Replace OS::MemCopy with OS::MemMove (just as fast but more flexible).

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 319 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)
-  // 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);
 
+  // Copy memory area. No restrictions.
+  static void MemMove(void* dest, const void* src, size_t size);
+  typedef void (*MemMoveFunction)(void* dest, const void* src, size_t size);
+
+  // Keep the distinction of "move" vs. "copy" for the benefit of other
+  // architectures.
+  static void MemCopy(void* dest, const void* src, size_t size) {
+    MemMove(dest, src, size);
+  }
 #else  // V8_TARGET_ARCH_IA32
+  // Copy memory area to disjoint memory area.
   static void MemCopy(void* dest, const void* src, size_t size) {
     memcpy(dest, src, size);
   }
+  static void MemMove(void* dest, const void* src, size_t size) {
+    memmove(dest, src, size);
+  }
   static const int kMinComplexMemCopy = 16 * kPointerSize;
 #endif  // V8_TARGET_ARCH_IA32
 
   static int GetCurrentProcessId();
 
  private:
   static const int msPerSecond = 1000;
 
   DISALLOW_IMPLICIT_CONSTRUCTORS(OS);
 };
@@ skipping 452 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_