Use generated Neon version of MemCopy() on ARM, if platform supports it.

src/platform.h

 // 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 95 matching lines @@
 namespace internal {
 
 // Use AtomicWord for a machine-sized pointer. It is assumed that
 // reads and writes of naturally aligned values of this type are atomic.
 #if defined(__OpenBSD__) && defined(__i386__)
 typedef Atomic32 AtomicWord;
 #else
 typedef intptr_t AtomicWord;
 #endif
 
+#if defined(V8_TARGET_ARCH_IA32) || defined(V8_TARGET_ARCH_ARM)
+#define V8_GENERATED_MEMCPY 1
+#endif
+
 class Semaphore;
 class Mutex;
 
 double ceiling(double x);
 double modulo(double x, double y);
 
 // Custom implementation of math functions.
 double fast_sin(double input);
 double fast_cos(double input);
 double fast_tan(double input);
@@ skipping 203 matching lines @@
 
   // Support runtime detection of FPU on MIPS CPUs.
   static bool MipsCpuHasFeature(CpuFeature feature);
 
   // Returns the activation frame alignment constraint or zero if
   // the platform doesn't care. Guaranteed to be a power of two.
   static int ActivationFrameAlignment();
 
   static void ReleaseStore(volatile AtomicWord* ptr, AtomicWord value);
 
-#if defined(V8_TARGET_ARCH_IA32)
+#if defined(V8_GENERATED_MEMCPY)
   // Copy memory area to disjoint memory area.
   static void MemCopy(void* dest, const void* src, size_t size);
   // Limit below which the extra overhead of the MemCopy function is likely
   // to outweigh the benefits of faster copying.
   static const int kMinComplexMemCopy = 64;
   typedef void (*MemCopyFunction)(void* dest, const void* src, size_t size);
 
-#else  // V8_TARGET_ARCH_IA32
+#else  // V8_GENERATED_MEMCPY
   static void MemCopy(void* dest, const void* src, size_t size) {
     memcpy(dest, src, size);
   }
   static const int kMinComplexMemCopy = 16 * kPointerSize;
-#endif  // V8_TARGET_ARCH_IA32
+#endif  // V8_GENERATED_MEMCPY
 
   static int GetCurrentProcessId();
 
  private:
   static const int msPerSecond = 1000;
 
   DISALLOW_IMPLICIT_CONSTRUCTORS(OS);
 };
 
 // Represents and controls an area of reserved memory.
@@ skipping 435 matching lines @@
   Atomic32 active_;
   PlatformData* data_;  // Platform specific data.
   int samples_taken_;  // Counts stack samples taken.
   DISALLOW_IMPLICIT_CONSTRUCTORS(Sampler);
 };
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_PLATFORM_H_