Implement type cast in the VM.

runtime/vm/flow_graph_builder.cc

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "vm/flow_graph_builder.h"
 
 #include "vm/ast_printer.h"
 #include "vm/bit_vector.h"
 #include "vm/code_descriptors.h"
 #include "vm/dart_entry.h"
@@ skipping 293 matching lines @@
 
 // Type nodes only occur as the right-hand side of instanceof comparisons,
 // and they are handled specially in that context.
 void EffectGraphVisitor::VisitTypeNode(TypeNode* node) { UNREACHABLE(); }
 
 
 // Returns true if the type check can be skipped, for example, if the
 // destination type is Dynamic or if the static type of the value is a subtype
 // of the destination type.
 static bool CanSkipTypeCheck(Value* value, const AbstractType& dst_type) {
-  ASSERT(FLAG_enable_type_checks);
   ASSERT(!dst_type.IsNull());
   ASSERT(dst_type.IsFinalized());
   if (!FLAG_eliminate_type_checks) {
     return false;
   }
 
   // Any expression is assignable to the Dynamic type and to the Object type.
   // Skip the test.
   if (!dst_type.IsMalformed() &&
       (dst_type.IsDynamicType() || dst_type.IsObjectType())) {
@@ skipping 325 matching lines @@
   return new AssertAssignableComp(token_pos,
                                   owner()->try_index(),
                                   value,
                                   instantiator,
                                   instantiator_type_arguments,
                                   dst_type,
                                   dst_name);
 }
 
 
-// Used to to test assignments.
+// Used for type casts and to test assignments.
 Value* EffectGraphVisitor::BuildAssignableValue(intptr_t token_pos,
                                                 Value* value,
                                                 const AbstractType& dst_type,
                                                 const String& dst_name) {
   if (CanSkipTypeCheck(value, dst_type)) {
     return value;
   }
   AssertAssignableComp* comp = BuildAssertAssignable(token_pos,
                                                      value,
                                                      dst_type,
                                                      dst_name);
   BindInstr* assert_assignable = new BindInstr(comp);
   AddInstruction(assert_assignable);
   return new UseVal(assert_assignable);
 }
 
 
-void EffectGraphVisitor::BuildInstanceOf(ComparisonNode* node) {
-  ASSERT(Token::IsInstanceofOperator(node->kind()));
+void EffectGraphVisitor::BuildTypeTest(ComparisonNode* node) {
+  ASSERT(Token::IsTypeTestOperator(node->kind()));
   EffectGraphVisitor for_left_value(owner(), temp_index());
   node->left()->Visit(&for_left_value);
   Append(for_left_value);
 }
 
 
-void ValueGraphVisitor::BuildInstanceOf(ComparisonNode* node) {
-  ASSERT(Token::IsInstanceofOperator(node->kind()));
+void EffectGraphVisitor::BuildTypeCast(ComparisonNode* node) {
+  ASSERT(Token::IsTypeCastOperator(node->kind()));
+  const AbstractType& type = node->right()->AsTypeNode()->type();
+  ASSERT(type.IsFinalized());  // The type in a type cast may be malformed.
+  ValueGraphVisitor for_value(owner(), temp_index());
+  node->left()->Visit(&for_value);
+  Append(for_value);
+  const String& dst_name = String::ZoneHandle(String::NewSymbol("type cast"));

[srdjan, 2012/06/23 00:04:29]

Factor out the string "type cast" used at least in two places.

[regis, 2012/06/25 17:34:56]

Done.

+  if (!CanSkipTypeCheck(for_value.value(), type)) {
+    AssertAssignableComp* assert_assignable =
+        BuildAssertAssignable(node->token_pos(),
+                              for_value.value(),
+                              type,
+                              dst_name);
+    AddInstruction(new DoInstr(assert_assignable));
+  }
+}
+
+
+void ValueGraphVisitor::BuildTypeTest(ComparisonNode* node) {
+  ASSERT(Token::IsTypeTestOperator(node->kind()));
   const Bool& bool_true = Bool::ZoneHandle(Bool::True());
   const Bool& bool_false = Bool::ZoneHandle(Bool::False());
   const AbstractType& type = node->right()->AsTypeNode()->type();
   ASSERT(type.IsFinalized() && !type.IsMalformed());
   const bool negate_result = (node->kind() == Token::kISNOT);
   // All objects are instances of type T if Object type is a subtype of type T.
-  const Type& object_type =
-      Type::Handle(Isolate::Current()->object_store()->object_type());
+  const Type& object_type = Type::Handle(Type::ObjectType());
   Error& malformed_error = Error::Handle();
   if (type.IsInstantiated() &&
       object_type.IsSubtypeOf(type, &malformed_error)) {
     // Must evaluate left side.
     EffectGraphVisitor for_left_value(owner(), temp_index());
     node->left()->Visit(&for_left_value);
     Append(for_left_value);
     ReturnComputation(new ConstantVal(negate_result ? bool_false : bool_true));
     return;
   }
@@ skipping 44 matching lines @@
                          owner()->try_index(),
                          for_left_value.value(),
                          instantiator,
                          instantiator_type_arguments,
                          node->right()->AsTypeNode()->type(),
                          (node->kind() == Token::kISNOT));
   ReturnComputation(instance_of);
 }
 
 
+void ValueGraphVisitor::BuildTypeCast(ComparisonNode* node) {
+  ASSERT(Token::IsTypeCastOperator(node->kind()));
+  const AbstractType& type = node->right()->AsTypeNode()->type();
+  ASSERT(type.IsFinalized());  // The type in a type cast may be malformed.
+  ValueGraphVisitor for_value(owner(), temp_index());
+  node->left()->Visit(&for_value);
+  Append(for_value);
+  const String& dst_name = String::ZoneHandle(String::NewSymbol("type cast"));
+  ReturnValue(BuildAssignableValue(node->token_pos(),
+                                   for_value.value(),
+                                   type,
+                                   dst_name));
+}
+
+
 // <Expression> :: Comparison { kind:  Token::Kind
 //                              left:  <Expression>
 //                              right: <Expression> }
 // TODO(srdjan): Implement new equality.
 void EffectGraphVisitor::VisitComparisonNode(ComparisonNode* node) {
-  if (Token::IsInstanceofOperator(node->kind())) {
-    BuildInstanceOf(node);
+  if (Token::IsTypeTestOperator(node->kind())) {
+    BuildTypeTest(node);
+    return;
+  } else if (Token::IsTypeCastOperator(node->kind())) {

[srdjan, 2012/06/23 00:04:29]

No else needed.

[regis, 2012/06/25 17:34:56]

Done.

+    BuildTypeCast(node);
     return;
   }
   if ((node->kind() == Token::kEQ_STRICT) ||
       (node->kind() == Token::kNE_STRICT)) {
     ValueGraphVisitor for_left_value(owner(), temp_index());
     node->left()->Visit(&for_left_value);
     Append(for_left_value);
     ValueGraphVisitor for_right_value(owner(), temp_index());
     node->right()->Visit(&for_right_value);
     Append(for_right_value);
@@ skipping 1952 matching lines @@
   char* chars = reinterpret_cast<char*>(
       Isolate::Current()->current_zone()->Allocate(len));
   OS::SNPrint(chars, len, kFormat, function_name, reason);
   const Error& error = Error::Handle(
       LanguageError::New(String::Handle(String::New(chars))));
   Isolate::Current()->long_jump_base()->Jump(1, error);
 }
 
 
 }  // namespace dart