[interpreter] Support for ES6 class literals.

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 "src/ast/scopes.h"
 #include "src/compiler.h"
 #include "src/interpreter/bytecode-register-allocator.h"
 #include "src/interpreter/control-flow-builders.h"
@@ skipping 1208 matching lines @@
   Handle<SharedFunctionInfo> shared_info =
       Compiler::GetSharedFunctionInfo(expr, info()->script(), info());
   CHECK(!shared_info.is_null());  // TODO(rmcilroy): Set stack overflow?
   builder()->CreateClosure(shared_info,
                            expr->pretenure() ? TENURED : NOT_TENURED);
   execution_result()->SetResultInAccumulator();
 }
 
 
 void BytecodeGenerator::VisitClassLiteral(ClassLiteral* expr) {
-  UNIMPLEMENTED();
+  if (expr->scope()->ContextLocalCount() > 0) {
+    VisitNewLocalBlockContext(expr->scope());
+    ContextScope scope(this, expr->scope());
+    VisitDeclarations(expr->scope()->declarations());
+    VisitClassLiteralContents(expr);
+  } else {
+    VisitDeclarations(expr->scope()->declarations());
+    VisitClassLiteralContents(expr);
+  }
 }
 
+void BytecodeGenerator::VisitClassLiteralContents(ClassLiteral* expr) {
+  VisitClassLiteralForRuntimeDefinition(expr);
+  // The prototype is ensured to exist by Runtime_DefineClass in
+  // VisitClassForRuntimeDefinition. No access check is needed here
+  // since the constructor is created by the class literal.
+  register_allocator()->PrepareForConsecutiveAllocations(2);
+  Register literal = register_allocator()->NextConsecutiveRegister();
+  Register prototype = register_allocator()->NextConsecutiveRegister();
+  builder()->StoreAccumulatorInRegister(literal);
+  builder()->LoadPrototypeOrInitialMap();

[rmcilroy, 2016/02/04 14:56:41]

nit - chain builders (in functions below too) ?

[oth, 2016/02/04 16:59:48]

Done.

+  builder()->StoreAccumulatorInRegister(prototype);
+  VisitClassLiteralProperties(expr, literal, prototype);
+
+  // Set both the prototype and constructor to have fast properties, and also
+  // freeze them in strong mode.

[rmcilroy, 2016/02/04 14:56:41]

Remove the comment about strong mode (we don't support it and AFAIK it is being
ripped out soon)

[oth, 2016/02/04 16:59:48]

Done.

+  builder()->CallRuntime(Runtime::kFinalizeClassDefinition, literal, 2);
+  // Assign to class variable.
+  if (expr->class_variable_proxy() != nullptr) {
+    Variable* var = expr->class_variable_proxy()->var();
+    FeedbackVectorSlot slot = expr->NeedsProxySlot()
+                                  ? expr->ProxySlot()
+                                  : FeedbackVectorSlot::Invalid();
+    VisitVariableAssignment(var, slot);
+  }
+  execution_result()->SetResultInAccumulator();
+}
+
+void BytecodeGenerator::VisitClassLiteralForRuntimeDefinition(
+    ClassLiteral* expr) {
+  AccumulatorResultScope result_scope(this);
+  register_allocator()->PrepareForConsecutiveAllocations(4);
+  Register extends = register_allocator()->NextConsecutiveRegister();
+  Register constructor = register_allocator()->NextConsecutiveRegister();
+  Register start_position = register_allocator()->NextConsecutiveRegister();
+  Register end_position = register_allocator()->NextConsecutiveRegister();
+  VisitForAccumulatorValueOrTheHole(expr->extends());

[rmcilroy, 2016/02/04 14:56:41]

nit - newline above (bit of a wall of text otherwise :)).

[oth, 2016/02/04 16:59:48]

Done.

+  builder()->StoreAccumulatorInRegister(extends);
+  VisitForAccumulatorValue(expr->constructor());
+  builder()->StoreAccumulatorInRegister(constructor);
+  builder()->LoadLiteral(Smi::FromInt(expr->start_position()));
+  builder()->StoreAccumulatorInRegister(start_position);
+  builder()->LoadLiteral(Smi::FromInt(expr->end_position()));
+  builder()->StoreAccumulatorInRegister(end_position);
+  builder()->CallRuntime(Runtime::kDefineClass, extends, 4);
+  result_scope.SetResultInAccumulator();
+}
+
+void BytecodeGenerator::VisitClassLiteralProperties(ClassLiteral* expr,
+                                                    Register literal,
+                                                    Register prototype) {
+  EffectResultScope result_scope(this);

[rmcilroy, 2016/02/04 14:56:41]

Remove please (or replace with a RegisterAllocationScope)

[oth, 2016/02/04 16:59:48]

Done.

