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

src/x64/assembler-x64.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 467 matching lines @@
   // Clear the buffer in debug mode. Use 'int3' instructions to make
   // sure to get into problems if we ever run uninitialized code.
 #ifdef DEBUG
   memset(desc.buffer, 0xCC, desc.buffer_size);
 #endif
 
   // Copy the data.
   intptr_t pc_delta = desc.buffer - buffer_;
   intptr_t rc_delta = (desc.buffer + desc.buffer_size) -
       (buffer_ + buffer_size_);
-  memmove(desc.buffer, buffer_, desc.instr_size);
-  memmove(rc_delta + reloc_info_writer.pos(),
-          reloc_info_writer.pos(), desc.reloc_size);
+  OS::MemMove(desc.buffer, buffer_, desc.instr_size);
+  OS::MemMove(rc_delta + reloc_info_writer.pos(),
+              reloc_info_writer.pos(), desc.reloc_size);
 
   // Switch buffers.
   if (isolate() != NULL &&
       isolate()->assembler_spare_buffer() == NULL &&
       buffer_size_ == kMinimalBufferSize) {
     isolate()->set_assembler_spare_buffer(buffer_);
   } else {
     DeleteArray(buffer_);
   }
   buffer_ = desc.buffer;
@@ skipping 2584 matching lines @@
 bool RelocInfo::IsCodedSpecially() {
   // The deserializer needs to know whether a pointer is specially coded.  Being
   // specially coded on x64 means that it is a relative 32 bit address, as used
   // by branch instructions.
   return (1 << rmode_) & kApplyMask;
 }
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_X64