Use C++11 alignment primitives

base/lazy_instance.h

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // The LazyInstance<Type, Traits> class manages a single instance of Type,
 // which will be lazily created on the first time it's accessed.  This class is
 // useful for places you would normally use a function-level static, but you
 // need to have guaranteed thread-safety.  The Type constructor will only ever
 // be called once, even if two threads are racing to create the object.  Get()
 // and Pointer() will always return the same, completely initialized instance.
@@ skipping 23 matching lines @@
 
 #ifndef BASE_LAZY_INSTANCE_H_
 #define BASE_LAZY_INSTANCE_H_
 
 #include <new>  // For placement new.
 
 #include "base/atomicops.h"
 #include "base/base_export.h"
 #include "base/debug/leak_annotations.h"
 #include "base/logging.h"
-#include "base/memory/aligned_memory.h"
 #include "base/threading/thread_restrictions.h"
 
 // LazyInstance uses its own struct initializer-list style static
 // initialization, as base's LINKER_INITIALIZED requires a constructor and on
 // some compilers (notably gcc 4.4) this still ends up needing runtime
 // initialization.
 #define LAZY_INSTANCE_INITIALIZER {0}
 
 namespace base {
 
 template <typename Type>
 struct LazyInstanceTraitsBase {
   static Type* New(void* instance) {
-    DCHECK_EQ(reinterpret_cast<uintptr_t>(instance) & (ALIGNOF(Type) - 1), 0u);
+    DCHECK_EQ(reinterpret_cast<uintptr_t>(instance) & (alignof(Type) - 1), 0u);
     // Use placement new to initialize our instance in our preallocated space.
     // The parenthesis is very important here to force POD type initialization.
     return new (instance) Type();
   }
 
   static void CallDestructor(Type* instance) {
     // Explicitly call the destructor.
     instance->~Type();
   }
 };
@@ skipping 103 matching lines @@
     // Since a thread sees private_instance_ == 0 or kLazyInstanceStateCreating
     // at most once, the load is taken out of NeedsInstance() as a fast-path.
     // The load has acquire memory ordering as a thread which sees
     // private_instance_ > creating needs to acquire visibility over
     // the associated data (private_buf_). Pairing Release_Store is in
     // CompleteLazyInstance().
     subtle::AtomicWord value = subtle::Acquire_Load(&private_instance_);
     if (!(value & kLazyInstanceCreatedMask) &&
         internal::NeedsLazyInstance(&private_instance_)) {
       // Create the instance in the space provided by |private_buf_|.
-      value = reinterpret_cast<subtle::AtomicWord>(
-          Traits::New(private_buf_.void_data()));
+      value = reinterpret_cast<subtle::AtomicWord>(Traits::New(private_buf_));
       internal::CompleteLazyInstance(&private_instance_, value, this,
                                      Traits::kRegisterOnExit ? OnExit : NULL);
     }
     return instance();
   }
 
   bool operator==(Type* p) {
     switch (subtle::NoBarrier_Load(&private_instance_)) {
       case 0:
         return p == NULL;
       case internal::kLazyInstanceStateCreating:
-        return static_cast<void*>(p) == private_buf_.void_data();
+        return static_cast<void*>(p) == private_buf_;
       default:
         return p == instance();
     }
   }
 
+  // MSVC gives a warning that the alignment expands the size of the
+  // LazyInstance struct to make the size a multiple of the alignment. This
+  // is expected in this case.
+#if defined(OS_WIN)
+#pragma warning(push)
+#pragma warning(disable: 4324)
+#endif
+
   // Effectively private: member data is only public to allow the linker to
   // statically initialize it and to maintain a POD class. DO NOT USE FROM
   // OUTSIDE THIS CLASS.
+  subtle::AtomicWord private_instance_;
 
-  subtle::AtomicWord private_instance_;
   // Preallocated space for the Type instance.
-  base::AlignedMemory<sizeof(Type), ALIGNOF(Type)> private_buf_;
+  alignas(Type) char private_buf_[sizeof(Type)];
+
+#if defined(OS_WIN)
+#pragma warning(pop)
+#endif
 
  private:
   Type* instance() {
     return reinterpret_cast<Type*>(subtle::NoBarrier_Load(&private_instance_));
   }
 
   // Adapter function for use with AtExit.  This should be called single
   // threaded, so don't synchronize across threads.
   // Calling OnExit while the instance is in use by other threads is a mistake.
   static void OnExit(void* lazy_instance) {
     LazyInstance<Type, Traits>* me =
         reinterpret_cast<LazyInstance<Type, Traits>*>(lazy_instance);
     Traits::Delete(me->instance());
     subtle::NoBarrier_Store(&me->private_instance_, 0);
   }
 };
 
 }  // namespace base
 
 #endif  // BASE_LAZY_INSTANCE_H_