+
+  register_allocator()->PrepareForConsecutiveAllocations(4);
+  Register receiver = register_allocator()->NextConsecutiveRegister();
+  Register key = register_allocator()->NextConsecutiveRegister();
+  Register value = register_allocator()->NextConsecutiveRegister();
+  Register attr = register_allocator()->NextConsecutiveRegister();
+
+  bool attr_assigned = false;
+  Register old_receiver = Register::invalid_value();
+
+  // Create nodes to store method values into the literal.
+  for (int i = 0; i < expr->properties()->length(); i++) {
+    ObjectLiteral::Property* property = expr->properties()->at(i);
+
+    // Set-up receiver.
+    Register new_receiver = property->is_static() ? literal : prototype;
+    if (new_receiver != old_receiver) {
+      builder()->MoveRegister(new_receiver, receiver);
+      old_receiver = new_receiver;
+    }
+
+    VisitForAccumulatorValue(property->key());
+    builder()->CastAccumulatorToName();
+    builder()->StoreAccumulatorInRegister(key);
+    // The static prototype property is read only. We handle the non computed
+    // property name case in the parser. Since this is the only case where we
+    // need to check for an own read only property we special case this so we do
+    // not need to do this for every property.

[rmcilroy, 2016/02/04 14:56:40]

I think this comment might make more sense in
VisitClassLiteralStaticPrototypeWithComputedName, WDYT?

[oth, 2016/02/04 16:59:48]

It seems like the right place as it explains the purpose of the path that the if
statement exposes. If you'd still like it moved, I don't feel too strongly about
it.

[rmcilroy, 2016/02/04 17:37:06]

Yeah sorry you are right, it belongs here.

+    if (property->is_static() && property->is_computed_name()) {
+      VisitClassLiteralStaticPrototypeWithComputedName(key);
+    }
+    VisitForAccumulatorValue(property->value());
+    builder()->StoreAccumulatorInRegister(value);
+
+    VisitSetHomeObject(value, receiver, property);
+
+    if ((property->kind() == ObjectLiteral::Property::GETTER ||
+         property->kind() == ObjectLiteral::Property::SETTER) &&
+        !attr_assigned) {
+      builder()
+          ->LoadLiteral(Smi::FromInt(DONT_ENUM))
+          .StoreAccumulatorInRegister(attr);
+      attr_assigned = true;
+    }
+
+    switch (property->kind()) {
+      case ObjectLiteral::Property::CONSTANT:
+      case ObjectLiteral::Property::MATERIALIZED_LITERAL:
+      case ObjectLiteral::Property::PROTOTYPE:
+        UNREACHABLE();

[rmcilroy, 2016/02/04 14:56:41]

nit - comment on why this should be unreachable and also add break;

[oth, 2016/02/04 16:59:48]

Done.

+      case ObjectLiteral::Property::COMPUTED: {
+        builder()->CallRuntime(Runtime::kDefineClassMethod, receiver, 3);
+        break;
+      }
+      case ObjectLiteral::Property::GETTER: {
+        builder()->CallRuntime(Runtime::kDefineGetterPropertyUnchecked,
+                               receiver, 4);
+        break;
+      }
+      case ObjectLiteral::Property::SETTER: {
+        builder()->CallRuntime(Runtime::kDefineSetterPropertyUnchecked,
+                               receiver, 4);
+        break;
+      }
+    }
+  }
+}
+
+void BytecodeGenerator::VisitClassLiteralStaticPrototypeWithComputedName(
+    Register key) {
+  BytecodeLabel done;
+  builder()->LoadLiteral(isolate()->factory()->prototype_string());
+  builder()->CompareOperation(Token::Value::EQ_STRICT, key, Strength::WEAK);
+  builder()->JumpIfFalse(&done);
+  builder()->CallRuntime(Runtime::kThrowStaticPrototypeError, Register(0), 0);
+  builder()->Bind(&done);
+}
 
 void BytecodeGenerator::VisitNativeFunctionLiteral(
     NativeFunctionLiteral* expr) {
   // Find or build a shared function info for the native function template.
   Handle<SharedFunctionInfo> shared_info =
       Compiler::GetSharedFunctionInfoForNative(expr->extension(), expr->name());
   builder()->CreateClosure(shared_info, NOT_TENURED);
   execution_result()->SetResultInAccumulator();
 }
 
@@ skipping 1269 matching lines @@
   execution_result()->SetResultInAccumulator();
 }
 
 
 // Visits the expression |expr| and places the result in the accumulator.
 void BytecodeGenerator::VisitForAccumulatorValue(Expression* expr) {
   AccumulatorResultScope accumulator_scope(this);
   Visit(expr);
 }
 
+void BytecodeGenerator::VisitForAccumulatorValueOrTheHole(Expression* expr) {
+  if (expr == nullptr) {
+    builder()->LoadTheHole();
+  } else {
+    VisitForAccumulatorValue(expr);
+  }
+}
 
 // Visits the expression |expr| and discards the result.
 void BytecodeGenerator::VisitForEffect(Expression* expr) {
   EffectResultScope effect_scope(this);
   Visit(expr);
 }
 
 
 // Visits the expression |expr| and returns the register containing
 // the expression result.
@@ skipping 21 matching lines @@
 }
 
 
 int BytecodeGenerator::feedback_index(FeedbackVectorSlot slot) const {
   return info()->feedback_vector()->GetIndex(slot);
 }
 
 }  // namespace interpreter
 }  // namespace internal
 }  // namespace v8