Bugfix: allow handle dereference only when we have a valid hydrogen graph or lithium chunk.

src/hydrogen.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 10493 matching lines @@
   } else {
     CodeStub::Major major_key = info->code_stub()->MajorKey();
     PrintStringProperty("name", CodeStub::MajorName(major_key, false));
     PrintStringProperty("method", "stub");
   }
   PrintLongProperty("date", static_cast<int64_t>(OS::TimeCurrentMillis()));
 }
 
 
 void HTracer::TraceLithium(const char* name, LChunk* chunk) {
+  AllowHandleDereference allow_handle_deref(chunk->graph()->isolate());
   Trace(name, chunk->graph(), chunk);
 }
 
 
 void HTracer::TraceHydrogen(const char* name, HGraph* graph) {
+  AllowHandleDereference allow_handle_deref(graph->isolate());
   Trace(name, graph, NULL);
 }
 
 
 void HTracer::Trace(const char* name, HGraph* graph, LChunk* chunk) {
   Tag tag(this, "cfg");
   PrintStringProperty("name", name);
   const ZoneList<HBasicBlock*>* blocks = graph->blocks();
   for (int i = 0; i < blocks->length(); i++) {
     HBasicBlock* current = blocks->at(i);
@@ skipping 287 matching lines @@
   if (FLAG_hydrogen_stats) {
     int64_t end = OS::Ticks();
     unsigned size = Zone::allocation_size_ - start_allocation_size_;
     HStatistics::Instance()->SaveTiming(name_, end - start_, size);
   }
 
   // Produce trace output if flag is set so that the first letter of the
   // phase name matches the command line parameter FLAG_trace_phase.
   if (FLAG_trace_hydrogen &&
       OS::StrChr(const_cast<char*>(FLAG_trace_phase), name_[0]) != NULL) {
-    AllowHandleDereference allow_handle_deref(graph_->isolate());
     if (graph_ != NULL) HTracer::Instance()->TraceHydrogen(name_, graph_);
     if (chunk_ != NULL) HTracer::Instance()->TraceLithium(name_, chunk_);
     if (allocator_ != NULL) {
       HTracer::Instance()->TraceLiveRanges(name_, allocator_);
     }
   }
 
 #ifdef DEBUG
   if (graph_ != NULL) graph_->Verify(false);  // No full verify.
   if (allocator_ != NULL) allocator_->Verify();
 #endif
 }
 
 } }  // namespace v8::internal