- Determine whether the simulator is being used in globals.h

runtime/vm/simulator_arm.h

 // Copyright (c) 2013, 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.
 
 // Declares a Simulator for ARM instructions if we are not generating a native
 // ARM binary. This Simulator allows us to run and debug ARM code generation on
 // regular desktop machines.
 // Dart calls into generated code by "calling" the InvokeDartCode stub,
 // which will start execution in the Simulator or forwards to the real entry
 // on a ARM HW platform.
 
 #ifndef VM_SIMULATOR_ARM_H_
 #define VM_SIMULATOR_ARM_H_
 
 #ifndef VM_SIMULATOR_H_
 #error Do not include simulator_arm.h directly; use simulator.h.
 #endif
 
 #include "vm/constants_arm.h"
 
 namespace dart {
 
 class Isolate;
 class Mutex;
 class RawObject;
 class SimulatorSetjmpBuffer;
 class Thread;
 
+#if !defined(SIMD_VALUE_T_)
 typedef struct {
   union {
     uint32_t u;
     float f;
   } data_[4];
 } simd_value_t;
+#endif
 
 class Simulator {
  public:
   static const uword kSimulatorStackUnderflowSize = 64;
 
   Simulator();
   ~Simulator();
 
   // The currently executing Simulator instance, which is associated to the
   // current isolate
@@ skipping 227 matching lines @@
   }
 
   friend class SimulatorDebugger;
   friend class SimulatorSetjmpBuffer;
   DISALLOW_COPY_AND_ASSIGN(Simulator);
 };
 
 }  // namespace dart
 
 #endif  // VM_SIMULATOR_ARM_H_