Improve static type propagation.

runtime/vm/intermediate_language.cc

Index: runtime/vm/intermediate_language.cc
===================================================================
--- runtime/vm/intermediate_language.cc	(revision 9904)
+++ runtime/vm/intermediate_language.cc	(working copy)
@@ -319,6 +319,12 @@
 }
 
 
+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;
 }
@@ -335,6 +341,13 @@
 }
 
 
+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;
 }
@@ -628,6 +641,11 @@
 
 
 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();
 }
 
@@ -659,6 +677,8 @@
 
 
 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();
 }
 
@@ -679,13 +699,7 @@
 
 
 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();
 }
 
 
@@ -729,14 +743,7 @@
 
 
 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();
 }
 
 
@@ -746,13 +753,7 @@
 
 
 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();
 }
 
 
@@ -762,13 +763,7 @@
 
 
 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();
 }
 
 
@@ -814,14 +809,7 @@
 
 
 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();
 }