();
   }
 }
 
 
 void BytecodeGenerator::VisitCountOperation(CountOperation* expr) {
-  UNIMPLEMENTED();
+  DCHECK(expr->expression()->IsValidReferenceExpressionOrThis());
+
+  // Left-hand side can only be a property, a global or a variable slot.
+  Property* property = expr->expression()->AsProperty();
+  LhsKind assign_type = Property::GetAssignType(property);
+
+  // TODO(rmcilroy): Set is_postfix to false if visiting for effect.
+  bool is_postfix = expr->is_postfix();
+
+  // Evaluate LHS expression and get old value.
+  TemporaryRegisterScope temporary_register_scope(builder());
+  Register obj, key, old_value;
+  switch (assign_type) {
+    case VARIABLE: {
+      VariableProxy* proxy = expr->expression()->AsVariableProxy();
+      VisitVariableLoad(proxy->var(), proxy->VariableFeedbackSlot());
+      break;
+    }
+    case NAMED_PROPERTY: {
+      obj = temporary_register_scope.NewRegister();
+      key = temporary_register_scope.NewRegister();
+      FeedbackVectorSlot slot = property->PropertyFeedbackSlot();
+      Visit(property->obj());
+      builder()
+          ->StoreAccumulatorInRegister(obj)
+          .LoadLiteral(property->key()->AsLiteral()->AsPropertyName())
+          .StoreAccumulatorInRegister(key)
+          .LoadNamedProperty(obj, feedback_index(slot), language_mode());
+      break;
+    }
+    case KEYED_PROPERTY: {
+      obj = temporary_register_scope.NewRegister();
+      key = temporary_register_scope.NewRegister();
+      FeedbackVectorSlot slot = property->PropertyFeedbackSlot();
+      Visit(property->obj());
+      builder()->StoreAccumulatorInRegister(obj);
+      Visit(property->key());
+      builder()->StoreAccumulatorInRegister(key).LoadKeyedProperty(
+          obj, feedback_index(slot), language_mode());
+      break;
+    }
+    case NAMED_SUPER_PROPERTY:
+    case KEYED_SUPER_PROPERTY:
+      UNIMPLEMENTED();
+  }
+
+  // Convert old value into a number.
+  if (!is_strong(language_mode())) {
+    builder()->CastAccumulatorToNumber();
+  }
+
+  // Save result for postfix expressions.
+  if (is_postfix) {
+    old_value = temporary_register_scope.NewRegister();
+    builder()->StoreAccumulatorInRegister(old_value);
+  }
+
+  // Perform +1/-1 operation.
+  builder()->CountOperation(expr->binary_op(), language_mode_strength());
+
+  // Store the value.
+  FeedbackVectorSlot feedback_slot = expr->CountSlot();
+  switch (assign_type) {
+    case VARIABLE: {
+      Variable* variable = expr->expression()->AsVariableProxy()->var();
+      VisitVariableAssignment(variable, feedback_slot);
+      break;
+    }
+    case NAMED_PROPERTY: {
+      builder()->StoreNamedProperty(obj, key, feedback_index(feedback_slot),
+                                    language_mode());
+      break;
+    }
+    case KEYED_PROPERTY: {
+      builder()->StoreKeyedProperty(obj, key, feedback_index(feedback_slot),
+                                    language_mode());
+      break;
+    }
+    case NAMED_SUPER_PROPERTY:
+    case KEYED_SUPER_PROPERTY:
+      UNIMPLEMENTED();
+  }
+
+  // Restore old value for postfix expressions.
+  if (is_postfix) builder()->LoadAccumulatorWithRegister(old_value);
 }
 
 
 void BytecodeGenerator::VisitBinaryOperation(BinaryOperation* binop) {
   switch (binop->op()) {
     case Token::COMMA:
       VisitCommaExpression(binop);
       break;
     case Token::OR:
       VisitLogicalOrExpression(binop);
@@ skipping 251 matching lines @@
 }
 
 
 int BytecodeGenerator::feedback_index(FeedbackVectorSlot slot) const {
   return info()->feedback_vector()->GetIndex(slot);
 }
 
 }  // namespace interpreter
 }  // namespace internal
 }  // namespace v8