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"
@@ skipping 301 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?

[srdjan, 2012/07/25 21:50:06]

I guess with FLAG_enable_type_checks we can use the type of the passed in
parameter.

[regis, 2012/07/26 15:08:50]

Good point. You probably mean the type of the formal parameter, though.

Since I am not sure exactly when this ParameterInstr is used, I did not change
the code yet, but added a comment. Indeed, it would be bad if this
ParameterInstr was used to load the value for the parameter type check, which
would then be wrongly eliminated.

+  return Type::DynamicType();
+}
+
+
 intptr_t GraphEntryInstr::InputCount() const {
   return 0;
 }
 
 
 Value* GraphEntryInstr::InputAt(intptr_t i) const {
   UNREACHABLE();
   return NULL;
 }
 
@@ skipping 273 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();

[srdjan, 2012/07/25 21:50:06]

Is the type of the receiver setup correctly in locals?

[regis, 2012/07/26 15:08:50]

Good question. I have added a todo to verify.
I also added a test, since using the declared type only works in checked mode. I
did the same for other cases below.

 }
 
 
 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();
 }
 
 
 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();
 }
 
 
 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 465 matching lines @@
   const ExternalLabel label(closure_function.ToCString(), stub.EntryPoint());
   compiler->GenerateCall(token_pos(), try_index(), &label,
                          PcDescriptors::kOther);
   __ Drop(2);  // Discard type arguments and receiver.
 }
 
 
 #undef __
 
 }  // namespace dart