null value can be the receiver of methods on Object (e.g. hashCode).

runtime/vm/il_printer.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/il_printer.h"
 
 #include "vm/intermediate_language.h"
 #include "vm/os.h"
 #include "vm/parser.h"
 
@@ skipping 14 matching lines @@
   intptr_t available = size_ - position_;
   if (available <= 0) return;
   intptr_t written =
       OS::VSNPrint(buffer_ + position_, available, format, args);
   if (written >= 0) {
     position_ += (available <= written) ? available : written;
   }
 }
 
 
+void FlowGraphPrinter::PrintGraph(const char* phase, FlowGraph* flow_graph) {
+  OS::Print("*** BEGIN CFG\n%s\n", phase);
+  FlowGraphPrinter printer(*flow_graph);
+  printer.PrintBlocks();
+  OS::Print("*** END CFG\n");
+}
+
+
 void FlowGraphPrinter::PrintBlocks() {
   if (!function_.IsNull()) {
     OS::Print("==== %s\n", function_.ToFullyQualifiedCString());
   }
 
   for (intptr_t i = 0; i < block_order_.length(); ++i) {
     // Print the block entry.
     PrintInstruction(block_order_[i]);
     // And all the successors until an exit, branch, or a block entry.
     Instruction* current = block_order_[i];
@@ skipping 661 matching lines @@
       f->Print(" [");
       locations_[i].PrintTo(f);
       f->Print("]");
     }
   }
   f->Print(" }");
   if (outer_ != NULL) outer_->PrintTo(f);
 }
 
 }  // namespace dart