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

src/debug.cc

Index: src/debug.cc
diff --git a/src/debug.cc b/src/debug.cc
index b862c51b0f26a5308f5bbe1266b0b21f6cf31c33..4af2194ea5f7455a6c0e7b2166b53755cc294130 100644
--- a/src/debug.cc
+++ b/src/debug.cc
@@ -551,9 +551,9 @@ void Debug::ThreadInit() {
 
 char* Debug::ArchiveDebug(char* storage) {
   char* to = storage;
-  memcpy(to, reinterpret_cast<char*>(&thread_local_), sizeof(ThreadLocal));
+  OS::MemCopy(to, reinterpret_cast<char*>(&thread_local_), sizeof(ThreadLocal));
   to += sizeof(ThreadLocal);
-  memcpy(to, reinterpret_cast<char*>(&registers_), sizeof(registers_));
+  OS::MemCopy(to, reinterpret_cast<char*>(&registers_), sizeof(registers_));
   ThreadInit();
   ASSERT(to <= storage + ArchiveSpacePerThread());
   return storage + ArchiveSpacePerThread();
@@ -562,9 +562,10 @@ char* Debug::ArchiveDebug(char* storage) {
 
 char* Debug::RestoreDebug(char* storage) {
   char* from = storage;
-  memcpy(reinterpret_cast<char*>(&thread_local_), from, sizeof(ThreadLocal));
+  OS::MemCopy(
+      reinterpret_cast<char*>(&thread_local_), from, sizeof(ThreadLocal));
   from += sizeof(ThreadLocal);
-  memcpy(reinterpret_cast<char*>(&registers_), from, sizeof(registers_));
+  OS::MemCopy(reinterpret_cast<char*>(&registers_), from, sizeof(registers_));
   ASSERT(from <= storage + ArchiveSpacePerThread());
   return storage + ArchiveSpacePerThread();
 }