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

src/execution.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 484 matching lines @@
   ExecutionAccess access(isolate_);
   thread_local_.interrupt_flags_ &= ~static_cast<int>(after_what);
   if (!should_postpone_interrupts(access) && !has_pending_interrupts(access)) {
     reset_limits(access);
   }
 }
 
 
 char* StackGuard::ArchiveStackGuard(char* to) {
   ExecutionAccess access(isolate_);
-  memcpy(to, reinterpret_cast<char*>(&thread_local_), sizeof(ThreadLocal));
+  OS::MemCopy(to, reinterpret_cast<char*>(&thread_local_), sizeof(ThreadLocal));
   ThreadLocal blank;
 
   // Set the stack limits using the old thread_local_.
   // TODO(isolates): This was the old semantics of constructing a ThreadLocal
   //                 (as the ctor called SetStackLimits, which looked at the
   //                 current thread_local_ from StackGuard)-- but is this
   //                 really what was intended?
   isolate_->heap()->SetStackLimits();
   thread_local_ = blank;
 
   return to + sizeof(ThreadLocal);
 }
 
 
 char* StackGuard::RestoreStackGuard(char* from) {
   ExecutionAccess access(isolate_);
-  memcpy(reinterpret_cast<char*>(&thread_local_), from, sizeof(ThreadLocal));
+  OS::MemCopy(
+      reinterpret_cast<char*>(&thread_local_), from, sizeof(ThreadLocal));
   isolate_->heap()->SetStackLimits();
   return from + sizeof(ThreadLocal);
 }
 
 
 void StackGuard::FreeThreadResources() {
   Isolate::PerIsolateThreadData* per_thread =
       isolate_->FindOrAllocatePerThreadDataForThisThread();
   per_thread->set_stack_limit(thread_local_.real_climit_);
 }
@@ skipping 380 matching lines @@
   }
   if (stack_guard->IsFullDeopt()) {
     stack_guard->Continue(FULL_DEOPT);
     Deoptimizer::DeoptimizeAll(isolate);
   }
   return isolate->heap()->undefined_value();
 }
 
 
 } }  // namespace v8::internal