Fix receiver's type for constructors.

runtime/vm/flow_graph_optimizer.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_optimizer.h"
 
 #include "vm/bit_vector.h"
 #include "vm/cha.h"
 #include "vm/flow_graph_builder.h"
 #include "vm/flow_graph_compiler.h"
@@ skipping 2113 matching lines @@
 
 
 void FlowGraphTypePropagator::VisitParameter(ParameterInstr* param) {
   // TODO(regis): Once we inline functions, the propagated type of the formal
   // parameter will reflect the compile type of the passed-in argument.
   // For now, we do not know anything about the argument type and therefore set
   // it to the DynamicType, unless the argument is a compiler generated value,
   // i.e. the receiver argument or the constructor phase argument.
   AbstractType& param_type = AbstractType::Handle(Type::DynamicType());
   param->SetPropagatedCid(kDynamicCid);
-  if (param->index() < 2) {
+  bool param_type_is_known = false;
+  if (param->index() == 0) {
     const Function& function = parsed_function().function();
-    if (((param->index() == 0) && function.IsDynamicFunction()) ||

[regis, 2012/10/16 16:10:11]

It looks like your change is only inserting || function.IsConstructor() here. It
is otherwise just style, or do I miss something?

[srdjan, 2012/10/16 16:18:19]

Yes. IMO, it was hard to read and I thought that we have two different cases and
keep them separate.

-        ((param->index() == 1) && function.IsConstructor())) {
-      // Parameter is the receiver or the constructor phase.
-      LocalScope* scope = parsed_function().node_sequence()->scope();
-      param_type = scope->VariableAt(param->index())->type().raw();
-      if (FLAG_use_cha) {
-        const intptr_t cid = Class::Handle(param_type.type_class()).id();
-        if (!CHA::HasSubclasses(cid)) {
-          // Receiver's class has no subclasses.
-          param->SetPropagatedCid(cid);
-        }
+    if ((function.IsDynamicFunction() || function.IsConstructor())) {
+      // Parameter is the receiver .
+      param_type_is_known = true;
+    }
+  }
+  if ((param->index() == 1) && parsed_function().function().IsConstructor()) {

[regis, 2012/10/16 16:10:11]

How about an else here?

[srdjan, 2012/10/16 16:18:19]

Done.

+    // Parameter is the constructor phase.
+    param_type_is_known = true;
+  }
+  if (param_type_is_known) {
+    LocalScope* scope = parsed_function().node_sequence()->scope();
+    param_type = scope->VariableAt(param->index())->type().raw();
+    if (FLAG_use_cha) {
+      const intptr_t cid = Class::Handle(param_type.type_class()).id();
+      if (!CHA::HasSubclasses(cid)) {
+        // Receiver's class has no subclasses.
+        param->SetPropagatedCid(cid);
       }
     }
   }
   bool changed = param->SetPropagatedType(param_type);
   if (changed) {
     still_changing_ = true;
   }
 }
 
 
@@ skipping 1121 matching lines @@
 
   if (FLAG_trace_constant_propagation) {
     OS::Print("\n==== After constant propagation ====\n");
     FlowGraphPrinter printer(*graph_);
     printer.PrintBlocks();
   }
 }
 
 
 }  // namespace dart