Merged r17130 into trunk branch.

src/assembler.cc

 // Copyright (c) 1994-2006 Sun Microsystems Inc.
 // 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.
 //
@@ skipping 193 matching lines @@
   assembler_->set_enabled_cpu_features(old_enabled_);
 }
 #endif
 
 
 // -----------------------------------------------------------------------------
 // Implementation of PlatformFeatureScope
 
 PlatformFeatureScope::PlatformFeatureScope(CpuFeature f)
     : old_cross_compile_(CpuFeatures::cross_compile_) {
+  // CpuFeatures is a global singleton, therefore this is only safe in
+  // single threaded code.
+  ASSERT(Serializer::enabled());
   uint64_t mask = static_cast<uint64_t>(1) << f;
   CpuFeatures::cross_compile_ |= mask;
 }
 
 
 PlatformFeatureScope::~PlatformFeatureScope() {
   CpuFeatures::cross_compile_ = old_cross_compile_;
 }
 
 
@@ skipping 1467 matching lines @@
     assembler_->RecordRelocInfo(RelocInfo::POSITION, state_.current_position);
     state_.written_position = state_.current_position;
     written = true;
   }
 
   // Return whether something was written.
   return written;
 }
 
 } }  // namespace v8::internal