Improve static type propagation.

runtime/vm/intermediate_language.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/intermediate_language.h"
 
 #include "vm/bit_vector.h"
 #include "vm/dart_entry.h"
 #include "vm/flow_graph_builder.h"
 #include "vm/flow_graph_compiler.h"
 #include "vm/locations.h"
 #include "vm/object.h"
 #include "vm/os.h"
 #include "vm/scopes.h"
 #include "vm/stub_code.h"
 #include "vm/symbols.h"
 
 namespace dart {
 
+DECLARE_FLAG(bool, enable_type_checks);
+
+
 MethodRecognizer::Kind MethodRecognizer::RecognizeKind(
     const Function& function) {
   // Only core library methods can be recognized.
   const Library& core_lib = Library::Handle(Library::CoreLibrary());
   const Library& core_impl_lib = Library::Handle(Library::CoreImplLibrary());
   const Class& function_class = Class::Handle(function.owner());
   if ((function_class.library() != core_lib.raw()) &&
       (function_class.library() != core_impl_lib.raw())) {
     return kUnknown;
   }
@@ skipping 290 matching lines @@
 Value* PhiInstr::InputAt(intptr_t i) const {
   return inputs_[i];
 }
 
 
 void PhiInstr::SetInputAt(intptr_t i, Value* value) {
   inputs_[i] = value;
 }
 
 
+RawAbstractType* PhiInstr::StaticType() const {
+  // TODO(regis): Return the least upper bound of the input static types.
+  return Type::DynamicType();
+}
+
+
 intptr_t ParameterInstr::InputCount() const {
   return 0;
 }
 
 
 Value* ParameterInstr::InputAt(intptr_t i) const {
   UNREACHABLE();
   return NULL;
 }
 
 
 void ParameterInstr::SetInputAt(intptr_t i, Value* value) {
   UNREACHABLE();
 }
 
 
+RawAbstractType* ParameterInstr::StaticType() const {
+  // TODO(regis): Can type feedback provide information about the static type
+  // of a passed-in parameter?
+  // Note that in checked mode, we could return the static type of the formal
+  // parameter. However, this would be wrong if ParameterInstr is used to type
+  // check the passed-in parameter, since the type check would then always be
+  // wrongly eliminated.
+  return Type::DynamicType();
+}
+
+
 intptr_t GraphEntryInstr::InputCount() const {
   return 0;
 }
 
 
 Value* GraphEntryInstr::InputAt(intptr_t i) const {
   UNREACHABLE();
   return NULL;
 }
 
@@ skipping 287 matching lines @@
   }
 }
 
 
 RawAbstractType* UseVal::StaticType() const {
   return definition()->StaticType();
 }
 
 
 RawAbstractType* AssertAssignableComp::StaticType() const {
+  const AbstractType& value_static_type =
+      AbstractType::Handle(value()->StaticType());
+  if (value_static_type.IsMoreSpecificThan(dst_type(), NULL)) {
+    return value_static_type.raw();
+  }
   return dst_type().raw();
 }
 
 
 RawAbstractType* AssertBooleanComp::StaticType() const {
   return Type::BoolInterface();
 }
 
 
 RawAbstractType* CurrentContextComp::StaticType() const {
@@ skipping 11 matching lines @@
 RawAbstractType* ClosureCallComp::StaticType() const {
   // Because of function subtyping rules, the static return type of a closure
   // call cannot be relied upon for static type analysis. For example, a
   // function returning Dynamic can be assigned to a closure variable declared
   // to return int and may actually return a double at run-time.
   return Type::DynamicType();
 }
 
 
 RawAbstractType* InstanceCallComp::StaticType() const {
+  // TODO(regis): Return a more specific type than Dynamic for recognized
+  // combinations of receiver static type and method name.
   return Type::DynamicType();
 }
 
 
 RawAbstractType* PolymorphicInstanceCallComp::StaticType() const {
   return Type::DynamicType();
 }
 
 
 RawAbstractType* StaticCallComp::StaticType() const {
   return function().result_type();
 }
 
