Add thread-safety to creation of MemCopy and modulo functions.

src/platform-posix.cc

-// Copyright 2009 the V8 project authors. All rights reserved.
+// Copyright 2011 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
 //       with the distribution.
@@ skipping 186 matching lines @@
     // If the length is zero, the assignment fails.
     if (str.length() > 0)
       str[str.length() - 1] = '\0';
     return -1;
   } else {
     return n;
   }
 }
 
 
+#if defined(V8_TARGET_ARCH_IA32)
+static OS::MemCopyFunction memcopy_function = NULL;
+static Mutex* memcopy_function_mutex = OS::CreateMutex();
+// Defined in codegen-ia32.cc.
+OS::MemCopyFunction CreateMemCopyFunction();
+
+// Copy memory area to disjoint memory area.
+void OS::MemCopy(void* dest, const void* src, size_t size) {
+  if (memcopy_function == NULL) {
+    ScopedLock lock(memcopy_function_mutex);
+    Isolate::EnsureDefaultIsolate();
+    if (memcopy_function == NULL) {
+      Release_Store(reinterpret_cast<AtomicWord*>(&memcopy_function),
+                    reinterpret_cast<AtomicWord>(CreateMemCopyFunction()));
+    }
+  }
+  (*memcopy_function)(dest, src, size);
+#ifdef DEBUG
+  CHECK_EQ(0, memcmp(dest, src, size));
+#endif
+}
+#endif  // V8_TARGET_ARCH_IA32
+
 // ----------------------------------------------------------------------------
 // POSIX string support.
 //
 
 char* OS::StrChr(char* str, int c) {
   return strchr(str, c);
 }
 
 
 void OS::StrNCpy(Vector<char> dest, const char* src, size_t n) {
@@ skipping 172 matching lines @@
   return ntohl(value);
 }
 
 
 Socket* OS::CreateSocket() {
   return new POSIXSocket();
 }
 
 
 } }  // namespace v8::internal