Propagate class ids using existing type propagation framework.

runtime/vm/intermediate_language.cc

Index: runtime/vm/intermediate_language.cc
===================================================================
--- runtime/vm/intermediate_language.cc	(revision 10775)
+++ runtime/vm/intermediate_language.cc	(working copy)
@@ -329,6 +329,14 @@
 }
 
 
+intptr_t BindInstr::GetPropagatedCid() {
+  if (has_propagated_cid()) return propagated_cid();
+  intptr_t cid = computation()->ResultCid();
+  ASSERT(cid != kIllegalCid);
+  SetPropagatedCid(cid);
+  return cid;
+}
+
 void BindInstr::RecordAssignedVars(BitVector* assigned_vars,
                                    intptr_t fixed_parameter_count) {
   computation()->RecordAssignedVars(assigned_vars, fixed_parameter_count);
@@ -568,6 +576,19 @@
 }
 
 
+intptr_t ConstantVal::ResultCid() const {
+  if (value().IsNull()) {
+    return kNullCid;
+  }
+  if (value().IsInstance()) {
+    return Class::Handle(value().clazz()).id();
+  } else {
+    ASSERT(value().IsAbstractTypeArguments());
+    return kDynamicCid;
+  }
+}
+
+
 RawAbstractType* UseVal::CompileType() const {
   if (definition()->HasPropagatedType()) {
     return definition()->PropagatedType();
@@ -581,6 +602,11 @@
 }
 
 
+intptr_t UseVal::ResultCid() const {
+  return definition()->GetPropagatedCid();
+}
+
+
 RawAbstractType* AssertAssignableComp::CompileType() const {
   const AbstractType& value_compile_type =
       AbstractType::Handle(value()->CompileType());