 
 RawAbstractType* LoadLocalComp::StaticType() const {
-  return local().type().raw();
+  // TODO(regis): Verify that the type of the receiver is properly set.
+  if (FLAG_enable_type_checks) {
+    return local().type().raw();
+  }
+  return Type::DynamicType();
 }
 
 
 RawAbstractType* StoreLocalComp::StaticType() const {
-  const AbstractType& assigned_value_type =
-      AbstractType::Handle(value()->StaticType());
-  if (assigned_value_type.IsDynamicType()) {
-    // Static type of assigned value is unknown, return static type of local.
-    return local().type().raw();
-  }
-  return assigned_value_type.raw();
+  return value()->StaticType();
 }
 
 
 RawAbstractType* StrictCompareComp::StaticType() const {
   return Type::BoolInterface();
 }
 
 
 RawAbstractType* EqualityCompareComp::StaticType() const {
   return Type::BoolInterface();
@@ skipping 23 matching lines @@
   return AbstractType::null();
 }
 
 
 RawAbstractType* InstanceSetterComp::StaticType() const {
   return value()->StaticType();
 }
 
 
 RawAbstractType* StaticSetterComp::StaticType() const {
-  const AbstractType& assigned_value_type =
-      AbstractType::Handle(value()->StaticType());
-  if (assigned_value_type.IsDynamicType()) {
-    // Static type of assigned value is unknown, return static type of setter
-    // value parameter.
-    return setter_function().ParameterTypeAt(0);
-  }
-  return assigned_value_type.raw();
+  return value()->StaticType();
 }
 
 
 RawAbstractType* LoadInstanceFieldComp::StaticType() const {
-  return field().type();
+  if (FLAG_enable_type_checks) {
+    return field().type();
+  }
+  return Type::DynamicType();
 }
 
 
 RawAbstractType* StoreInstanceFieldComp::StaticType() const {
-  const AbstractType& assigned_value_type =
-      AbstractType::Handle(value()->StaticType());
-  if (assigned_value_type.IsDynamicType()) {
-    // Static type of assigned value is unknown, return static type of field.
-    return field().type();
-  }
-  return assigned_value_type.raw();
+  return value()->StaticType();
 }
 
 
 RawAbstractType* LoadStaticFieldComp::StaticType() const {
-  return field().type();
+  if (FLAG_enable_type_checks) {
+    return field().type();
+  }
+  return Type::DynamicType();
 }
 
 
 RawAbstractType* StoreStaticFieldComp::StaticType() const {
-  const AbstractType& assigned_value_type =
-      AbstractType::Handle(value()->StaticType());
-  if (assigned_value_type.IsDynamicType()) {
-    // Static type of assigned value is unknown, return static type of field.
-    return field().type();
-  }
-  return assigned_value_type.raw();
+  return value()->StaticType();
 }
 
 
 RawAbstractType* BooleanNegateComp::StaticType() const {
   return Type::BoolInterface();
 }
 
 
 RawAbstractType* InstanceOfComp::StaticType() const {
   return Type::BoolInterface();
@@ skipping 25 matching lines @@
 }
 
 
 RawAbstractType* LoadVMFieldComp::StaticType() const {
   ASSERT(!type().IsNull());
   return type().raw();
 }
 
 
 RawAbstractType* StoreVMFieldComp::StaticType() const {
-  ASSERT(!type().IsNull());
-  const AbstractType& assigned_value_type =
-      AbstractType::Handle(value()->StaticType());
-  if (assigned_value_type.IsDynamicType()) {
-    // Static type of assigned value is unknown, return static type of field.
-    return type().raw();
-  }
-  return assigned_value_type.raw();
+  return value()->StaticType();
 }
 
 
 RawAbstractType* InstantiateTypeArgumentsComp::StaticType() const {
   UNREACHABLE();
   return AbstractType::null();
 }
 
 
 RawAbstractType* ExtractConstructorTypeArgumentsComp::StaticType() const {
@@ skipping 486 matching lines @@
   if (compiler->is_ssa()) {
     ASSERT(locs()->in(0).IsRegister());
     __ PushRegister(locs()->in(0).reg());
   }
 }
 
 
 #undef __
 
 }  // namespace dart