Use classifying token position for control flow IR instructions

runtime/vm/ast.cc

 // Copyright (c) 2011, 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/ast.h"
 #include "vm/compiler.h"
 #include "vm/dart_entry.h"
 #include "vm/isolate.h"
+#include "vm/log.h"
 #include "vm/object_store.h"
 #include "vm/resolver.h"
 
 
 namespace dart {
 
+DEFINE_FLAG(bool, trace_ast_visitor, false,
+            "Trace AstVisitor.");
+
 #define DEFINE_VISIT_FUNCTION(BaseName)                                        \
 void BaseName##Node::Visit(AstNodeVisitor* visitor) {                          \
+  if (FLAG_trace_ast_visitor) {                                                \
+    THR_Print("Visiting %s\n", PrettyName());                                  \
+  }                                                                            \
   visitor->Visit##BaseName##Node(this);                                        \
 }
 
 FOR_EACH_NODE(DEFINE_VISIT_FUNCTION)
 #undef DEFINE_VISIT_FUNCTION
 
 
 #define DEFINE_NAME_FUNCTION(BaseName)                                         \
 const char* BaseName##Node::PrettyName() const {                               \
   return #BaseName;                                                            \
@@ skipping 746 matching lines @@
   if (result.IsError() || result.IsNull()) {
     // TODO(turnidge): We could get better error messages by returning
     // the Error object directly to the parser.  This will involve
     // replumbing all of the EvalConstExpr methods.
     return NULL;
   }
   return &Instance::ZoneHandle(Instance::Cast(result).raw());
 }
 
 }  // namespace dart