Do not dereference handles during relocation.

src/optimizing-compiler-thread.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 70 matching lines @@
   Barrier_AtomicIncrement(&queue_length_, static_cast<Atomic32>(-1));
 
   // The function may have already been optimized by OSR.  Simply continue.
   OptimizingCompiler::Status status = optimizing_compiler->OptimizeGraph();
   USE(status);   // Prevent an unused-variable error in release mode.
   ASSERT(status != OptimizingCompiler::FAILED);
 
   // The function may have already been optimized by OSR.  Simply continue.
   // Mark it for installing before queuing so that we can be sure of the write
   // order: marking first and (after being queued) installing code second.
-  optimizing_compiler->info()->closure()->MarkForInstallingRecompiledCode();
+  { Heap::RelocationLock relocation_lock(isolate_->heap());
+    optimizing_compiler->info()->closure()->MarkForInstallingRecompiledCode();
+  }
   output_queue_.Enqueue(optimizing_compiler);
 }
 
 
 void OptimizingCompilerThread::Stop() {
   ASSERT(!IsOptimizerThread());
   Release_Store(&stop_thread_, static_cast<AtomicWord>(true));
   input_queue_semaphore_->Signal();
   stop_semaphore_->Wait();
 
@@ skipping 42 matching lines @@
 
 #ifdef DEBUG
 bool OptimizingCompilerThread::IsOptimizerThread() {
   if (!FLAG_parallel_recompilation) return false;
   return ThreadId::Current().ToInteger() == thread_id_;
 }
 #endif
 
 
 } }  // namespace v8::internal